Skip to content

[ASan][X86] Mark asan_globals section large #74514

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Dec 7, 2023
Merged

[ASan][X86] Mark asan_globals section large #74514

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c651790
[ASan][X86] Mark asan_globals section large
aeubanks Dec 5, 2023
88ca657
update comment
aeubanks Dec 7, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2144,6 +2144,11 @@ ModuleAddressSanitizer::CreateMetadataGlobal(Module &M, Constant *Initializer,
M, Initializer->getType(), false, Linkage, Initializer,
Twine("__asan_global_") + GlobalValue::dropLLVMManglingEscape(OriginalName));
Metadata->setSection(getGlobalMetadataSection());
// Move metadata section out of the way for x86-64 ELF binaries to mitigate
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Place metadata in a large section for ... to mitigate ...

// relocation pressure.
if (TargetTriple.getArch() == Triple::x86_64 &&
TargetTriple.getObjectFormat() == Triple::ELF)
Metadata->setCodeModel(CodeModel::Large);
return Metadata;
}

Expand Down
10 changes: 10 additions & 0 deletions llvm/test/Instrumentation/AddressSanitizer/global_metadata_code_model.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
; RUN: opt < %s -mtriple=x86_64-unknown-linux-gnu -passes=asan -S | FileCheck %s --check-prefix=LARGE
; RUN: opt < %s -mtriple=aarch64-unknown-linux-gnu -passes=asan -S | FileCheck %s --check-prefix=NORMAL
; RUN: opt < %s -mtriple=x86_64-pc-windows -passes=asan -S | FileCheck %s --check-prefix=NORMAL

; check that asan globals metadata are emitted to a large section for x86-64 ELF

; LARGE: @__asan_global_global = {{.*}}global {{.*}}, code_model "large"
; NORMAL-NOT: code_model "large"

@global = global i32 0, align 4
4 changes: 2 additions & 2 deletions llvm/test/Instrumentation/AddressSanitizer/global_with_comdat.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -102,8 +102,8 @@ target triple = "x86_64-unknown-linux-gnu"
;; Don't place the instrumented globals in a comdat when the unique module ID is empty.
; NOMODULEID: @.str = internal constant { [4 x i8], [28 x i8] } { [4 x i8] c"str\00", [28 x i8] zeroinitializer }, align 32
; NOMODULEID: @_ZL3buf = internal global { [4 x i8], [28 x i8] } zeroinitializer, align 32
; NOMODULEID: @__asan_global_.str = private global {{.*}}, section "asan_globals", !associated !0
; NOMODULEID: @__asan_global__ZL3buf = private global {{.*}}, section "asan_globals", !associated !1
; NOMODULEID: @__asan_global_.str = private global {{.*}}, section "asan_globals"{{.*}}, !associated !0
; NOMODULEID: @__asan_global__ZL3buf = private global {{.*}}, section "asan_globals"{{.*}}, !associated !1
; NOMODULEID: @llvm.compiler.used = appending global [4 x ptr] [ptr @.str, ptr @_ZL3buf, ptr @__asan_global_.str, ptr @__asan_global__ZL3buf]

; NOMODULEID: define internal void @asan.module_ctor() #[[#]] comdat {
Expand Down