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//===-- sanitizer_stacktrace.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 shared between AddressSanitizer and ThreadSanitizer
// run-time libraries.
//===----------------------------------------------------------------------===//
#include "sanitizer_common.h"
#include "sanitizer_flags.h"
#include "sanitizer_procmaps.h"
#include "sanitizer_stacktrace.h"
#include "sanitizer_symbolizer.h"
namespace __sanitizer {
uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
#ifdef __arm__
// Cancel Thumb bit.
pc = pc & (~1);
#endif
#if defined(__powerpc__) || defined(__powerpc64__)
// PCs are always 4 byte aligned.
return pc - 4;
#elif defined(__sparc__)
return pc - 8;
#else
return pc - 1;
#endif
}
static void PrintStackFramePrefix(uptr frame_num, uptr pc) {
Printf(" #%zu 0x%zx", frame_num, pc);
}
void StackTrace::PrintStack(const uptr *addr, uptr size, bool symbolize,
SymbolizeCallback symbolize_callback) {
MemoryMappingLayout proc_maps(/*cache_enabled*/true);
InternalScopedBuffer<char> buff(GetPageSizeCached() * 2);
InternalScopedBuffer<AddressInfo> addr_frames(64);
uptr frame_num = 0;
for (uptr i = 0; i < size && addr[i]; i++) {
// PCs in stack traces are actually the return addresses, that is,
// addresses of the next instructions after the call.
uptr pc = GetPreviousInstructionPc(addr[i]);
uptr addr_frames_num = 0; // The number of stack frames for current
// instruction address.
if (symbolize_callback) {
if (symbolize_callback((void*)pc, buff.data(), buff.size())) {
addr_frames_num = 1;
PrintStackFramePrefix(frame_num, pc);
// 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(" %s\n",
StripPathPrefix(buff.data(), common_flags()->strip_path_prefix));
frame_num++;
}
}
if (symbolize && addr_frames_num == 0) {
// Use our own (online) symbolizer, if necessary.
if (Symbolizer *sym = Symbolizer::GetOrNull())
addr_frames_num =
sym->SymbolizeCode(pc, addr_frames.data(), addr_frames.size());
for (uptr j = 0; j < addr_frames_num; j++) {
AddressInfo &info = addr_frames[j];
PrintStackFramePrefix(frame_num, pc);
if (info.function) {
Printf(" in %s", info.function);
}
if (info.file) {
Printf(" ");
PrintSourceLocation(info.file, info.line, info.column);
} else if (info.module) {
Printf(" ");
PrintModuleAndOffset(info.module, info.module_offset);
}
Printf("\n");
info.Clear();
frame_num++;
}
}
if (addr_frames_num == 0) {
// If online symbolization failed, try to output at least module and
// offset for instruction.
PrintStackFramePrefix(frame_num, pc);
uptr offset;
if (proc_maps.GetObjectNameAndOffset(pc, &offset,
buff.data(), buff.size(),
/* protection */0)) {
Printf(" ");
PrintModuleAndOffset(buff.data(), offset);
}
Printf("\n");
frame_num++;
}
}
}
uptr StackTrace::GetCurrentPc() {
return GET_CALLER_PC();
}
void StackTrace::FastUnwindStack(uptr pc, uptr bp,
uptr stack_top, uptr stack_bottom,
uptr max_depth) {
if (max_depth == 0) {
size = 0;
return;
}
trace[0] = pc;
size = 1;
uhwptr *frame = (uhwptr *)bp;
uhwptr *prev_frame = frame - 1;
if (stack_top < 4096) return; // Sanity check for stack top.
// Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
while (frame > prev_frame &&
frame < (uhwptr *)stack_top - 2 &&
frame > (uhwptr *)stack_bottom &&
IsAligned((uptr)frame, sizeof(*frame)) &&
size < max_depth) {
uhwptr pc1 = frame[1];
if (pc1 != pc) {
trace[size++] = (uptr) pc1;
}
prev_frame = frame;
frame = (uhwptr *)frame[0];
}
}
void StackTrace::PopStackFrames(uptr count) {
CHECK(size >= count);
size -= count;
for (uptr i = 0; i < size; i++) {
trace[i] = trace[i + count];
}
}
// 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 StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
#if SANITIZER_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_EQ((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 // SANITIZER_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_EQ(0, REAL(memcmp)(check_stack.trace, stack->trace,
check_stack.size * sizeof(uptr)));
#endif
return res;
}
void StackTrace::UncompressStack(StackTrace *stack,
u32 *compressed, uptr size) {
#if SANITIZER_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 // SANITIZER_WORDSIZE
}
} // namespace __sanitizer
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