diff options
| -rw-r--r-- | gold/ChangeLog | 5 | ||||
| -rw-r--r-- | gold/testsuite/ifunc-sel.h | 88 |
2 files changed, 82 insertions, 11 deletions
diff --git a/gold/ChangeLog b/gold/ChangeLog index b0c5fc7..efd7752 100644 --- a/gold/ChangeLog +++ b/gold/ChangeLog @@ -1,5 +1,10 @@ 2013-03-07 Alan Modra <amodra@gmail.com> + * testsuite/ifunc-sel.h (ifunc_sel, ifunc_one): Mark + always_inline. Add assembly for powerpc to avoid GOT. + +2013-03-07 Alan Modra <amodra@gmail.com> + * testsuite/script_test_10.sh: Don't test .bss section header number. diff --git a/gold/testsuite/ifunc-sel.h b/gold/testsuite/ifunc-sel.h index 6a27b69..9439659 100644 --- a/gold/testsuite/ifunc-sel.h +++ b/gold/testsuite/ifunc-sel.h @@ -4,23 +4,89 @@ extern int global; -static inline void * +static inline __attribute__ ((always_inline)) void * ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void)) { - switch (global) - { - case 1: - return f1; - case -1: - return f2; - default: - return f3; - } +#ifdef __powerpc__ + /* When generating PIC, powerpc gcc loads the address of "global" + from the GOT, but the GOT may not have been relocated. + Similarly, "f1", "f2" and "f3" may be loaded from non-relocated + GOT entries. + + There is NO WAY to make this ill conceived IFUNC misfeature + reliably work on targets that use a GOT for function or variable + addresses, short of implementing two passes over relocations in + ld.so, with ifunc relocations being applied after all other + relocations, globally. + + Cheat. Don't use the GOT. Rely on this function being inlined + and calculate all variable and function addresses relative to pc. + Using the 'X' constraint is risky, but that's the only way to + make the asm here see the function names for %4, %5 and %6. + Sadly, powerpc64 gcc doesn't accept use of %3 here with 'X' for + some reason, so we expand it ourselves. */ + register void *ret __asm__ ("r3"); + void *temp1, *temp2; + __asm__ ("mflr %1\n\t" + "bcl 20,31,1f\n" + "1:\tmflr %2\n\t" + "mtlr %1\n\t" + "addis %1,%2,global-1b@ha\n\t" + "lwz %1,global-1b@l(%1)\n\t" + "addis %0,%2,%4-1b@ha\n\t" + "addi %0,%0,%4-1b@l\n\t" + "cmpwi %1,1\n\t" + "beqlr\n\t" + "addis %0,%2,%5-1b@ha\n\t" + "addi %0,%0,%5-1b@l\n\t" + "cmpwi %1,-1\n\t" + "beqlr\n\t" + "addis %0,%2,%6-1b@ha\n\t" + "addi %0,%0,%6-1b@l" + : "=&b" (ret), "=&b" (temp1), "=&b" (temp2) + : "X" (&global), "X" (f1), "X" (f2), "X" (f3)); + return ret; +#else + switch (global) + { + case 1: + return f1; + case -1: + return f2; + default: + return f3; + } +#endif } -static inline void * +static inline __attribute__ ((always_inline)) void * ifunc_one (int (*f1) (void)) { +#ifdef __powerpc__ + /* As above, PIC may use an unrelocated GOT entry for f1. + + Case study: ifuncmain6pie's shared library, ifuncmod6.so, wants + the address of "foo" in function get_foo(). So there is a GOT + entry for "foo" in ifuncmod6.so. ld.so relocates ifuncmod6.so + *before* ifuncmain6pie, and on finding "foo" to be STT_GNU_IFUNC, + calls this function with f1 set to "one". But the address of + "one" is loaded from ifuncmain6pie's GOT, which hasn't been + relocated yet. + + Cheat as for ifunc-sel. */ + register void *ret __asm__ ("r3"); + void *temp; + __asm__ ("mflr %1\n\t" + "bcl 20,31,1f\n" + "1:\tmflr %0\n\t" + "mtlr %1\n\t" + "addis %0,%0,%2-1b@ha\n\t" + "addi %0,%0,%2-1b@l" + : "=&b" (ret), "=&r" (temp) + : "X" (f1)); + return ret; +#else return f1; +#endif } #endif |