[PATCH] x86-64: Convert load to mov only for GOTPCRELX relocations

H.J. Lu hjl.tools@gmail.com
Sat Dec 5 02:57:52 GMT 2020


Since converting load to mov needs to rewrite the REX byte and we don't
know if there is a REX byte with GOTPCREL relocation, do it only for
GOTPCRELX relocations.

bfd/

	PR ld/27016
	* elf64-x86-64.c (elf_x86_64_convert_load_reloc): Convert load
	to mov only for GOTPCRELX relocations.

ld/

	PR ld/27016
	* testsuite/ld-x86-64/x86-64.exp: Run pr27016a and pr27016b.
	* testsuite/ld-x86-64/pr27016a.d: New file.
	* testsuite/ld-x86-64/pr27016a.s: Likewise.
	* testsuite/ld-x86-64/pr27016b.d: Likewise.
	* testsuite/ld-x86-64/pr27016b.s: Likewise.
---
 bfd/ChangeLog                     |  6 ++++++
 bfd/elf64-x86-64.c                |  2 +-
 ld/ChangeLog                      |  9 +++++++++
 ld/testsuite/ld-x86-64/pr27016a.d | 23 +++++++++++++++++++++++
 ld/testsuite/ld-x86-64/pr27016a.s | 23 +++++++++++++++++++++++
 ld/testsuite/ld-x86-64/pr27016b.d | 23 +++++++++++++++++++++++
 ld/testsuite/ld-x86-64/pr27016b.s |  4 ++++
 ld/testsuite/ld-x86-64/x86-64.exp |  2 ++
 8 files changed, 91 insertions(+), 1 deletion(-)
 create mode 100644 ld/testsuite/ld-x86-64/pr27016a.d
 create mode 100644 ld/testsuite/ld-x86-64/pr27016a.s
 create mode 100644 ld/testsuite/ld-x86-64/pr27016b.d
 create mode 100644 ld/testsuite/ld-x86-64/pr27016b.s

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index fa29df2267..2d1e4da18f 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+2020-12-04  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/27016
+	* elf64-x86-64.c (elf_x86_64_convert_load_reloc): Convert load
+	to mov only for GOTPCRELX relocations.
+
 2020-12-04  Alan Modra  <amodra@gmail.com>
 
 	PR 26978
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 549a8be6a6..bb33967171 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -1731,7 +1731,7 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
 
       if (opcode == 0x8b)
 	{
-	  if (abs_symbol && local_ref)
+	  if (abs_symbol && local_ref && relocx)
 	    to_reloc_pc32 = FALSE;
 
 	  if (to_reloc_pc32)
diff --git a/ld/ChangeLog b/ld/ChangeLog
index 0bbb576c56..f33bd41b01 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,12 @@
+2020-12-04  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/27016
+	* testsuite/ld-x86-64/x86-64.exp: Run pr27016a and pr27016b.
+	* testsuite/ld-x86-64/pr27016a.d: New file.
+	* testsuite/ld-x86-64/pr27016a.s: Likewise.
+	* testsuite/ld-x86-64/pr27016b.d: Likewise.
+	* testsuite/ld-x86-64/pr27016b.s: Likewise.
+
 2020-12-04  Alan Modra  <amodra@gmail.com>
 
 	* testsuite/ld-elf/pr26978a.d,
diff --git a/ld/testsuite/ld-x86-64/pr27016a.d b/ld/testsuite/ld-x86-64/pr27016a.d
new file mode 100644
index 0000000000..88fba0a37f
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr27016a.d
@@ -0,0 +1,23 @@
+#source: pr27016a.s
+#source: pr27016b.s
+#as: --64 -mx86-used-note=no -mrelax-relocations=no
+#ld: -m elf_x86_64 -z max-page-size=0x200000 -z noseparate-code -e main
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+0+4000e8 <main>:
+ +[a-f0-9]+:	55                   	push   %rbp
+ +[a-f0-9]+:	48 89 e5             	mov    %rsp,%rbp
+ +[a-f0-9]+:	4c 8d 1d 39 3f 00 00 	lea    0x3f39\(%rip\),%r11        # 40402c <thesym>
+ +[a-f0-9]+:	41 8b 03             	mov    \(%r11\),%eax
+ +[a-f0-9]+:	8d 50 01             	lea    0x1\(%rax\),%edx
+ +[a-f0-9]+:	4c 8d 1d 2c 3f 00 00 	lea    0x3f2c\(%rip\),%r11        # 40402c <thesym>
+ +[a-f0-9]+:	41 89 13             	mov    %edx,\(%r11\)
+ +[a-f0-9]+:	b8 00 00 00 00       	mov    \$0x0,%eax
+ +[a-f0-9]+:	5d                   	pop    %rbp
+ +[a-f0-9]+:	c3                   	ret    
+#pass
diff --git a/ld/testsuite/ld-x86-64/pr27016a.s b/ld/testsuite/ld-x86-64/pr27016a.s
new file mode 100644
index 0000000000..b64851a5ff
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr27016a.s
@@ -0,0 +1,23 @@
+        .text
+        .comm   global_int,4,4
+        .globl  main
+        .type   main, @function
+main:
+        .cfi_startproc
+        pushq   %rbp
+        .cfi_def_cfa_offset 16
+        .cfi_offset 6, -16
+        movq    %rsp, %rbp
+        .cfi_def_cfa_register 6
+        movq    thesym@GOTPCREL(%rip), %r11
+        movl    (%r11), %eax
+        leal    1(%rax), %edx
+        movq    thesym@GOTPCREL(%rip), %r11
+        movl    %edx, (%r11)
+        movl    $0, %eax
+        popq    %rbp
+        .cfi_def_cfa 7, 8
+        ret
+        .cfi_endproc
+        .size   main, .-main
+        .section        .note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-x86-64/pr27016b.d b/ld/testsuite/ld-x86-64/pr27016b.d
new file mode 100644
index 0000000000..b172736321
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr27016b.d
@@ -0,0 +1,23 @@
+#source: pr27016a.s
+#source: pr27016b.s
+#as: --64 -mx86-used-note=no -mrelax-relocations=yes
+#ld: -m elf_x86_64 -z max-page-size=0x200000 -z noseparate-code -e main
+#objdump: -dw
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+0+4000e8 <main>:
+ +[a-f0-9]+:	55                   	push   %rbp
+ +[a-f0-9]+:	48 89 e5             	mov    %rsp,%rbp
+ +[a-f0-9]+:	49 c7 c3 2c 40 40 00 	mov    \$0x40402c,%r11
+ +[a-f0-9]+:	41 8b 03             	mov    \(%r11\),%eax
+ +[a-f0-9]+:	8d 50 01             	lea    0x1\(%rax\),%edx
+ +[a-f0-9]+:	49 c7 c3 2c 40 40 00 	mov    \$0x40402c,%r11
+ +[a-f0-9]+:	41 89 13             	mov    %edx,\(%r11\)
+ +[a-f0-9]+:	b8 00 00 00 00       	mov    \$0x0,%eax
+ +[a-f0-9]+:	5d                   	pop    %rbp
+ +[a-f0-9]+:	c3                   	ret    
+#pass
diff --git a/ld/testsuite/ld-x86-64/pr27016b.s b/ld/testsuite/ld-x86-64/pr27016b.s
new file mode 100644
index 0000000000..ded8d7a826
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr27016b.s
@@ -0,0 +1,4 @@
+	.globl thesym
+thesym = 0x40402c
+
+	.section        .note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index 99c8a33c3e..41d385bf05 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -661,6 +661,8 @@ run_dump_test "pr22048"
 run_dump_test "pr22929"
 run_dump_test "pr26939"
 run_dump_test "pr26939-x32"
+run_dump_test "pr27016a"
+run_dump_test "pr27016b"
 
 proc undefined_weak {cflags ldflags} {
     set testname "Undefined weak symbol"
-- 
2.28.0



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