aboutsummaryrefslogtreecommitdiff
path: root/gdb/gdbserver/linux-low.c
blob: a88f4d1f02e8192477898c72082ee034a4d20571 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
/* Low level interface to ptrace, for the remote server for GDB.
   Copyright (C) 1995, 1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   2006, 2007, 2008, 2009 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "server.h"
#include "linux-low.h"
#include "ansidecl.h" /* For ATTRIBUTE_PACKED, must be bug in external.h.  */
#include "elf/common.h"
#include "elf/external.h"

#include <sys/wait.h>
#include <stdio.h>
#include <sys/param.h>
#include <sys/ptrace.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/syscall.h>
#include <sched.h>
#include <ctype.h>
#include <pwd.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/vfs.h>

#ifndef SPUFS_MAGIC
#define SPUFS_MAGIC 0x23c9b64e
#endif

#ifndef PTRACE_GETSIGINFO
# define PTRACE_GETSIGINFO 0x4202
# define PTRACE_SETSIGINFO 0x4203
#endif

#ifndef O_LARGEFILE
#define O_LARGEFILE 0
#endif

/* If the system headers did not provide the constants, hard-code the normal
   values.  */
#ifndef PTRACE_EVENT_FORK

#define PTRACE_SETOPTIONS	0x4200
#define PTRACE_GETEVENTMSG	0x4201

/* options set using PTRACE_SETOPTIONS */
#define PTRACE_O_TRACESYSGOOD	0x00000001
#define PTRACE_O_TRACEFORK	0x00000002
#define PTRACE_O_TRACEVFORK	0x00000004
#define PTRACE_O_TRACECLONE	0x00000008
#define PTRACE_O_TRACEEXEC	0x00000010
#define PTRACE_O_TRACEVFORKDONE	0x00000020
#define PTRACE_O_TRACEEXIT	0x00000040

/* Wait extended result codes for the above trace options.  */
#define PTRACE_EVENT_FORK	1
#define PTRACE_EVENT_VFORK	2
#define PTRACE_EVENT_CLONE	3
#define PTRACE_EVENT_EXEC	4
#define PTRACE_EVENT_VFORK_DONE	5
#define PTRACE_EVENT_EXIT	6

#endif /* PTRACE_EVENT_FORK */

/* We can't always assume that this flag is available, but all systems
   with the ptrace event handlers also have __WALL, so it's safe to use
   in some contexts.  */
#ifndef __WALL
#define __WALL          0x40000000 /* Wait for any child.  */
#endif

#ifdef __UCLIBC__
#if !(defined(__UCLIBC_HAS_MMU__) || defined(__ARCH_HAS_MMU__))
#define HAS_NOMMU
#endif
#endif

/* ``all_threads'' is keyed by the LWP ID, which we use as the GDB protocol
   representation of the thread ID.

   ``all_lwps'' is keyed by the process ID - which on Linux is (presently)
   the same as the LWP ID.

   ``all_processes'' is keyed by the "overall process ID", which
   GNU/Linux calls tgid, "thread group ID".  */

struct inferior_list all_lwps;

/* A list of all unknown processes which receive stop signals.  Some other
   process will presumably claim each of these as forked children
   momentarily.  */

struct inferior_list stopped_pids;

/* FIXME this is a bit of a hack, and could be removed.  */
int stopping_threads;

/* FIXME make into a target method?  */
int using_threads = 1;

/* This flag is true iff we've just created or attached to our first
   inferior but it has not stopped yet.  As soon as it does, we need
   to call the low target's arch_setup callback.  Doing this only on
   the first inferior avoids reinializing the architecture on every
   inferior, and avoids messing with the register caches of the
   already running inferiors.  NOTE: this assumes all inferiors under
   control of gdbserver have the same architecture.  */
static int new_inferior;

static void linux_resume_one_lwp (struct lwp_info *lwp,
				  int step, int signal, siginfo_t *info);
static void linux_resume (struct thread_resume *resume_info, size_t n);
static void stop_all_lwps (void);
static int linux_wait_for_event (ptid_t ptid, int *wstat, int options);
static int check_removed_breakpoint (struct lwp_info *event_child);
static void *add_lwp (ptid_t ptid);
static int my_waitpid (int pid, int *status, int flags);
static int linux_stopped_by_watchpoint (void);
static void mark_lwp_dead (struct lwp_info *lwp, int wstat);

struct pending_signals
{
  int signal;
  siginfo_t info;
  struct pending_signals *prev;
};

#define PTRACE_ARG3_TYPE long
#define PTRACE_XFER_TYPE long

#ifdef HAVE_LINUX_REGSETS
static char *disabled_regsets;
static int num_regsets;
#endif

/* The read/write ends of the pipe registered as waitable file in the
   event loop.  */
static int linux_event_pipe[2] = { -1, -1 };

/* True if we're currently in async mode.  */
#define target_is_async_p() (linux_event_pipe[0] != -1)

static void send_sigstop (struct inferior_list_entry *entry);
static void wait_for_sigstop (struct inferior_list_entry *entry);

/* Accepts an integer PID; Returns a string representing a file that
   can be opened to get info for the child process.
   Space for the result is malloc'd, caller must free.  */

char *
linux_child_pid_to_exec_file (int pid)
{
  char *name1, *name2;

  name1 = xmalloc (MAXPATHLEN);
  name2 = xmalloc (MAXPATHLEN);
  memset (name2, 0, MAXPATHLEN);

  sprintf (name1, "/proc/%d/exe", pid);
  if (readlink (name1, name2, MAXPATHLEN) > 0)
    {
      free (name1);
      return name2;
    }
  else
    {
      free (name2);
      return name1;
    }
}

/* Return non-zero if HEADER is a 64-bit ELF file.  */

static int
elf_64_header_p (const Elf64_External_Ehdr *header)
{
  return (header->e_ident[EI_MAG0] == ELFMAG0
          && header->e_ident[EI_MAG1] == ELFMAG1
          && header->e_ident[EI_MAG2] == ELFMAG2
          && header->e_ident[EI_MAG3] == ELFMAG3
          && header->e_ident[EI_CLASS] == ELFCLASS64);
}

/* Return non-zero if FILE is a 64-bit ELF file,
   zero if the file is not a 64-bit ELF file,
   and -1 if the file is not accessible or doesn't exist.  */

int
elf_64_file_p (const char *file)
{
  Elf64_External_Ehdr header;
  int fd;

  fd = open (file, O_RDONLY);
  if (fd < 0)
    return -1;

  if (read (fd, &header, sizeof (header)) != sizeof (header))
    {
      close (fd);
      return 0;
    }
  close (fd);

  return elf_64_header_p (&header);
}

static void
delete_lwp (struct lwp_info *lwp)
{
  remove_thread (get_lwp_thread (lwp));
  remove_inferior (&all_lwps, &lwp->head);
  free (lwp->arch_private);
  free (lwp);
}

/* Add a process to the common process list, and set its private
   data.  */

static struct process_info *
linux_add_process (int pid, int attached)
{
  struct process_info *proc;

  /* Is this the first process?  If so, then set the arch.  */
  if (all_processes.head == NULL)
    new_inferior = 1;

  proc = add_process (pid, attached);
  proc->private = xcalloc (1, sizeof (*proc->private));

  if (the_low_target.new_process != NULL)
    proc->private->arch_private = the_low_target.new_process ();

  return proc;
}

/* Remove a process from the common process list,
   also freeing all private data.  */

static void
linux_remove_process (struct process_info *process)
{
  free (process->private->arch_private);
  free (process->private);
  remove_process (process);
}

/* Handle a GNU/Linux extended wait response.  If we see a clone
   event, we need to add the new LWP to our list (and not report the
   trap to higher layers).  */

static void
handle_extended_wait (struct lwp_info *event_child, int wstat)
{
  int event = wstat >> 16;
  struct lwp_info *new_lwp;

  if (event == PTRACE_EVENT_CLONE)
    {
      ptid_t ptid;
      unsigned long new_pid;
      int ret, status = W_STOPCODE (SIGSTOP);

      ptrace (PTRACE_GETEVENTMSG, lwpid_of (event_child), 0, &new_pid);

      /* If we haven't already seen the new PID stop, wait for it now.  */
      if (! pull_pid_from_list (&stopped_pids, new_pid))
	{
	  /* The new child has a pending SIGSTOP.  We can't affect it until it
	     hits the SIGSTOP, but we're already attached.  */

	  ret = my_waitpid (new_pid, &status, __WALL);

	  if (ret == -1)
	    perror_with_name ("waiting for new child");
	  else if (ret != new_pid)
	    warning ("wait returned unexpected PID %d", ret);
	  else if (!WIFSTOPPED (status))
	    warning ("wait returned unexpected status 0x%x", status);
	}

      ptrace (PTRACE_SETOPTIONS, new_pid, 0, PTRACE_O_TRACECLONE);

      ptid = ptid_build (pid_of (event_child), new_pid, 0);
      new_lwp = (struct lwp_info *) add_lwp (ptid);
      add_thread (ptid, new_lwp);

      /* Either we're going to immediately resume the new thread
	 or leave it stopped.  linux_resume_one_lwp is a nop if it
	 thinks the thread is currently running, so set this first
	 before calling linux_resume_one_lwp.  */
      new_lwp->stopped = 1;

      /* Normally we will get the pending SIGSTOP.  But in some cases
	 we might get another signal delivered to the group first.
	 If we do get another signal, be sure not to lose it.  */
      if (WSTOPSIG (status) == SIGSTOP)
	{
	  if (! stopping_threads)
	    linux_resume_one_lwp (new_lwp, 0, 0, NULL);
	}
      else
	{
	  new_lwp->stop_expected = 1;
	  if (stopping_threads)
	    {
	      new_lwp->status_pending_p = 1;
	      new_lwp->status_pending = status;
	    }
	  else
	    /* Pass the signal on.  This is what GDB does - except
	       shouldn't we really report it instead?  */
	    linux_resume_one_lwp (new_lwp, 0, WSTOPSIG (status), NULL);
	}

      /* Always resume the current thread.  If we are stopping
	 threads, it will have a pending SIGSTOP; we may as well
	 collect it now.  */
      linux_resume_one_lwp (event_child, event_child->stepping, 0, NULL);
    }
}

/* This function should only be called if the process got a SIGTRAP.
   The SIGTRAP could mean several things.

   On i386, where decr_pc_after_break is non-zero:
   If we were single-stepping this process using PTRACE_SINGLESTEP,
   we will get only the one SIGTRAP (even if the instruction we
   stepped over was a breakpoint).  The value of $eip will be the
   next instruction.
   If we continue the process using PTRACE_CONT, we will get a
   SIGTRAP when we hit a breakpoint.  The value of $eip will be
   the instruction after the breakpoint (i.e. needs to be
   decremented).  If we report the SIGTRAP to GDB, we must also
   report the undecremented PC.  If we cancel the SIGTRAP, we
   must resume at the decremented PC.

   (Presumably, not yet tested) On a non-decr_pc_after_break machine
   with hardware or kernel single-step:
   If we single-step over a breakpoint instruction, our PC will
   point at the following instruction.  If we continue and hit a
   breakpoint instruction, our PC will point at the breakpoint
   instruction.  */

static CORE_ADDR
get_stop_pc (void)
{
  CORE_ADDR stop_pc = (*the_low_target.get_pc) ();

  if (! get_thread_lwp (current_inferior)->stepping)
    stop_pc -= the_low_target.decr_pc_after_break;

  if (debug_threads)
    fprintf (stderr, "stop pc is 0x%lx\n", (long) stop_pc);

  return stop_pc;
}

static void *
add_lwp (ptid_t ptid)
{
  struct lwp_info *lwp;

  lwp = (struct lwp_info *) xmalloc (sizeof (*lwp));
  memset (lwp, 0, sizeof (*lwp));

  lwp->head.id = ptid;

  if (the_low_target.new_thread != NULL)
    lwp->arch_private = the_low_target.new_thread ();

  add_inferior_to_list (&all_lwps, &lwp->head);

  return lwp;
}

/* Start an inferior process and returns its pid.
   ALLARGS is a vector of program-name and args. */

static int
linux_create_inferior (char *program, char **allargs)
{
  struct lwp_info *new_lwp;
  int pid;
  ptid_t ptid;

#if defined(__UCLIBC__) && defined(HAS_NOMMU)
  pid = vfork ();
#else
  pid = fork ();
#endif
  if (pid < 0)
    perror_with_name ("fork");

  if (pid == 0)
    {
      ptrace (PTRACE_TRACEME, 0, 0, 0);

      signal (__SIGRTMIN + 1, SIG_DFL);

      setpgid (0, 0);

      execv (program, allargs);
      if (errno == ENOENT)
	execvp (program, allargs);

      fprintf (stderr, "Cannot exec %s: %s.\n", program,
	       strerror (errno));
      fflush (stderr);
      _exit (0177);
    }

  linux_add_process (pid, 0);

  ptid = ptid_build (pid, pid, 0);
  new_lwp = add_lwp (ptid);
  add_thread (ptid, new_lwp);
  new_lwp->must_set_ptrace_flags = 1;

  return pid;
}

/* Attach to an inferior process.  */

static void
linux_attach_lwp_1 (unsigned long lwpid, int initial)
{
  ptid_t ptid;
  struct lwp_info *new_lwp;

  if (ptrace (PTRACE_ATTACH, lwpid, 0, 0) != 0)
    {
      if (!initial)
	{
	  /* If we fail to attach to an LWP, just warn.  */
	  fprintf (stderr, "Cannot attach to lwp %ld: %s (%d)\n", lwpid,
		   strerror (errno), errno);
	  fflush (stderr);
	  return;
	}
      else
	/* If we fail to attach to a process, report an error.  */
	error ("Cannot attach to lwp %ld: %s (%d)\n", lwpid,
	       strerror (errno), errno);
    }

  if (initial)
    /* NOTE/FIXME: This lwp might have not been the tgid.  */
    ptid = ptid_build (lwpid, lwpid, 0);
  else
    {
      /* Note that extracting the pid from the current inferior is
	 safe, since we're always called in the context of the same
	 process as this new thread.  */
      int pid = pid_of (get_thread_lwp (current_inferior));
      ptid = ptid_build (pid, lwpid, 0);
    }

  new_lwp = (struct lwp_info *) add_lwp (ptid);
  add_thread (ptid, new_lwp);

  /* We need to wait for SIGSTOP before being able to make the next
     ptrace call on this LWP.  */
  new_lwp->must_set_ptrace_flags = 1;

  /* The next time we wait for this LWP we'll see a SIGSTOP as PTRACE_ATTACH
     brings it to a halt.

     There are several cases to consider here:

     1) gdbserver has already attached to the process and is being notified
	of a new thread that is being created.
	In this case we should ignore that SIGSTOP and resume the process.
	This is handled below by setting stop_expected = 1.

     2) This is the first thread (the process thread), and we're attaching
	to it via attach_inferior.
	In this case we want the process thread to stop.
	This is handled by having linux_attach clear stop_expected after
	we return.
	??? If the process already has several threads we leave the other
	threads running.

     3) GDB is connecting to gdbserver and is requesting an enumeration of all
	existing threads.
	In this case we want the thread to stop.
	FIXME: This case is currently not properly handled.
	We should wait for the SIGSTOP but don't.  Things work apparently
	because enough time passes between when we ptrace (ATTACH) and when
	gdb makes the next ptrace call on the thread.

     On the other hand, if we are currently trying to stop all threads, we
     should treat the new thread as if we had sent it a SIGSTOP.  This works
     because we are guaranteed that the add_lwp call above added us to the
     end of the list, and so the new thread has not yet reached
     wait_for_sigstop (but will).  */
  if (! stopping_threads)
    new_lwp->stop_expected = 1;
}

void
linux_attach_lwp (unsigned long lwpid)
{
  linux_attach_lwp_1 (lwpid, 0);
}

int
linux_attach (unsigned long pid)
{
  struct lwp_info *lwp;

  linux_attach_lwp_1 (pid, 1);

  linux_add_process (pid, 1);

  if (!non_stop)
    {
      /* Don't ignore the initial SIGSTOP if we just attached to this
	 process.  It will be collected by wait shortly.  */
      lwp = (struct lwp_info *) find_inferior_id (&all_lwps,
						  ptid_build (pid, pid, 0));
      lwp->stop_expected = 0;
    }

  return 0;
}

struct counter
{
  int pid;
  int count;
};

static int
second_thread_of_pid_p (struct inferior_list_entry *entry, void *args)
{
  struct counter *counter = args;

  if (ptid_get_pid (entry->id) == counter->pid)
    {
      if (++counter->count > 1)
	return 1;
    }

  return 0;
}

static int
last_thread_of_process_p (struct thread_info *thread)
{
  ptid_t ptid = ((struct inferior_list_entry *)thread)->id;
  int pid = ptid_get_pid (ptid);
  struct counter counter = { pid , 0 };

  return (find_inferior (&all_threads,
			 second_thread_of_pid_p, &counter) == NULL);
}

/* Kill the inferior lwp.  */

static int
linux_kill_one_lwp (struct inferior_list_entry *entry, void *args)
{
  struct thread_info *thread = (struct thread_info *) entry;
  struct lwp_info *lwp = get_thread_lwp (thread);
  int wstat;
  int pid = * (int *) args;

  if (ptid_get_pid (entry->id) != pid)
    return 0;

  /* We avoid killing the first thread here, because of a Linux kernel (at
     least 2.6.0-test7 through 2.6.8-rc4) bug; if we kill the parent before
     the children get a chance to be reaped, it will remain a zombie
     forever.  */

  if (lwpid_of (lwp) == pid)
    {
      if (debug_threads)
	fprintf (stderr, "lkop: is last of process %s\n",
		 target_pid_to_str (entry->id));
      return 0;
    }

  /* If we're killing a running inferior, make sure it is stopped
     first, as PTRACE_KILL will not work otherwise.  */
  if (!lwp->stopped)
    send_sigstop (&lwp->head);

  do
    {
      ptrace (PTRACE_KILL, lwpid_of (lwp), 0, 0);

      /* Make sure it died.  The loop is most likely unnecessary.  */
      pid = linux_wait_for_event (lwp->head.id, &wstat, __WALL);
    } while (pid > 0 && WIFSTOPPED (wstat));

  return 0;
}

static int
linux_kill (int pid)
{
  struct process_info *process;
  struct lwp_info *lwp;
  struct thread_info *thread;
  int wstat;
  int lwpid;

  process = find_process_pid (pid);
  if (process == NULL)
    return -1;

  find_inferior (&all_threads, linux_kill_one_lwp, &pid);

  /* See the comment in linux_kill_one_lwp.  We did not kill the first
     thread in the list, so do so now.  */
  lwp = find_lwp_pid (pid_to_ptid (pid));
  thread = get_lwp_thread (lwp);

  if (debug_threads)
    fprintf (stderr, "lk_1: killing lwp %ld, for pid: %d\n",
	     lwpid_of (lwp), pid);

  /* If we're killing a running inferior, make sure it is stopped
     first, as PTRACE_KILL will not work otherwise.  */
  if (!lwp->stopped)
    send_sigstop (&lwp->head);

  do
    {
      ptrace (PTRACE_KILL, lwpid_of (lwp), 0, 0);

      /* Make sure it died.  The loop is most likely unnecessary.  */
      lwpid = linux_wait_for_event (lwp->head.id, &wstat, __WALL);
    } while (lwpid > 0 && WIFSTOPPED (wstat));

  delete_lwp (lwp);
  linux_remove_process (process);
  return 0;
}

static int
linux_detach_one_lwp (struct inferior_list_entry *entry, void *args)
{
  struct thread_info *thread = (struct thread_info *) entry;
  struct lwp_info *lwp = get_thread_lwp (thread);
  int pid = * (int *) args;

  if (ptid_get_pid (entry->id) != pid)
    return 0;

  /* If we're detaching from a running inferior, make sure it is
     stopped first, as PTRACE_DETACH will not work otherwise.  */
  if (!lwp->stopped)
    {
      int lwpid = lwpid_of (lwp);

      stopping_threads = 1;
      send_sigstop (&lwp->head);

      /* If this detects a new thread through a clone event, the new
	 thread is appended to the end of the lwp list, so we'll
	 eventually detach from it.  */
      wait_for_sigstop (&lwp->head);
      stopping_threads = 0;

      /* If LWP exits while we're trying to stop it, there's nothing
	 left to do.  */
      lwp = find_lwp_pid (pid_to_ptid (lwpid));
      if (lwp == NULL)
	return 0;
    }

  /* Make sure the process isn't stopped at a breakpoint that's
     no longer there.  */
  check_removed_breakpoint (lwp);

  /* If this process is stopped but is expecting a SIGSTOP, then make
     sure we take care of that now.  This isn't absolutely guaranteed
     to collect the SIGSTOP, but is fairly likely to.  */
  if (lwp->stop_expected)
    {
      int wstat;
      /* Clear stop_expected, so that the SIGSTOP will be reported.  */
      lwp->stop_expected = 0;
      if (lwp->stopped)
	linux_resume_one_lwp (lwp, 0, 0, NULL);
      linux_wait_for_event (lwp->head.id, &wstat, __WALL);
    }

  /* Flush any pending changes to the process's registers.  */
  regcache_invalidate_one ((struct inferior_list_entry *)
			   get_lwp_thread (lwp));

  /* Finally, let it resume.  */
  ptrace (PTRACE_DETACH, lwpid_of (lwp), 0, 0);

  delete_lwp (lwp);
  return 0;
}

static int
any_thread_of (struct inferior_list_entry *entry, void *args)
{
  int *pid_p = args;

  if (ptid_get_pid (entry->id) == *pid_p)
    return 1;

  return 0;
}

static int
linux_detach (int pid)
{
  struct process_info *process;

  process = find_process_pid (pid);
  if (process == NULL)
    return -1;

  current_inferior =
    (struct thread_info *) find_inferior (&all_threads, any_thread_of, &pid);

  delete_all_breakpoints ();
  find_inferior (&all_threads, linux_detach_one_lwp, &pid);
  linux_remove_process (process);
  return 0;
}

static void
linux_join (int pid)
{
  int status, ret;
  struct process_info *process;

  process = find_process_pid (pid);
  if (process == NULL)
    return;

  do {
    ret = my_waitpid (pid, &status, 0);
    if (WIFEXITED (status) || WIFSIGNALED (status))
      break;
  } while (ret != -1 || errno != ECHILD);
}

/* Return nonzero if the given thread is still alive.  */
static int
linux_thread_alive (ptid_t ptid)
{
  struct lwp_info *lwp = find_lwp_pid (ptid);

  /* We assume we always know if a thread exits.  If a whole process
     exited but we still haven't been able to report it to GDB, we'll
     hold on to the last lwp of the dead process.  */
  if (lwp != NULL)
    return !lwp->dead;
  else
    return 0;
}

/* Return nonzero if this process stopped at a breakpoint which
   no longer appears to be inserted.  Also adjust the PC
   appropriately to resume where the breakpoint used to be.  */
static int
check_removed_breakpoint (struct lwp_info *event_child)
{
  CORE_ADDR stop_pc;
  struct thread_info *saved_inferior;

  if (event_child->pending_is_breakpoint == 0)
    return 0;

  if (debug_threads)
    fprintf (stderr, "Checking for breakpoint in lwp %ld.\n",
	     lwpid_of (event_child));

  saved_inferior = current_inferior;
  current_inferior = get_lwp_thread (event_child);

  stop_pc = get_stop_pc ();

  /* If the PC has changed since we stopped, then we shouldn't do
     anything.  This happens if, for instance, GDB handled the
     decr_pc_after_break subtraction itself.  */
  if (stop_pc != event_child->pending_stop_pc)
    {
      if (debug_threads)
	fprintf (stderr, "Ignoring, PC was changed.  Old PC was 0x%08llx\n",
		 event_child->pending_stop_pc);

      event_child->pending_is_breakpoint = 0;
      current_inferior = saved_inferior;
      return 0;
    }

  /* If the breakpoint is still there, we will report hitting it.  */
  if ((*the_low_target.breakpoint_at) (stop_pc))
    {
      if (debug_threads)
	fprintf (stderr, "Ignoring, breakpoint is still present.\n");
      current_inferior = saved_inferior;
      return 0;
    }

  if (debug_threads)
    fprintf (stderr, "Removed breakpoint.\n");

  /* For decr_pc_after_break targets, here is where we perform the
     decrement.  We go immediately from this function to resuming,
     and can not safely call get_stop_pc () again.  */
  if (the_low_target.set_pc != NULL)
    {
      if (debug_threads)
	fprintf (stderr, "Set pc to 0x%lx\n", (long) stop_pc);
      (*the_low_target.set_pc) (stop_pc);
    }

  /* We consumed the pending SIGTRAP.  */
  event_child->pending_is_breakpoint = 0;
  event_child->status_pending_p = 0;
  event_child->status_pending = 0;

  current_inferior = saved_inferior;
  return 1;
}

/* Return 1 if this lwp has an interesting status pending.  This
   function may silently resume an inferior lwp.  */
static int
status_pending_p (struct inferior_list_entry *entry, void *arg)
{
  struct lwp_info *lwp = (struct lwp_info *) entry;
  ptid_t ptid = * (ptid_t *) arg;

  /* Check if we're only interested in events from a specific process
     or its lwps.  */
  if (!ptid_equal (minus_one_ptid, ptid)
      && ptid_get_pid (ptid) != ptid_get_pid (lwp->head.id))
    return 0;

  if (lwp->status_pending_p && !lwp->suspended)
    if (check_removed_breakpoint (lwp))
      {
	/* This thread was stopped at a breakpoint, and the breakpoint
	   is now gone.  We were told to continue (or step...) all threads,
	   so GDB isn't trying to single-step past this breakpoint.
	   So instead of reporting the old SIGTRAP, pretend we got to
	   the breakpoint just after it was removed instead of just
	   before; resume the process.  */
	linux_resume_one_lwp (lwp, 0, 0, NULL);
	return 0;
      }

  return (lwp->status_pending_p && !lwp->suspended);
}

static int
same_lwp (struct inferior_list_entry *entry, void *data)
{
  ptid_t ptid = *(ptid_t *) data;
  int lwp;

  if (ptid_get_lwp (ptid) != 0)
    lwp = ptid_get_lwp (ptid);
  else
    lwp = ptid_get_pid (ptid);

  if (ptid_get_lwp (entry->id) == lwp)
    return 1;

  return 0;
}

struct lwp_info *
find_lwp_pid (ptid_t ptid)
{
  return (struct lwp_info*) find_inferior (&all_lwps, same_lwp, &ptid);
}

static struct lwp_info *
linux_wait_for_lwp (ptid_t ptid, int *wstatp, int options)
{
  int ret;
  int to_wait_for = -1;
  struct lwp_info *child = NULL;

  if (debug_threads)
    fprintf (stderr, "linux_wait_for_lwp: %s\n", target_pid_to_str (ptid));

  if (ptid_equal (ptid, minus_one_ptid))
    to_wait_for = -1;			/* any child */
  else
    to_wait_for = ptid_get_lwp (ptid);	/* this lwp only */

  options |= __WALL;

retry:

  ret = my_waitpid (to_wait_for, wstatp, options);
  if (ret == 0 || (ret == -1 && errno == ECHILD && (options & WNOHANG)))
    return NULL;
  else if (ret == -1)
    perror_with_name ("waitpid");

  if (debug_threads
      && (!WIFSTOPPED (*wstatp)
	  || (WSTOPSIG (*wstatp) != 32
	      && WSTOPSIG (*wstatp) != 33)))
    fprintf (stderr, "Got an event from %d (%x)\n", ret, *wstatp);

  child = find_lwp_pid (pid_to_ptid (ret));

  /* If we didn't find a process, one of two things presumably happened:
     - A process we started and then detached from has exited.  Ignore it.
     - A process we are controlling has forked and the new child's stop
     was reported to us by the kernel.  Save its PID.  */
  if (child == NULL && WIFSTOPPED (*wstatp))
    {
      add_pid_to_list (&stopped_pids, ret);
      goto retry;
    }
  else if (child == NULL)
    goto retry;

  child->stopped = 1;
  child->pending_is_breakpoint = 0;

  child->last_status = *wstatp;

  /* Architecture-specific setup after inferior is running.
     This needs to happen after we have attached to the inferior
     and it is stopped for the first time, but before we access
     any inferior registers.  */
  if (new_inferior)
    {
      the_low_target.arch_setup ();
#ifdef HAVE_LINUX_REGSETS
      memset (disabled_regsets, 0, num_regsets);
#endif
      new_inferior = 0;
    }

  if (debug_threads
      && WIFSTOPPED (*wstatp)
      && the_low_target.get_pc != NULL)
    {
      struct thread_info *saved_inferior = current_inferior;
      CORE_ADDR pc;

      current_inferior = (struct thread_info *)
	find_inferior_id (&all_threads, child->head.id);
      pc = (*the_low_target.get_pc) ();
      fprintf (stderr, "linux_wait_for_lwp: pc is 0x%lx\n", (long) pc);
      current_inferior = saved_inferior;
    }

  return child;
}

/* Wait for an event from child PID.  If PID is -1, wait for any
   child.  Store the stop status through the status pointer WSTAT.
   OPTIONS is passed to the waitpid call.  Return 0 if no child stop
   event was found and OPTIONS contains WNOHANG.  Return the PID of
   the stopped child otherwise.  */

static int
linux_wait_for_event_1 (ptid_t ptid, int *wstat, int options)
{
  CORE_ADDR stop_pc;
  struct lwp_info *event_child = NULL;
  int bp_status;
  struct lwp_info *requested_child = NULL;

  /* Check for a lwp with a pending status.  */
  /* It is possible that the user changed the pending task's registers since
     it stopped.  We correctly handle the change of PC if we hit a breakpoint
     (in check_removed_breakpoint); signals should be reported anyway.  */

  if (ptid_equal (ptid, minus_one_ptid)
      || ptid_equal (pid_to_ptid (ptid_get_pid (ptid)), ptid))
    {
      event_child = (struct lwp_info *)
	find_inferior (&all_lwps, status_pending_p, &ptid);
      if (debug_threads && event_child)
	fprintf (stderr, "Got a pending child %ld\n", lwpid_of (event_child));
    }
  else
    {
      requested_child = find_lwp_pid (ptid);
      if (requested_child->status_pending_p
	  && !check_removed_breakpoint (requested_child))
	event_child = requested_child;
    }

  if (event_child != NULL)
    {
      if (debug_threads)
	fprintf (stderr, "Got an event from pending child %ld (%04x)\n",
		 lwpid_of (event_child), event_child->status_pending);
      *wstat = event_child->status_pending;
      event_child->status_pending_p = 0;
      event_child->status_pending = 0;
      current_inferior = get_lwp_thread (event_child);
      return lwpid_of (event_child);
    }

  /* We only enter this loop if no process has a pending wait status.  Thus
     any action taken in response to a wait status inside this loop is
     responding as soon as we detect the status, not after any pending
     events.  */
  while (1)
    {
      event_child = linux_wait_for_lwp (ptid, wstat, options);

      if ((options & WNOHANG) && event_child == NULL)
	return 0;

      if (event_child == NULL)
	error ("event from unknown child");

      current_inferior = get_lwp_thread (event_child);

      /* Check for thread exit.  */
      if (! WIFSTOPPED (*wstat))
	{
	  if (debug_threads)
	    fprintf (stderr, "LWP %ld exiting\n", lwpid_of (event_child));

	  /* If the last thread is exiting, just return.  */
	  if (last_thread_of_process_p (current_inferior))
	    {
	      if (debug_threads)
		fprintf (stderr, "LWP %ld is last lwp of process\n",
			 lwpid_of (event_child));
	      return lwpid_of (event_child);
	    }

	  delete_lwp (event_child);

	  if (!non_stop)
	    {
	      current_inferior = (struct thread_info *) all_threads.head;
	      if (debug_threads)
		fprintf (stderr, "Current inferior is now %ld\n",
			 lwpid_of (get_thread_lwp (current_inferior)));
	    }
	  else
	    {
	      current_inferior = NULL;
	      if (debug_threads)
		fprintf (stderr, "Current inferior is now <NULL>\n");
	    }

	  /* If we were waiting for this particular child to do something...
	     well, it did something.  */
	  if (requested_child != NULL)
	    return lwpid_of (event_child);

	  /* Wait for a more interesting event.  */
	  continue;
	}

      if (event_child->must_set_ptrace_flags)
	{
	  ptrace (PTRACE_SETOPTIONS, lwpid_of (event_child),
		  0, PTRACE_O_TRACECLONE);
	  event_child->must_set_ptrace_flags = 0;
	}

      if (WIFSTOPPED (*wstat)
	  && WSTOPSIG (*wstat) == SIGSTOP
	  && event_child->stop_expected)
	{
	  if (debug_threads)
	    fprintf (stderr, "Expected stop.\n");
	  event_child->stop_expected = 0;
	  linux_resume_one_lwp (event_child, event_child->stepping, 0, NULL);
	  continue;
	}

      if (WIFSTOPPED (*wstat) && WSTOPSIG (*wstat) == SIGTRAP
	  && *wstat >> 16 != 0)
	{
	  handle_extended_wait (event_child, *wstat);
	  continue;
	}

      /* If GDB is not interested in this signal, don't stop other
	 threads, and don't report it to GDB.  Just resume the
	 inferior right away.  We do this for threading-related
	 signals as well as any that GDB specifically requested we
	 ignore.  But never ignore SIGSTOP if we sent it ourselves,
	 and do not ignore signals when stepping - they may require
	 special handling to skip the signal handler.  */
      /* FIXME drow/2002-06-09: Get signal numbers from the inferior's
	 thread library?  */
      if (WIFSTOPPED (*wstat)
	  && !event_child->stepping
	  && (
#ifdef USE_THREAD_DB
	      (current_process ()->private->thread_db_active
	       && (WSTOPSIG (*wstat) == __SIGRTMIN
		   || WSTOPSIG (*wstat) == __SIGRTMIN + 1))
	      ||
#endif
	      (pass_signals[target_signal_from_host (WSTOPSIG (*wstat))]
	       && (WSTOPSIG (*wstat) != SIGSTOP || !stopping_threads))))
	{
	  siginfo_t info, *info_p;

	  if (debug_threads)
	    fprintf (stderr, "Ignored signal %d for LWP %ld.\n",
		     WSTOPSIG (*wstat), lwpid_of (event_child));

	  if (ptrace (PTRACE_GETSIGINFO, lwpid_of (event_child), 0, &info) == 0)
	    info_p = &info;
	  else
	    info_p = NULL;
	  linux_resume_one_lwp (event_child,
				event_child->stepping,
				WSTOPSIG (*wstat), info_p);
	  continue;
	}

      /* If this event was not handled above, and is not a SIGTRAP, report
	 it.  */
      if (!WIFSTOPPED (*wstat) || WSTOPSIG (*wstat) != SIGTRAP)
	return lwpid_of (event_child);

      /* If this target does not support breakpoints, we simply report the
	 SIGTRAP; it's of no concern to us.  */
      if (the_low_target.get_pc == NULL)
	return lwpid_of (event_child);

      stop_pc = get_stop_pc ();

      /* bp_reinsert will only be set if we were single-stepping.
	 Notice that we will resume the process after hitting
	 a gdbserver breakpoint; single-stepping to/over one
	 is not supported (yet).  */
      if (event_child->bp_reinsert != 0)
	{
	  if (debug_threads)
	    fprintf (stderr, "Reinserted breakpoint.\n");
	  reinsert_breakpoint (event_child->bp_reinsert);
	  event_child->bp_reinsert = 0;

	  /* Clear the single-stepping flag and SIGTRAP as we resume.  */
	  linux_resume_one_lwp (event_child, 0, 0, NULL);
	  continue;
	}

      bp_status = check_breakpoints (stop_pc);

      if (bp_status != 0)
	{
	  if (debug_threads)
	    fprintf (stderr, "Hit a gdbserver breakpoint.\n");

	  /* We hit one of our own breakpoints.  We mark it as a pending
	     breakpoint, so that check_removed_breakpoint () will do the PC
	     adjustment for us at the appropriate time.  */
	  event_child->pending_is_breakpoint = 1;
	  event_child->pending_stop_pc = stop_pc;

	  /* We may need to put the breakpoint back.  We continue in the event
	     loop instead of simply replacing the breakpoint right away,
	     in order to not lose signals sent to the thread that hit the
	     breakpoint.  Unfortunately this increases the window where another
	     thread could sneak past the removed breakpoint.  For the current
	     use of server-side breakpoints (thread creation) this is
	     acceptable; but it needs to be considered before this breakpoint
	     mechanism can be used in more general ways.  For some breakpoints
	     it may be necessary to stop all other threads, but that should
	     be avoided where possible.

	     If breakpoint_reinsert_addr is NULL, that means that we can
	     use PTRACE_SINGLESTEP on this platform.  Uninsert the breakpoint,
	     mark it for reinsertion, and single-step.

	     Otherwise, call the target function to figure out where we need
	     our temporary breakpoint, create it, and continue executing this
	     process.  */

	  /* NOTE: we're lifting breakpoints in non-stop mode.  This
	     is currently only used for thread event breakpoints, so
	     it isn't that bad as long as we have PTRACE_EVENT_CLONE
	     events.  */
	  if (bp_status == 2)
	    /* No need to reinsert.  */
	    linux_resume_one_lwp (event_child, 0, 0, NULL);
	  else if (the_low_target.breakpoint_reinsert_addr == NULL)
	    {
	      event_child->bp_reinsert = stop_pc;
	      uninsert_breakpoint (stop_pc);
	      linux_resume_one_lwp (event_child, 1, 0, NULL);
	    }
	  else
	    {
	      reinsert_breakpoint_by_bp
		(stop_pc, (*the_low_target.breakpoint_reinsert_addr) ());
	      linux_resume_one_lwp (event_child, 0, 0, NULL);
	    }

	  continue;
	}

      if (debug_threads)
	fprintf (stderr, "Hit a non-gdbserver breakpoint.\n");

      /* If we were single-stepping, we definitely want to report the
	 SIGTRAP.  Although the single-step operation has completed,
	 do not clear clear the stepping flag yet; we need to check it
	 in wait_for_sigstop.  */
      if (event_child->stepping)
	return lwpid_of (event_child);

      /* A SIGTRAP that we can't explain.  It may have been a breakpoint.
	 Check if it is a breakpoint, and if so mark the process information
	 accordingly.  This will handle both the necessary fiddling with the
	 PC on decr_pc_after_break targets and suppressing extra threads
	 hitting a breakpoint if two hit it at once and then GDB removes it
	 after the first is reported.  Arguably it would be better to report
	 multiple threads hitting breakpoints simultaneously, but the current
	 remote protocol does not allow this.  */
      if ((*the_low_target.breakpoint_at) (stop_pc))
	{
	  event_child->pending_is_breakpoint = 1;
	  event_child->pending_stop_pc = stop_pc;
	}

      return lwpid_of (event_child);
    }

  /* NOTREACHED */
  return 0;
}

static int
linux_wait_for_event (ptid_t ptid, int *wstat, int options)
{
  ptid_t wait_ptid;

  if (ptid_is_pid (ptid))
    {
      /* A request to wait for a specific tgid.  This is not possible
	 with waitpid, so instead, we wait for any child, and leave
	 children we're not interested in right now with a pending
	 status to report later.  */
      wait_ptid = minus_one_ptid;
    }
  else
    wait_ptid = ptid;

  while (1)
    {
      int event_pid;

      event_pid = linux_wait_for_event_1 (wait_ptid, wstat, options);

      if (event_pid > 0
	  && ptid_is_pid (ptid) && ptid_get_pid (ptid) != event_pid)
	{
	  struct lwp_info *event_child = find_lwp_pid (pid_to_ptid (event_pid));

	  if (! WIFSTOPPED (*wstat))
	    mark_lwp_dead (event_child, *wstat);
	  else
	    {
	      event_child->status_pending_p = 1;
	      event_child->status_pending = *wstat;
	    }
	}
      else
	return event_pid;
    }
}

/* Wait for process, returns status.  */

static ptid_t
linux_wait_1 (ptid_t ptid,
	      struct target_waitstatus *ourstatus, int target_options)
{
  int w;
  struct thread_info *thread = NULL;
  struct lwp_info *lwp = NULL;
  int options;
  int pid;

  /* Translate generic target options into linux options.  */
  options = __WALL;
  if (target_options & TARGET_WNOHANG)
    options |= WNOHANG;

retry:
  ourstatus->kind = TARGET_WAITKIND_IGNORE;

  /* If we were only supposed to resume one thread, only wait for
     that thread - if it's still alive.  If it died, however - which
     can happen if we're coming from the thread death case below -
     then we need to make sure we restart the other threads.  We could
     pick a thread at random or restart all; restarting all is less
     arbitrary.  */
  if (!non_stop
      && !ptid_equal (cont_thread, null_ptid)
      && !ptid_equal (cont_thread, minus_one_ptid))
    {
      thread = (struct thread_info *) find_inferior_id (&all_threads,
							cont_thread);

      /* No stepping, no signal - unless one is pending already, of course.  */
      if (thread == NULL)
	{
	  struct thread_resume resume_info;
	  resume_info.thread = minus_one_ptid;
	  resume_info.kind = resume_continue;
	  resume_info.sig = 0;
	  linux_resume (&resume_info, 1);
	}
      else
	ptid = cont_thread;
    }

  pid = linux_wait_for_event (ptid, &w, options);
  if (pid == 0) /* only if TARGET_WNOHANG */
    return null_ptid;

  lwp = get_thread_lwp (current_inferior);

  /* If we are waiting for a particular child, and it exited,
     linux_wait_for_event will return its exit status.  Similarly if
     the last child exited.  If this is not the last child, however,
     do not report it as exited until there is a 'thread exited' response
     available in the remote protocol.  Instead, just wait for another event.
     This should be safe, because if the thread crashed we will already
     have reported the termination signal to GDB; that should stop any
     in-progress stepping operations, etc.

     Report the exit status of the last thread to exit.  This matches
     LinuxThreads' behavior.  */

  if (last_thread_of_process_p (current_inferior))
    {
      if (WIFEXITED (w) || WIFSIGNALED (w))
	{
	  int pid = pid_of (lwp);
	  struct process_info *process = find_process_pid (pid);

	  delete_lwp (lwp);
	  linux_remove_process (process);

	  current_inferior = NULL;

	  if (WIFEXITED (w))
	    {
	      ourstatus->kind = TARGET_WAITKIND_EXITED;
	      ourstatus->value.integer = WEXITSTATUS (w);

	      if (debug_threads)
		fprintf (stderr, "\nChild exited with retcode = %x \n", WEXITSTATUS (w));
	    }
	  else
	    {
	      ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
	      ourstatus->value.sig = target_signal_from_host (WTERMSIG (w));

	      if (debug_threads)
		fprintf (stderr, "\nChild terminated with signal = %x \n", WTERMSIG (w));

	    }

	  return pid_to_ptid (pid);
	}
    }
  else
    {
      if (!WIFSTOPPED (w))
	goto retry;
    }

  /* In all-stop, stop all threads.  Be careful to only do this if
     we're about to report an event to GDB.  */
  if (!non_stop)
    stop_all_lwps ();

  ourstatus->kind = TARGET_WAITKIND_STOPPED;

  if (lwp->suspended && WSTOPSIG (w) == SIGSTOP)
    {
      /* A thread that has been requested to stop by GDB with vCont;t,
	 and it stopped cleanly, so report as SIG0.  The use of
	 SIGSTOP is an implementation detail.  */
      ourstatus->value.sig = TARGET_SIGNAL_0;
    }
  else if (lwp->suspended && WSTOPSIG (w) != SIGSTOP)
    {
      /* A thread that has been requested to stop by GDB with vCont;t,
	 but, it stopped for other reasons.  Set stop_expected so the
	 pending SIGSTOP is ignored and the LWP is resumed.  */
      lwp->stop_expected = 1;
      ourstatus->value.sig = target_signal_from_host (WSTOPSIG (w));
    }
  else
    {
      ourstatus->value.sig = target_signal_from_host (WSTOPSIG (w));
    }

  if (debug_threads)
    fprintf (stderr, "linux_wait ret = %s, %d, %d\n",
	     target_pid_to_str (lwp->head.id),
	     ourstatus->kind,
	     ourstatus->value.sig);

  return lwp->head.id;
}

/* Get rid of any pending event in the pipe.  */
static void
async_file_flush (void)
{
  int ret;
  char buf;

  do
    ret = read (linux_event_pipe[0], &buf, 1);
  while (ret >= 0 || (ret == -1 && errno == EINTR));
}

/* Put something in the pipe, so the event loop wakes up.  */
static void
async_file_mark (void)
{
  int ret;

  async_file_flush ();

  do
    ret = write (linux_event_pipe[1], "+", 1);
  while (ret == 0 || (ret == -1 && errno == EINTR));

  /* Ignore EAGAIN.  If the pipe is full, the event loop will already
     be awakened anyway.  */
}

static ptid_t
linux_wait (ptid_t ptid,
	    struct target_waitstatus *ourstatus, int target_options)
{
  ptid_t event_ptid;

  if (debug_threads)
    fprintf (stderr, "linux_wait: [%s]\n", target_pid_to_str (ptid));

  /* Flush the async file first.  */
  if (target_is_async_p ())
    async_file_flush ();

  event_ptid = linux_wait_1 (ptid, ourstatus, target_options);

  /* If at least one stop was reported, there may be more.  A single
     SIGCHLD can signal more than one child stop.  */
  if (target_is_async_p ()
      && (target_options & TARGET_WNOHANG) != 0
      && !ptid_equal (event_ptid, null_ptid))
    async_file_mark ();

  return event_ptid;
}

/* Send a signal to an LWP.  For LinuxThreads, kill is enough; however, if
   thread groups are in use, we need to use tkill.  */

static int
kill_lwp (unsigned long lwpid, int signo)
{
  static int tkill_failed;

  errno = 0;

#ifdef SYS_tkill
  if (!tkill_failed)
    {
      int ret = syscall (SYS_tkill, lwpid, signo);
      if (errno != ENOSYS)
	return ret;
      errno = 0;
      tkill_failed = 1;
    }
#endif

  return kill (lwpid, signo);
}

static void
send_sigstop (struct inferior_list_entry *entry)
{
  struct lwp_info *lwp = (struct lwp_info *) entry;
  int pid;

  if (lwp->stopped)
    return;

  pid = lwpid_of (lwp);

  /* If we already have a pending stop signal for this process, don't
     send another.  */
  if (lwp->stop_expected)
    {
      if (debug_threads)
	fprintf (stderr, "Have pending sigstop for lwp %d\n", pid);

      /* We clear the stop_expected flag so that wait_for_sigstop
	 will receive the SIGSTOP event (instead of silently resuming and
	 waiting again).  It'll be reset below.  */
      lwp->stop_expected = 0;
      return;
    }

  if (debug_threads)
    fprintf (stderr, "Sending sigstop to lwp %d\n", pid);

  kill_lwp (pid, SIGSTOP);
}

static void
mark_lwp_dead (struct lwp_info *lwp, int wstat)
{
  /* It's dead, really.  */
  lwp->dead = 1;

  /* Store the exit status for later.  */
  lwp->status_pending_p = 1;
  lwp->status_pending = wstat;

  /* So that check_removed_breakpoint doesn't try to figure out if
     this is stopped at a breakpoint.  */
  lwp->pending_is_breakpoint = 0;

  /* Prevent trying to stop it.  */
  lwp->stopped = 1;

  /* No further stops are expected from a dead lwp.  */
  lwp->stop_expected = 0;
}

static void
wait_for_sigstop (struct inferior_list_entry *entry)
{
  struct lwp_info *lwp = (struct lwp_info *) entry;
  struct thread_info *saved_inferior;
  int wstat;
  ptid_t saved_tid;
  ptid_t ptid;

  if (lwp->stopped)
    return;

  saved_inferior = current_inferior;
  if (saved_inferior != NULL)
    saved_tid = ((struct inferior_list_entry *) saved_inferior)->id;
  else
    saved_tid = null_ptid; /* avoid bogus unused warning */

  ptid = lwp->head.id;

  linux_wait_for_event (ptid, &wstat, __WALL);

  /* If we stopped with a non-SIGSTOP signal, save it for later
     and record the pending SIGSTOP.  If the process exited, just
     return.  */
  if (WIFSTOPPED (wstat)
      && WSTOPSIG (wstat) != SIGSTOP)
    {
      if (debug_threads)
	fprintf (stderr, "LWP %ld stopped with non-sigstop status %06x\n",
		 lwpid_of (lwp), wstat);

      /* Do not leave a pending single-step finish to be reported to
	 the client.  The client will give us a new action for this
	 thread, possibly a continue request --- otherwise, the client
	 would consider this pending SIGTRAP reported later a spurious
	 signal.  */
      if (WSTOPSIG (wstat) == SIGTRAP
	  && lwp->stepping
	  && !linux_stopped_by_watchpoint ())
	{
	  if (debug_threads)
	    fprintf (stderr, "  single-step SIGTRAP ignored\n");
	}
      else
	{
	  lwp->status_pending_p = 1;
	  lwp->status_pending = wstat;
	}
      lwp->stop_expected = 1;
    }
  else if (!WIFSTOPPED (wstat))
    {
      if (debug_threads)
	fprintf (stderr, "Process %ld exited while stopping LWPs\n",
		 lwpid_of (lwp));

      /* Leave this status pending for the next time we're able to
	 report it.  In the mean time, we'll report this lwp as dead
	 to GDB, so GDB doesn't try to read registers and memory from
	 it.  */
      mark_lwp_dead (lwp, wstat);
    }

  if (saved_inferior == NULL || linux_thread_alive (saved_tid))
    current_inferior = saved_inferior;
  else
    {
      if (debug_threads)
	fprintf (stderr, "Previously current thread died.\n");

      if (non_stop)
	{
	  /* We can't change the current inferior behind GDB's back,
	     otherwise, a subsequent command may apply to the wrong
	     process.  */
	  current_inferior = NULL;
	}
      else
	{
	  /* Set a valid thread as current.  */
	  set_desired_inferior (0);
	}
    }
}

static void
stop_all_lwps (void)
{
  stopping_threads = 1;
  for_each_inferior (&all_lwps, send_sigstop);
  for_each_inferior (&all_lwps, wait_for_sigstop);
  stopping_threads = 0;
}

/* Resume execution of the inferior process.
   If STEP is nonzero, single-step it.
   If SIGNAL is nonzero, give it that signal.  */

static void
linux_resume_one_lwp (struct lwp_info *lwp,
		      int step, int signal, siginfo_t *info)
{
  struct thread_info *saved_inferior;

  if (lwp->stopped == 0)
    return;

  /* If we have pending signals or status, and a new signal, enqueue the
     signal.  Also enqueue the signal if we are waiting to reinsert a
     breakpoint; it will be picked up again below.  */
  if (signal != 0
      && (lwp->status_pending_p || lwp->pending_signals != NULL
	  || lwp->bp_reinsert != 0))
    {
      struct pending_signals *p_sig;
      p_sig = xmalloc (sizeof (*p_sig));
      p_sig->prev = lwp->pending_signals;
      p_sig->signal = signal;
      if (info == NULL)
	memset (&p_sig->info, 0, sizeof (siginfo_t));
      else
	memcpy (&p_sig->info, info, sizeof (siginfo_t));
      lwp->pending_signals = p_sig;
    }

  if (lwp->status_pending_p && !check_removed_breakpoint (lwp))
    return;

  saved_inferior = current_inferior;
  current_inferior = get_lwp_thread (lwp);

  if (debug_threads)
    fprintf (stderr, "Resuming lwp %ld (%s, signal %d, stop %s)\n",
	     lwpid_of (lwp), step ? "step" : "continue", signal,
	     lwp->stop_expected ? "expected" : "not expected");

  /* This bit needs some thinking about.  If we get a signal that
     we must report while a single-step reinsert is still pending,
     we often end up resuming the thread.  It might be better to
     (ew) allow a stack of pending events; then we could be sure that
     the reinsert happened right away and not lose any signals.

     Making this stack would also shrink the window in which breakpoints are
     uninserted (see comment in linux_wait_for_lwp) but not enough for
     complete correctness, so it won't solve that problem.  It may be
     worthwhile just to solve this one, however.  */
  if (lwp->bp_reinsert != 0)
    {
      if (debug_threads)
	fprintf (stderr, "  pending reinsert at %08lx", (long)lwp->bp_reinsert);
      if (step == 0)
	fprintf (stderr, "BAD - reinserting but not stepping.\n");
      step = 1;

      /* Postpone any pending signal.  It was enqueued above.  */
      signal = 0;
    }

  check_removed_breakpoint (lwp);

  if (debug_threads && the_low_target.get_pc != NULL)
    {
      CORE_ADDR pc = (*the_low_target.get_pc) ();
      fprintf (stderr, "  resuming from pc 0x%lx\n", (long) pc);
    }

  /* If we have pending signals, consume one unless we are trying to reinsert
     a breakpoint.  */
  if (lwp->pending_signals != NULL && lwp->bp_reinsert == 0)
    {
      struct pending_signals **p_sig;

      p_sig = &lwp->pending_signals;
      while ((*p_sig)->prev != NULL)
	p_sig = &(*p_sig)->prev;

      signal = (*p_sig)->signal;
      if ((*p_sig)->info.si_signo != 0)
	ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp), 0, &(*p_sig)->info);

      free (*p_sig);
      *p_sig = NULL;
    }

  if (the_low_target.prepare_to_resume != NULL)
    the_low_target.prepare_to_resume (lwp);

  regcache_invalidate_one ((struct inferior_list_entry *)
			   get_lwp_thread (lwp));
  errno = 0;
  lwp->stopped = 0;
  lwp->stepping = step;
  ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, lwpid_of (lwp), 0, signal);

  current_inferior = saved_inferior;
  if (errno)
    {
      /* ESRCH from ptrace either means that the thread was already
	 running (an error) or that it is gone (a race condition).  If
	 it's gone, we will get a notification the next time we wait,
	 so we can ignore the error.  We could differentiate these
	 two, but it's tricky without waiting; the thread still exists
	 as a zombie, so sending it signal 0 would succeed.  So just
	 ignore ESRCH.  */
      if (errno == ESRCH)
	return;

      perror_with_name ("ptrace");
    }
}

struct thread_resume_array
{
  struct thread_resume *resume;
  size_t n;
};

/* This function is called once per thread.  We look up the thread
   in RESUME_PTR, and mark the thread with a pointer to the appropriate
   resume request.

   This algorithm is O(threads * resume elements), but resume elements
   is small (and will remain small at least until GDB supports thread
   suspension).  */
static int
linux_set_resume_request (struct inferior_list_entry *entry, void *arg)
{
  struct lwp_info *lwp;
  struct thread_info *thread;
  int ndx;
  struct thread_resume_array *r;

  thread = (struct thread_info *) entry;
  lwp = get_thread_lwp (thread);
  r = arg;

  for (ndx = 0; ndx < r->n; ndx++)
    {
      ptid_t ptid = r->resume[ndx].thread;
      if (ptid_equal (ptid, minus_one_ptid)
	  || ptid_equal (ptid, entry->id)
	  || (ptid_is_pid (ptid)
	      && (ptid_get_pid (ptid) == pid_of (lwp)))
	  || (ptid_get_lwp (ptid) == -1
	      && (ptid_get_pid (ptid) == pid_of (lwp))))
	{
	  lwp->resume = &r->resume[ndx];
	  return 0;
	}
    }

  /* No resume action for this thread.  */
  lwp->resume = NULL;

  return 0;
}


/* Set *FLAG_P if this lwp has an interesting status pending.  */
static int
resume_status_pending_p (struct inferior_list_entry *entry, void *flag_p)
{
  struct lwp_info *lwp = (struct lwp_info *) entry;

  /* LWPs which will not be resumed are not interesting, because
     we might not wait for them next time through linux_wait.  */
  if (lwp->resume == NULL)
    return 0;

  /* If this thread has a removed breakpoint, we won't have any
     events to report later, so check now.  check_removed_breakpoint
     may clear status_pending_p.  We avoid calling check_removed_breakpoint
     for any thread that we are not otherwise going to resume - this
     lets us preserve stopped status when two threads hit a breakpoint.
     GDB removes the breakpoint to single-step a particular thread
     past it, then re-inserts it and resumes all threads.  We want
     to report the second thread without resuming it in the interim.  */
  if (lwp->status_pending_p)
    check_removed_breakpoint (lwp);

  if (lwp->status_pending_p)
    * (int *) flag_p = 1;

  return 0;
}

/* This function is called once per thread.  We check the thread's resume
   request, which will tell us whether to resume, step, or leave the thread
   stopped; and what signal, if any, it should be sent.

   For threads which we aren't explicitly told otherwise, we preserve
   the stepping flag; this is used for stepping over gdbserver-placed
   breakpoints.

   If pending_flags was set in any thread, we queue any needed
   signals, since we won't actually resume.  We already have a pending
   event to report, so we don't need to preserve any step requests;
   they should be re-issued if necessary.  */

static int
linux_resume_one_thread (struct inferior_list_entry *entry, void *arg)
{
  struct lwp_info *lwp;
  struct thread_info *thread;
  int step;
  int pending_flag = * (int *) arg;

  thread = (struct thread_info *) entry;
  lwp = get_thread_lwp (thread);

  if (lwp->resume == NULL)
    return 0;

  if (lwp->resume->kind == resume_stop)
    {
      if (debug_threads)
	fprintf (stderr, "suspending LWP %ld\n", lwpid_of (lwp));

      if (!lwp->stopped)
	{
	  if (debug_threads)
	    fprintf (stderr, "running -> suspending LWP %ld\n", lwpid_of (lwp));

	  lwp->suspended = 1;
	  send_sigstop (&lwp->head);
	}
      else
	{
	  if (debug_threads)
	    {
	      if (lwp->suspended)
		fprintf (stderr, "already stopped/suspended LWP %ld\n",
			 lwpid_of (lwp));
	      else
		fprintf (stderr, "already stopped/not suspended LWP %ld\n",
			 lwpid_of (lwp));
	    }

	  /* Make sure we leave the LWP suspended, so we don't try to
	     resume it without GDB telling us to.  FIXME: The LWP may
	     have been stopped in an internal event that was not meant
	     to be notified back to GDB (e.g., gdbserver breakpoint),
	     so we should be reporting a stop event in that case
	     too.  */
	  lwp->suspended = 1;
	}

      /* For stop requests, we're done.  */
      lwp->resume = NULL;
      return 0;
    }
  else
    lwp->suspended = 0;

  /* If this thread which is about to be resumed has a pending status,
     then don't resume any threads - we can just report the pending
     status.  Make sure to queue any signals that would otherwise be
     sent.  In all-stop mode, we do this decision based on if *any*
     thread has a pending status.  */
  if (non_stop)
    resume_status_pending_p (&lwp->head, &pending_flag);

  if (!pending_flag)
    {
      if (debug_threads)
	fprintf (stderr, "resuming LWP %ld\n", lwpid_of (lwp));

      if (ptid_equal (lwp->resume->thread, minus_one_ptid)
	  && lwp->stepping
	  && lwp->pending_is_breakpoint)
	step = 1;
      else
	step = (lwp->resume->kind == resume_step);

      linux_resume_one_lwp (lwp, step, lwp->resume->sig, NULL);
    }
  else
    {
      if (debug_threads)
	fprintf (stderr, "leaving LWP %ld stopped\n", lwpid_of (lwp));

      /* If we have a new signal, enqueue the signal.  */
      if (lwp->resume->sig != 0)
	{
	  struct pending_signals *p_sig;
	  p_sig = xmalloc (sizeof (*p_sig));
	  p_sig->prev = lwp->pending_signals;
	  p_sig->signal = lwp->resume->sig;
	  memset (&p_sig->info, 0, sizeof (siginfo_t));

	  /* If this is the same signal we were previously stopped by,
	     make sure to queue its siginfo.  We can ignore the return
	     value of ptrace; if it fails, we'll skip
	     PTRACE_SETSIGINFO.  */
	  if (WIFSTOPPED (lwp->last_status)
	      && WSTOPSIG (lwp->last_status) == lwp->resume->sig)
	    ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp), 0, &p_sig->info);

	  lwp->pending_signals = p_sig;
	}
    }

  lwp->resume = NULL;
  return 0;
}

static void
linux_resume (struct thread_resume *resume_info, size_t n)
{
  int pending_flag;
  struct thread_resume_array array = { resume_info, n };

  find_inferior (&all_threads, linux_set_resume_request, &array);

  /* If there is a thread which would otherwise be resumed, which
     has a pending status, then don't resume any threads - we can just
     report the pending status.  Make sure to queue any signals
     that would otherwise be sent.  In non-stop mode, we'll apply this
     logic to each thread individually.  */
  pending_flag = 0;
  if (!non_stop)
    find_inferior (&all_lwps, resume_status_pending_p, &pending_flag);

  if (debug_threads)
    {
      if (pending_flag)
	fprintf (stderr, "Not resuming, pending status\n");
      else
	fprintf (stderr, "Resuming, no pending status\n");
    }

  find_inferior (&all_threads, linux_resume_one_thread, &pending_flag);
}

#ifdef HAVE_LINUX_USRREGS

int
register_addr (int regnum)
{
  int addr;

  if (regnum < 0 || regnum >= the_low_target.num_regs)
    error ("Invalid register number %d.", regnum);

  addr = the_low_target.regmap[regnum];

  return addr;
}

/* Fetch one register.  */
static void
fetch_register (int regno)
{
  CORE_ADDR regaddr;
  int i, size;
  char *buf;
  int pid;

  if (regno >= the_low_target.num_regs)
    return;
  if ((*the_low_target.cannot_fetch_register) (regno))
    return;

  regaddr = register_addr (regno);
  if (regaddr == -1)
    return;

  pid = lwpid_of (get_thread_lwp (current_inferior));
  size = ((register_size (regno) + sizeof (PTRACE_XFER_TYPE) - 1)
	  & - sizeof (PTRACE_XFER_TYPE));
  buf = alloca (size);
  for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE))
    {
      errno = 0;
      *(PTRACE_XFER_TYPE *) (buf + i) =
	ptrace (PTRACE_PEEKUSER, pid, (PTRACE_ARG3_TYPE) regaddr, 0);
      regaddr += sizeof (PTRACE_XFER_TYPE);
      if (errno != 0)
	{
	  /* Warning, not error, in case we are attached; sometimes the
	     kernel doesn't let us at the registers.  */
	  char *err = strerror (errno);
	  char *msg = alloca (strlen (err) + 128);
	  sprintf (msg, "reading register %d: %s", regno, err);
	  error (msg);
	  goto error_exit;
	}
    }

  if (the_low_target.supply_ptrace_register)
    the_low_target.supply_ptrace_register (regno, buf);
  else
    supply_register (regno, buf);

error_exit:;
}

/* Fetch all registers, or just one, from the child process.  */
static void
usr_fetch_inferior_registers (int regno)
{
  if (regno == -1)
    for (regno = 0; regno < the_low_target.num_regs; regno++)
      fetch_register (regno);
  else
    fetch_register (regno);
}

/* Store our register values back into the inferior.
   If REGNO is -1, do this for all registers.
   Otherwise, REGNO specifies which register (so we can save time).  */
static void
usr_store_inferior_registers (int regno)
{
  CORE_ADDR regaddr;
  int i, size;
  char *buf;
  int pid;

  if (regno >= 0)
    {
      if (regno >= the_low_target.num_regs)
	return;

      if ((*the_low_target.cannot_store_register) (regno) == 1)
	return;

      regaddr = register_addr (regno);
      if (regaddr == -1)
	return;
      errno = 0;
      size = (register_size (regno) + sizeof (PTRACE_XFER_TYPE) - 1)
	     & - sizeof (PTRACE_XFER_TYPE);
      buf = alloca (size);
      memset (buf, 0, size);

      if (the_low_target.collect_ptrace_register)
	the_low_target.collect_ptrace_register (regno, buf);
      else
	collect_register (regno, buf);

      pid = lwpid_of (get_thread_lwp (current_inferior));
      for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE))
	{
	  errno = 0;
	  ptrace (PTRACE_POKEUSER, pid, (PTRACE_ARG3_TYPE) regaddr,
		  *(PTRACE_XFER_TYPE *) (buf + i));
	  if (errno != 0)
	    {
	      /* At this point, ESRCH should mean the process is
		 already gone, in which case we simply ignore attempts
		 to change its registers.  See also the related
		 comment in linux_resume_one_lwp.  */
	      if (errno == ESRCH)
		return;

	      if ((*the_low_target.cannot_store_register) (regno) == 0)
		{
		  char *err = strerror (errno);
		  char *msg = alloca (strlen (err) + 128);
		  sprintf (msg, "writing register %d: %s",
			   regno, err);
		  error (msg);
		  return;
		}
	    }
	  regaddr += sizeof (PTRACE_XFER_TYPE);
	}
    }
  else
    for (regno = 0; regno < the_low_target.num_regs; regno++)
      usr_store_inferior_registers (regno);
}
#endif /* HAVE_LINUX_USRREGS */



#ifdef HAVE_LINUX_REGSETS

static int
regsets_fetch_inferior_registers ()
{
  struct regset_info *regset;
  int saw_general_regs = 0;
  int pid;

  regset = target_regsets;

  pid = lwpid_of (get_thread_lwp (current_inferior));
  while (regset->size >= 0)
    {
      void *buf;
      int res;

      if (regset->size == 0 || disabled_regsets[regset - target_regsets])
	{
	  regset ++;
	  continue;
	}

      buf = xmalloc (regset->size);
#ifndef __sparc__
      res = ptrace (regset->get_request, pid, 0, buf);
#else
      res = ptrace (regset->get_request, pid, buf, 0);
#endif
      if (res < 0)
	{
	  if (errno == EIO)
	    {
	      /* If we get EIO on a regset, do not try it again for
		 this process.  */
	      disabled_regsets[regset - target_regsets] = 1;
	      free (buf);
	      continue;
	    }
	  else
	    {
	      char s[256];
	      sprintf (s, "ptrace(regsets_fetch_inferior_registers) PID=%d",
		       pid);
	      perror (s);
	    }
	}
      else if (regset->type == GENERAL_REGS)
	saw_general_regs = 1;
      regset->store_function (buf);
      regset ++;
      free (buf);
    }
  if (saw_general_regs)
    return 0;
  else
    return 1;
}

static int
regsets_store_inferior_registers ()
{
  struct regset_info *regset;
  int saw_general_regs = 0;
  int pid;

  regset = target_regsets;

  pid = lwpid_of (get_thread_lwp (current_inferior));
  while (regset->size >= 0)
    {
      void *buf;
      int res;

      if (regset->size == 0 || disabled_regsets[regset - target_regsets])
	{
	  regset ++;
	  continue;
	}

      buf = xmalloc (regset->size);

      /* First fill the buffer with the current register set contents,
	 in case there are any items in the kernel's regset that are
	 not in gdbserver's regcache.  */
#ifndef __sparc__
      res = ptrace (regset->get_request, pid, 0, buf);
#else
      res = ptrace (regset->get_request, pid, buf, 0);
#endif

      if (res == 0)
	{
	  /* Then overlay our cached registers on that.  */
	  regset->fill_function (buf);

	  /* Only now do we write the register set.  */
#ifndef __sparc__
	  res = ptrace (regset->set_request, pid, 0, buf);
#else
	  res = ptrace (regset->set_request, pid, buf, 0);
#endif
	}

      if (res < 0)
	{
	  if (errno == EIO)
	    {
	      /* If we get EIO on a regset, do not try it again for
		 this process.  */
	      disabled_regsets[regset - target_regsets] = 1;
	      free (buf);
	      continue;
	    }
	  else if (errno == ESRCH)
	    {
	      /* At this point, ESRCH should mean the process is
		 already gone, in which case we simply ignore attempts
		 to change its registers.  See also the related
		 comment in linux_resume_one_lwp.  */
	      free (buf);
	      return 0;
	    }
	  else
	    {
	      perror ("Warning: ptrace(regsets_store_inferior_registers)");
	    }
	}
      else if (regset->type == GENERAL_REGS)
	saw_general_regs = 1;
      regset ++;
      free (buf);
    }
  if (saw_general_regs)
    return 0;
  else
    return 1;
  return 0;
}

#endif /* HAVE_LINUX_REGSETS */


void
linux_fetch_registers (int regno)
{
#ifdef HAVE_LINUX_REGSETS
  if (regsets_fetch_inferior_registers () == 0)
    return;
#endif
#ifdef HAVE_LINUX_USRREGS
  usr_fetch_inferior_registers (regno);
#endif
}

void
linux_store_registers (int regno)
{
#ifdef HAVE_LINUX_REGSETS
  if (regsets_store_inferior_registers () == 0)
    return;
#endif
#ifdef HAVE_LINUX_USRREGS
  usr_store_inferior_registers (regno);
#endif
}


/* Copy LEN bytes from inferior's memory starting at MEMADDR
   to debugger memory starting at MYADDR.  */

static int
linux_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
{
  register int i;
  /* Round starting address down to longword boundary.  */
  register CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE);
  /* Round ending address up; get number of longwords that makes.  */
  register int count
    = (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1)
      / sizeof (PTRACE_XFER_TYPE);
  /* Allocate buffer of that many longwords.  */
  register PTRACE_XFER_TYPE *buffer
    = (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
  int fd;
  char filename[64];
  int pid = lwpid_of (get_thread_lwp (current_inferior));

  /* Try using /proc.  Don't bother for one word.  */
  if (len >= 3 * sizeof (long))
    {
      /* We could keep this file open and cache it - possibly one per
	 thread.  That requires some juggling, but is even faster.  */
      sprintf (filename, "/proc/%d/mem", pid);
      fd = open (filename, O_RDONLY | O_LARGEFILE);
      if (fd == -1)
	goto no_proc;

      /* If pread64 is available, use it.  It's faster if the kernel
	 supports it (only one syscall), and it's 64-bit safe even on
	 32-bit platforms (for instance, SPARC debugging a SPARC64
	 application).  */
#ifdef HAVE_PREAD64
      if (pread64 (fd, myaddr, len, memaddr) != len)
#else
      if (lseek (fd, memaddr, SEEK_SET) == -1 || read (fd, memaddr, len) != len)
#endif
	{
	  close (fd);
	  goto no_proc;
	}

      close (fd);
      return 0;
    }

 no_proc:
  /* Read all the longwords */
  for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
    {
      errno = 0;
      buffer[i] = ptrace (PTRACE_PEEKTEXT, pid, (PTRACE_ARG3_TYPE) addr, 0);
      if (errno)
	return errno;
    }

  /* Copy appropriate bytes out of the buffer.  */
  memcpy (myaddr,
	  (char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)),
	  len);

  return 0;
}

/* Copy LEN bytes of data from debugger memory at MYADDR
   to inferior's memory at MEMADDR.
   On failure (cannot write the inferior)
   returns the value of errno.  */

static int
linux_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
{
  register int i;
  /* Round starting address down to longword boundary.  */
  register CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE);
  /* Round ending address up; get number of longwords that makes.  */
  register int count
  = (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1) / sizeof (PTRACE_XFER_TYPE);
  /* Allocate buffer of that many longwords.  */
  register PTRACE_XFER_TYPE *buffer = (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
  int pid = lwpid_of (get_thread_lwp (current_inferior));

  if (debug_threads)
    {
      /* Dump up to four bytes.  */
      unsigned int val = * (unsigned int *) myaddr;
      if (len == 1)
	val = val & 0xff;
      else if (len == 2)
	val = val & 0xffff;
      else if (len == 3)
	val = val & 0xffffff;
      fprintf (stderr, "Writing %0*x to 0x%08lx\n", 2 * ((len < 4) ? len : 4),
	       val, (long)memaddr);
    }

  /* Fill start and end extra bytes of buffer with existing memory data.  */

  buffer[0] = ptrace (PTRACE_PEEKTEXT, pid, (PTRACE_ARG3_TYPE) addr, 0);

  if (count > 1)
    {
      buffer[count - 1]
	= ptrace (PTRACE_PEEKTEXT, pid,
		  (PTRACE_ARG3_TYPE) (addr + (count - 1)
				      * sizeof (PTRACE_XFER_TYPE)),
		  0);
    }

  /* Copy data to be written over corresponding part of buffer */

  memcpy ((char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)), myaddr, len);

  /* Write the entire buffer.  */

  for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
    {
      errno = 0;
      ptrace (PTRACE_POKETEXT, pid, (PTRACE_ARG3_TYPE) addr, buffer[i]);
      if (errno)
	return errno;
    }

  return 0;
}

static int linux_supports_tracefork_flag;

/* Helper functions for linux_test_for_tracefork, called via clone ().  */

static int
linux_tracefork_grandchild (void *arg)
{
  _exit (0);
}

#define STACK_SIZE 4096

static int
linux_tracefork_child (void *arg)
{
  ptrace (PTRACE_TRACEME, 0, 0, 0);
  kill (getpid (), SIGSTOP);
#ifdef __ia64__
  __clone2 (linux_tracefork_grandchild, arg, STACK_SIZE,
	    CLONE_VM | SIGCHLD, NULL);
#else
  clone (linux_tracefork_grandchild, arg + STACK_SIZE,
	 CLONE_VM | SIGCHLD, NULL);
#endif
  _exit (0);
}

/* Wrapper function for waitpid which handles EINTR, and emulates
   __WALL for systems where that is not available.  */

static int
my_waitpid (int pid, int *status, int flags)
{
  int ret, out_errno;

  if (debug_threads)
    fprintf (stderr, "my_waitpid (%d, 0x%x)\n", pid, flags);

  if (flags & __WALL)
    {
      sigset_t block_mask, org_mask, wake_mask;
      int wnohang;

      wnohang = (flags & WNOHANG) != 0;
      flags &= ~(__WALL | __WCLONE);
      flags |= WNOHANG;

      /* Block all signals while here.  This avoids knowing about
	 LinuxThread's signals.  */
      sigfillset (&block_mask);
      sigprocmask (SIG_BLOCK, &block_mask, &org_mask);

      /* ... except during the sigsuspend below.  */
      sigemptyset (&wake_mask);

      while (1)
	{
	  /* Since all signals are blocked, there's no need to check
	     for EINTR here.  */
	  ret = waitpid (pid, status, flags);
	  out_errno = errno;

	  if (ret == -1 && out_errno != ECHILD)
	    break;
	  else if (ret > 0)
	    break;

	  if (flags & __WCLONE)
	    {
	      /* We've tried both flavors now.  If WNOHANG is set,
		 there's nothing else to do, just bail out.  */
	      if (wnohang)
		break;

	      if (debug_threads)
		fprintf (stderr, "blocking\n");

	      /* Block waiting for signals.  */
	      sigsuspend (&wake_mask);
	    }

	  flags ^= __WCLONE;
	}

      sigprocmask (SIG_SETMASK, &org_mask, NULL);
    }
  else
    {
      do
	ret = waitpid (pid, status, flags);
      while (ret == -1 && errno == EINTR);
      out_errno = errno;
    }

  if (debug_threads)
    fprintf (stderr, "my_waitpid (%d, 0x%x): status(%x), %d\n",
	     pid, flags, status ? *status : -1, ret);

  errno = out_errno;
  return ret;
}

/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events.  Make
   sure that we can enable the option, and that it had the desired
   effect.  */

static void
linux_test_for_tracefork (void)
{
  int child_pid, ret, status;
  long second_pid;
  char *stack = xmalloc (STACK_SIZE * 4);

  linux_supports_tracefork_flag = 0;

  /* Use CLONE_VM instead of fork, to support uClinux (no MMU).  */
#ifdef __ia64__
  child_pid = __clone2 (linux_tracefork_child, stack, STACK_SIZE,
			CLONE_VM | SIGCHLD, stack + STACK_SIZE * 2);
#else
  child_pid = clone (linux_tracefork_child, stack + STACK_SIZE,
		     CLONE_VM | SIGCHLD, stack + STACK_SIZE * 2);
#endif
  if (child_pid == -1)
    perror_with_name ("clone");

  ret = my_waitpid (child_pid, &status, 0);
  if (ret == -1)
    perror_with_name ("waitpid");
  else if (ret != child_pid)
    error ("linux_test_for_tracefork: waitpid: unexpected result %d.", ret);
  if (! WIFSTOPPED (status))
    error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status);

  ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0, PTRACE_O_TRACEFORK);
  if (ret != 0)
    {
      ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
      if (ret != 0)
	{
	  warning ("linux_test_for_tracefork: failed to kill child");
	  return;
	}

      ret = my_waitpid (child_pid, &status, 0);
      if (ret != child_pid)
	warning ("linux_test_for_tracefork: failed to wait for killed child");
      else if (!WIFSIGNALED (status))
	warning ("linux_test_for_tracefork: unexpected wait status 0x%x from "
		 "killed child", status);

      return;
    }

  ret = ptrace (PTRACE_CONT, child_pid, 0, 0);
  if (ret != 0)
    warning ("linux_test_for_tracefork: failed to resume child");

  ret = my_waitpid (child_pid, &status, 0);

  if (ret == child_pid && WIFSTOPPED (status)
      && status >> 16 == PTRACE_EVENT_FORK)
    {
      second_pid = 0;
      ret = ptrace (PTRACE_GETEVENTMSG, child_pid, 0, &second_pid);
      if (ret == 0 && second_pid != 0)
	{
	  int second_status;

	  linux_supports_tracefork_flag = 1;
	  my_waitpid (second_pid, &second_status, 0);
	  ret = ptrace (PTRACE_KILL, second_pid, 0, 0);
	  if (ret != 0)
	    warning ("linux_test_for_tracefork: failed to kill second child");
	  my_waitpid (second_pid, &status, 0);
	}
    }
  else
    warning ("linux_test_for_tracefork: unexpected result from waitpid "
	     "(%d, status 0x%x)", ret, status);

  do
    {
      ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
      if (ret != 0)
	warning ("linux_test_for_tracefork: failed to kill child");
      my_waitpid (child_pid, &status, 0);
    }
  while (WIFSTOPPED (status));

  free (stack);
}


static void
linux_look_up_symbols (void)
{
#ifdef USE_THREAD_DB
  struct process_info *proc = current_process ();

  if (proc->private->thread_db_active)
    return;

  proc->private->thread_db_active
    = thread_db_init (!linux_supports_tracefork_flag);
#endif
}

static void
linux_request_interrupt (void)
{
  extern unsigned long signal_pid;

  if (!ptid_equal (cont_thread, null_ptid)
      && !ptid_equal (cont_thread, minus_one_ptid))
    {
      struct lwp_info *lwp;
      int lwpid;

      lwp = get_thread_lwp (current_inferior);
      lwpid = lwpid_of (lwp);
      kill_lwp (lwpid, SIGINT);
    }
  else
    kill_lwp (signal_pid, SIGINT);
}

/* Copy LEN bytes from inferior's auxiliary vector starting at OFFSET
   to debugger memory starting at MYADDR.  */

static int
linux_read_auxv (CORE_ADDR offset, unsigned char *myaddr, unsigned int len)
{
  char filename[PATH_MAX];
  int fd, n;
  int pid = lwpid_of (get_thread_lwp (current_inferior));

  snprintf (filename, sizeof filename, "/proc/%d/auxv", pid);

  fd = open (filename, O_RDONLY);
  if (fd < 0)
    return -1;

  if (offset != (CORE_ADDR) 0
      && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
    n = -1;
  else
    n = read (fd, myaddr, len);

  close (fd);

  return n;
}

/* These breakpoint and watchpoint related wrapper functions simply
   pass on the function call if the target has registered a
   corresponding function.  */

static int
linux_insert_point (char type, CORE_ADDR addr, int len)
{
  if (the_low_target.insert_point != NULL)
    return the_low_target.insert_point (type, addr, len);
  else
    /* Unsupported (see target.h).  */
    return 1;
}

static int
linux_remove_point (char type, CORE_ADDR addr, int len)
{
  if (the_low_target.remove_point != NULL)
    return the_low_target.remove_point (type, addr, len);
  else
    /* Unsupported (see target.h).  */
    return 1;
}

static int
linux_stopped_by_watchpoint (void)
{
  if (the_low_target.stopped_by_watchpoint != NULL)
    return the_low_target.stopped_by_watchpoint ();
  else
    return 0;
}

static CORE_ADDR
linux_stopped_data_address (void)
{
  if (the_low_target.stopped_data_address != NULL)
    return the_low_target.stopped_data_address ();
  else
    return 0;
}

#if defined(__UCLIBC__) && defined(HAS_NOMMU)
#if defined(__mcoldfire__)
/* These should really be defined in the kernel's ptrace.h header.  */
#define PT_TEXT_ADDR 49*4
#define PT_DATA_ADDR 50*4
#define PT_TEXT_END_ADDR  51*4
#endif

/* Under uClinux, programs are loaded at non-zero offsets, which we need
   to tell gdb about.  */

static int
linux_read_offsets (CORE_ADDR *text_p, CORE_ADDR *data_p)
{
#if defined(PT_TEXT_ADDR) && defined(PT_DATA_ADDR) && defined(PT_TEXT_END_ADDR)
  unsigned long text, text_end, data;
  int pid = lwpid_of (get_thread_lwp (current_inferior));

  errno = 0;

  text = ptrace (PTRACE_PEEKUSER, pid, (long)PT_TEXT_ADDR, 0);
  text_end = ptrace (PTRACE_PEEKUSER, pid, (long)PT_TEXT_END_ADDR, 0);
  data = ptrace (PTRACE_PEEKUSER, pid, (long)PT_DATA_ADDR, 0);

  if (errno == 0)
    {
      /* Both text and data offsets produced at compile-time (and so
	 used by gdb) are relative to the beginning of the program,
	 with the data segment immediately following the text segment.
	 However, the actual runtime layout in memory may put the data
	 somewhere else, so when we send gdb a data base-address, we
	 use the real data base address and subtract the compile-time
	 data base-address from it (which is just the length of the
	 text segment).  BSS immediately follows data in both
	 cases.  */
      *text_p = text;
      *data_p = data - (text_end - text);

      return 1;
    }
#endif
 return 0;
}
#endif

static int
linux_qxfer_osdata (const char *annex,
		    unsigned char *readbuf, unsigned const char *writebuf,
		    CORE_ADDR offset, int len)
{
  /* We make the process list snapshot when the object starts to be
     read.  */
  static const char *buf;
  static long len_avail = -1;
  static struct buffer buffer;

  DIR *dirp;

  if (strcmp (annex, "processes") != 0)
    return 0;

  if (!readbuf || writebuf)
    return 0;

  if (offset == 0)
    {
      if (len_avail != -1 && len_avail != 0)
       buffer_free (&buffer);
      len_avail = 0;
      buf = NULL;
      buffer_init (&buffer);
      buffer_grow_str (&buffer, "<osdata type=\"processes\">");

      dirp = opendir ("/proc");
      if (dirp)
       {
	 struct dirent *dp;
	 while ((dp = readdir (dirp)) != NULL)
	   {
	     struct stat statbuf;
	     char procentry[sizeof ("/proc/4294967295")];

	     if (!isdigit (dp->d_name[0])
		 || strlen (dp->d_name) > sizeof ("4294967295") - 1)
	       continue;

	     sprintf (procentry, "/proc/%s", dp->d_name);
	     if (stat (procentry, &statbuf) == 0
		 && S_ISDIR (statbuf.st_mode))
	       {
		 char pathname[128];
		 FILE *f;
		 char cmd[MAXPATHLEN + 1];
		 struct passwd *entry;

		 sprintf (pathname, "/proc/%s/cmdline", dp->d_name);
		 entry = getpwuid (statbuf.st_uid);

		 if ((f = fopen (pathname, "r")) != NULL)
		   {
		     size_t len = fread (cmd, 1, sizeof (cmd) - 1, f);
		     if (len > 0)
		       {
			 int i;
			 for (i = 0; i < len; i++)
			   if (cmd[i] == '\0')
			     cmd[i] = ' ';
			 cmd[len] = '\0';

			 buffer_xml_printf (
			   &buffer,
			   "<item>"
			   "<column name=\"pid\">%s</column>"
			   "<column name=\"user\">%s</column>"
			   "<column name=\"command\">%s</column>"
			   "</item>",
			   dp->d_name,
			   entry ? entry->pw_name : "?",
			   cmd);
		       }
		     fclose (f);
		   }
	       }
	   }

	 closedir (dirp);
       }
      buffer_grow_str0 (&buffer, "</osdata>\n");
      buf = buffer_finish (&buffer);
      len_avail = strlen (buf);
    }

  if (offset >= len_avail)
    {
      /* Done.  Get rid of the data.  */
      buffer_free (&buffer);
      buf = NULL;
      len_avail = 0;
      return 0;
    }

  if (len > len_avail - offset)
    len = len_avail - offset;
  memcpy (readbuf, buf + offset, len);

  return len;
}

/* Convert a native/host siginfo object, into/from the siginfo in the
   layout of the inferiors' architecture.  */

static void
siginfo_fixup (struct siginfo *siginfo, void *inf_siginfo, int direction)
{
  int done = 0;

  if (the_low_target.siginfo_fixup != NULL)
    done = the_low_target.siginfo_fixup (siginfo, inf_siginfo, direction);

  /* If there was no callback, or the callback didn't do anything,
     then just do a straight memcpy.  */
  if (!done)
    {
      if (direction == 1)
	memcpy (siginfo, inf_siginfo, sizeof (struct siginfo));
      else
	memcpy (inf_siginfo, siginfo, sizeof (struct siginfo));
    }
}

static int
linux_xfer_siginfo (const char *annex, unsigned char *readbuf,
		    unsigned const char *writebuf, CORE_ADDR offset, int len)
{
  int pid;
  struct siginfo siginfo;
  char inf_siginfo[sizeof (struct siginfo)];

  if (current_inferior == NULL)
    return -1;

  pid = lwpid_of (get_thread_lwp (current_inferior));

  if (debug_threads)
    fprintf (stderr, "%s siginfo for lwp %d.\n",
	     readbuf != NULL ? "Reading" : "Writing",
	     pid);

  if (offset > sizeof (siginfo))
    return -1;

  if (ptrace (PTRACE_GETSIGINFO, pid, 0, &siginfo) != 0)
    return -1;

  /* When GDBSERVER is built as a 64-bit application, ptrace writes into
     SIGINFO an object with 64-bit layout.  Since debugging a 32-bit
     inferior with a 64-bit GDBSERVER should look the same as debugging it
     with a 32-bit GDBSERVER, we need to convert it.  */
  siginfo_fixup (&siginfo, inf_siginfo, 0);

  if (offset + len > sizeof (siginfo))
    len = sizeof (siginfo) - offset;

  if (readbuf != NULL)
    memcpy (readbuf, inf_siginfo + offset, len);
  else
    {
      memcpy (inf_siginfo + offset, writebuf, len);

      /* Convert back to ptrace layout before flushing it out.  */
      siginfo_fixup (&siginfo, inf_siginfo, 1);

      if (ptrace (PTRACE_SETSIGINFO, pid, 0, &siginfo) != 0)
	return -1;
    }

  return len;
}

/* SIGCHLD handler that serves two purposes: In non-stop/async mode,
   so we notice when children change state; as the handler for the
   sigsuspend in my_waitpid.  */

static void
sigchld_handler (int signo)
{
  int old_errno = errno;

  if (debug_threads)
    /* fprintf is not async-signal-safe, so call write directly.  */
    write (2, "sigchld_handler\n", sizeof ("sigchld_handler\n") - 1);

  if (target_is_async_p ())
    async_file_mark (); /* trigger a linux_wait */

  errno = old_errno;
}

static int
linux_supports_non_stop (void)
{
  return 1;
}

static int
linux_async (int enable)
{
  int previous = (linux_event_pipe[0] != -1);

  if (previous != enable)
    {
      sigset_t mask;
      sigemptyset (&mask);
      sigaddset (&mask, SIGCHLD);

      sigprocmask (SIG_BLOCK, &mask, NULL);

      if (enable)
	{
	  if (pipe (linux_event_pipe) == -1)
	    fatal ("creating event pipe failed.");

	  fcntl (linux_event_pipe[0], F_SETFL, O_NONBLOCK);
	  fcntl (linux_event_pipe[1], F_SETFL, O_NONBLOCK);

	  /* Register the event loop handler.  */
	  add_file_handler (linux_event_pipe[0],
			    handle_target_event, NULL);

	  /* Always trigger a linux_wait.  */
	  async_file_mark ();
	}
      else
	{
	  delete_file_handler (linux_event_pipe[0]);

	  close (linux_event_pipe[0]);
	  close (linux_event_pipe[1]);
	  linux_event_pipe[0] = -1;
	  linux_event_pipe[1] = -1;
	}

      sigprocmask (SIG_UNBLOCK, &mask, NULL);
    }

  return previous;
}

static int
linux_start_non_stop (int nonstop)
{
  /* Register or unregister from event-loop accordingly.  */
  linux_async (nonstop);
  return 0;
}

static int
linux_supports_multi_process (void)
{
  return 1;
}


/* Enumerate spufs IDs for process PID.  */
static int
spu_enumerate_spu_ids (long pid, unsigned char *buf, CORE_ADDR offset, int len)
{
  int pos = 0;
  int written = 0;
  char path[128];
  DIR *dir;
  struct dirent *entry;

  sprintf (path, "/proc/%ld/fd", pid);
  dir = opendir (path);
  if (!dir)
    return -1;

  rewinddir (dir);
  while ((entry = readdir (dir)) != NULL)
    {
      struct stat st;
      struct statfs stfs;
      int fd;

      fd = atoi (entry->d_name);
      if (!fd)
        continue;

      sprintf (path, "/proc/%ld/fd/%d", pid, fd);
      if (stat (path, &st) != 0)
        continue;
      if (!S_ISDIR (st.st_mode))
        continue;

      if (statfs (path, &stfs) != 0)
        continue;
      if (stfs.f_type != SPUFS_MAGIC)
        continue;

      if (pos >= offset && pos + 4 <= offset + len)
        {
          *(unsigned int *)(buf + pos - offset) = fd;
          written += 4;
        }
      pos += 4;
    }

  closedir (dir);
  return written;
}

/* Implements the to_xfer_partial interface for the TARGET_OBJECT_SPU
   object type, using the /proc file system.  */
static int
linux_qxfer_spu (const char *annex, unsigned char *readbuf,
		 unsigned const char *writebuf,
		 CORE_ADDR offset, int len)
{
  long pid = lwpid_of (get_thread_lwp (current_inferior));
  char buf[128];
  int fd = 0;
  int ret = 0;

  if (!writebuf && !readbuf)
    return -1;

  if (!*annex)
    {
      if (!readbuf)
	return -1;
      else
	return spu_enumerate_spu_ids (pid, readbuf, offset, len);
    }

  sprintf (buf, "/proc/%ld/fd/%s", pid, annex);
  fd = open (buf, writebuf? O_WRONLY : O_RDONLY);
  if (fd <= 0)
    return -1;

  if (offset != 0
      && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
    {
      close (fd);
      return 0;
    }

  if (writebuf)
    ret = write (fd, writebuf, (size_t) len);
  else
    ret = read (fd, readbuf, (size_t) len);

  close (fd);
  return ret;
}

static struct target_ops linux_target_ops = {
  linux_create_inferior,
  linux_attach,
  linux_kill,
  linux_detach,
  linux_join,
  linux_thread_alive,
  linux_resume,
  linux_wait,
  linux_fetch_registers,
  linux_store_registers,
  linux_read_memory,
  linux_write_memory,
  linux_look_up_symbols,
  linux_request_interrupt,
  linux_read_auxv,
  linux_insert_point,
  linux_remove_point,
  linux_stopped_by_watchpoint,
  linux_stopped_data_address,
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
  linux_read_offsets,
#else
  NULL,
#endif
#ifdef USE_THREAD_DB
  thread_db_get_tls_address,
#else
  NULL,
#endif
  linux_qxfer_spu,
  hostio_last_error_from_errno,
  linux_qxfer_osdata,
  linux_xfer_siginfo,
  linux_supports_non_stop,
  linux_async,
  linux_start_non_stop,
  linux_supports_multi_process
};

static void
linux_init_signals ()
{
  /* FIXME drow/2002-06-09: As above, we should check with LinuxThreads
     to find what the cancel signal actually is.  */
  signal (__SIGRTMIN+1, SIG_IGN);
}

void
initialize_low (void)
{
  struct sigaction sigchld_action;
  memset (&sigchld_action, 0, sizeof (sigchld_action));
  set_target_ops (&linux_target_ops);
  set_breakpoint_data (the_low_target.breakpoint,
		       the_low_target.breakpoint_len);
  linux_init_signals ();
  linux_test_for_tracefork ();
#ifdef HAVE_LINUX_REGSETS
  for (num_regsets = 0; target_regsets[num_regsets].size >= 0; num_regsets++)
    ;
  disabled_regsets = xmalloc (num_regsets);
#endif

  sigchld_action.sa_handler = sigchld_handler;
  sigemptyset (&sigchld_action.sa_mask);
  sigchld_action.sa_flags = SA_RESTART;
  sigaction (SIGCHLD, &sigchld_action, NULL);
}