[AArch64] Also puts value in place for R_AARCH64_RELATIVE

When handling absolute relocations for global symbols bind within the
shared object, AArch64 will generate one dynamic RELATIVE relocation,
but won't apply the value for this absolution relocations at static
linking stage. This is different from AArch64 gold linker and x86-64.

This is not a bug as AArch64 is RELA, there is only guarantee that
relocation addend is placed in the relocation entry.  But some
system softwares originally writen for x86-64 might assume AArch64
bfd linker gets the same behavior as x86-64, then they could take
advantage of this buy skipping those RELATIVE dynamic relocations
if the load address is the same as the static linking address.

This patch makes AArch64 BFD linker applies absolution relocations at
static linking stage for scenario described above.  Meanwhile old AArch64
android loader has a bug (PR19163) which relies on current linker behavior
as a workaround, so the same option --no-apply-dynamic-relocs added.

9 files changed, 89 insertions, 1 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 92596b7..7d8d8ee 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,15 @@
+2016-05-03  Jiong Wang  <jiong.wang@arm.com>
+
+	* emultempl/aarch64elf.em (--no-apply-dynamic-relocs): New option.
+	* NEWS: Mention --no-apply-dynamic-relocs.
+	* ld.texinfo (ld and the ARM family): Document
+	--no-apply-dynamic-relocs.
+	* testsuite/ld-aarch64/rela-abs-relative.s: New test source.
+	* testsuite/ld-aarch64/rela-abs-relative.d: New expected result.
+	* testsuite/ld-aarch64/rela-abs-relative-be.d: Likewise for big-endian.
+	* estsuite/ld-aarch64/rela-abs-relative-opt.d: Likewise, but enable new
+	option.
+
 2016-05-03  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
 
 	* testsuite/ld-elfcomm/elfcomm.exp: Check for shared lib support
diff --git a/ld/NEWS b/ld/NEWS
index b4abd0b..228fddf 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -11,6 +11,9 @@
 
 * The NOCROSSREFSTO command was added to the linker script language.
 
+* Add --no-apply-dynamic-relocs to the AArch64 linker to do not apply link-time
+  values for dynamic relocations.
+
 Changes in 2.26:
 
 * Add --fix-stm32l4xx-629360 to the ARM linker to enable a link-time
diff --git a/ld/emultempl/aarch64elf.em b/ld/emultempl/aarch64elf.em
index 9923be3..a17553a 100644
--- a/ld/emultempl/aarch64elf.em
+++ b/ld/emultempl/aarch64elf.em
@@ -32,6 +32,7 @@ static int no_wchar_size_warning = 0;
 static int pic_veneer = 0;
 static int fix_erratum_835769 = 0;
 static int fix_erratum_843419 = 0;
+static int no_apply_dynamic_relocs = 0;
 
 static void
 gld${EMULATION_NAME}_before_parse (void)
@@ -305,7 +306,8 @@ aarch64_elf_create_output_section_statements (void)
 				 no_enum_size_warning,
 				 no_wchar_size_warning,
 				 pic_veneer,
-				 fix_erratum_835769, fix_erratum_843419);
+				 fix_erratum_835769, fix_erratum_843419,
+				 no_apply_dynamic_relocs);
 
   stub_file = lang_add_input_file ("linker stubs",
 				   lang_input_file_is_fake_enum,
@@ -356,6 +358,7 @@ PARSE_AND_LIST_PROLOGUE='
 #define OPTION_NO_WCHAR_SIZE_WARNING	312
 #define OPTION_FIX_ERRATUM_835769	313
 #define OPTION_FIX_ERRATUM_843419	314
+#define OPTION_NO_APPLY_DYNAMIC_RELOCS	315
 '
 
 PARSE_AND_LIST_SHORTOPTS=p
@@ -368,6 +371,7 @@ PARSE_AND_LIST_LONGOPTS='
   { "no-wchar-size-warning", no_argument, NULL, OPTION_NO_WCHAR_SIZE_WARNING},
   { "fix-cortex-a53-835769", no_argument, NULL, OPTION_FIX_ERRATUM_835769},
   { "fix-cortex-a53-843419", no_argument, NULL, OPTION_FIX_ERRATUM_843419},
+  { "no-apply-dynamic-relocs", no_argument, NULL, OPTION_NO_APPLY_DYNAMIC_RELOCS},
 '
 
 PARSE_AND_LIST_OPTIONS='
@@ -387,6 +391,7 @@ PARSE_AND_LIST_OPTIONS='
 		   ));
   fprintf (file, _("  --fix-cortex-a53-835769      Fix erratum 835769\n"));
   fprintf (file, _("  --fix-cortex-a53-843419      Fix erratum 843419\n"));
+  fprintf (file, _("  --no-apply-dynamic-relocs	   Do not apply link-time values for dynamic relocations\n"));
 '
 
 PARSE_AND_LIST_ARGS_CASES='
@@ -414,6 +419,10 @@ PARSE_AND_LIST_ARGS_CASES='
       fix_erratum_843419 = 1;
       break;
 
+    case OPTION_NO_APPLY_DYNAMIC_RELOCS:
+      no_apply_dynamic_relocs = 1;
+      break;
+
     case OPTION_STUBGROUP_SIZE:
       {
 	const char *end;
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index 7a2ed3a..bc16764 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -6848,6 +6848,11 @@ The @samp{--long-plt} option enables the use of 16 byte PLT entries
 which support up to 4Gb of code.  The default is to use 12 byte PLT
 entries which only support 512Mb of code.
 
+@kindex --no-apply-dynamic-relocs
+@cindex AArch64 rela addend
+The @samp{--no-apply-dynamic-relocs} option makes AArch64 linker do not apply
+link-time values for dynamic relocations.
+
 @ifclear GENERIC
 @lowersections
 @end ifclear
diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index b9c4133..b27da52 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -285,6 +285,10 @@ run_dump_test "dt_textrel"
 
 run_dump_test "plt_mapping_symbol"
 
+run_dump_test "rela-abs-relative"
+run_dump_test "rela-abs-relative-be"
+run_dump_test "rela-abs-relative-opt"
+
 set aarch64elflinktests {
   {"ld-aarch64/so with global symbol" "-shared" "" "" {copy-reloc-so.s}
     {} "copy-reloc-so.so"}
diff --git a/ld/testsuite/ld-aarch64/rela-abs-relative-be.d b/ld/testsuite/ld-aarch64/rela-abs-relative-be.d
new file mode 100644
index 0000000..88ba58d
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/rela-abs-relative-be.d
@@ -0,0 +1,13 @@
+#name: rela-abs-relative (big endian)
+#source: rela-abs-relative.s
+#ld: -shared -Ttext-segment=0x100000 -Tdata=0x200000 -Trelocs.ld
+#target: aarch64_be-*-*
+#objdump: -dR -j .data
+#...
+
+Disassembly of section .data:
+
+.* <a>:
+  200000:	00 00 00 00 ca fe ca fe 00 00 00 00 00 01 00 ca.*
+			200008: R_AARCH64_RELATIVE	\*ABS\*\+0x100ca
+  200010:	00 00 00 00 de ad de ad.*
diff --git a/ld/testsuite/ld-aarch64/rela-abs-relative-opt.d b/ld/testsuite/ld-aarch64/rela-abs-relative-opt.d
new file mode 100644
index 0000000..a1e5ca0
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/rela-abs-relative-opt.d
@@ -0,0 +1,13 @@
+#name: rela-abs-relative --no-apply-dynamic-relocs
+#source: rela-abs-relative.s
+#ld: -shared -Ttext-segment=0x100000 -Tdata=0x200000 -Trelocs.ld --no-apply-dynamic-relocs
+#notarget: aarch64_be-*-*
+#objdump: -dR -j .data
+#...
+
+Disassembly of section .data:
+
+.* <a>:
+  200000:	fe ca fe ca 00 00 00 00 00 00 00 00 00 00 00 00.*
+			200008: R_AARCH64_RELATIVE	\*ABS\*\+0x100ca
+  200010:	ad de ad de 00 00 00 00.*
diff --git a/ld/testsuite/ld-aarch64/rela-abs-relative.d b/ld/testsuite/ld-aarch64/rela-abs-relative.d
new file mode 100644
index 0000000..aba876b
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/rela-abs-relative.d
@@ -0,0 +1,13 @@
+#name: rela-abs-relative
+#source: rela-abs-relative.s
+#ld: -shared -Ttext-segment=0x100000 -Tdata=0x200000 -Trelocs.ld
+#notarget: aarch64_be-*-*
+#objdump: -dR -j .data
+#...
+
+Disassembly of section .data:
+
+.* <a>:
+  200000:	fe ca fe ca 00 00 00 00 ca 00 01 00 00 00 00 00.*
+			200008: R_AARCH64_RELATIVE	\*ABS\*\+0x100ca
+  200010:	ad de ad de 00 00 00 00.*
diff --git a/ld/testsuite/ld-aarch64/rela-abs-relative.s b/ld/testsuite/ld-aarch64/rela-abs-relative.s
new file mode 100644
index 0000000..d4c4663
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/rela-abs-relative.s
@@ -0,0 +1,16 @@
+	.section	.rodata
+	.align	3
+	.type	string1, %object
+	.size	string1, 8
+local_foo:
+	.string	"local_foo"
+
+	.section	.data,"aw",%progbits
+	.align	3
+	.global	a
+	.type	a, %object
+	.size	a, 24
+a:
+	.xword	0xcafecafe
+	.xword	local_foo + 0xca
+	.xword	0xdeaddead