[hwasan] Add hwasan-static-linking option (#154529)

Discarding the `.note.hwasan.globals` section in ldscript causes a
linker error, since `hwasan_globals` refers to the discarded section.
The issue comes from `hwasan.dummy.global` being associated via metadata
with `.note.hwasan.globals`.

Add a new `-hwasan-static-linking` option to skip inserting
`.note.hwasan.globals` for static binaries, as it is only needed for
instrumenting globals from dynamic libraries. In static binaries, the
global variables section can be accessed directly via the
`__start_hwasan_globals` and `__stop_hwasan_globals` symbols inserted by
the linker.

Author: jakosv

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

@@ -212,6 +212,15 @@ static cl::opt<float>
                               "OR because of the hot percentile cutoff, if "
                               "both are supplied."));
 
+static cl::opt<bool> ClStaticLinking(
+    "hwasan-static-linking",
+    cl::desc("Don't use .note.hwasan.globals section to instrument globals "
+             "from loadable libraries. "
+             "Note: in static binaries, the global variables section can be "
+             "accessed directly via linker-provided "
+             "__start_hwasan_globals and __stop_hwasan_globals symbols"),
+    cl::Hidden, cl::init(false));
+
 STATISTIC(NumTotalFuncs, "Number of total funcs");
 STATISTIC(NumInstrumentedFuncs, "Number of instrumented funcs");
 STATISTIC(NumNoProfileSummaryFuncs, "Number of funcs without PS");
@@ -335,6 +344,7 @@ class HWAddressSanitizer {
                                           FunctionAnalysisManager &FAM) const;
   void initializeModule();
   void createHwasanCtorComdat();
+  void createHwasanNote();
 
   void initializeCallbacks(Module &M);
 
@@ -533,20 +543,7 @@ void HWAddressSanitizerPass::printPipeline(
   OS << '>';
 }
 
-void HWAddressSanitizer::createHwasanCtorComdat() {
-  std::tie(HwasanCtorFunction, std::ignore) =
-      getOrCreateSanitizerCtorAndInitFunctions(
-          M, kHwasanModuleCtorName, kHwasanInitName,
-          /*InitArgTypes=*/{},
-          /*InitArgs=*/{},
-          // This callback is invoked when the functions are created the first
-          // time. Hook them into the global ctors list in that case:
-          [&](Function *Ctor, FunctionCallee) {
-            Comdat *CtorComdat = M.getOrInsertComdat(kHwasanModuleCtorName);
-            Ctor->setComdat(CtorComdat);
-            appendToGlobalCtors(M, Ctor, 0, Ctor);
-          });
-
+void HWAddressSanitizer::createHwasanNote() {
   // Create a note that contains pointers to the list of global
   // descriptors. Adding a note to the output file will cause the linker to
   // create a PT_NOTE program header pointing to the note that we can use to
@@ -630,6 +627,29 @@ void HWAddressSanitizer::createHwasanCtorComdat() {
   appendToCompilerUsed(M, Dummy);
 }
 
+void HWAddressSanitizer::createHwasanCtorComdat() {
+  std::tie(HwasanCtorFunction, std::ignore) =
+      getOrCreateSanitizerCtorAndInitFunctions(
+          M, kHwasanModuleCtorName, kHwasanInitName,
+          /*InitArgTypes=*/{},
+          /*InitArgs=*/{},
+          // This callback is invoked when the functions are created the first
+          // time. Hook them into the global ctors list in that case:
+          [&](Function *Ctor, FunctionCallee) {
+            Comdat *CtorComdat = M.getOrInsertComdat(kHwasanModuleCtorName);
+            Ctor->setComdat(CtorComdat);
+            appendToGlobalCtors(M, Ctor, 0, Ctor);
+          });
+
+  // Do not create .note.hwasan.globals for static binaries, as it is only
+  // needed for instrumenting globals from dynamic libraries. In static
+  // binaries, the global variables section can be accessed directly via the
+  // __start_hwasan_globals and __stop_hwasan_globals symbols inserted by the
+  // linker.
+  if (!ClStaticLinking)
+    createHwasanNote();
+}
+
 /// Module-level initialization.
 ///
 /// inserts a call to __hwasan_init to the module's constructor list.

llvm/test/Instrumentation/HWAddressSanitizer/globals.ll

@@ -1,4 +1,5 @@
 ; RUN: opt < %s -S -passes=hwasan -mtriple=aarch64--linux-android29 | FileCheck --check-prefixes=CHECK,CHECK29,NOALLGLOBALS %s
+; RUN: opt < %s -S -passes=hwasan -mtriple=aarch64--linux-android29 -hwasan-static-linking=1 | FileCheck --check-prefixes=CHECK29,STATICLINKING %s
 ; RUN: opt < %s -S -passes=hwasan -mtriple=aarch64--linux-android30 | FileCheck --check-prefixes=CHECK,CHECK30,NOALLGLOBALS %s
 ; RUN: opt < %s -S -passes=hwasan -mtriple=riscv64-unknown-elf -hwasan-globals=1 -hwasan-all-globals=1 | FileCheck --check-prefixes=CHECK,CHECK30,ALLGLOBALS %s
 
@@ -24,6 +25,8 @@
 
 ; CHECK: @hwasan.note = private constant { i32, i32, i32, [8 x i8], i32, i32 } { i32 8, i32 8, i32 3, [8 x i8] c"LLVM\00\00\00\00", i32 trunc (i64 sub (i64 ptrtoint (ptr @__start_hwasan_globals to i64), i64 ptrtoint (ptr @hwasan.note to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @__stop_hwasan_globals to i64), i64 ptrtoint (ptr @hwasan.note to i64)) to i32) }, section ".note.hwasan.globals", comdat($hwasan.module_ctor), align 4
 
+; STATICLINKING-NOT: @hwasan.note = private constant { i32, i32, i32, [8 x i8], i32, i32 } { i32 8, i32 8, i32 3, [8 x i8] c"LLVM\00\00\00\00", i32 trunc (i64 sub (i64 ptrtoint (ptr @__start_hwasan_globals to i64), i64 ptrtoint (ptr @hwasan.note to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @__stop_hwasan_globals to i64), i64 ptrtoint (ptr @hwasan.note to i64)) to i32) }, section ".note.hwasan.globals", comdat($hwasan.module_ctor), align 4
+
 ; CHECK: @hwasan.dummy.global = private constant [0 x i8] zeroinitializer, section "hwasan_globals", comdat($hwasan.module_ctor), !associated [[NOTE:![0-9]+]]
 
 ; CHECK30: @four = alias i32, inttoptr (i64 add (i64 ptrtoint (ptr @four.hwasan to i64), i64 -6052837899185946624) to ptr)