-fsanitize=function: fix .subsections_via_symbols #87527
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@llvm/pr-subscribers-backend-aarch64 @llvm/pr-subscribers-backend-x86 Author: Leonard Grey (speednoisemovement) Changes-fsanitize=function emits a signature and function hash before a function. Similar to 7f6e2c9, these can be sheared off when This change uses the same technique 7f6e2c9 introduced for prefixes: emitting a symbol for the metadata, then marking the actual function entry as an .alt_entry symbol. Full diff: https://github.com/llvm/llvm-project/pull/87527.diff 4 Files Affected:
diff --git a/llvm/include/llvm/CodeGen/AsmPrinter.h b/llvm/include/llvm/CodeGen/AsmPrinter.h
index a7fbf4aeb74494..f5abea8342d587 100644
--- a/llvm/include/llvm/CodeGen/AsmPrinter.h
+++ b/llvm/include/llvm/CodeGen/AsmPrinter.h
@@ -868,6 +868,9 @@ class AsmPrinter : public MachineFunctionPass {
/// This method emits a comment next to header for the current function.
virtual void emitFunctionHeaderComment();
+ /// This method emits prefix-like data before the current function.
+ void emitFunctionPrefix(const SmallVector<const Constant *, 1> &Prefix);
+
/// Emit a blob of inline asm to the output streamer.
void
emitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 293bb5a3c6f6eb..bb6994b96288ed 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -927,6 +927,30 @@ void AsmPrinter::emitDebugValue(const MCExpr *Value, unsigned Size) const {
void AsmPrinter::emitFunctionHeaderComment() {}
+void AsmPrinter::emitFunctionPrefix(
+ const SmallVector<const Constant *, 1> &Prefix) {
+ const Function &F = MF->getFunction();
+ if (!MAI->hasSubsectionsViaSymbols()) {
+ for (auto &C : Prefix) {
+ emitGlobalConstant(F.getParent()->getDataLayout(), C);
+ }
+ return;
+ }
+ // Preserving prefix data on platforms which use subsections-via-symbols
+ // is a bit tricky. Here we introduce a symbol for the prefix data
+ // and use the .alt_entry attribute to mark the function's real entry point
+ // as an alternative entry point to the prefix-data symbol.
+ MCSymbol *PrefixSym = OutContext.createLinkerPrivateTempSymbol();
+ OutStreamer->emitLabel(PrefixSym);
+
+ for (auto &C : Prefix) {
+ emitGlobalConstant(F.getParent()->getDataLayout(), C);
+ }
+
+ // Emit an .alt_entry directive for the actual function symbol.
+ OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_AltEntry);
+}
+
/// EmitFunctionHeader - This method emits the header for the current
/// function.
void AsmPrinter::emitFunctionHeader() {
@@ -967,21 +991,7 @@ void AsmPrinter::emitFunctionHeader() {
// Emit the prefix data.
if (F.hasPrefixData()) {
- if (MAI->hasSubsectionsViaSymbols()) {
- // Preserving prefix data on platforms which use subsections-via-symbols
- // is a bit tricky. Here we introduce a symbol for the prefix data
- // and use the .alt_entry attribute to mark the function's real entry point
- // as an alternative entry point to the prefix-data symbol.
- MCSymbol *PrefixSym = OutContext.createLinkerPrivateTempSymbol();
- OutStreamer->emitLabel(PrefixSym);
-
- emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData());
-
- // Emit an .alt_entry directive for the actual function symbol.
- OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_AltEntry);
- } else {
- emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData());
- }
+ emitFunctionPrefix({F.getPrefixData()});
}
// Emit KCFI type information before patchable-function-prefix nops.
@@ -1014,8 +1024,7 @@ void AsmPrinter::emitFunctionHeader() {
auto *PrologueSig = mdconst::extract<Constant>(MD->getOperand(0));
auto *TypeHash = mdconst::extract<Constant>(MD->getOperand(1));
- emitGlobalConstant(F.getParent()->getDataLayout(), PrologueSig);
- emitGlobalConstant(F.getParent()->getDataLayout(), TypeHash);
+ emitFunctionPrefix({PrologueSig, TypeHash});
}
if (isVerbose()) {
diff --git a/llvm/test/CodeGen/AArch64/func-sanitizer.ll b/llvm/test/CodeGen/AArch64/func-sanitizer.ll
index 89f23e7ed80e88..eb059a7d36b44c 100644
--- a/llvm/test/CodeGen/AArch64/func-sanitizer.ll
+++ b/llvm/test/CodeGen/AArch64/func-sanitizer.ll
@@ -1,4 +1,5 @@
; RUN: llc -mtriple=aarch64-unknown-linux-gnu < %s | FileCheck %s
+; RUN: llc -mtriple=arm64-apple-darwin < %s | FileCheck %s --check-prefix=MACHO
; CHECK-LABEL: .type _Z3funv,@function
; CHECK-NEXT: .word 3238382334 // 0xc105cafe
@@ -7,6 +8,14 @@
; CHECK-NEXT: // %bb.0:
; CHECK-NEXT: ret
+; MACHO: ltmp0
+; MACHO-NEXT: .long 3238382334 ; 0xc105cafe
+; MACHO-NEXT: .long 42 ; 0x2a
+; MACHO-NEXT: .alt_entry __Z3funv
+; MACHO-NEXT: __Z3funv:
+; MACHO-NEXT: ; %bb.0:
+; MACHO-NEXT: ret
+
define dso_local void @_Z3funv() nounwind !func_sanitize !0 {
ret void
}
diff --git a/llvm/test/CodeGen/X86/func-sanitizer.ll b/llvm/test/CodeGen/X86/func-sanitizer.ll
index b421cb53ddfecf..016cc0f07db796 100644
--- a/llvm/test/CodeGen/X86/func-sanitizer.ll
+++ b/llvm/test/CodeGen/X86/func-sanitizer.ll
@@ -1,4 +1,5 @@
; RUN: llc -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
+; RUN: llc -mtriple=x86_64-apple-darwin < %s | FileCheck %s --check-prefix=MACHO
; CHECK: .type _Z3funv,@function
; CHECK-NEXT: .long 3238382334 # 0xc105cafe
@@ -8,6 +9,15 @@
; CHECK-NEXT: # %bb.0:
; CHECK-NEXT: retq
+; MACHO: ltmp0
+; MACHO-NEXT: .long 3238382334 ## 0xc105cafe
+; MACHO-NEXT: .long 42 ## 0x2a
+; MACHO-NEXT: .alt_entry __Z3funv
+; MACHO-NEXT: __Z3funv:
+; MACHO-NEXT: .cfi_startproc
+; MACHO-NEXT: # %bb.0:
+; MACHO-NEXT: retq
+
define dso_local void @_Z3funv() !func_sanitize !0 {
ret void
}
|
MaskRay
approved these changes
Apr 6, 2024
| @@ -7,6 +8,14 @@ | |||
| ; CHECK-NEXT: // %bb.0: | |||
| ; CHECK-NEXT: ret | |||
|
|
|||
| ; MACHO: ltmp0 | |||
| @@ -8,6 +9,15 @@ | |||
| ; CHECK-NEXT: # %bb.0: | |||
| ; CHECK-NEXT: retq | |||
|
|
|||
| ; MACHO: ltmp0 | |||
There was a problem hiding this comment.
; MACHO: ltmp0:
add a colon to ensure we are testing a label
| const Function &F = MF->getFunction(); | ||
| if (!MAI->hasSubsectionsViaSymbols()) { | ||
| for (auto &C : Prefix) { | ||
| emitGlobalConstant(F.getParent()->getDataLayout(), C); |
There was a problem hiding this comment.
| OutStreamer->emitLabel(PrefixSym); | ||
|
|
||
| for (auto &C : Prefix) { | ||
| emitGlobalConstant(F.getParent()->getDataLayout(), C); |
There was a problem hiding this comment.
| } else { | ||
| emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData()); | ||
| } | ||
| emitFunctionPrefix({F.getPrefixData()}); | ||
| } |
| return; | ||
| } | ||
| // Preserving prefix data on platforms which use subsections-via-symbols | ||
| // is a bit tricky. Here we introduce a symbol for the prefix data |
There was a problem hiding this comment.
The comment about "prefix data" should be adjusted
| // and use the .alt_entry attribute to mark the function's real entry point | ||
| // as an alternative entry point to the prefix-data symbol. | ||
| MCSymbol *PrefixSym = OutContext.createLinkerPrivateTempSymbol(); | ||
| OutStreamer->emitLabel(PrefixSym); |
There was a problem hiding this comment.
OutStreamer->emitLabel(OutContext.createLinkerPrivateTempSymbol());
MaskRay
reviewed
Apr 6, 2024
| @@ -868,6 +868,9 @@ class AsmPrinter : public MachineFunctionPass { | |||
| /// This method emits a comment next to header for the current function. | |||
| virtual void emitFunctionHeaderComment(); | |||
|
|
|||
| /// This method emits prefix-like data before the current function. | |||
| void emitFunctionPrefix(const SmallVector<const Constant *, 1> &Prefix); | |||
There was a problem hiding this comment.
Use ArrayRef like https://github.com/MaskRay/llvm-project/tree/pr87527-edit
MaskRay
approved these changes
Apr 8, 2024
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-fsanitize=function emits a signature and function hash before a function. Similar to 7f6e2c9, these can be sheared off when
.subsections_via_symbolsis used.This change uses the same technique 7f6e2c9 introduced for prefixes: emitting a symbol for the metadata, then marking the actual function entry as an .alt_entry symbol.