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[compiler-rt][hwasan] Add fiber switch for HwASan #153822

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Merged
merged 6 commits into from
Aug 20, 2025
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[compiler-rt][hwasan] Add fiber switch for HwASan #153822

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612b7e6
[compiler-rt][hwasan] Add fiber switch for HwASan
Tomahawkd Aug 15, 2025
77cc939
Minor adjustment from reviewer:
Tomahawkd Aug 15, 2025
538b8f8
refine testcase to test on aarch64
Tomahawkd Aug 16, 2025
f225e34
clang format fix
Tomahawkd Aug 19, 2025
1fb1bca
use uninstrumented global to simulate allocation
Tomahawkd Aug 19, 2025
70f830b
clang format fix
Tomahawkd Aug 19, 2025
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74 changes: 42 additions & 32 deletions compiler-rt/test/hwasan/TestCases/Linux/swapcontext_annotation.cpp
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Original file line number Diff line number Diff line change
@@ -1,19 +1,18 @@
// Check that HwASan plays well with annotated makecontext/swapcontext.

// RUN: %clangxx_hwasan -std=c++11 -lpthread -O0 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_hwasan -std=c++11 -lpthread -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_hwasan -std=c++11 -lpthread -O2 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_hwasan -std=c++11 -lpthread -O3 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: seq 60 | xargs -i -- grep LOOPCHECK %s > %t.checks
// RUN: %clangxx_hwasan -std=c++11 -lpthread -O0 %s -o %t && %run %t 2>&1 | FileCheck %t.checks --check-prefix LOOPCHECK
// RUN: %clangxx_hwasan -std=c++11 -lpthread -O1 %s -o %t && %run %t 2>&1 | FileCheck %t.checks --check-prefix LOOPCHECK
// RUN: %clangxx_hwasan -std=c++11 -lpthread -O2 %s -o %t && %run %t 2>&1 | FileCheck %t.checks --check-prefix LOOPCHECK
// RUN: %clangxx_hwasan -std=c++11 -lpthread -O3 %s -o %t && %run %t 2>&1 | FileCheck %t.checks --check-prefix LOOPCHECK
// Test hwasan __sanitizer_start_switch_fiber and __sanitizer_finish_switch_fiber interface.

// RUN: %clangxx_hwasan -std=c++11 -lpthread -ldl -O0 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_hwasan -std=c++11 -lpthread -ldl -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_hwasan -std=c++11 -lpthread -ldl -O2 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: %clangxx_hwasan -std=c++11 -lpthread -ldl -O3 %s -o %t && %run %t 2>&1 | FileCheck %s
// RUN: seq 30 | xargs -i -- grep LOOPCHECK %s > %t.checks
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@fmayer fmayer Aug 18, 2025

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Out of interest, why this change?

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@Tomahawkd Tomahawkd Aug 19, 2025

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Original asan testcase tests on stack and heap, therefore it has 60 LOOPCHECK messages.

// RUN: %clangxx_hwasan -std=c++11 -lpthread -ldl -O0 %s -o %t && %run %t 2>&1 | FileCheck %t.checks --check-prefix LOOPCHECK
// RUN: %clangxx_hwasan -std=c++11 -lpthread -ldl -O1 %s -o %t && %run %t 2>&1 | FileCheck %t.checks --check-prefix LOOPCHECK
// RUN: %clangxx_hwasan -std=c++11 -lpthread -ldl -O2 %s -o %t && %run %t 2>&1 | FileCheck %t.checks --check-prefix LOOPCHECK
// RUN: %clangxx_hwasan -std=c++11 -lpthread -ldl -O3 %s -o %t && %run %t 2>&1 | FileCheck %t.checks --check-prefix LOOPCHECK

//
// This test is too subtle to try on non-x86 arch for now.
// Android and musl do not support swapcontext.
// REQUIRES: x86-target-arch && glibc-2.27
// REQUIRES: glibc-2.27

#include <pthread.h>
#include <setjmp.h>
Expand All @@ -22,6 +21,7 @@
#include <sys/time.h>
#include <ucontext.h>
#include <unistd.h>
#include <dlfcn.h>

#include <sanitizer/common_interface_defs.h>

Expand Down Expand Up @@ -125,31 +125,30 @@ int Run(int arg, int mode, char *child_stack) {
}
makecontext(&child_context, (void (*)())Child, 1, mode);
CallNoReturn();
void *fake_stack_save;
__sanitizer_start_switch_fiber(&fake_stack_save, child_context.uc_stack.ss_sp,
__sanitizer_start_switch_fiber(nullptr, child_context.uc_stack.ss_sp,
child_context.uc_stack.ss_size);
CallNoReturn();
if (swapcontext(&orig_context, &child_context) < 0) {
perror("swapcontext");
_exit(1);
}
CallNoReturn();
__sanitizer_finish_switch_fiber(fake_stack_save, &from_stack,
&from_stacksize);
__sanitizer_finish_switch_fiber(nullptr, &from_stack, &from_stacksize);
CallNoReturn();
printf("Main context from: %p %zu\n", from_stack, from_stacksize);

// Touch childs's stack to make sure it's unpoisoned.
for (int i = 0; i < kStackSize; i++) {
child_stack[i] = i;
}
return child_stack[arg];
}

void handler(int sig) { CallNoReturn(); }

int main(int argc, char **argv) {
// removed huge stack test since hwasan has no huge stack limitations
// This testcase is copied from ASan's swapcontext_annotation.cpp testcase
// and adapted to HWASan:
// 1. removed huge stack test since hwasan has no huge stack limitations
// 2. stack allocations are now done with original malloc/free instead of
// hwasan interceptor, since HWASan does not support tagged stack pointer
// in longjmp (see __hwasan_handle_longjmp)

// set up a signal that will spam and trigger __hwasan_handle_vfork at
// tricky moments
Expand All @@ -169,34 +168,45 @@ int main(int argc, char **argv) {
_exit(1);
}

char *heap = new char[kStackSize + 1];
next_child_stack = new char[kStackSize + 1];
char stack[kStackSize + 1];
// We search malloc/free here because the original symbol is intercepted.
// Unfortunately, hwasan does not support longjmp with tagged stack pointer,
// so we use RTLD_NEXT to search original symbols assuming hwasan is
// statically linked (default behavior currently).
void *(*malloc_func)(size_t) = (void *(*)(size_t)) dlsym(RTLD_NEXT, "malloc");
if (malloc_func == nullptr) {
perror("dlsym malloc");
_exit(1);
}
void (*free_func)(void *) = (void (*)(void *)) dlsym(RTLD_NEXT, "free");
if (free_func == nullptr) {
perror("dlsym free");
_exit(1);
}

char *heap = (char *)malloc_func(kStackSize + 1);
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@fmayer fmayer Aug 18, 2025

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Could we just make these two global variables and get rid of the dlsym dance?

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@Tomahawkd Tomahawkd Aug 19, 2025

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Fixed

next_child_stack = (char *)malloc_func(kStackSize + 1);
int ret = 0;
// CHECK-NOT: WARNING: HWASan is ignoring requested __hwasan_handle_vfork
for (unsigned int i = 0; i < 30; ++i) {
ret += Run(argc - 1, 0, stack);
// LOOPCHECK: Child stack: [[CHILD_STACK:0x[0-9a-f]*]]
// LOOPCHECK: Main context from: [[CHILD_STACK]] 524288
ret += Run(argc - 1, 1, stack);
ret += Run(argc - 1, 0, heap);
// LOOPCHECK: Child stack: [[CHILD_STACK:0x[0-9a-f]*]]
// LOOPCHECK: Main context from: [[CHILD_STACK]] 524288
ret += Run(argc - 1, 2, stack);
ret += Run(argc - 1, 1, heap);
// LOOPCHECK: Child stack: [[CHILD_STACK:0x[0-9a-f]*]]
// LOOPCHECK: NextChild stack: [[NEXT_CHILD_STACK:0x[0-9a-f]*]]
// LOOPCHECK: NextChild from: [[CHILD_STACK]] 524288
// LOOPCHECK: Main context from: [[NEXT_CHILD_STACK]] 524288
ret += Run(argc - 1, 0, heap);
ret += Run(argc - 1, 1, heap);
ret += Run(argc - 1, 2, heap);
printf("Iteration %d passed\n", i);
}

// CHECK: Test passed
printf("Test passed\n");

delete[] heap;
delete[] next_child_stack;
free_func(heap);
free_func(next_child_stack);

return ret;
}
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