leonardchan created this revision.
leonardchan added reviewers: phosek, rnk, MaskRay, Lekensteyn, rsmith, echristo.
leonardchan added a project: LLVM.
Herald added subscribers: cfe-commits, ormris, hiraditya.
Herald added a project: clang.
leonardchan updated this revision to Diff 251289.
Some asan-instrumented binaries that are distributed as part of a clang
toolchain result in different sizes depending on the length of the build path.
This is because ASan is including the path to the source file from the module
ID and sanitizer metadata. To have a deterministic build independent of the
source file's location, we can extend the usage of `-ffile-prefix-map` to also
apply to sanitizers.
In this patch:
- Add a StringMap that can be used by anyone with access to `CodeGenOptions`
that holds all mappings passed to `-ffile-prefix-map`.
- Replace path prefixes for module IDs on module creation.
- Replace path prefixes for sanitizer metadata source locations when creating a
`GlobalsMetadata` object.
Design considerations:
- We avoid adding a new flag for sanitizers to prevent adding an extra knob. We
would also expect that `-ffile-prefix-map` generally apply to all instances of
paths we would see emitted into a stripped object file.
- I applied the mapping on `GlobalsMetadata` creation when the
`ASanGlobalsMetadataWrapperPass` runs because I couldn't think of a better
place to apply the prefix mapping. The path was originally passed down as a
StringRef all the way from a `PresumedLoc` in
`SanitizerMetadata::getLocationMetadata()`, which cannot be edited with
`replace_path_prefix`.
- I added the mapping as metadata (`llvm.asan.file.prefix.map`) to prevent
having to pass the original StringMap from clang all the way down to ASan and
iterating over the map whenever ASan creates a private string. Adding it to
metadata that `ASanGlobalsMetadataWrapperPass` can read should allow us to do
this once when that pass is created.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D76416
Files:
clang/include/clang/Basic/CodeGenOptions.h
clang/lib/CodeGen/ModuleBuilder.cpp
clang/lib/CodeGen/SanitizerMetadata.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Frontend/CompilerInvocation.cpp
clang/test/CodeGen/asan-globals-file-prefix-map.cpp
llvm/include/llvm/Transforms/Instrumentation/AddressSanitizer.h
llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
llvm/test/Instrumentation/AddressSanitizer/asan_file_prefix_map.ll
llvm/test/Instrumentation/AddressSanitizer/asan_no_file_prefix_map.ll
Index: llvm/test/Instrumentation/AddressSanitizer/asan_no_file_prefix_map.ll
===================================================================
--- /dev/null
+++ llvm/test/Instrumentation/AddressSanitizer/asan_no_file_prefix_map.ll
@@ -0,0 +1,20 @@
+; RUN: opt < %s -asan -asan-module -S | FileCheck %s
+
+target triple = "x86_64-unknown-linux-gnu"
+
+@global = global i32 0, align 4
+@global2 = global i32 0, align 4
+
+; Check that the string used for the source location has its original prefix.
+; CHECK: @___asan_gen_.{{[0-9]+}} = private unnamed_addr constant [22 x i8] c"/tmp/asan-globals.cpp\00", align 1
+; CHECK: @___asan_gen_.{{[0-9]+}} = private unnamed_addr constant [22 x i8] c"blah/asan-globals.cpp\00", align 1
+
+!llvm.asan.globals = !{!0, !1}
+!101 = !{!"/tmp", !"/some/other/tmp"}
+!102 = !{!"blah", !"../some/other/blah"}
+
+!0 = !{i32* @global, !6, !"global", i1 false, i1 false}
+!1 = !{i32* @global2, !7, !"global2", i1 false, i1 false}
+
+!6 = !{!"/tmp/asan-globals.cpp", i32 5, i32 5}
+!7 = !{!"blah/asan-globals.cpp", i32 5, i32 5}
Index: llvm/test/Instrumentation/AddressSanitizer/asan_file_prefix_map.ll
===================================================================
--- /dev/null
+++ llvm/test/Instrumentation/AddressSanitizer/asan_file_prefix_map.ll
@@ -0,0 +1,21 @@
+; RUN: opt < %s -asan -asan-module -S | FileCheck %s
+
+target triple = "x86_64-unknown-linux-gnu"
+
+@global = global i32 0, align 4
+@global2 = global i32 0, align 4
+
+; Check that the string used for the source location has it's prefix replaced if llvm.asan.file.prefix.map is present.
+; CHECK: @___asan_gen_.{{[0-9]+}} = private unnamed_addr constant [33 x i8] c"/some/other/tmp/asan-globals.cpp\00", align 1
+; CHECK: @___asan_gen_.{{[0-9]+}} = private unnamed_addr constant [36 x i8] c"../some/other/blah/asan-globals.cpp\00", align 1
+
+!llvm.asan.globals = !{!0, !1}
+!llvm.asan.file.prefix.map = !{!101, !102}
+!101 = !{!"/tmp", !"/some/other/tmp"}
+!102 = !{!"blah", !"../some/other/blah"}
+
+!0 = !{i32* @global, !6, !"global", i1 false, i1 false}
+!1 = !{i32* @global2, !7, !"global2", i1 false, i1 false}
+
+!6 = !{!"/tmp/asan-globals.cpp", i32 5, i32 5}
+!7 = !{!"blah/asan-globals.cpp", i32 5, i32 5}
Index: llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1151,6 +1151,26 @@
mdconst::extract<ConstantInt>(MDN->getOperand(4));
E.IsBlacklisted |= IsBlacklisted->isOne();
}
+
+ // Go through the file prefix map to replace prefixes in metadata that may
+ // contain filepaths. Do this once in the globals metadata pass so we don't
+ // need to run over the map in ASan for each metadata instance.
+ NamedMDNode *PrefixMap = M.getNamedMetadata("llvm.asan.file.prefix.map");
+ if (!PrefixMap)
+ return;
+ for (auto &Entry : Entries) {
+ for (auto MDN : PrefixMap->operands()) {
+ assert(MDN->getNumOperands() == 2 &&
+ "Each node in the prefix map should be a pair");
+ StringRef Prefix = cast<MDString>(MDN->getOperand(0))->getString();
+ StringRef Replacement = cast<MDString>(MDN->getOperand(1))->getString();
+ if (llvm::sys::path::replace_path_prefix(
+ Entry.second.SourceLoc.Filename, Prefix, Replacement,
+ llvm::sys::path::Style::native, true)) {
+ break;
+ }
+ }
+ }
}
AnalysisKey ASanGlobalsMetadataAnalysis::Key;
Index: llvm/include/llvm/Transforms/Instrumentation/AddressSanitizer.h
===================================================================
--- llvm/include/llvm/Transforms/Instrumentation/AddressSanitizer.h
+++ llvm/include/llvm/Transforms/Instrumentation/AddressSanitizer.h
@@ -22,7 +22,7 @@
/// Frontend-provided metadata for source location.
struct LocationMetadata {
- StringRef Filename;
+ llvm::SmallString<64> Filename;
int LineNo = 0;
int ColumnNo = 0;
Index: clang/test/CodeGen/asan-globals-file-prefix-map.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGen/asan-globals-file-prefix-map.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 %s -fsanitize=address -ffile-prefix-map=%S=/tmp -S -emit-llvm -o - %s -triple x86_64-unknown-linux-gnu| FileCheck %s
+
+int global;
+
+// Check that the __asan_gen_* contants use the prefix map.
+// CHECK: @global = global { i32, [60 x i8] } zeroinitializer, align 32
+// CHECK: @___asan_gen_{{\.?[0-9]*}} = private constant [38 x i8] c"/tmp/asan-globals-file-prefix-map.cpp\00", align 1
+// CHECK: @___asan_gen_{{\.?[0-9]*}} = private unnamed_addr constant [38 x i8] c"/tmp/asan-globals-file-prefix-map.cpp\00", align 1
+
+// Check that the `llvm.asan.file.prefix.map` metadata is emitted.
+// CHECK: !llvm.asan.globals = !{[[GLOBAL:\![0-9]+]]}
+// CHECK: !llvm.asan.file.prefix.map = !{[[MAPPING:\![0-9]+]]}
+
+// CHECK: [[GLOBAL]] = !{i32* getelementptr{{.*}} [[MDLOC:![0-9]+]], !"global"
+// CHECK: [[MDLOC]] = !{!"[[PATH:.+]]/asan-globals-file-prefix-map.cpp"
+// CHECK: [[MAPPING]] = !{!"[[PATH]]", !"/tmp"}
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -775,6 +775,12 @@
{std::string(Split.first), std::string(Split.second)});
}
+ for (const auto &Arg : Args.getAllArgValues(OPT_ffile_prefix_map_EQ)) {
+ auto Split = StringRef(Arg).split('=');
+ Opts.FilePrefixMap.insert(
+ {std::string(Split.first), std::string(Split.second)});
+ }
+
if (const Arg *A =
Args.getLastArg(OPT_emit_llvm_uselists, OPT_no_emit_llvm_uselists))
Opts.EmitLLVMUseLists = A->getOption().getID() == OPT_emit_llvm_uselists;
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -661,6 +661,20 @@
}
}
+/// Add a CC1 option to specify the file path prefix map.
+static void addFilePrefixMapArgMapArg(const Driver &D, const ArgList &Args,
+ ArgStringList &CmdArgs) {
+ for (const Arg *A : Args.filtered(options::OPT_ffile_prefix_map_EQ)) {
+ StringRef Map = A->getValue();
+ if (Map.find('=') == StringRef::npos)
+ D.Diag(diag::err_drv_invalid_argument_to_option)
+ << Map << A->getOption().getName();
+ else
+ CmdArgs.push_back(Args.MakeArgString("-ffile-prefix-map=" + Map));
+ A->claim();
+ }
+}
+
/// Vectorize at all optimization levels greater than 1 except for -Oz.
/// For -Oz the loop vectorizer is disabled, while the slp vectorizer is
/// enabled.
@@ -4994,6 +5008,7 @@
addDebugCompDirArg(Args, CmdArgs, D.getVFS());
addDebugPrefixMapArg(D, Args, CmdArgs);
+ addFilePrefixMapArgMapArg(D, Args, CmdArgs);
if (Arg *A = Args.getLastArg(options::OPT_ftemplate_depth_,
options::OPT_ftemplate_depth_EQ)) {
Index: clang/lib/CodeGen/SanitizerMetadata.cpp
===================================================================
--- clang/lib/CodeGen/SanitizerMetadata.cpp
+++ clang/lib/CodeGen/SanitizerMetadata.cpp
@@ -20,6 +20,9 @@
using namespace clang;
using namespace CodeGen;
+static constexpr char kASanFilePrefixMapMetadata[] =
+ "llvm.asan.file.prefix.map";
+
SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) {
@@ -59,6 +62,30 @@
llvm::NamedMDNode *AsanGlobals =
CGM.getModule().getOrInsertNamedMetadata("llvm.asan.globals");
AsanGlobals->addOperand(ThisGlobal);
+
+ // Add metadata to propgate file prefix mappings down to ASan. We can't edit
+ // the existing metadata passed to llvm.asan.globals because the metadata
+ // contains StringRefs that we can't edit. These refs point to strings all the
+ // way back to strings from the SourceManager.
+ //
+ // This will be an array of key-value pairs from the prefix mapping stored in
+ // the codegen options. These can be used to adjust the paths used during the
+ // ASanGlobalsMetadata analysis.
+
+ // Make sure not to add the prefix metadata more than once.
+ if (CGM.getModule().getNamedMetadata(kASanFilePrefixMapMetadata))
+ return;
+
+ llvm::NamedMDNode *AsanPrefixMapGlobals =
+ CGM.getModule().getOrInsertNamedMetadata(kASanFilePrefixMapMetadata);
+ for (const auto &Entry : CGM.getCodeGenOpts().FilePrefixMap) {
+ llvm::Metadata *PrefixPairMetadata[] = {
+ llvm::MDString::get(VMContext, Entry.getKey()),
+ llvm::MDString::get(VMContext, Entry.getValue()),
+ };
+ AsanPrefixMapGlobals->addOperand(
+ llvm::MDNode::get(VMContext, PrefixPairMetadata));
+ }
}
void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
Index: clang/lib/CodeGen/ModuleBuilder.cpp
===================================================================
--- clang/lib/CodeGen/ModuleBuilder.cpp
+++ clang/lib/CodeGen/ModuleBuilder.cpp
@@ -65,11 +65,18 @@
private:
SmallVector<FunctionDecl *, 8> DeferredInlineMemberFuncDefs;
- static llvm::StringRef ExpandModuleName(llvm::StringRef ModuleName,
- const CodeGenOptions &CGO) {
- if (ModuleName == "-" && !CGO.MainFileName.empty())
- return CGO.MainFileName;
- return ModuleName;
+ static llvm::SmallString<64> ExpandModuleName(llvm::StringRef ModuleName,
+ const CodeGenOptions &CGO) {
+ llvm::SmallString<64> Name =
+ (ModuleName == "-" && !CGO.MainFileName.empty()) ? CGO.MainFileName
+ : ModuleName;
+ for (const auto &Entry : CGO.FilePrefixMap) {
+ if (llvm::sys::path::replace_path_prefix(
+ Name, Entry.getKey(), Entry.getValue(),
+ llvm::sys::path::Style::native, true))
+ break;
+ }
+ return Name;
}
public:
@@ -80,8 +87,9 @@
CoverageSourceInfo *CoverageInfo = nullptr)
: Diags(diags), Ctx(nullptr), HeaderSearchOpts(HSO),
PreprocessorOpts(PPO), CodeGenOpts(CGO), HandlingTopLevelDecls(0),
- CoverageInfo(CoverageInfo),
- M(new llvm::Module(ExpandModuleName(ModuleName, CGO), C)) {
+ CoverageInfo(CoverageInfo) {
+ auto ExpandedName = ExpandModuleName(ModuleName, CGO);
+ M.reset(new llvm::Module(ExpandedName, C));
C.setDiscardValueNames(CGO.DiscardValueNames);
}
@@ -129,7 +137,8 @@
llvm::Module *StartModule(llvm::StringRef ModuleName,
llvm::LLVMContext &C) {
assert(!M && "Replacing existing Module?");
- M.reset(new llvm::Module(ExpandModuleName(ModuleName, CodeGenOpts), C));
+ auto ExpandedName = ExpandModuleName(ModuleName, CodeGenOpts);
+ M.reset(new llvm::Module(ExpandedName, C));
Initialize(*Ctx);
return M.get();
}
Index: clang/include/clang/Basic/CodeGenOptions.h
===================================================================
--- clang/include/clang/Basic/CodeGenOptions.h
+++ clang/include/clang/Basic/CodeGenOptions.h
@@ -17,6 +17,7 @@
#include "clang/Basic/Sanitizers.h"
#include "clang/Basic/XRayInstr.h"
#include "llvm/ADT/FloatingPointMode.h"
+#include "llvm/ADT/StringMap.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/Regex.h"
#include "llvm/Target/TargetOptions.h"
@@ -160,6 +161,9 @@
std::map<std::string, std::string> DebugPrefixMap;
+ /// Prefix mapping for file prefixes.
+ llvm::StringMap<std::string> FilePrefixMap;
+
/// The ABI to use for passing floating point arguments.
std::string FloatABI;
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