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//===-- asan_stack.cc -----------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// Code for ASan stack trace.
//===----------------------------------------------------------------------===//
#include "asan_interface.h"
#include "asan_stack.h"
#include "sanitizer_common/sanitizer_procmaps.h"
#include "sanitizer_common/sanitizer_symbolizer.h"
namespace __asan {
static __asan_symbolize_callback symbolize_callback;
static const char *StripPathPrefix(const char *filepath) {
const char *path_prefix = flags()->strip_path_prefix;
if (filepath == internal_strstr(filepath, path_prefix))
return filepath + internal_strlen(path_prefix);
return filepath;
}
// ----------------------- StackTrace ----------------------------- {{{1
// PCs in stack traces are actually the return addresses, that is,
// addresses of the next instructions after the call. That's why we
// decrement them.
static uptr patch_pc(uptr pc) {
#ifdef __arm__
// Cancel Thumb bit.
pc = pc & (~1);
#endif
return pc - 1;
}
void StackTrace::PrintStack(uptr *addr, uptr size) {
MemoryMappingLayout proc_maps;
uptr frame_num = 0;
for (uptr i = 0; i < size && addr[i]; i++) {
uptr pc = patch_pc(addr[i]);
if (symbolize_callback) {
char buff[4096];
symbolize_callback((void*)pc, buff, sizeof(buff));
// We can't know anything about the string returned by external
// symbolizer, but if it starts with filename, try to strip path prefix
// from it.
Printf(" #%zu 0x%zx %s\n", frame_num, pc, StripPathPrefix(buff));
frame_num++;
continue;
}
AddressInfo addr_frames[64];
uptr addr_frames_num = 0;
if (flags()->symbolize) {
addr_frames_num = SymbolizeCode(pc, addr_frames, ARRAY_SIZE(addr_frames));
}
if (addr_frames_num > 0) {
for (uptr j = 0; j < addr_frames_num; j++) {
AddressInfo &info = addr_frames[j];
Printf(" #%zu 0x%zx", frame_num, pc);
if (info.function) {
Printf(" in %s", info.function);
}
if (info.file) {
Printf(" %s:%d:%d", StripPathPrefix(info.file), info.line,
info.column);
} else if (info.module) {
Printf(" (%s+0x%zx)", StripPathPrefix(info.module),
info.module_offset);
}
Printf("\n");
info.Clear();
frame_num++;
}
} else {
uptr offset;
char filename[4096];
if (proc_maps.GetObjectNameAndOffset(pc, &offset,
filename, sizeof(filename))) {
Printf(" #%zu 0x%zx (%s+0x%zx)\n",
frame_num, pc, StripPathPrefix(filename), offset);
} else {
Printf(" #%zu 0x%zx\n", frame_num, pc);
}
frame_num++;
}
}
}
uptr StackTrace::GetCurrentPc() {
return GET_CALLER_PC();
}
void StackTrace::FastUnwindStack(uptr pc, uptr bp,
uptr stack_top, uptr stack_bottom) {
CHECK(size == 0 && trace[0] == pc);
size = 1;
uptr *frame = (uptr*)bp;
uptr *prev_frame = frame;
while (frame >= prev_frame &&
frame < (uptr*)stack_top - 2 &&
frame > (uptr*)stack_bottom &&
size < max_size) {
uptr pc1 = frame[1];
if (pc1 != pc) {
trace[size++] = pc1;
}
prev_frame = frame;
frame = (uptr*)frame[0];
}
}
// On 32-bits we don't compress stack traces.
// On 64-bits we compress stack traces: if a given pc differes slightly from
// the previous one, we record a 31-bit offset instead of the full pc.
SANITIZER_INTERFACE_ATTRIBUTE
uptr StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
#if __WORDSIZE == 32
// Don't compress, just copy.
uptr res = 0;
for (uptr i = 0; i < stack->size && i < size; i++) {
compressed[i] = stack->trace[i];
res++;
}
if (stack->size < size)
compressed[stack->size] = 0;
#else // 64 bits, compress.
uptr prev_pc = 0;
const uptr kMaxOffset = (1ULL << 30) - 1;
uptr c_index = 0;
uptr res = 0;
for (uptr i = 0, n = stack->size; i < n; i++) {
uptr pc = stack->trace[i];
if (!pc) break;
if ((s64)pc < 0) break;
// Printf("C pc[%zu] %zx\n", i, pc);
if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
uptr offset = (s64)(pc - prev_pc);
offset |= (1U << 31);
if (c_index >= size) break;
// Printf("C co[%zu] offset %zx\n", i, offset);
compressed[c_index++] = offset;
} else {
uptr hi = pc >> 32;
uptr lo = (pc << 32) >> 32;
CHECK((hi & (1 << 31)) == 0);
if (c_index + 1 >= size) break;
// Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
compressed[c_index++] = hi;
compressed[c_index++] = lo;
}
res++;
prev_pc = pc;
}
if (c_index < size)
compressed[c_index] = 0;
if (c_index + 1 < size)
compressed[c_index + 1] = 0;
#endif // __WORDSIZE
// debug-only code
#if 0
StackTrace check_stack;
UncompressStack(&check_stack, compressed, size);
if (res < check_stack.size) {
Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
check_stack.size, size);
}
// |res| may be greater than check_stack.size, because
// UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
CHECK(res >= check_stack.size);
CHECK(0 == REAL(memcmp)(check_stack.trace, stack->trace,
check_stack.size * sizeof(uptr)));
#endif
return res;
}
SANITIZER_INTERFACE_ATTRIBUTE
void StackTrace::UncompressStack(StackTrace *stack,
u32 *compressed, uptr size) {
#if __WORDSIZE == 32
// Don't uncompress, just copy.
stack->size = 0;
for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
if (!compressed[i]) break;
stack->size++;
stack->trace[i] = compressed[i];
}
#else // 64 bits, uncompress
uptr prev_pc = 0;
stack->size = 0;
for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
u32 x = compressed[i];
uptr pc = 0;
if (x & (1U << 31)) {
// Printf("U co[%zu] offset: %x\n", i, x);
// this is an offset
s32 offset = x;
offset = (offset << 1) >> 1; // remove the 31-byte and sign-extend.
pc = prev_pc + offset;
CHECK(pc);
} else {
// CHECK(i + 1 < size);
if (i + 1 >= size) break;
uptr hi = x;
uptr lo = compressed[i+1];
// Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
i++;
pc = (hi << 32) | lo;
if (!pc) break;
}
// Printf("U pc[%zu] %zx\n", stack->size, pc);
stack->trace[stack->size++] = pc;
prev_pc = pc;
}
#endif // __WORDSIZE
}
} // namespace __asan
// ------------------ Interface -------------- {{{1
using namespace __asan; // NOLINT
void NOINLINE __asan_set_symbolize_callback(
__asan_symbolize_callback callback) {
symbolize_callback = callback;
}