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The purpose of __attribute__((no_sanitizer_instrumentation)) is to
prevent all kinds of sanitizer instrumentation applied to a certain
function.
The no_sanitize(...) attribute drops instrumentation checks, but may
still insert code preventing false positive reports. In some cases
though (e.g. when building Linux kernel with -fsanitize=kernel-memory
or -fsanitize=thread) the users may want to avoid any kind of
instrumentation.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D108029
Files:
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttrDocs.td
clang/lib/CodeGen/CodeGenFunction.cpp
clang/lib/CodeGen/CodeGenFunction.h
clang/test/CodeGen/attr-no-sanitize-coverage.c
clang/test/Misc/pragma-attribute-supported-attributes-list.test
llvm/include/llvm/AsmParser/LLToken.h
llvm/include/llvm/IR/Attributes.td
Index: llvm/include/llvm/IR/Attributes.td
===================================================================
--- llvm/include/llvm/IR/Attributes.td
+++ llvm/include/llvm/IR/Attributes.td
@@ -175,6 +175,9 @@
/// No SanitizeCoverage instrumentation.
def NoSanitizeCoverage : EnumAttr<"nosanitize_coverage", [FnAttr]>;
+/// Do not instrument function with sanitizers.
+def NoSanitizerInstrumentation: EnumAttr<"no_sanitizer_instrumentation", [FnAttr]>;
+
/// Null pointer in address space zero is valid.
def NullPointerIsValid : EnumAttr<"null_pointer_is_valid", [FnAttr]>;
Index: llvm/include/llvm/AsmParser/LLToken.h
===================================================================
--- llvm/include/llvm/AsmParser/LLToken.h
+++ llvm/include/llvm/AsmParser/LLToken.h
@@ -219,6 +219,7 @@
kw_nocf_check,
kw_nounwind,
kw_nosanitize_coverage,
+ kw_no_sanitizer_instrumentation,
kw_null_pointer_is_valid,
kw_optforfuzzing,
kw_optnone,
Index: clang/test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -102,6 +102,7 @@
// CHECK-NEXT: NoProfileFunction (SubjectMatchRule_function)
// CHECK-NEXT: NoSanitize (SubjectMatchRule_function, SubjectMatchRule_objc_method, SubjectMatchRule_variable_is_global)
// CHECK-NEXT: NoSanitizeSpecific (SubjectMatchRule_function, SubjectMatchRule_variable_is_global)
+// CHECK-NEXT: NoSanitizerInstrumentation (SubjectMatchRule_function)
// CHECK-NEXT: NoSpeculativeLoadHardening (SubjectMatchRule_function, SubjectMatchRule_objc_method)
// CHECK-NEXT: NoSplitStack (SubjectMatchRule_function)
// CHECK-NEXT: NoStackProtector (SubjectMatchRule_function)
Index: clang/test/CodeGen/attr-no-sanitize-coverage.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/attr-no-sanitize-coverage.c
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -debug-info-kind=limited %s -emit-llvm -o - | FileCheck %s
+
+void t1() __attribute__((no_sanitizer_instrumentation)) {
+}
+// CHECK: no_sanitizer_instrumentation
+// CHECK-NEXT: void @t1
+
+// CHECK-NOT: no_sanitizer_instrumentation
+// CHECK: void @t2
+void t2() {
+}
Index: clang/lib/CodeGen/CodeGenFunction.h
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.h
+++ clang/lib/CodeGen/CodeGenFunction.h
@@ -2285,6 +2285,7 @@
/// ShouldInstrumentFunction - Return true if the current function should be
/// instrumented with __cyg_profile_func_* calls
bool ShouldInstrumentFunction();
+ bool ShouldSkipSanitizerInstrumentation();
/// ShouldXRayInstrument - Return true if the current function should be
/// instrumented with XRay nop sleds.
Index: clang/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.cpp
+++ clang/lib/CodeGen/CodeGenFunction.cpp
@@ -381,6 +381,9 @@
"__cyg_profile_func_exit");
}
+ if (ShouldSkipSanitizerInstrumentation())
+ CurFn->addFnAttr(llvm::Attribute::NoSanitizerInstrumentation);
+
// Emit debug descriptor for function end.
if (CGDebugInfo *DI = getDebugInfo())
DI->EmitFunctionEnd(Builder, CurFn);
@@ -517,6 +520,14 @@
return true;
}
+bool CodeGenFunction::ShouldSkipSanitizerInstrumentation() {
+ if (!CurFuncDecl)
+ return false;
+ if (CurFuncDecl->hasAttr<NoSanitizerInstrumentationAttr>())
+ return true;
+ return false;
+}
+
/// ShouldXRayInstrument - Return true if the current function should be
/// instrumented with XRay nop sleds.
bool CodeGenFunction::ShouldXRayInstrumentFunction() const {
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -2592,6 +2592,17 @@
}];
}
+def NoSanitizerInstrumentationDocs : Documentation {
+ let Category = DocCatFunction;
+ let Content = [{
+Use the ``no_sanitizer_instrumentation`` attribute on a function to specify
+that no sanitizer instrumentation should be applied.
+
+This is not the same as ``__attribute__((no_sanitize(...)))``, which depending
+on the tool may still insert instrumentation to prevent false positive reports.
+ }];
+}
+
def NoSanitizeAddressDocs : Documentation {
let Category = DocCatFunction;
// This function has multiple distinct spellings, and so it requires a custom
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -2940,6 +2940,13 @@
let ASTNode = 0;
}
+def NoSanitizerInstrumentation : InheritableAttr {
+ let Spellings = [Clang<"no_sanitizer_instrumentation">];
+ let Subjects = SubjectList<[Function]>;
+ let Documentation = [NoSanitizerInstrumentationDocs];
+ let SimpleHandler = 1;
+}
+
def CFICanonicalJumpTable : InheritableAttr {
let Spellings = [Clang<"cfi_canonical_jump_table">];
let Subjects = SubjectList<[Function], ErrorDiag>;
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