[lld] 398b810 - [ELF] Don't crash on R_X86_64_GOTPCRELX for test/binop instructions
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Sat Oct 24 15:14:34 PDT 2020
Author: Fangrui Song
Date: 2020-10-24T15:14:17-07:00
New Revision: 398b81067c8202d2b3e4fec23547b6b64d181459
URL: https://github.com/llvm/llvm-project/commit/398b81067c8202d2b3e4fec23547b6b64d181459
DIFF: https://github.com/llvm/llvm-project/commit/398b81067c8202d2b3e4fec23547b6b64d181459.diff
LOG: [ELF] Don't crash on R_X86_64_GOTPCRELX for test/binop instructions
While MC did not produce R_X86_64_GOTPCRELX for test/binop instructions
(movl/adcl/addl/andl/...) before the previous commit, this code path has been
exercised by -fno-integrated-as for GNU as since 2016: -no-pie relaxing
may incorrectly access loc[-3] and produce a corrupted instruction.
Simply handle test/binop R_X86_64_GOTPCRELX like R_X86_64_GOTPCREL.
Added:
Modified:
lld/ELF/Arch/X86_64.cpp
lld/test/ELF/x86-64-gotpc-relax-nopic.s
Removed:
################################################################################
diff --git a/lld/ELF/Arch/X86_64.cpp b/lld/ELF/Arch/X86_64.cpp
index 24711ec210a4..93fd8ecb7c8e 100644
--- a/lld/ELF/Arch/X86_64.cpp
+++ b/lld/ELF/Arch/X86_64.cpp
@@ -746,11 +746,12 @@ RelExpr X86_64::adjustRelaxExpr(RelType type, const uint8_t *data,
if (op == 0xff && (modRm == 0x15 || modRm == 0x25))
return R_RELAX_GOT_PC;
+ // We don't support test/binop instructions without a REX prefix.
+ if (type == R_X86_64_GOTPCRELX)
+ return relExpr;
+
// Relaxation of test, adc, add, and, cmp, or, sbb, sub, xor.
// If PIC then no relaxation is available.
- // We also don't relax test/binop instructions without REX byte,
- // they are 32bit operations and not common to have.
- assert(type == R_X86_64_REX_GOTPCRELX);
return config->isPic ? relExpr : R_RELAX_GOT_PC_NOPIC;
}
diff --git a/lld/test/ELF/x86-64-gotpc-relax-nopic.s b/lld/test/ELF/x86-64-gotpc-relax-nopic.s
index b927ecff6383..501414f7bdde 100644
--- a/lld/test/ELF/x86-64-gotpc-relax-nopic.s
+++ b/lld/test/ELF/x86-64-gotpc-relax-nopic.s
@@ -1,8 +1,8 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -relax-relocations -triple=x86_64-unknown-linux %s -o %t.o
-# RUN: ld.lld --hash-style=sysv %t.o -o %t1
+# RUN: ld.lld %t.o -o %t1
# RUN: llvm-readobj --symbols -r %t1 | FileCheck --check-prefix=SYMRELOC %s
-# RUN: llvm-objdump -d --no-show-raw-insn %t1 | FileCheck --check-prefix=DISASM %s
+# RUN: llvm-objdump -d --no-show-raw-insn --print-imm-hex %t1 | FileCheck --check-prefix=DISASM %s
## There is no relocations.
# SYMRELOC: Relocations [
@@ -10,21 +10,30 @@
# SYMRELOC: Symbols [
# SYMRELOC: Symbol {
# SYMRELOC: Name: bar
-# SYMRELOC-NEXT: Value: 0x202197
+# SYMRELOC-NEXT: Value: 0x203248
## 2105751 = 0x202197 (bar)
# DISASM: Disassembly of section .text:
# DISASM-EMPTY:
# DISASM-NEXT: <_start>:
-# DISASM-NEXT: 201158: adcq $2105751, %rax
-# DISASM-NEXT: addq $2105751, %rbx
-# DISASM-NEXT: andq $2105751, %rcx
-# DISASM-NEXT: cmpq $2105751, %rdx
-# DISASM-NEXT: orq $2105751, %rdi
-# DISASM-NEXT: sbbq $2105751, %rsi
-# DISASM-NEXT: subq $2105751, %rbp
-# DISASM-NEXT: xorq $2105751, %r8
-# DISASM-NEXT: testq $2105751, %r15
+# DISASM-NEXT: 2011c8: adcl {{.*}}(%rip), %eax # 202240
+# DISASM-NEXT: addl {{.*}}(%rip), %ebx # 202240
+# DISASM-NEXT: andl {{.*}}(%rip), %ecx # 202240
+# DISASM-NEXT: cmpl {{.*}}(%rip), %edx # 202240
+# DISASM-NEXT: orl {{.*}}(%rip), %edi # 202240
+# DISASM-NEXT: sbbl {{.*}}(%rip), %esi # 202240
+# DISASM-NEXT: subl {{.*}}(%rip), %ebp # 202240
+# DISASM-NEXT: xorl {{.*}}(%rip), %r8d # 202240
+# DISASM-NEXT: testl %r15d, {{.*}}(%rip) # 202240
+# DISASM-NEXT: 201200: adcq $0x203248, %rax
+# DISASM-NEXT: addq $0x203248, %rbx
+# DISASM-NEXT: andq $0x203248, %rcx
+# DISASM-NEXT: cmpq $0x203248, %rdx
+# DISASM-NEXT: orq $0x203248, %rdi
+# DISASM-NEXT: sbbq $0x203248, %rsi
+# DISASM-NEXT: subq $0x203248, %rbp
+# DISASM-NEXT: xorq $0x203248, %r8
+# DISASM-NEXT: testq $0x203248, %r15
# RUN: ld.lld --hash-style=sysv -shared %t.o -o %t2
# RUN: llvm-readobj -S -r -d %t2 | FileCheck --check-prefix=SEC-PIC %s
@@ -37,8 +46,8 @@
# SEC-PIC-NEXT: SHF_ALLOC
# SEC-PIC-NEXT: SHF_WRITE
# SEC-PIC-NEXT: ]
-# SEC-PIC-NEXT: Address: 0x2348
-# SEC-PIC-NEXT: Offset: 0x348
+# SEC-PIC-NEXT: Address: 0x2380
+# SEC-PIC-NEXT: Offset: 0x380
# SEC-PIC-NEXT: Size: 8
# SEC-PIC-NEXT: Link:
# SEC-PIC-NEXT: Info:
@@ -48,25 +57,32 @@
# SEC-PIC: 0x000000006FFFFFF9 RELACOUNT 1
# SEC-PIC: Relocations [
# SEC-PIC-NEXT: Section ({{.*}}) .rela.dyn {
-# SEC-PIC-NEXT: 0x2348 R_X86_64_RELATIVE - 0x3350
+# SEC-PIC-NEXT: 0x2380 R_X86_64_RELATIVE - 0x3388
# SEC-PIC-NEXT: }
# SEC-PIC-NEXT: ]
## Check that there was no relaxation performed. All values refer to got entry.
-## Ex: 0x1000 + 4249 + 7 = 0x20A0
-## 0x102a + 4207 + 7 = 0x20A0
# DISASM-PIC: Disassembly of section .text:
# DISASM-PIC-EMPTY:
# DISASM-PIC-NEXT: <_start>:
-# DISASM-PIC-NEXT: 1268: adcq 4313(%rip), %rax
-# DISASM-PIC-NEXT: addq 4306(%rip), %rbx
-# DISASM-PIC-NEXT: andq 4299(%rip), %rcx
-# DISASM-PIC-NEXT: cmpq 4292(%rip), %rdx
-# DISASM-PIC-NEXT: orq 4285(%rip), %rdi
-# DISASM-PIC-NEXT: sbbq 4278(%rip), %rsi
-# DISASM-PIC-NEXT: subq 4271(%rip), %rbp
-# DISASM-PIC-NEXT: xorq 4264(%rip), %r8
-# DISASM-PIC-NEXT: testq %r15, 4257(%rip)
+# DISASM-PIC-NEXT: 1268: adcl {{.*}}(%rip), %eax # 2380
+# DISASM-PIC-NEXT: addl {{.*}}(%rip), %ebx # 2380
+# DISASM-PIC-NEXT: andl {{.*}}(%rip), %ecx # 2380
+# DISASM-PIC-NEXT: cmpl {{.*}}(%rip), %edx # 2380
+# DISASM-PIC-NEXT: orl {{.*}}(%rip), %edi # 2380
+# DISASM-PIC-NEXT: sbbl {{.*}}(%rip), %esi # 2380
+# DISASM-PIC-NEXT: subl {{.*}}(%rip), %ebp # 2380
+# DISASM-PIC-NEXT: xorl {{.*}}(%rip), %r8d # 2380
+# DISASM-PIC-NEXT: testl %r15d, {{.*}}(%rip) # 2380
+# DISASM-PIC-NEXT: 12a0: adcq {{.*}}(%rip), %rax # 2380
+# DISASM-PIC-NEXT: addq {{.*}}(%rip), %rbx # 2380
+# DISASM-PIC-NEXT: andq {{.*}}(%rip), %rcx # 2380
+# DISASM-PIC-NEXT: cmpq {{.*}}(%rip), %rdx # 2380
+# DISASM-PIC-NEXT: orq {{.*}}(%rip), %rdi # 2380
+# DISASM-PIC-NEXT: sbbq {{.*}}(%rip), %rsi # 2380
+# DISASM-PIC-NEXT: subq {{.*}}(%rip), %rbp # 2380
+# DISASM-PIC-NEXT: xorq {{.*}}(%rip), %r8 # 2380
+# DISASM-PIC-NEXT: testq %r15, {{.*}}(%rip) # 2380
.data
.type bar, @object
@@ -78,6 +94,18 @@ bar:
.globl _start
.type _start, @function
_start:
+## R_X86_64_GOTPCRELX
+ adcl bar at GOTPCREL(%rip), %eax
+ addl bar at GOTPCREL(%rip), %ebx
+ andl bar at GOTPCREL(%rip), %ecx
+ cmpl bar at GOTPCREL(%rip), %edx
+ orl bar at GOTPCREL(%rip), %edi
+ sbbl bar at GOTPCREL(%rip), %esi
+ subl bar at GOTPCREL(%rip), %ebp
+ xorl bar at GOTPCREL(%rip), %r8d
+ testl %r15d, bar at GOTPCREL(%rip)
+
+## R_X86_64_REX_GOTPCRELX
adcq bar at GOTPCREL(%rip), %rax
addq bar at GOTPCREL(%rip), %rbx
andq bar at GOTPCREL(%rip), %rcx
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