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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_interceptors.h"
#include "asan_lock.h"
#include "asan_procmaps.h"
#include "asan_stack.h"
#include "asan_thread.h"
#include "asan_thread_registry.h"
#include "sanitizer_common/sanitizer_symbolizer.h"
using namespace __sanitizer; // NOLINT
#ifdef ASAN_USE_EXTERNAL_SYMBOLIZER
extern bool
ASAN_USE_EXTERNAL_SYMBOLIZER(const void *pc, char *out, int out_size);
#endif
namespace __asan {
// ----------------------- AsanStackTrace ----------------------------- {{{1
#if defined(ASAN_USE_EXTERNAL_SYMBOLIZER)
void AsanStackTrace::PrintStack(uptr *addr, uptr size) {
for (uptr i = 0; i < size && addr[i]; i++) {
uptr pc = addr[i];
char buff[4096];
ASAN_USE_EXTERNAL_SYMBOLIZER((void*)pc, buff, sizeof(buff));
Printf(" #%zu 0x%zx %s\n", i, pc, buff);
}
}
#else // ASAN_USE_EXTERNAL_SYMBOLIZER
void AsanStackTrace::PrintStack(uptr *addr, uptr size) {
AsanProcMaps proc_maps;
uptr frame_num = 0;
for (uptr i = 0; i < size && addr[i]; i++) {
proc_maps.Reset();
uptr pc = addr[i];
uptr offset;
char filename[4096];
if (FLAG_symbolize) {
AddressInfoList *address_info_list = SymbolizeCode(pc);
for (AddressInfoList *entry = address_info_list; entry;
entry = entry->next) {
AddressInfo info = entry->info;
Printf(" #%zu 0x%zx %s:%d:%d\n", frame_num, pc,
(info.file) ? info.file : "",
info.line, info.column);
frame_num++;
}
address_info_list->Clear();
} else {
if (proc_maps.GetObjectNameAndOffset(pc, &offset,
filename, sizeof(filename))) {
Printf(" #%zu 0x%zx (%s+0x%zx)\n", frame_num, pc, filename,
offset);
} else {
Printf(" #%zu 0x%zx\n", frame_num, pc);
}
frame_num++;
}
}
}
#endif // ASAN_USE_EXTERNAL_SYMBOLIZER
uptr AsanStackTrace::GetCurrentPc() {
return GET_CALLER_PC();
}
void AsanStackTrace::FastUnwindStack(uptr pc, uptr bp) {
CHECK(size == 0 && trace[0] == pc);
size = 1;
if (!asan_inited) return;
AsanThread *t = asanThreadRegistry().GetCurrent();
if (!t) return;
uptr *frame = (uptr*)bp;
uptr *prev_frame = frame;
uptr *top = (uptr*)t->stack_top();
uptr *bottom = (uptr*)t->stack_bottom();
while (frame >= prev_frame &&
frame < top - 2 &&
frame > 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.
uptr AsanStackTrace::CompressStack(AsanStackTrace *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
AsanStackTrace 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;
}
void AsanStackTrace::UncompressStack(AsanStackTrace *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
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