[AArch64] Relax long branch veneer insertion for non STT_FUNC symbol
authorJiong Wang <jiong.wang@arm.com>
Wed, 20 Jan 2016 16:57:59 +0000 (16:57 +0000)
committerJiong Wang <jiong.wang@arm.com>
Thu, 21 Jan 2016 09:57:09 +0000 (09:57 +0000)
  As defined at AArch64 ELF Specification (4.6.7 Call and Jump
  relocations), symbol with type of non STT_FUNC but in different input
  section with relocation place should insert long branch veneer also.

  Meanwhile the current long branch veneer infrastructure havn't considered
  the situation where the branch destination is "sym_value + rela->addend".

  This was OK because we only insert veneer for long call destination is
  STT_FUNC symbol for which the addend is always zero. But as we relax the
  support to other situations by this patch, we need to handle addend be
  non-zero value. For example, for static function, relocation against
  "local symbol" are turned into relocation against "section symbol + offset"
  where there is a valid addend.

  bfd/
* elfnn-aarch64.c (aarch64_type_of_stub): Allow insert long branch
veneer for sym_sec != input_sec.
(elfNN_aarch64_size_stub): Support STT_SECTION symbol.
(elfNN_aarch64_final_link_relocate): Take rela addend into account when
calculation destination.

  ld/
* testsuite/ld-aarch64/farcall-section.d: Delete.
* testsuite/ld-aarch64/farcall-section.s: Delete.
* testsuite/ld-aarch64/farcall-b-section.d: New expectation file.
* testsuite/ld-aarch64/farcall-bl-section.d: Likewise.
* testsuite/ld-aarch64/farcall-b-section.s: New testcase.
* testsuite/ld-aarch64/farcall-bl-section.s: Likewise.
* testsuite/ld-aarch64/aarch64-elf.exp: Likewise.

12 files changed:
bfd/ChangeLog
bfd/elfnn-aarch64.c
ld/ChangeLog
ld/testsuite/ld-aarch64/aarch64-elf.exp
ld/testsuite/ld-aarch64/farcall-b-none-function.d
ld/testsuite/ld-aarch64/farcall-b-section.d [new file with mode: 0644]
ld/testsuite/ld-aarch64/farcall-b-section.s [new file with mode: 0644]
ld/testsuite/ld-aarch64/farcall-bl-none-function.d
ld/testsuite/ld-aarch64/farcall-bl-section.d [new file with mode: 0644]
ld/testsuite/ld-aarch64/farcall-bl-section.s [new file with mode: 0644]
ld/testsuite/ld-aarch64/farcall-section.d [deleted file]
ld/testsuite/ld-aarch64/farcall-section.s [deleted file]

index dcf21ce..c4fd0bb 100644 (file)
@@ -1,3 +1,11 @@
+2016-01-21  Jiong Wang  <jiong.wang@arm.com>
+
+       * elfnn-aarch64.c (aarch64_type_of_stub): Allow insert long branch
+       veneer for sym_sec != input_sec.
+       (elfNN_aarch64_size_stub): Support STT_SECTION symbol.
+       (elfNN_aarch64_final_link_relocate): Take rela addend into account when
+       calculation destination.
+
 2016-01-21  Alan Modra  <amodra@gmail.com>
 
        * elf-linux-core.h (swap_linux_prpsinfo32_out): New function.
index 70251f1..292470d 100644 (file)
@@ -2655,7 +2655,7 @@ aarch64_type_of_stub (struct bfd_link_info *info,
   bfd_boolean via_plt_p;
 
   if (st_type != STT_FUNC
-      && (sym_sec != bfd_abs_section_ptr))
+      && (sym_sec == input_sec))
     return stub_type;
 
   globals = elf_aarch64_hash_table (info);
@@ -4174,7 +4174,7 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
                      goto error_ret_free_internal;
                    }
 
-                 stub_entry->target_value = sym_value;
+                 stub_entry->target_value = sym_value + irela->r_addend;
                  stub_entry->target_section = sym_sec;
                  stub_entry->stub_type = stub_type;
                  stub_entry->h = hash;
@@ -5280,15 +5280,28 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
        /* Check if a stub has to be inserted because the destination
           is too far away.  */
        struct elf_aarch64_stub_hash_entry *stub_entry = NULL;
-       if (! aarch64_valid_branch_p (value, place))
+
+       /* If the branch destination is directed to plt stub, "value" will be
+          the final destination, otherwise we should plus signed_addend, it may
+          contain non-zero value, for example call to local function symbol
+          which are turned into "sec_sym + sec_off", and sec_off is kept in
+          signed_addend.  */
+       if (! aarch64_valid_branch_p (via_plt_p ? value : value + signed_addend,
+                                     place))
          /* The target is out of reach, so redirect the branch to
             the local stub for this function.  */
        stub_entry = elfNN_aarch64_get_stub_entry (input_section, sym_sec, h,
                                                   rel, globals);
        if (stub_entry != NULL)
-         value = (stub_entry->stub_offset
-                  + stub_entry->stub_sec->output_offset
-                  + stub_entry->stub_sec->output_section->vma);
+         {
+           value = (stub_entry->stub_offset
+                    + stub_entry->stub_sec->output_offset
+                    + stub_entry->stub_sec->output_section->vma);
+
+           /* We have redirected the destination to stub entry address,
+              so ignore any addend record in the original rela entry.  */
+           signed_addend = 0;
+         }
       }
       value = _bfd_aarch64_elf_resolve_relocation (bfd_r_type, place, value,
                                                   signed_addend, weak_undef_p);
index fc01ed6..a6494b8 100644 (file)
@@ -1,3 +1,13 @@
+2016-01-20  Jiong Wang  <jiong.wang@arm.com>
+
+       * testsuite/ld-aarch64/farcall-section.d: Delete.
+       * testsuite/ld-aarch64/farcall-section.s: Delete.
+       * testsuite/ld-aarch64/farcall-b-section.d: New expectation file.
+       * testsuite/ld-aarch64/farcall-bl-section.d: Likewise.
+       * testsuite/ld-aarch64/farcall-b-section.s: New testcase.
+       * testsuite/ld-aarch64/farcall-bl-section.s: Likewise.
+       * testsuite/ld-aarch64/aarch64-elf.exp: Likewise.
+
 2016-01-20  Nick Clifton  <nickc@redhat.com>
 
        PR 19457
index c5c9ad0..939539e 100644 (file)
@@ -170,7 +170,6 @@ run_dump_test "pcrel_pic_defined_local"
 
 run_dump_test "limit-b"
 run_dump_test "limit-bl"
-run_dump_test "farcall-section"
 run_dump_test "farcall-back"
 run_dump_test "farcall-b-defsym"
 run_dump_test "farcall-bl-defsym"
@@ -181,6 +180,8 @@ run_dump_test "farcall-bl"
 run_dump_test "farcall-b"
 run_dump_test "farcall-b-none-function"
 run_dump_test "farcall-bl-none-function"
+run_dump_test "farcall-b-section"
+run_dump_test "farcall-bl-section"
 
 run_dump_test "tls-relax-all"
 run_dump_test "tls-relax-gd-le"
index 34a6568..ba2981f 100644 (file)
@@ -2,4 +2,23 @@
 #source: farcall-b-none-function.s
 #as:
 #ld: -Ttext 0x1000 --section-start .foo=0x8001000
-#error: .*\(.text\+0x0\): relocation truncated to fit: R_AARCH64_JUMP26 against symbol `bar'.*
+#objdump: -dr
+#...
+
+Disassembly of section .text:
+
+.* <_start>:
+    1000:      14000003        b       100c <__bar_veneer>
+    1004:      d65f03c0        ret
+    1008:      14000007        b       1024 <__bar_veneer\+0x18>
+
+.* <__bar_veneer>:
+    100c:      90040010        adrp    x16, 8001000 <bar>
+    1010:      91000210        add     x16, x16, #0x0
+    1014:      d61f0200        br      x16
+       ...
+
+Disassembly of section .foo:
+
+.* <bar>:
+ 8001000:      d65f03c0        ret
diff --git a/ld/testsuite/ld-aarch64/farcall-b-section.d b/ld/testsuite/ld-aarch64/farcall-b-section.d
new file mode 100644 (file)
index 0000000..4745c0f
--- /dev/null
@@ -0,0 +1,34 @@
+#name: aarch64-farcall-b-section
+#source: farcall-b-section.s
+#as:
+#ld: -Ttext 0x1000 --section-start .foo=0x8001000
+#objdump: -dr
+#...
+
+Disassembly of section .text:
+
+.* <_start>:
+    1000:      14000008        b       1020 <___veneer>
+    1004:      14000003        b       1010 <___veneer>
+    1008:      d65f03c0        ret
+    100c:      1400000d        b       1040 <___veneer\+0x20>
+
+.* <___veneer>:
+    1010:      90040010        adrp    x16, 8001000 <bar>
+    1014:      91001210        add     x16, x16, #0x4
+    1018:      d61f0200        br      x16
+    101c:      00000000        .inst   0x00000000 ; undefined
+
+.* <___veneer>:
+    1020:      90040010        adrp    x16, 8001000 <bar>
+    1024:      91000210        add     x16, x16, #0x0
+    1028:      d61f0200        br      x16
+       ...
+
+Disassembly of section .foo:
+
+.* <bar>:
+ 8001000:      d65f03c0        ret
+
+.* <bar2>:
+ 8001004:      d65f03c0        ret
diff --git a/ld/testsuite/ld-aarch64/farcall-b-section.s b/ld/testsuite/ld-aarch64/farcall-b-section.s
new file mode 100644 (file)
index 0000000..1a135ef
--- /dev/null
@@ -0,0 +1,20 @@
+.global _start
+
+# We will place the section .text at 0x1000.
+
+       .text
+
+_start:
+       b bar
+       b bar2
+       ret
+
+# We will place the section .foo at 0x8001000.
+
+       .section .foo, "xa"
+       .type bar, @function
+bar:
+       ret
+       .type bar2, @function
+bar2:
+       ret
index 6ce9ca4..b6a4dda 100644 (file)
@@ -2,4 +2,23 @@
 #source: farcall-bl-none-function.s
 #as:
 #ld: -Ttext 0x1000 --section-start .foo=0x8001000
-#error: .*\(.text\+0x0\): relocation truncated to fit: R_AARCH64_CALL26 against symbol `bar'.*
+#objdump: -dr
+#...
+
+Disassembly of section .text:
+
+.* <_start>:
+    1000:      94000003        bl      100c <__bar_veneer>
+    1004:      d65f03c0        ret
+    1008:      14000007        b       1024 <__bar_veneer\+0x18>
+
+.* <__bar_veneer>:
+    100c:      90040010        adrp    x16, 8001000 <bar>
+    1010:      91000210        add     x16, x16, #0x0
+    1014:      d61f0200        br      x16
+       ...
+
+Disassembly of section .foo:
+
+.* <bar>:
+ 8001000:      d65f03c0        ret
diff --git a/ld/testsuite/ld-aarch64/farcall-bl-section.d b/ld/testsuite/ld-aarch64/farcall-bl-section.d
new file mode 100644 (file)
index 0000000..2bd4f85
--- /dev/null
@@ -0,0 +1,34 @@
+#name: aarch64-farcall-bl-section
+#source: farcall-bl-section.s
+#as:
+#ld: -Ttext 0x1000 --section-start .foo=0x8001000
+#objdump: -dr
+#...
+
+Disassembly of section .text:
+
+.* <_start>:
+    1000:      94000008        bl      1020 <___veneer>
+    1004:      94000003        bl      1010 <___veneer>
+    1008:      d65f03c0        ret
+    100c:      1400000d        b       1040 <___veneer\+0x20>
+
+.* <___veneer>:
+    1010:      90040010        adrp    x16, 8001000 <bar>
+    1014:      91001210        add     x16, x16, #0x4
+    1018:      d61f0200        br      x16
+    101c:      00000000        .inst   0x00000000 ; undefined
+
+.* <___veneer>:
+    1020:      90040010        adrp    x16, 8001000 <bar>
+    1024:      91000210        add     x16, x16, #0x0
+    1028:      d61f0200        br      x16
+       ...
+
+Disassembly of section .foo:
+
+.* <bar>:
+ 8001000:      d65f03c0        ret
+
+.* <bar2>:
+ 8001004:      d65f03c0        ret
diff --git a/ld/testsuite/ld-aarch64/farcall-bl-section.s b/ld/testsuite/ld-aarch64/farcall-bl-section.s
new file mode 100644 (file)
index 0000000..4469d4d
--- /dev/null
@@ -0,0 +1,20 @@
+       .global _start
+
+# We will place the section .text at 0x1000.
+
+       .text
+
+_start:
+       bl bar
+       bl bar2
+       ret
+
+# We will place the section .foo at 0x8001000.
+
+       .section .foo, "xa"
+       .type bar, @function
+bar:
+       ret
+       .type bar2, @function
+bar2:
+       ret
diff --git a/ld/testsuite/ld-aarch64/farcall-section.d b/ld/testsuite/ld-aarch64/farcall-section.d
deleted file mode 100644 (file)
index 85775e1..0000000
+++ /dev/null
@@ -1,5 +0,0 @@
-#name: Aarch64 farcall to symbol of type STT_SECTION
-#source: farcall-section.s
-#as:
-#ld: -Ttext 0x1000 --section-start .foo=0x8001014
-#error: .*\(.text\+0x0\): relocation truncated to fit: R_AARCH64_CALL26 against `.foo'
diff --git a/ld/testsuite/ld-aarch64/farcall-section.s b/ld/testsuite/ld-aarch64/farcall-section.s
deleted file mode 100644 (file)
index 86a070c..0000000
+++ /dev/null
@@ -1,19 +0,0 @@
-# Test to ensure that an Aarch64 call exceeding 128MB generates an error
-# if the destination is of type STT_SECTION (eg non-global symbol)
-
-       .global _start
-
-# We will place the section .text at 0x1000.
-
-       .text
-
-_start:
-       bl bar
-
-# We will place the section .foo at 0x8001020.
-
-       .section .foo, "xa"
-
-bar:
-       ret
-