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[ELF] -r/--emit-relocs: Fix crash when processing .rela.text before .text #156354

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Merged
MaskRay merged 5 commits into from
Sep 20, 2025
Merged

[ELF] -r/--emit-relocs: Fix crash when processing .rela.text before .text #156354

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3cc58a3
[lld][ELF] Fix crash when relocations proceed relocated section
mykouHW Aug 29, 2025
2b54668
Merge branch 'main' into fix-orphan-sections-init
mykouHW Sep 16, 2025
f1e714b
Better fix for 156417
MaskRay Sep 18, 2025
cc33e42
delete old test
MaskRay Sep 19, 2025
280cfd7
Merge branch 'main' into fix-orphan-sections-init
mykouHW Sep 19, 2025
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12 changes: 9 additions & 3 deletions lld/ELF/LinkerScript.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1037,10 +1037,16 @@ void LinkerScript::addOrphanSections() {
if (ctx.arg.relocatable && (isec->flags & SHF_LINK_ORDER))
continue;

if (auto *sec = dyn_cast<InputSection>(isec))
if (InputSectionBase *rel = sec->getRelocatedSection())
if (auto *relIS = dyn_cast_or_null<InputSectionBase>(rel->parent))
if (auto *sec = dyn_cast<InputSection>(isec)) {
if (InputSectionBase *relocated = sec->getRelocatedSection()) {
// Ensure creation of OutputSection for relocated section before
// relocation section
if (auto *relIS = dyn_cast_or_null<InputSectionBase>(relocated))
add(relIS);
if (auto *relIS = dyn_cast_or_null<InputSectionBase>(relocated->parent))
add(relIS);
}
}
add(isec);
if (ctx.arg.relocatable)
for (InputSectionBase *depSec : isec->dependentSections)
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37 changes: 37 additions & 0 deletions lld/test/ELF/linkerscript/orphan-sections-init.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,37 @@
# REQUIRES: x86
# RUN: rm -rf %t && mkdir -p %t
# RUN: split-file %s %t && cd %t

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@smithp35 smithp35 Sep 2, 2025

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Could you add a comment to explain the test. Without context the steps look strange. LLD uses an additional comment character to distinguish comments from lit commands, so comment lines would start ##

For example:

Test that lld's orphan section placement can handle a relocatable link where the relocation section is seen before the relocated section. To create a test case we need to first need to create a relocatable object with
the relocations before the relocated section. Then we rename these to make these orphans.

I tried to see if I could create the test case without llvm-objcopy but it seemed like I needed the linker script to have .rela.text as the pattern to get it to place first.

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@MaskRay MaskRay Sep 18, 2025

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The llvm-objcopy is unnecessary. Apply https://github.com/MaskRay/llvm-project/tree/lld-156354 to get the code/comment/test changes

## Test that lld's orphan section placement can handle a relocatable link where
## the relocation section is seen before the relocated section.

## Create a relocatable object with the relocations before the relocated section
# RUN: llvm-mc -filetype=obj -triple=x86_64 foo.s -o foo.o
# RUN: ld.lld -r foo.o -T script.ld -o foo_mc.o

## Rename the sections to make them orphans
# RUN: llvm-objcopy \
# RUN: --rename-section .text=.com.text \
# RUN: --rename-section .rela.text=.rela.com.text \
# RUN: foo_mc.o foo_mc.o

# RUN: ld.lld -r foo_mc.o -T script.ld -o foo_mc_after.o
# RUN: llvm-readelf -S foo_mc_after.o | FileCheck %s
# CHECK: .com.text PROGBITS 0000000000000000 000040 000007 00 AX 0 0 16
# CHECK-NEXT: .rela.com.text RELA 0000000000000000 000048 000018 18 I 4 1 8

#--- foo.s
.text
.globl foo
.p2align 4
.type foo,@function
foo:
mov $bar, %rax

#--- script.ld
SECTIONS
{
.rela.text 0 : { *(.rela.text) }
.text 0 : { *(.text) }
}