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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdint.h>
#include <ucontext.h>
#include <memory>
#include <string>
#define UNW_LOCAL_ONLY
#include <libunwind.h>
#include <android-base/logging.h>
#include <backtrace/Backtrace.h>
#include "BacktraceLog.h"
#include "UnwindCurrent.h"
std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
if (!initialized_) {
// If init local is not called, then trying to get a function name will
// fail, so try to initialize first.
std::unique_ptr<unw_cursor_t> cursor(new unw_cursor_t);
if (unw_init_local(cursor.get(), &context_) < 0) {
return "";
}
initialized_ = true;
}
*offset = 0;
char buf[512];
unw_word_t value;
if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf),
&value, &context_) >= 0 && buf[0] != '\0') {
*offset = static_cast<uintptr_t>(value);
return buf;
}
return "";
}
void UnwindCurrent::GetUnwContextFromUcontext(const ucontext_t* ucontext) {
unw_tdep_context_t* unw_context = reinterpret_cast<unw_tdep_context_t*>(&context_);
#if defined(__arm__)
unw_context->regs[0] = ucontext->uc_mcontext.arm_r0;
unw_context->regs[1] = ucontext->uc_mcontext.arm_r1;
unw_context->regs[2] = ucontext->uc_mcontext.arm_r2;
unw_context->regs[3] = ucontext->uc_mcontext.arm_r3;
unw_context->regs[4] = ucontext->uc_mcontext.arm_r4;
unw_context->regs[5] = ucontext->uc_mcontext.arm_r5;
unw_context->regs[6] = ucontext->uc_mcontext.arm_r6;
unw_context->regs[7] = ucontext->uc_mcontext.arm_r7;
unw_context->regs[8] = ucontext->uc_mcontext.arm_r8;
unw_context->regs[9] = ucontext->uc_mcontext.arm_r9;
unw_context->regs[10] = ucontext->uc_mcontext.arm_r10;
unw_context->regs[11] = ucontext->uc_mcontext.arm_fp;
unw_context->regs[12] = ucontext->uc_mcontext.arm_ip;
unw_context->regs[13] = ucontext->uc_mcontext.arm_sp;
unw_context->regs[14] = ucontext->uc_mcontext.arm_lr;
unw_context->regs[15] = ucontext->uc_mcontext.arm_pc;
#else
unw_context->uc_mcontext = ucontext->uc_mcontext;
#endif
}
bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, ucontext_t* ucontext) {
if (ucontext == nullptr) {
int ret = unw_getcontext(&context_);
if (ret < 0) {
BACK_LOGW("unw_getcontext failed %d", ret);
error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
return false;
}
} else {
GetUnwContextFromUcontext(ucontext);
}
// The cursor structure is pretty large, do not put it on the stack.
std::unique_ptr<unw_cursor_t> cursor(new unw_cursor_t);
int ret = unw_init_local(cursor.get(), &context_);
if (ret < 0) {
BACK_LOGW("unw_init_local failed %d", ret);
error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
return false;
}
initialized_ = true;
size_t num_frames = 0;
do {
unw_word_t pc;
ret = unw_get_reg(cursor.get(), UNW_REG_IP, &pc);
if (ret < 0) {
BACK_LOGW("Failed to read IP %d", ret);
break;
}
unw_word_t sp;
ret = unw_get_reg(cursor.get(), UNW_REG_SP, &sp);
if (ret < 0) {
BACK_LOGW("Failed to read SP %d", ret);
break;
}
frames_.resize(num_frames+1);
backtrace_frame_data_t* frame = &frames_.at(num_frames);
frame->num = num_frames;
frame->pc = static_cast<uintptr_t>(pc);
frame->sp = static_cast<uintptr_t>(sp);
frame->stack_size = 0;
FillInMap(frame->pc, &frame->map);
// Check to see if we should skip this frame because it's coming
// from within the library, and we are doing a local unwind.
if (ucontext != nullptr || num_frames != 0 || !DiscardFrame(*frame)) {
if (num_ignore_frames == 0) {
// GetFunctionName is an expensive call, only do it if we are
// keeping the frame.
frame->func_name = GetFunctionName(frame->pc, &frame->func_offset, &frame->map);
if (num_frames > 0) {
// Set the stack size for the previous frame.
backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
prev->stack_size = frame->sp - prev->sp;
}
if (BacktraceMap::IsValid(frame->map)) {
frame->rel_pc = frame->pc - frame->map.start + frame->map.load_bias;
} else {
frame->rel_pc = frame->pc;
}
num_frames++;
} else {
num_ignore_frames--;
// Set the number of frames to zero to remove the frame added
// above. By definition, if we still have frames to ignore
// there should only be one frame in the vector.
CHECK(num_frames == 0);
frames_.resize(0);
}
}
// If the pc is in a device map, then don't try to step.
if (frame->map.flags & PROT_DEVICE_MAP) {
break;
}
// Verify the sp is not in a device map too.
backtrace_map_t map;
FillInMap(frame->sp, &map);
if (map.flags & PROT_DEVICE_MAP) {
break;
}
ret = unw_step (cursor.get());
} while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
return true;
}
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