170 lines · cpp
1//===-- sanitizer_stacktrace.cpp ------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file is shared between AddressSanitizer and ThreadSanitizer10// run-time libraries.11//===----------------------------------------------------------------------===//12 13#include "sanitizer_stacktrace.h"14 15#include "sanitizer_common.h"16#include "sanitizer_flags.h"17#include "sanitizer_platform.h"18#include "sanitizer_ptrauth.h"19 20namespace __sanitizer {21 22uptr StackTrace::GetNextInstructionPc(uptr pc) {23#if defined(__aarch64__)24 return STRIP_PAC_PC((void *)pc) + 4;25#elif defined(__sparc__) || defined(__mips__)26 return pc + 8;27#elif SANITIZER_RISCV6428 // Current check order is 4 -> 2 -> 6 -> 829 u8 InsnByte = *(u8 *)(pc);30 if (((InsnByte & 0x3) == 0x3) && ((InsnByte & 0x1c) != 0x1c)) {31 // xxxxxxxxxxxbbb11 | 32 bit | bbb != 11132 return pc + 4;33 }34 if ((InsnByte & 0x3) != 0x3) {35 // xxxxxxxxxxxxxxaa | 16 bit | aa != 1136 return pc + 2;37 }38 // RISC-V encoding allows instructions to be up to 8 bytes long39 if ((InsnByte & 0x3f) == 0x1f) {40 // xxxxxxxxxx011111 | 48 bit |41 return pc + 6;42 }43 if ((InsnByte & 0x7f) == 0x3f) {44 // xxxxxxxxx0111111 | 64 bit |45 return pc + 8;46 }47 // bail-out if could not figure out the instruction size48 return 0;49#elif SANITIZER_S390 || SANITIZER_I386 || SANITIZER_X32 || SANITIZER_X6450 return pc + 1;51#else52 return pc + 4;53#endif54}55 56uptr StackTrace::GetCurrentPc() {57 return GET_CALLER_PC();58}59 60void BufferedStackTrace::Init(const uptr *pcs, uptr cnt, uptr extra_top_pc) {61 size = cnt + !!extra_top_pc;62 CHECK_LE(size, kStackTraceMax);63 internal_memcpy(trace_buffer, pcs, cnt * sizeof(trace_buffer[0]));64 if (extra_top_pc)65 trace_buffer[cnt] = extra_top_pc;66 top_frame_bp = 0;67}68 69// Sparc implementation is in its own file.70#if !defined(__sparc__)71 72// In GCC on ARM bp points to saved lr, not fp, so we should check the next73// cell in stack to be a saved frame pointer. GetCanonicFrame returns the74// pointer to saved frame pointer in any case.75static inline uhwptr *GetCanonicFrame(uptr bp,76 uptr stack_top,77 uptr stack_bottom) {78 CHECK_GT(stack_top, stack_bottom);79#ifdef __arm__80 if (!IsValidFrame(bp, stack_top, stack_bottom)) return 0;81 uhwptr *bp_prev = (uhwptr *)bp;82 if (IsValidFrame((uptr)bp_prev[0], stack_top, stack_bottom)) return bp_prev;83 // The next frame pointer does not look right. This could be a GCC frame, step84 // back by 1 word and try again.85 if (IsValidFrame((uptr)bp_prev[-1], stack_top, stack_bottom))86 return bp_prev - 1;87 // Nope, this does not look right either. This means the frame after next does88 // not have a valid frame pointer, but we can still extract the caller PC.89 // Unfortunately, there is no way to decide between GCC and LLVM frame90 // layouts. Assume LLVM.91 return bp_prev;92#else93 return (uhwptr*)bp;94#endif95}96 97void BufferedStackTrace::UnwindFast(uptr pc, uptr bp, uptr stack_top,98 uptr stack_bottom, u32 max_depth) {99 // TODO(yln): add arg sanity check for stack_top/stack_bottom100 CHECK_GE(max_depth, 2);101 const uptr kPageSize = GetPageSizeCached();102 trace_buffer[0] = pc;103 size = 1;104 if (stack_top < 4096) return; // Sanity check for stack top.105 uhwptr *frame = GetCanonicFrame(bp, stack_top, stack_bottom);106 // Lowest possible address that makes sense as the next frame pointer.107 // Goes up as we walk the stack.108 uptr bottom = stack_bottom;109 // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.110 while (IsValidFrame((uptr)frame, stack_top, bottom) &&111 IsAligned((uptr)frame, sizeof(*frame)) &&112 size < max_depth) {113#ifdef __powerpc__114 // PowerPC ABIs specify that the return address is saved at offset115 // 16 of the *caller's* stack frame. Thus we must dereference the116 // back chain to find the caller frame before extracting it.117 uhwptr *caller_frame = (uhwptr*)frame[0];118 if (!IsValidFrame((uptr)caller_frame, stack_top, bottom) ||119 !IsAligned((uptr)caller_frame, sizeof(uhwptr)))120 break;121 uhwptr pc1 = caller_frame[2];122#elif defined(__s390__)123 uhwptr pc1 = frame[14];124#elif defined(__loongarch__) || defined(__riscv)125 // frame[-1] contains the return address126 uhwptr pc1 = frame[-1];127#else128 uhwptr pc1 = STRIP_PAC_PC((void *)frame[1]);129#endif130 // Let's assume that any pointer in the 0th page (i.e. <0x1000 on i386 and131 // x86_64) is invalid and stop unwinding here. If we're adding support for132 // a platform where this isn't true, we need to reconsider this check.133 if (pc1 < kPageSize)134 break;135 if (pc1 != pc) {136 trace_buffer[size++] = (uptr) pc1;137 }138 bottom = (uptr)frame;139#if defined(__loongarch__) || defined(__riscv)140 // frame[-2] contain fp of the previous frame141 uptr new_bp = (uptr)frame[-2];142#else143 uptr new_bp = (uptr)frame[0];144#endif145 frame = GetCanonicFrame(new_bp, stack_top, bottom);146 }147}148 149#endif // !defined(__sparc__)150 151void BufferedStackTrace::PopStackFrames(uptr count) {152 CHECK_LT(count, size);153 size -= count;154 for (uptr i = 0; i < size; ++i) {155 trace_buffer[i] = trace_buffer[i + count];156 }157}158 159static uptr Distance(uptr a, uptr b) { return a < b ? b - a : a - b; }160 161uptr BufferedStackTrace::LocatePcInTrace(uptr pc) {162 uptr best = 0;163 for (uptr i = 1; i < size; ++i) {164 if (Distance(trace[i], pc) < Distance(trace[best], pc)) best = i;165 }166 return best;167}168 169} // namespace __sanitizer170