// Copyright (c) 2010 Google Inc. // All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following disclaimer // in the documentation and/or other materials provided with the // distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // stackwalker_arm.cc: arm-specific stackwalker. // // See stackwalker_arm.h for documentation. // // Author: Mark Mentovai, Ted Mielczarek, Jim Blandy #include #include "common/scoped_ptr.h" #include "google_breakpad/processor/call_stack.h" #include "google_breakpad/processor/memory_region.h" #include "google_breakpad/processor/source_line_resolver_interface.h" #include "google_breakpad/processor/stack_frame_cpu.h" #include "google_breakpad/processor/system_info.h" #include "processor/cfi_frame_info.h" #include "processor/logging.h" #include "processor/stackwalker_arm.h" namespace google_breakpad { StackwalkerARM::StackwalkerARM(const SystemInfo* system_info, const MDRawContextARM* context, int fp_register, MemoryRegion* memory, const CodeModules* modules, StackFrameSymbolizer* resolver_helper) : Stackwalker(system_info, memory, modules, resolver_helper), context_(context), fp_register_(fp_register), context_frame_validity_(StackFrameARM::CONTEXT_VALID_ALL) { } StackFrame* StackwalkerARM::GetContextFrame() { if (!context_) { BPLOG(ERROR) << "Can't get context frame without context"; return NULL; } StackFrameARM* frame = new StackFrameARM(); // The instruction pointer is stored directly in a register (r15), so pull it // straight out of the CPU context structure. frame->context = *context_; frame->context_validity = context_frame_validity_; frame->trust = StackFrame::FRAME_TRUST_CONTEXT; frame->instruction = frame->context.iregs[MD_CONTEXT_ARM_REG_PC]; return frame; } StackFrameARM* StackwalkerARM::GetCallerByCFIFrameInfo( const vector& frames, CFIFrameInfo* cfi_frame_info) { StackFrameARM* last_frame = static_cast(frames.back()); static const char* register_names[] = { "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "sp", "lr", "pc", "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", "fps", "cpsr", NULL }; // Populate a dictionary with the valid register values in last_frame. CFIFrameInfo::RegisterValueMap callee_registers; for (int i = 0; register_names[i]; i++) if (last_frame->context_validity & StackFrameARM::RegisterValidFlag(i)) callee_registers[register_names[i]] = last_frame->context.iregs[i]; // Use the STACK CFI data to recover the caller's register values. CFIFrameInfo::RegisterValueMap caller_registers; if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_, &caller_registers)) return NULL; // Construct a new stack frame given the values the CFI recovered. scoped_ptr frame(new StackFrameARM()); for (int i = 0; register_names[i]; i++) { CFIFrameInfo::RegisterValueMap::iterator entry = caller_registers.find(register_names[i]); if (entry != caller_registers.end()) { // We recovered the value of this register; fill the context with the // value from caller_registers. frame->context_validity |= StackFrameARM::RegisterValidFlag(i); frame->context.iregs[i] = entry->second; } else if (4 <= i && i <= 11 && (last_frame->context_validity & StackFrameARM::RegisterValidFlag(i))) { // If the STACK CFI data doesn't mention some callee-saves register, and // it is valid in the callee, assume the callee has not yet changed it. // Registers r4 through r11 are callee-saves, according to the Procedure // Call Standard for the ARM Architecture, which the Linux ABI follows. frame->context_validity |= StackFrameARM::RegisterValidFlag(i); frame->context.iregs[i] = last_frame->context.iregs[i]; } } // If the CFI doesn't recover the PC explicitly, then use .ra. if (!(frame->context_validity & StackFrameARM::CONTEXT_VALID_PC)) { CFIFrameInfo::RegisterValueMap::iterator entry = caller_registers.find(".ra"); if (entry != caller_registers.end()) { if (fp_register_ == -1) { frame->context_validity |= StackFrameARM::CONTEXT_VALID_PC; frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = entry->second; } else { // The CFI updated the link register and not the program counter. // Handle getting the program counter from the link register. frame->context_validity |= StackFrameARM::CONTEXT_VALID_PC; frame->context_validity |= StackFrameARM::CONTEXT_VALID_LR; frame->context.iregs[MD_CONTEXT_ARM_REG_LR] = entry->second; frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = last_frame->context.iregs[MD_CONTEXT_ARM_REG_LR]; } } } // If the CFI doesn't recover the SP explicitly, then use .cfa. if (!(frame->context_validity & StackFrameARM::CONTEXT_VALID_SP)) { CFIFrameInfo::RegisterValueMap::iterator entry = caller_registers.find(".cfa"); if (entry != caller_registers.end()) { frame->context_validity |= StackFrameARM::CONTEXT_VALID_SP; frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = entry->second; } } // If we didn't recover the PC and the SP, then the frame isn't very useful. static const int essentials = (StackFrameARM::CONTEXT_VALID_SP | StackFrameARM::CONTEXT_VALID_PC); if ((frame->context_validity & essentials) != essentials) return NULL; frame->trust = StackFrame::FRAME_TRUST_CFI; return frame.release(); } StackFrameARM* StackwalkerARM::GetCallerByStackScan( const vector& frames) { StackFrameARM* last_frame = static_cast(frames.back()); uint32_t last_sp = last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP]; uint32_t caller_sp, caller_pc; if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc, frames.size() == 1 /* is_context_frame */)) { // No plausible return address was found. return NULL; } // ScanForReturnAddress found a reasonable return address. Advance // %sp to the location above the one where the return address was // found. caller_sp += 4; // Create a new stack frame (ownership will be transferred to the caller) // and fill it in. StackFrameARM* frame = new StackFrameARM(); frame->trust = StackFrame::FRAME_TRUST_SCAN; frame->context = last_frame->context; frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = caller_pc; frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = caller_sp; frame->context_validity = StackFrameARM::CONTEXT_VALID_PC | StackFrameARM::CONTEXT_VALID_SP; return frame; } StackFrameARM* StackwalkerARM::GetCallerByFramePointer( const vector& frames) { StackFrameARM* last_frame = static_cast(frames.back()); if (!(last_frame->context_validity & StackFrameARM::RegisterValidFlag(fp_register_))) { return NULL; } uint32_t last_fp = last_frame->context.iregs[fp_register_]; uint32_t caller_fp = 0; if (last_fp && !memory_->GetMemoryAtAddress(last_fp, &caller_fp)) { BPLOG(ERROR) << "Unable to read caller_fp from last_fp: 0x" << std::hex << last_fp; return NULL; } uint32_t caller_lr = 0; if (last_fp && !memory_->GetMemoryAtAddress(last_fp + 4, &caller_lr)) { BPLOG(ERROR) << "Unable to read caller_lr from last_fp + 4: 0x" << std::hex << (last_fp + 4); return NULL; } uint32_t caller_sp = last_fp ? last_fp + 8 : last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP]; // Create a new stack frame (ownership will be transferred to the caller) // and fill it in. StackFrameARM* frame = new StackFrameARM(); frame->trust = StackFrame::FRAME_TRUST_FP; frame->context = last_frame->context; frame->context.iregs[fp_register_] = caller_fp; frame->context.iregs[MD_CONTEXT_ARM_REG_SP] = caller_sp; frame->context.iregs[MD_CONTEXT_ARM_REG_PC] = last_frame->context.iregs[MD_CONTEXT_ARM_REG_LR]; frame->context.iregs[MD_CONTEXT_ARM_REG_LR] = caller_lr; frame->context_validity = StackFrameARM::CONTEXT_VALID_PC | StackFrameARM::CONTEXT_VALID_LR | StackFrameARM::RegisterValidFlag(fp_register_) | StackFrameARM::CONTEXT_VALID_SP; return frame; } StackFrame* StackwalkerARM::GetCallerFrame(const CallStack* stack, bool stack_scan_allowed) { if (!memory_ || !stack) { BPLOG(ERROR) << "Can't get caller frame without memory or stack"; return NULL; } const vector& frames = *stack->frames(); StackFrameARM* last_frame = static_cast(frames.back()); scoped_ptr frame; // See if there is DWARF call frame information covering this address. // TODO(jperaza): Ignore iOS CFI info until it is properly collected. // https://bugs.chromium.org/p/google-breakpad/issues/detail?id=764 if (!system_info_ || system_info_->os != "iOS") { scoped_ptr cfi_frame_info( frame_symbolizer_->FindCFIFrameInfo(last_frame)); if (cfi_frame_info.get()) frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get())); } // If CFI failed, or there wasn't CFI available, fall back // to frame pointer, if this is configured. if (fp_register_ >= 0 && !frame.get()) frame.reset(GetCallerByFramePointer(frames)); // If everuthing failed, fall back to stack scanning. if (stack_scan_allowed && !frame.get()) frame.reset(GetCallerByStackScan(frames)); // If nothing worked, tell the caller. if (!frame.get()) return NULL; // Should we terminate the stack walk? (end-of-stack or broken invariant) if (TerminateWalk(frame->context.iregs[MD_CONTEXT_ARM_REG_PC], frame->context.iregs[MD_CONTEXT_ARM_REG_SP], last_frame->context.iregs[MD_CONTEXT_ARM_REG_SP], frames.size() == 1)) { return NULL; } // The new frame's context's PC is the return address, which is one // instruction past the instruction that caused us to arrive at the // callee. Set new_frame->instruction to one less than the PC. This won't // reference the beginning of the call instruction, but it's at least // within it, which is sufficient to get the source line information to // match up with the line that contains the function call. Callers that // require the exact return address value may access // frame->context.iregs[MD_CONTEXT_ARM_REG_PC]. frame->instruction = frame->context.iregs[MD_CONTEXT_ARM_REG_PC] - 2; return frame.release(); } } // namespace google_breakpad