[lld] [X86][LLD] Handle R_X86_64_CODE_6_GOTTPOFF relocation type (PR #117675)
Feng Zou via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 26 19:01:41 PST 2024
https://github.com/fzou1 updated https://github.com/llvm/llvm-project/pull/117675
>From b9cfa5550f6a8a7a025b5e8a8e79050022cf6159 Mon Sep 17 00:00:00 2001
From: Feng Zou <feng.zou at intel.com>
Date: Tue, 26 Nov 2024 14:21:11 +0800
Subject: [PATCH 1/3] [X86][LLD] Handle R_X86_64_CODE_6_GOTTPOFF relocation
type
For
add %reg1, name at GOTTPOFF(%rip), %reg2
add name at GOTTPOFF(%rip), %reg1, %reg2
{nf} add %reg1, name at GOTTPOFF(%rip), %reg2
{nf} add name at GOTTPOFF(%rip), %reg1, %reg2
{nf} add name at GOTTPOFF(%rip), %reg
add
R_X86_64_CODE_6_GOTTPOFF = 50
in #117277.
Linker can treat R_X86_64_CODE_6_GOTTPOFF as R_X86_64_GOTTPOFF or convert the
instructions above to
add $name at tpoff, %reg1, %reg2
add $name at tpoff, %reg1, %reg2
{nf} add $name at tpoff, %reg1, %reg2
{nf} add $name at tpoff, %reg1, %reg2
{nf} add $name at tpoff, %reg
if the first byte of the instruction at the relocation offset - 6 is 0x62
(namely, encoded w/EVEX prefix) when possible.
Binutils patch: bminor/binutils-gdb at 5bc71c2
Binutils mailthread: https://sourceware.org/pipermail/binutils/2024-February/132351.html
ABI discussion: https://groups.google.com/g/x86-64-abi/c/FhEZjCtDLFw/m/VHDjN4orAgAJ
Blog: https://kanrobert.github.io/rfc/All-about-APX-relocation
---
lld/ELF/Arch/X86_64.cpp | 28 ++++++++++++++++++++++++++--
lld/test/ELF/tls-opt.s | 17 +++++++++++++++++
2 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/lld/ELF/Arch/X86_64.cpp b/lld/ELF/Arch/X86_64.cpp
index dd0dc83189d265..af2354ad690e0e 100644
--- a/lld/ELF/Arch/X86_64.cpp
+++ b/lld/ELF/Arch/X86_64.cpp
@@ -401,6 +401,7 @@ RelExpr X86_64::getRelExpr(RelType type, const Symbol &s,
case R_X86_64_CODE_4_GOTPCRELX:
case R_X86_64_GOTTPOFF:
case R_X86_64_CODE_4_GOTTPOFF:
+ case R_X86_64_CODE_6_GOTTPOFF:
return R_GOT_PC;
case R_X86_64_GOTOFF64:
return R_GOTPLTREL;
@@ -562,8 +563,9 @@ void X86_64::relaxTlsGdToIe(uint8_t *loc, const Relocation &rel,
}
}
-// In some conditions, R_X86_64_GOTTPOFF/R_X86_64_CODE_4_GOTTPOFF relocation can
-// be optimized to R_X86_64_TPOFF32 so that it does not use GOT.
+// In some conditions,
+// R_X86_64_GOTTPOFF/R_X86_64_CODE_4_GOTTPOFF/R_X86_64_CODE_6_GOTTPOFF
+// relocation can be optimized to R_X86_64_TPOFF32 so that it does not use GOT.
void X86_64::relaxTlsIeToLe(uint8_t *loc, const Relocation &rel,
uint64_t val) const {
uint8_t *inst = loc - 3;
@@ -623,6 +625,26 @@ void X86_64::relaxTlsIeToLe(uint8_t *loc, const Relocation &rel,
<< "R_X86_64_CODE_4_GOTTPOFF must be used in MOVQ or ADDQ "
"instructions only";
}
+ } else if (rel.type == R_X86_64_CODE_6_GOTTPOFF) {
+ if (loc[-6] != 0x62) {
+ Err(ctx) << getErrorLoc(ctx, loc - 6)
+ << "Invalid prefix with R_X86_64_CODE_6_GOTTPOFF!";
+ return;
+ }
+ if (loc[-2] == 0x3 || loc[-2] == 0x1) {
+ // "addq foo at gottpoff(%rip), %reg1, %reg2" -> "addq $foo, %reg1, %reg2"
+ loc[-2] = 0x81;
+ // Move R bits to B bits in EVEX payloads and ModRM byte.
+ if ((loc[-5] & (1 << 7)) == 0)
+ loc[-5] = (loc[-5] | (1 << 7)) & ~(1 << 5);
+ if ((loc[-5] & (1 << 4)) == 0)
+ loc[-5] = loc[-5] | (1 << 4) | (1 << 3);
+ *regSlot = 0xc0 | reg;
+ } else {
+ Err(ctx)
+ << getErrorLoc(ctx, loc - 6)
+ << "R_X86_64_CODE_6_GOTTPOFF must be used in ADDQ instructions only";
+ }
} else {
llvm_unreachable("Unsupported relocation type!");
}
@@ -782,6 +804,7 @@ int64_t X86_64::getImplicitAddend(const uint8_t *buf, RelType type) const {
case R_X86_64_PC32:
case R_X86_64_GOTTPOFF:
case R_X86_64_CODE_4_GOTTPOFF:
+ case R_X86_64_CODE_6_GOTTPOFF:
case R_X86_64_PLT32:
case R_X86_64_TLSGD:
case R_X86_64_TLSLD:
@@ -893,6 +916,7 @@ void X86_64::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const {
break;
case R_X86_64_GOTTPOFF:
case R_X86_64_CODE_4_GOTTPOFF:
+ case R_X86_64_CODE_6_GOTTPOFF:
if (rel.expr == R_RELAX_TLS_IE_TO_LE) {
relaxTlsIeToLe(loc, rel, val);
} else {
diff --git a/lld/test/ELF/tls-opt.s b/lld/test/ELF/tls-opt.s
index 818203ee19cb7c..6d072686b4859a 100644
--- a/lld/test/ELF/tls-opt.s
+++ b/lld/test/ELF/tls-opt.s
@@ -26,6 +26,14 @@
// DISASM-NEXT: addq $-8, %r16
// DISASM-NEXT: addq $-8, %r28
// DISASM-NEXT: addq $-4, %r16
+// DISASM-NEXT: addq $-10, %r16, %r16
+// DISASM-NEXT: addq $-10, %r16, %r20
+// DISASM-NEXT: addq $-10, %r16, %rax
+// DISASM-NEXT: addq $-10, %rax, %r16
+// DISASM-NEXT: addq $-10, %r8, %r16
+// DISASM-NEXT: addq $-10, %rax, %r12
+// DISASM-NEXT: {nf} addq $-10, %r8, %r16
+// DISASM-NEXT: {nf} addq $-10, %rax, %r12
// LD to LE:
// DISASM-NEXT: movq %fs:0, %rax
@@ -82,6 +90,15 @@ _start:
addq tls0 at GOTTPOFF(%rip), %r16
addq tls0 at GOTTPOFF(%rip), %r28
addq tls1 at GOTTPOFF(%rip), %r16
+# NDD
+ addq tls0 at GOTTPOFF(%rip), %r16, %r16
+ addq tls0 at GOTTPOFF(%rip), %r16, %r20
+ addq tls0 at GOTTPOFF(%rip), %r16, %rax
+ addq tls0 at GOTTPOFF(%rip), %rax, %r16
+ addq %r8, tls0 at GOTTPOFF(%rip), %r16
+ addq tls0 at GOTTPOFF(%rip), %rax, %r12
+ {nf} addq %r8, tls0 at GOTTPOFF(%rip), %r16
+ {nf} addq tls0 at GOTTPOFF(%rip), %rax, %r12
// LD to LE
leaq tls0 at tlsld(%rip), %rdi
>From 8d56798bb0e97532b2fe4e29a1e575279ffb3cc3 Mon Sep 17 00:00:00 2001
From: Feng Zou <feng.zou at intel.com>
Date: Tue, 26 Nov 2024 18:08:29 +0800
Subject: [PATCH 2/3] Updated tests
---
lld/test/ELF/pack-dyn-relocs-tls-x86-64.s | 5 +++
lld/test/ELF/tls-opt.s | 10 +++++-
lld/test/ELF/x86-64-tls-ie-local.s | 42 ++++++++++++++++-------
3 files changed, 44 insertions(+), 13 deletions(-)
diff --git a/lld/test/ELF/pack-dyn-relocs-tls-x86-64.s b/lld/test/ELF/pack-dyn-relocs-tls-x86-64.s
index c6464b4bece097..c54d6f705080d0 100644
--- a/lld/test/ELF/pack-dyn-relocs-tls-x86-64.s
+++ b/lld/test/ELF/pack-dyn-relocs-tls-x86-64.s
@@ -13,6 +13,7 @@
foo:
movq tlsvar at GOTTPOFF(%rip), %rcx
movq tlsvar2 at GOTTPOFF(%rip), %r31
+ addq tlsvar3 at GOTTPOFF(%rip), %rcx, %r16
.section .tdata,"awT", at progbits
@@ -21,7 +22,11 @@ tlsvar:
.word 42
tlsvar2:
.word 42
+tlsvar3:
+ .word 42
+
// CHECK: Section ({{.+}}) .rela.dyn {
// CHECK-NEXT: R_X86_64_TPOFF64 - 0x1234
// CHECK-NEXT: R_X86_64_TPOFF64 - 0x1236
+// CHECK-NEXT: R_X86_64_TPOFF64 - 0x1238
// CHECK-NEXT: }
diff --git a/lld/test/ELF/tls-opt.s b/lld/test/ELF/tls-opt.s
index 6d072686b4859a..3b92478cc0bd3e 100644
--- a/lld/test/ELF/tls-opt.s
+++ b/lld/test/ELF/tls-opt.s
@@ -20,20 +20,25 @@
// DISASM-NEXT: leaq -4(%r15), %r15
// DISASM-NEXT: addq $-4, %rsp
// DISASM-NEXT: addq $-4, %r12
+ # EPGR
// DISASM-NEXT: movq $-8, %r16
// DISASM-NEXT: movq $-8, %r20
// DISASM-NEXT: movq $-4, %r16
// DISASM-NEXT: addq $-8, %r16
// DISASM-NEXT: addq $-8, %r28
// DISASM-NEXT: addq $-4, %r16
+ # NDD
// DISASM-NEXT: addq $-10, %r16, %r16
// DISASM-NEXT: addq $-10, %r16, %r20
// DISASM-NEXT: addq $-10, %r16, %rax
// DISASM-NEXT: addq $-10, %rax, %r16
// DISASM-NEXT: addq $-10, %r8, %r16
// DISASM-NEXT: addq $-10, %rax, %r12
+# NDD + NF
// DISASM-NEXT: {nf} addq $-10, %r8, %r16
// DISASM-NEXT: {nf} addq $-10, %rax, %r12
+# NF
+// DISASM-NEXT: {nf} addq $-10, %r12
// LD to LE:
// DISASM-NEXT: movq %fs:0, %rax
@@ -90,15 +95,18 @@ _start:
addq tls0 at GOTTPOFF(%rip), %r16
addq tls0 at GOTTPOFF(%rip), %r28
addq tls1 at GOTTPOFF(%rip), %r16
-# NDD
+ # NDD
addq tls0 at GOTTPOFF(%rip), %r16, %r16
addq tls0 at GOTTPOFF(%rip), %r16, %r20
addq tls0 at GOTTPOFF(%rip), %r16, %rax
addq tls0 at GOTTPOFF(%rip), %rax, %r16
addq %r8, tls0 at GOTTPOFF(%rip), %r16
addq tls0 at GOTTPOFF(%rip), %rax, %r12
+ # NDD + NF
{nf} addq %r8, tls0 at GOTTPOFF(%rip), %r16
{nf} addq tls0 at GOTTPOFF(%rip), %rax, %r12
+ # NF
+ {nf} addq tls0 at GOTTPOFF(%rip), %r12
// LD to LE
leaq tls0 at tlsld(%rip), %rdi
diff --git a/lld/test/ELF/x86-64-tls-ie-local.s b/lld/test/ELF/x86-64-tls-ie-local.s
index 340a654ef9c284..0a104e7d67277a 100644
--- a/lld/test/ELF/x86-64-tls-ie-local.s
+++ b/lld/test/ELF/x86-64-tls-ie-local.s
@@ -5,29 +5,47 @@
# RUN: llvm-readobj -r %t.so | FileCheck --check-prefix=REL %s
# RUN: llvm-objdump --no-print-imm-hex -d --no-show-raw-insn %t.so | FileCheck %s
-# SEC: .got PROGBITS 0000000000002348 000348 000010 00 WA 0 0 8
+# SEC: .got PROGBITS 0000000000002378 000378 000010 00 WA 0 0 8
## Dynamic relocations for non-preemptable symbols in a shared object have section index 0.
# REL: .rela.dyn {
-# REL-NEXT: 0x2348 R_X86_64_TPOFF64 - 0x0
-# REL-NEXT: 0x2350 R_X86_64_TPOFF64 - 0x4
+# REL-NEXT: 0x2378 R_X86_64_TPOFF64 - 0x0
+# REL-NEXT: 0x2380 R_X86_64_TPOFF64 - 0x4
# REL-NEXT: }
-## &.got[0] - 0x127f = 0x2348 - 0x127f = 4297
-## &.got[1] - 0x1286 = 0x2350 - 0x1286 = 4298
-## &.got[2] - 0x128e = 0x2348 - 0x128e = 4282
-## &.got[3] - 0x1296 = 0x2350 - 0x1296 = 4282
+## &.got[0] - 0x127f = 0x2378 - 0x127f = 4345
+## &.got[1] - 0x1286 = 0x2380 - 0x1286 = 4346
+## &.got[2] - 0x128e = 0x2378 - 0x128e = 4330
+## &.got[3] - 0x1296 = 0x2380 - 0x1296 = 4330
+## &.got[0] - 0x12a0 = 0x2376 - 0x12a0 = 4310
+## &.got[1] - 0x12aa = 0x237e - 0x12aa = 4308
+## &.got[0] - 0x12b4 = 0x2376 - 0x12b4 = 4290
+## &.got[1] - 0x12be = 0x237e - 0x12be = 4288
+## &.got[0] - 0x12c8 = 0x2376 - 0x12c8 = 4270
-# CHECK: 1278: addq 4297(%rip), %rax
-# CHECK-NEXT: 127f: addq 4298(%rip), %rax
-# CHECK-NEXT: 1286: addq 4282(%rip), %r16
-# CHECK-NEXT: 128e: addq 4282(%rip), %r16
+# CHECK: 1278: addq 4345(%rip), %rax
+# CHECK-NEXT: 127f: addq 4346(%rip), %rax
+# CHECK-NEXT: 1286: addq 4330(%rip), %r16
+# CHECK-NEXT: 128e: addq 4330(%rip), %r16
+# CHECK-NEXT: 1296: addq %r8, 4310(%rip), %r16
+# CHECK-NEXT: 12a0: addq 4308(%rip), %rax, %r12
+# CHECK-NEXT: 12aa: {nf} addq %r8, 4290(%rip), %r16
+# CHECK-NEXT: 12b4: {nf} addq 4288(%rip), %rax, %r12
+# CHECK-NEXT: 12be: {nf} addq 4270(%rip), %r12
addq foo at GOTTPOFF(%rip), %rax
addq bar at GOTTPOFF(%rip), %rax
+# EGPR
addq foo at GOTTPOFF(%rip), %r16
addq bar at GOTTPOFF(%rip), %r16
-
+# NDD
+addq %r8, foo at GOTTPOFF(%rip), %r16
+addq bar at GOTTPOFF(%rip), %rax, %r12
+# NDD + NF
+{nf} addq %r8, foo at GOTTPOFF(%rip), %r16
+{nf} addq bar at GOTTPOFF(%rip), %rax, %r12
+# NF
+{nf} addq foo at GOTTPOFF(%rip), %r12
.section .tbss,"awT", at nobits
foo:
>From 451a507f524a5ee5fa6e8fda431e664f97c8ebae Mon Sep 17 00:00:00 2001
From: Feng Zou <feng.zou at intel.com>
Date: Wed, 27 Nov 2024 11:00:49 +0800
Subject: [PATCH 3/3] Fix typo and identation.
---
lld/test/ELF/tls-opt.s | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lld/test/ELF/tls-opt.s b/lld/test/ELF/tls-opt.s
index 3b92478cc0bd3e..08cc52afd6411e 100644
--- a/lld/test/ELF/tls-opt.s
+++ b/lld/test/ELF/tls-opt.s
@@ -20,14 +20,14 @@
// DISASM-NEXT: leaq -4(%r15), %r15
// DISASM-NEXT: addq $-4, %rsp
// DISASM-NEXT: addq $-4, %r12
- # EPGR
+# EGPR
// DISASM-NEXT: movq $-8, %r16
// DISASM-NEXT: movq $-8, %r20
// DISASM-NEXT: movq $-4, %r16
// DISASM-NEXT: addq $-8, %r16
// DISASM-NEXT: addq $-8, %r28
// DISASM-NEXT: addq $-4, %r16
- # NDD
+# NDD
// DISASM-NEXT: addq $-10, %r16, %r16
// DISASM-NEXT: addq $-10, %r16, %r20
// DISASM-NEXT: addq $-10, %r16, %rax
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