[lld] [LLD][ARM] Allow R_ARM_SBREL32 relocations in debug info (PR #116956)
Oliver Stannard via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 21 02:21:41 PST 2024
https://github.com/ostannard updated https://github.com/llvm/llvm-project/pull/116956
>From 1e3c8beda361a59ce172db6c36f9f465225d7d96 Mon Sep 17 00:00:00 2001
From: Oliver Stannard <oliver.stannard at arm.com>
Date: Wed, 20 Nov 2024 11:28:15 +0000
Subject: [PATCH 1/3] [LLD][ARM] Allow R_ARM_SBREL32 relocations in debug info
The R_ARM_SBREL32 relocation is used in debug info for ARM RWPI
(read-write position independent) code. Compiler-generated DWARF info
will use an expression to add the relocated value to the actual value of
the static base (held in r9) at run-time, so it should be relocated as
if the static base is at address 0.
---
lld/ELF/InputSection.cpp | 2 +-
lld/test/ELF/arm-rwpi-debug-relocs.s | 57 ++++++++++++++++++++++++++++
2 files changed, 58 insertions(+), 1 deletion(-)
create mode 100644 lld/test/ELF/arm-rwpi-debug-relocs.s
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 1221f56dfe68a6..595545e194f815 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -1092,7 +1092,7 @@ void InputSection::relocateNonAlloc(Ctx &ctx, uint8_t *buf,
// R_ABS/R_DTPREL and some other relocations can be used from non-SHF_ALLOC
// sections.
if (LLVM_LIKELY(expr == R_ABS) || expr == R_DTPREL || expr == R_GOTPLTREL ||
- expr == R_RISCV_ADD) {
+ expr == R_RISCV_ADD || expr == R_ARM_SBREL) {
target.relocateNoSym(bufLoc, type,
SignExtend64<bits>(sym.getVA(ctx, addend)));
continue;
diff --git a/lld/test/ELF/arm-rwpi-debug-relocs.s b/lld/test/ELF/arm-rwpi-debug-relocs.s
new file mode 100644
index 00000000000000..47c2e0739377b9
--- /dev/null
+++ b/lld/test/ELF/arm-rwpi-debug-relocs.s
@@ -0,0 +1,57 @@
+// REQUIRES: arm
+// RUN: rm -rf %t && split-file %s %t && cd %t
+
+// RUN: llvm-mc -filetype=obj -triple=armv7a asm.s -o obj.o
+// RUN: ld.lld -T lds.ld obj.o -o exe.elf -e main 2>&1 | FileCheck %s --implicit-check-not=warning: --allow-empty
+// RUN: llvm-objdump -D exe.elf | FileCheck --check-prefix=DISASM %s
+
+// DISASM: Disassembly of section data1:
+// DISASM: 00001000 <rw>:
+// DISASM-NEXT: 1000: 0000002a
+
+// DISASM: Disassembly of section data2:
+// DISASM: 00002000 <rw2>:
+// DISASM-NEXT: 2000: 000004d2
+
+// DISASM: Disassembly of section .debug_something:
+// DISASM: 00000000 <.debug_something>:
+// DISASM-NEXT: 0: 00001000
+// DISASM-NEXT: ...
+// DISASM-NEXT: 104: 00002000
+
+// Test that R_ARM_SBREL32 relocations in debug info are relocated as if the
+// static base register (r9) is zero. Real DWARF info will use an expression to
+// add this to the real value of the static base at runtime.
+
+//--- lds.ld
+SECTIONS {
+ data1 0x1000 : { *(data1) }
+ data2 0x2000 : { *(data2) }
+}
+
+//--- asm.s
+ .text
+ .type main,%function
+ .globl main
+main:
+ bx lr
+ .size main, .-main
+
+ .section data1, "aw", %progbits
+ .type rw,%object
+ .globl rw
+rw:
+ .long 42
+ .size rw, 4
+
+ .section data2, "aw", %progbits
+ .type rw2,%object
+ .globl rw2
+rw2:
+ .long 1234
+ .size rw2, 4
+
+ .section .debug_something, "", %progbits
+ .long rw(sbrel)
+ .space 0x100
+ .long rw2(sbrel)
>From 086dd963bcb1365e012bc85519ac10019c99d96c Mon Sep 17 00:00:00 2001
From: Oliver Stannard <oliver.stannard at arm.com>
Date: Wed, 20 Nov 2024 14:03:26 +0000
Subject: [PATCH 2/3] Update test style
---
lld/test/ELF/arm-rwpi-debug-relocs.s | 35 +++++++++++++---------------
1 file changed, 16 insertions(+), 19 deletions(-)
diff --git a/lld/test/ELF/arm-rwpi-debug-relocs.s b/lld/test/ELF/arm-rwpi-debug-relocs.s
index 47c2e0739377b9..1a47e2220e768c 100644
--- a/lld/test/ELF/arm-rwpi-debug-relocs.s
+++ b/lld/test/ELF/arm-rwpi-debug-relocs.s
@@ -2,26 +2,23 @@
// RUN: rm -rf %t && split-file %s %t && cd %t
// RUN: llvm-mc -filetype=obj -triple=armv7a asm.s -o obj.o
-// RUN: ld.lld -T lds.ld obj.o -o exe.elf -e main 2>&1 | FileCheck %s --implicit-check-not=warning: --allow-empty
+// RUN: ld.lld -T lds.ld obj.o -o exe.elf 2>&1 | FileCheck %s --implicit-check-not=warning: --allow-empty
// RUN: llvm-objdump -D exe.elf | FileCheck --check-prefix=DISASM %s
-// DISASM: Disassembly of section data1:
-// DISASM: 00001000 <rw>:
-// DISASM-NEXT: 1000: 0000002a
+// DISASM-LABEL: <rw>:
+// DISASM-NEXT: 1000: 0000002a
-// DISASM: Disassembly of section data2:
-// DISASM: 00002000 <rw2>:
-// DISASM-NEXT: 2000: 000004d2
+// DISASM-LABEL: <rw2>:
+// DISASM-NEXT: 2000: 000004d2
-// DISASM: Disassembly of section .debug_something:
-// DISASM: 00000000 <.debug_something>:
-// DISASM-NEXT: 0: 00001000
-// DISASM-NEXT: ...
-// DISASM-NEXT: 104: 00002000
+// DISASM-LABEL: <.debug_something>:
+// DISASM-NEXT: 0: 00001000
+// DISASM-NEXT: ...
+// DISASM-NEXT: 104: 00002000
-// Test that R_ARM_SBREL32 relocations in debug info are relocated as if the
-// static base register (r9) is zero. Real DWARF info will use an expression to
-// add this to the real value of the static base at runtime.
+/// Test that R_ARM_SBREL32 relocations in debug info are relocated as if the
+/// static base register (r9) is zero. Real DWARF info will use an expression to
+/// add this to the real value of the static base at runtime.
//--- lds.ld
SECTIONS {
@@ -31,11 +28,11 @@ SECTIONS {
//--- asm.s
.text
- .type main,%function
- .globl main
-main:
+ .type _start,%function
+ .globl _start
+_start:
bx lr
- .size main, .-main
+ .size _start, .-_start
.section data1, "aw", %progbits
.type rw,%object
>From 7343ec253fa0fc4fbaca68724f2c6369685ca535 Mon Sep 17 00:00:00 2001
From: Oliver Stannard <oliver.stannard at arm.com>
Date: Thu, 21 Nov 2024 10:19:24 +0000
Subject: [PATCH 3/3] Review comments
Tabs->spaces
Move comment to top of file
---
lld/test/ELF/arm-rwpi-debug-relocs.s | 38 ++++++++++++++--------------
1 file changed, 19 insertions(+), 19 deletions(-)
diff --git a/lld/test/ELF/arm-rwpi-debug-relocs.s b/lld/test/ELF/arm-rwpi-debug-relocs.s
index 1a47e2220e768c..2bb968d4afa9ab 100644
--- a/lld/test/ELF/arm-rwpi-debug-relocs.s
+++ b/lld/test/ELF/arm-rwpi-debug-relocs.s
@@ -1,3 +1,7 @@
+/// Test that R_ARM_SBREL32 relocations in debug info are relocated as if the
+/// static base register (r9) is zero. Real DWARF info will use an expression to
+/// add this to the real value of the static base at runtime.
+
// REQUIRES: arm
// RUN: rm -rf %t && split-file %s %t && cd %t
@@ -16,10 +20,6 @@
// DISASM-NEXT: ...
// DISASM-NEXT: 104: 00002000
-/// Test that R_ARM_SBREL32 relocations in debug info are relocated as if the
-/// static base register (r9) is zero. Real DWARF info will use an expression to
-/// add this to the real value of the static base at runtime.
-
//--- lds.ld
SECTIONS {
data1 0x1000 : { *(data1) }
@@ -28,27 +28,27 @@ SECTIONS {
//--- asm.s
.text
- .type _start,%function
- .globl _start
+ .type _start,%function
+ .globl _start
_start:
bx lr
.size _start, .-_start
- .section data1, "aw", %progbits
- .type rw,%object
- .globl rw
+ .section data1, "aw", %progbits
+ .type rw,%object
+ .globl rw
rw:
- .long 42
- .size rw, 4
+ .long 42
+ .size rw, 4
- .section data2, "aw", %progbits
- .type rw2,%object
- .globl rw2
+ .section data2, "aw", %progbits
+ .type rw2,%object
+ .globl rw2
rw2:
- .long 1234
- .size rw2, 4
+ .long 1234
+ .size rw2, 4
- .section .debug_something, "", %progbits
- .long rw(sbrel)
+ .section .debug_something, "", %progbits
+ .long rw(sbrel)
.space 0x100
- .long rw2(sbrel)
+ .long rw2(sbrel)
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