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Backport bugfix

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This commit is contained in:
rfwang07 2024-09-04 16:15:30 +08:00
parent 4c2356043d
commit ef3756f462
2 changed files with 104 additions and 1 deletions
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96
0007-BOLT-Skip-PLT-search-for-zero-value-weak-reference-symbols.patch Normal file
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@ -0,0 +1,96 @@
From 6c8933e1a095028d648a5a26aecee0f569304dd0 Mon Sep 17 00:00:00 2001
From: sinan <sinan.lin@linux.alibaba.com>
Date: Wed, 7 Aug 2024 18:02:42 +0800
Subject: [PATCH] [BOLT] Skip PLT search for zero-value weak reference symbols
(#69136)
Take a common weak reference pattern for example
```
__attribute__((weak)) void undef_weak_fun();
if (&undef_weak_fun)
undef_weak_fun();
```
In this case, an undefined weak symbol `undef_weak_fun` has an address
of zero, and Bolt incorrectly changes the relocation for the
corresponding symbol to symbol@PLT, leading to incorrect runtime
behavior.
---
bolt/lib/Rewrite/RewriteInstance.cpp | 11 +++++-
.../AArch64/update-weak-reference-symbol.s | 34 +++++++++++++++++++
2 files changed, 44 insertions(+), 1 deletion(-)
create mode 100644 bolt/test/AArch64/update-weak-reference-symbol.s
diff --git a/bolt/lib/Rewrite/RewriteInstance.cpp b/bolt/lib/Rewrite/RewriteInstance.cpp
index 78b4889bf2ae..d2e2ca2f7553 100644
--- a/bolt/lib/Rewrite/RewriteInstance.cpp
+++ b/bolt/lib/Rewrite/RewriteInstance.cpp
@@ -2143,6 +2143,14 @@ bool RewriteInstance::analyzeRelocation(
if (!Relocation::isSupported(RType))
return false;
+ auto IsWeakReference = [](const SymbolRef &Symbol) {
+ Expected<uint32_t> SymFlagsOrErr = Symbol.getFlags();
+ if (!SymFlagsOrErr)
+ return false;
+ return (*SymFlagsOrErr & SymbolRef::SF_Undefined) &&
+ (*SymFlagsOrErr & SymbolRef::SF_Weak);
+ };
+
const bool IsAArch64 = BC->isAArch64();
const size_t RelSize = Relocation::getSizeForType(RType);
@@ -2174,7 +2182,8 @@ bool RewriteInstance::analyzeRelocation(
// Section symbols are marked as ST_Debug.
IsSectionRelocation = (cantFail(Symbol.getType()) == SymbolRef::ST_Debug);
// Check for PLT entry registered with symbol name
- if (!SymbolAddress && (IsAArch64 || BC->isRISCV())) {
+ if (!SymbolAddress && !IsWeakReference(Symbol) &&
+ (IsAArch64 || BC->isRISCV())) {
const BinaryData *BD = BC->getPLTBinaryDataByName(SymbolName);
SymbolAddress = BD ? BD->getAddress() : 0;
}
diff --git a/bolt/test/AArch64/update-weak-reference-symbol.s b/bolt/test/AArch64/update-weak-reference-symbol.s
new file mode 100644
index 000000000000..600a06b8b6d8
--- /dev/null
+++ b/bolt/test/AArch64/update-weak-reference-symbol.s
@@ -0,0 +1,34 @@
+// This test checks whether BOLT can correctly handle relocations against weak symbols.
+
+// RUN: %clang %cflags -Wl,-z,notext -shared -Wl,-q %s -o %t.so
+// RUN: llvm-bolt %t.so -o %t.so.bolt
+// RUN: llvm-nm -n %t.so.bolt > %t.out.txt
+// RUN: llvm-objdump -dj .rodata %t.so.bolt >> %t.out.txt
+// RUN: FileCheck %s --input-file=%t.out.txt
+
+# CHECK: w func_1
+# CHECK: {{0+}}[[#%x,ADDR:]] W func_2
+
+# CHECK: {{.*}} <.rodata>:
+# CHECK-NEXT: {{.*}} .word 0x00000000
+# CHECK-NEXT: {{.*}} .word 0x00000000
+# CHECK-NEXT: {{.*}} .word 0x{{[0]+}}[[#ADDR]]
+# CHECK-NEXT: {{.*}} .word 0x00000000
+
+ .text
+ .weak func_2
+ .weak func_1
+ .global wow
+ .type wow, %function
+wow:
+ bl func_1
+ bl func_2
+ ret
+ .type func_2, %function
+func_2:
+ ret
+ .section .rodata
+.LC0:
+ .xword func_1
+.LC1:
+ .xword func_2
--
2.39.3 (Apple Git-146)

9
llvm-bolt.spec
View File

@ -22,7 +22,7 @@
Name: %{pkg_name}
Version: %{bolt_version}
Release: 7
Release: 8
Summary: BOLT is a post-link optimizer developed to speed up large applications
License: Apache 2.0
URL: https://github.com/llvm/llvm-project/tree/main/bolt
@ -36,6 +36,7 @@ Patch3: 0003-AArch64-Add-AArch64-support-for-inline.patch
Patch4: 0004-Bolt-Solving-pie-support-issue.patch
Patch5: 0005-BOLT-AArch64-Don-t-change-layout-in-PatchEntries.patch
Patch6: 0006-AArch64-Add-CFG-block-count-correction-optimization.patch
Patch7: 0007-BOLT-Skip-PLT-search-for-zero-value-weak-reference-symbols.patch
BuildRequires: gcc
BuildRequires: gcc-c++
@ -147,6 +148,12 @@ rm -f %{buildroot}/%{_builddir}/%{bolt_srcdir}/%{_vpath_builddir}/%{_lib}/lib*.a
%doc %{install_docdir}
%changelog
* Wed Sep 04 2024 rfwang07 <wangrufeng5@huawei.com> 17.0.6-8
- Type:Backport
- ID:NA
- SUG:NA
- DESC: Backport bugfix.
* Fri Jul 12 2024 rfwang07 <wangrufeng5@huawei.com> 17.0.6-7
- Type:Feature
- ID:NA