[MIPS] Add support for Breakpad for MIPS

src/processor/stackwalker_mips.cc

Index: src/processor/stackwalker_mips.cc
===================================================================
--- src/processor/stackwalker_mips.cc	(revision 0)
+++ src/processor/stackwalker_mips.cc	(revision 0)
@@ -0,0 +1,302 @@
+// Copyright (c) 2013 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_mips.cc: MIPS-specific stackwalker.
+//
+// See stackwalker_mips.h for documentation.
+//
+// Author: Tata Elxsi
+
+#include "common/scoped_ptr.h"
+#include "google_breakpad/processor/call_stack.h"
+#include "google_breakpad/processor/code_modules.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 "processor/cfi_frame_info.h"
+#include "processor/logging.h"
+#include "processor/postfix_evaluator-inl.h"
+#include "processor/stackwalker_mips.h"
+#include "processor/windows_frame_info.h"
+#include "google_breakpad/common/minidump_cpu_mips.h"
+
+namespace google_breakpad {
+
+StackwalkerMIPS::StackwalkerMIPS(const SystemInfo* system_info,
+                                 const MDRawContextMIPS* context,
+                                 MemoryRegion* memory,
+                                 const CodeModules* modules,
+                                 StackFrameSymbolizer* resolver_helper)
+    : Stackwalker(system_info, memory, modules, resolver_helper),
+      context_(context) {
+  if (memory_ && memory_->GetBase() + memory_->GetSize() - 1 > 0xffffffff) {
+    BPLOG(ERROR) << "Memory out of range for stackwalking: "
+                 << HexString(memory_->GetBase())
+                 << "+"
+                 << HexString(memory_->GetSize())
+                 << " memory_ is:"
+                 << HexString(reinterpret_cast<uint32_t>(memory_));
+    memory_ = NULL;
+  }
+}
+
+StackFrame* StackwalkerMIPS::GetContextFrame() {
+  if (!context_) {
+    BPLOG(ERROR) << "Can't get context frame without context.";
+    return NULL;
+  }
+
+  StackFrameMIPS* frame = new StackFrameMIPS();
+
+  // The instruction pointer is stored directly in a register, so pull it
+  // straight out of the CPU context structure.
+  frame->context = *context_;
+  frame->context_validity = StackFrameMIPS::CONTEXT_VALID_ALL;
+  frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
+  frame->instruction = frame->context.epc;
+
+  return frame;
+}
+
+// Register names for mips.
+static const char* const kRegisterNames[] = {
+   "$zero", "$at", "$v0", "$v1", "$a0", "$a1", "$a2", "$a3", "$to", "$t1",
+   "$t2",   "$t3", "$t4", "$t5", "$t6", "$t7", "$s0", "$s1", "$s2", "$s3",
+   "$s4",   "$s5", "$s6", "$s7", "$t8", "$t9", "$k0", "$k1", "$gp", "$sp",
+   "$fp",   "$ra", NULL
+  // TODO(gordanac): add float point save registers
+};
+
+StackFrameMIPS* StackwalkerMIPS::GetCallerByCFIFrameInfo(
+    const vector<StackFrame*>& frames,
+    CFIFrameInfo* cfi_frame_info) {
+  StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
+
+  unsigned long sp = 0, pc = 0;
+
+  // Populate a dictionary with the valid register values in last_frame.
+  CFIFrameInfo::RegisterValueMap<uint32_t> callee_registers;
+  // Use the STACK CFI data to recover the caller's register values.
+  CFIFrameInfo::RegisterValueMap<uint32_t> caller_registers;
+
+  for (int i = 0; kRegisterNames[i]; ++i) {
+    caller_registers[kRegisterNames[i]] = last_frame->context.iregs[i];
+    callee_registers[kRegisterNames[i]] = last_frame->context.iregs[i];
+  }
+
+  if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_,
+                                      &caller_registers))  {
+    return NULL;
+  }
+
+  CFIFrameInfo::RegisterValueMap<uint32_t>::const_iterator entry =
+      caller_registers.find(".cfa");
+
+  if (entry != caller_registers.end()) {
+    sp = entry->second;
+    caller_registers["$sp"] = entry->second;
+  }
+
+  entry = caller_registers.find(".ra");
+  if (entry != caller_registers.end()) {
+    caller_registers["$ra"] = entry->second;
+    pc = entry->second - 2 * sizeof(pc);
+  }
+  caller_registers["$pc"] = pc;
+  // Construct a new stack frame given the values the CFI recovered.
+  scoped_ptr<StackFrameMIPS> frame(new StackFrameMIPS());
+
+  for (int i = 0; kRegisterNames[i]; ++i) {
+    CFIFrameInfo::RegisterValueMap<uint32_t>::const_iterator caller_entry =
+        caller_registers.find(kRegisterNames[i]);
+
+    if (caller_entry != caller_registers.end()) {
+      // The value of this register is recovered; fill the context with the
+      // value from caller_registers.
+      frame->context.iregs[i] = caller_entry->second;
+      frame->context_validity |= StackFrameMIPS::RegisterValidFlag(i);
+    } else if ((i >= INDEX_MIPS_REG_S0 && i <= INDEX_MIPS_REG_S7 ||
+                i > INDEX_MIPS_REG_GP && i < INDEX_MIPS_REG_RA) &&
+               (last_frame->context_validity &
+                StackFrameMIPS::RegisterValidFlag(i))) {
+      // If the STACK CFI data doesn't mention some callee-save register, and
+      // it is valid in the callee, assume the callee has not yet changed it.
+      // Calee-save registers according to the MIPS o32 ABI specification are:
+      // $s0 to $s7
+      // $sp, $s8
+      frame->context.iregs[i] = last_frame->context.iregs[i];
+      frame->context_validity |= StackFrameMIPS::RegisterValidFlag(i);
+    }
+  }
+
+  frame->context.epc = caller_registers["$pc"];
+  frame->instruction = caller_registers["$pc"];
+  frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_PC;
+  
+  frame->context.iregs[MD_CONTEXT_MIPS_REG_RA] = caller_registers["$ra"];
+  frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_RA;
+
+  frame->trust = StackFrame::FRAME_TRUST_CFI;
+
+  return frame.release();
+}
+
+StackFrame* StackwalkerMIPS::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<StackFrame*>& frames = *stack->frames();
+  StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
+  scoped_ptr<StackFrameMIPS> new_frame;
+
+  // See if there is DWARF call frame information covering this address.
+  scoped_ptr<CFIFrameInfo> cfi_frame_info(
+    frame_symbolizer_->FindCFIFrameInfo(last_frame));
+  if (cfi_frame_info.get())
+    new_frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get()));
+
+  // If caller frame is not found in CFI try analyzing the stack.
+  if (stack_scan_allowed && !new_frame.get()) {
+    new_frame.reset(GetCallerByStackScan(frames));
+  }
+
+  // If nothing worked, tell the caller.
+  if (!new_frame.get()) {
+    return NULL;
+  }
+
+  // Treat an instruction address of 0 as end-of-stack.
+  if (new_frame->context.epc == 0) {
+    return NULL;
+  }
+
+  // If the new stack pointer is at a lower address than the old, then
+  // that's clearly incorrect. Treat this as end-of-stack to enforce
+  // progress and avoid infinite loops.
+  if (new_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP] <=
+      last_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP]) {
+    return NULL;
+  }
+  
+  return new_frame.release();
+}
+
+StackFrameMIPS* StackwalkerMIPS::GetCallerByStackScan(
+    const vector<StackFrame*>& frames) {
+  const uint32_t kMaxFrameStackSize = 1024;
+  const uint32_t kMinArgsOnStack = 4;
+
+  StackFrameMIPS* last_frame = static_cast<StackFrameMIPS*>(frames.back());
+
+  uint32_t last_sp = last_frame->context.iregs[MD_CONTEXT_MIPS_REG_SP];
+  uint32_t caller_pc, caller_sp, caller_fp;
+
+  // Return address cannot be obtained directly.
+  // Force stackwalking.
+
+  // We cannot use frame pointer to get the return address.
+  // We'll scan the stack for a
+  // return address. This can happen if last_frame is executing code
+  // for a module for which we don't have symbols.
+  int count = kMaxFrameStackSize / sizeof(caller_pc);
+
+  if (frames.size() > 1) {
+      // In case of mips32 ABI stack frame of a nonleaf function
+      // must have minimum stack frame assigned for 4 arguments (4 words).
+      // Move stack pointer for 4 words to avoid reporting non-existing frames
+      // for all frames except the topmost one.
+      // There is no way of knowing if topmost frame belongs to a leaf or
+      // a nonleaf function.
+      last_sp +=  kMinArgsOnStack * sizeof(caller_pc);
+      // Adjust 'count' so that return address is scanned only in limits 
+      // of one stack frame.
+      count -= kMinArgsOnStack;
+  }
+
+  do {
+    // Scanning for return address from stack pointer of the last frame.
+    if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc, count)) {
+      // If we can't find an instruction pointer even with stack scanning,
+      // give up.
+      BPLOG(ERROR) << " ScanForReturnAddress failed ";
+      return NULL;
+    }
+    // Get $fp stored in the stack frame.
+    if (!memory_->GetMemoryAtAddress(caller_sp - sizeof(caller_pc),
+                                     &caller_fp)) {
+      BPLOG(INFO) << " GetMemoryAtAddress for fp failed " ;
+      return NULL;
+    }
+
+    count = count - (caller_sp - last_sp) / sizeof(caller_pc);
+    // Now scan the next address in the stack.
+    last_sp = caller_sp + sizeof(caller_pc);
+  } while ((caller_fp - caller_sp >= kMaxFrameStackSize) && count > 0);
+
+  if (!count) {
+    BPLOG(INFO) << " No frame 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 += sizeof(caller_pc);
+  // caller_pc is actually containing $ra value;
+  // $pc is two instructions before $ra,
+  // so the caller_pc needs to be decremented accordingly.
+  caller_pc -= 2 * sizeof(caller_pc);
+
+
+  // Create a new stack frame (ownership will be transferred to the caller)
+  // and fill it in.
+  StackFrameMIPS* frame = new StackFrameMIPS();
+  frame->trust = StackFrame::FRAME_TRUST_SCAN;
+  frame->context = last_frame->context;
+  frame->context.epc = caller_pc;
+  frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_PC;
+  frame->instruction = caller_pc;
+
+  frame->context.iregs[MD_CONTEXT_MIPS_REG_SP] = caller_sp;
+  frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_SP;
+  frame->context.iregs[MD_CONTEXT_MIPS_REG_FP] = caller_fp;
+  frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_FP;
+
+  frame->context.iregs[MD_CONTEXT_MIPS_REG_RA] =
+      caller_pc + 2 * sizeof(caller_pc);
+  frame->context_validity |= StackFrameMIPS::CONTEXT_VALID_RA;
+
+  return frame;
+}
+
+}  // namespace google_breakpad
+