[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.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 394e83c96174d68c24a70c27314646cf332d27f5..432ec9150231d9b7c14b17ac5727506afc9b7ba3 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,12 @@
+2016-05-03  Jiong Wang  <jiong.wang@arm.com>
+
+       * bfd-in.h (bfd_elf64_aarch64_set_options): Update prototype.
+       * bfd-in2.h (bfd_elf64_aarch64_set_options): Likewise.
+       * elfnn-aarch64.c (bfd_elfNN_aarch64_set_options): Initialize
+       no_apply_dynamic_relocs.
+       (elfNN_aarch64_final_link_relocate): Apply absolute relocations even though
+       dynamic relocations generated.
+
 2016-04-29  H.J. Lu  <hongjiu.lu@intel.com>
 
        * elf32-i386.c (elf_i386_size_dynamic_sections): Move interp

diff --git a/bfd/bfd-in.h b/bfd/bfd-in.h
index 5df2babf88b094524b11e8edf3ba6a6acaf1d3b8..46414056d60a139b525558745ccfa7eb8a839f52 100644 (file)
--- a/bfd/bfd-in.h
+++ b/bfd/bfd-in.h
@@ -961,10 +961,10 @@ extern void bfd_elf32_aarch64_init_maps
   (bfd *);
 
 extern void bfd_elf64_aarch64_set_options
-  (bfd *, struct bfd_link_info *, int, int, int, int, int);
+  (bfd *, struct bfd_link_info *, int, int, int, int, int, int);
 
 extern void bfd_elf32_aarch64_set_options
-  (bfd *, struct bfd_link_info *, int, int, int, int, int);
+  (bfd *, struct bfd_link_info *, int, int, int, int, int, int);
 
 /* ELF AArch64 mapping symbol support.  */
 #define BFD_AARCH64_SPECIAL_SYM_TYPE_MAP       (1 << 0)

diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index a19a6513992930442fa531235d58af73ef320ba2..f68c10766ae5d81a0ad436c48813546c009335bd 100644 (file)
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -968,10 +968,10 @@ extern void bfd_elf32_aarch64_init_maps
   (bfd *);
 
 extern void bfd_elf64_aarch64_set_options
-  (bfd *, struct bfd_link_info *, int, int, int, int, int);
+  (bfd *, struct bfd_link_info *, int, int, int, int, int, int);
 
 extern void bfd_elf32_aarch64_set_options
-  (bfd *, struct bfd_link_info *, int, int, int, int, int);
+  (bfd *, struct bfd_link_info *, int, int, int, int, int, int);
 
 /* ELF AArch64 mapping symbol support.  */
 #define BFD_AARCH64_SPECIAL_SYM_TYPE_MAP       (1 << 0)

diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 5b9878e8f3123bf12f739deb29d88716f762d687..eecbf87dc260258ec4e5f2eb5bebde03bbca83b2 100644 (file)
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -2289,6 +2289,9 @@ struct elf_aarch64_link_hash_table
   /* Enable ADRP->ADR rewrite for erratum 843419 workaround.  */
   int fix_erratum_843419_adr;
 
+  /* Don't apply link-time values for dynamic relocations.  */
+  int no_apply_dynamic_relocs;
+
   /* The number of bytes in the initial entry in the PLT.  */
   bfd_size_type plt_header_size;
 
@@ -4334,7 +4337,8 @@ bfd_elfNN_aarch64_set_options (struct bfd *output_bfd,
                               int no_enum_warn,
                               int no_wchar_warn, int pic_veneer,
                               int fix_erratum_835769,
-                              int fix_erratum_843419)
+                              int fix_erratum_843419,
+                              int no_apply_dynamic_relocs)
 {
   struct elf_aarch64_link_hash_table *globals;
 
@@ -4343,6 +4347,7 @@ bfd_elfNN_aarch64_set_options (struct bfd *output_bfd,
   globals->fix_erratum_835769 = fix_erratum_835769;
   globals->fix_erratum_843419 = fix_erratum_843419;
   globals->fix_erratum_843419_adr = TRUE;
+  globals->no_apply_dynamic_relocs = no_apply_dynamic_relocs;
 
   BFD_ASSERT (is_aarch64_elf (output_bfd));
   elf_aarch64_tdata (output_bfd)->no_enum_size_warning = no_enum_warn;
@@ -5208,6 +5213,7 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
                 relocate the text and data segments independently,
                 so the symbol does not matter.  */
              symbol = 0;
+             relocate = globals->no_apply_dynamic_relocs ? FALSE : TRUE;
              outrel.r_info = ELFNN_R_INFO (symbol, AARCH64_R (RELATIVE));
              outrel.r_addend += value;
            }

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 92596b7fe612172dc0c5e0f71baeb1b939f56e37..7d8d8ee995db0560d44c523b3c0636d8cc362827 100644 (file)
--- 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 b4abd0b5b8d22e1daa622db5c60017843cbdb2c6..228fddf71031ab6caf8e8f8b32c3117d00d7eacd 100644 (file)
--- 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 9923be3a6b685088cbd32377a13e1063206136ed..a17553a6a59e0a6e5c8180d279926003c21bd93e 100644 (file)
--- 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 7a2ed3abed3391d4022ddc794014e9ea54a93a6c..bc16764b0554851217316c438ada863843915307 100644 (file)
--- 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 b9c413307580f86dfb750316b4faf834a88d6eb8..b27da52acd8f11e017492e45122d96dc462c4d63 100644 (file)
--- 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 (file)
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 (file)
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 (file)
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 (file)
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