1// Copyright (c) 2006, Google Inc. 2// All rights reserved. 3// 4// Redistribution and use in source and binary forms, with or without 5// modification, are permitted provided that the following conditions are 6// met: 7// 8// * Redistributions of source code must retain the above copyright 9// notice, this list of conditions and the following disclaimer. 10// * Redistributions in binary form must reproduce the above 11// copyright notice, this list of conditions and the following disclaimer 12// in the documentation and/or other materials provided with the 13// distribution. 14// * Neither the name of Google Inc. nor the names of its 15// contributors may be used to endorse or promote products derived from 16// this software without specific prior written permission. 17// 18// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30// stackwalker_selftest.cc: Tests StackwalkerX86 or StackwalkerPPC using the 31// running process' stack as test data, if running on an x86 or ppc and 32// compiled with gcc. This test is not enabled in the "make check" suite 33// by default, because certain optimizations interfere with its proper 34// operation. To turn it on, configure with --enable-selftest. 35// 36// Optimizations that cause problems: 37// - stack frame reuse. The Recursor function here calls itself with 38// |return Recursor|. When the caller's frame is reused, it will cause 39// CountCallerFrames to correctly return the same number of frames 40// in both the caller and callee. This is considered an unexpected 41// condition in the test, which expects a callee to have one more 42// caller frame in the stack than its caller. 43// - frame pointer omission. Even with a stackwalker that understands 44// this optimization, the code to harness debug information currently 45// only exists to retrieve it from minidumps, not the current process. 46// 47// This test can also serve as a developmental and debugging aid if 48// PRINT_STACKS is defined. 49// 50// Author: Mark Mentovai 51 52#include <assert.h> 53 54#include "processor/logging.h" 55 56#if defined(__i386) && !defined(__i386__) 57#define __i386__ 58#endif 59#if defined(__sparc) && !defined(__sparc__) 60#define __sparc__ 61#endif 62 63#if (defined(__SUNPRO_CC) || defined(__GNUC__)) && \ 64 (defined(__i386__) || defined(__ppc__) || defined(__sparc__)) 65 66 67#include <stdio.h> 68 69#include "common/scoped_ptr.h" 70#include "google_breakpad/common/breakpad_types.h" 71#include "google_breakpad/common/minidump_format.h" 72#include "google_breakpad/processor/basic_source_line_resolver.h" 73#include "google_breakpad/processor/call_stack.h" 74#include "google_breakpad/processor/code_module.h" 75#include "google_breakpad/processor/memory_region.h" 76#include "google_breakpad/processor/stack_frame.h" 77#include "google_breakpad/processor/stack_frame_cpu.h" 78 79using google_breakpad::BasicSourceLineResolver; 80using google_breakpad::CallStack; 81using google_breakpad::CodeModule; 82using google_breakpad::MemoryRegion; 83using google_breakpad::scoped_ptr; 84using google_breakpad::StackFrame; 85using google_breakpad::StackFramePPC; 86using google_breakpad::StackFrameX86; 87using google_breakpad::StackFrameSPARC; 88 89#if defined(__i386__) 90#include "processor/stackwalker_x86.h" 91using google_breakpad::StackwalkerX86; 92#elif defined(__ppc__) 93#include "processor/stackwalker_ppc.h" 94using google_breakpad::StackwalkerPPC; 95#elif defined(__sparc__) 96#include "processor/stackwalker_sparc.h" 97using google_breakpad::StackwalkerSPARC; 98#endif // __i386__ || __ppc__ || __sparc__ 99 100#define RECURSION_DEPTH 100 101 102 103// A simple MemoryRegion subclass that provides direct access to this 104// process' memory space by pointer. 105class SelfMemoryRegion : public MemoryRegion { 106 public: 107 virtual uint64_t GetBase() const { return 0; } 108 virtual uint32_t GetSize() const { return 0xffffffff; } 109 110 bool GetMemoryAtAddress(uint64_t address, uint8_t* value) const { 111 return GetMemoryAtAddressInternal(address, value); } 112 bool GetMemoryAtAddress(uint64_t address, uint16_t* value) const { 113 return GetMemoryAtAddressInternal(address, value); } 114 bool GetMemoryAtAddress(uint64_t address, uint32_t* value) const { 115 return GetMemoryAtAddressInternal(address, value); } 116 bool GetMemoryAtAddress(uint64_t address, uint64_t* value) const { 117 return GetMemoryAtAddressInternal(address, value); } 118 void Print() const { 119 assert(false); 120 } 121 122 private: 123 template<typename T> bool GetMemoryAtAddressInternal(uint64_t address, 124 T* value) { 125 // Without knowing what addresses are actually mapped, just assume that 126 // everything low is not mapped. This helps the stackwalker catch the 127 // end of a stack when it tries to dereference a null or low pointer 128 // in an attempt to find the caller frame. Other unmapped accesses will 129 // cause the program to crash, but that would properly be a test failure. 130 if (address < 0x100) 131 return false; 132 133 uint8_t* memory = 0; 134 *value = *reinterpret_cast<const T*>(&memory[address]); 135 return true; 136 } 137}; 138 139 140#if defined(__GNUC__) 141 142 143#if defined(__i386__) 144 145// GetEBP returns the current value of the %ebp register. Because it's 146// implemented as a function, %ebp itself contains GetEBP's frame pointer 147// and not the caller's frame pointer. Dereference %ebp to obtain the 148// caller's frame pointer, which the compiler-generated preamble stored 149// on the stack (provided frame pointers are not being omitted.) Because 150// this function depends on the compiler-generated preamble, inlining is 151// disabled. 152static uint32_t GetEBP() __attribute__((noinline)); 153static uint32_t GetEBP() { 154 uint32_t ebp; 155 __asm__ __volatile__( 156 "movl (%%ebp), %0" 157 : "=a" (ebp) 158 ); 159 return ebp; 160} 161 162 163// The caller's %esp is 8 higher than the value of %ebp in this function, 164// assuming that it's not inlined and that the standard prolog is used. 165// The CALL instruction places a 4-byte return address on the stack above 166// the caller's %esp, and this function's prolog will save the caller's %ebp 167// on the stack as well, for another 4 bytes, before storing %esp in %ebp. 168static uint32_t GetESP() __attribute__((noinline)); 169static uint32_t GetESP() { 170 uint32_t ebp; 171 __asm__ __volatile__( 172 "movl %%ebp, %0" 173 : "=a" (ebp) 174 ); 175 return ebp + 8; 176} 177 178 179// GetEIP returns the instruction pointer identifying the next instruction 180// to execute after GetEIP returns. It obtains this information from the 181// stack, where it was placed by the call instruction that called GetEIP. 182// This function depends on frame pointers not being omitted. It is possible 183// to write a pure asm version of this routine that has no compiler-generated 184// preamble and uses %esp instead of %ebp; that would function in the 185// absence of frame pointers. However, the simpler approach is used here 186// because GetEBP and stackwalking necessarily depends on access to frame 187// pointers. Because this function depends on a call instruction and the 188// compiler-generated preamble, inlining is disabled. 189static uint32_t GetEIP() __attribute__((noinline)); 190static uint32_t GetEIP() { 191 uint32_t eip; 192 __asm__ __volatile__( 193 "movl 4(%%ebp), %0" 194 : "=a" (eip) 195 ); 196 return eip; 197} 198 199 200#elif defined(__ppc__) 201 202 203// GetSP returns the current value of the %r1 register, which by convention, 204// is the stack pointer on ppc. Because it's implemented as a function, 205// %r1 itself contains GetSP's own stack pointer and not the caller's stack 206// pointer. Dereference %r1 to obtain the caller's stack pointer, which the 207// compiler-generated prolog stored on the stack. Because this function 208// depends on the compiler-generated prolog, inlining is disabled. 209static uint32_t GetSP() __attribute__((noinline)); 210static uint32_t GetSP() { 211 uint32_t sp; 212 __asm__ __volatile__( 213 "lwz %0, 0(r1)" 214 : "=r" (sp) 215 ); 216 return sp; 217} 218 219 220// GetPC returns the program counter identifying the next instruction to 221// execute after GetPC returns. It obtains this information from the 222// link register, where it was placed by the branch instruction that called 223// GetPC. Because this function depends on the caller's use of a branch 224// instruction, inlining is disabled. 225static uint32_t GetPC() __attribute__((noinline)); 226static uint32_t GetPC() { 227 uint32_t lr; 228 __asm__ __volatile__( 229 "mflr %0" 230 : "=r" (lr) 231 ); 232 return lr; 233} 234 235 236#elif defined(__sparc__) 237 238 239// GetSP returns the current value of the %sp/%o6/%g_r[14] register, which 240// by convention, is the stack pointer on sparc. Because it's implemented 241// as a function, %sp itself contains GetSP's own stack pointer and not 242// the caller's stack pointer. Dereference to obtain the caller's stack 243// pointer, which the compiler-generated prolog stored on the stack. 244// Because this function depends on the compiler-generated prolog, inlining 245// is disabled. 246static uint32_t GetSP() __attribute__((noinline)); 247static uint32_t GetSP() { 248 uint32_t sp; 249 __asm__ __volatile__( 250 "mov %%fp, %0" 251 : "=r" (sp) 252 ); 253 return sp; 254} 255 256// GetFP returns the current value of the %fp register. Because it's 257// implemented as a function, %fp itself contains GetFP's frame pointer 258// and not the caller's frame pointer. Dereference %fp to obtain the 259// caller's frame pointer, which the compiler-generated preamble stored 260// on the stack (provided frame pointers are not being omitted.) Because 261// this function depends on the compiler-generated preamble, inlining is 262// disabled. 263static uint32_t GetFP() __attribute__((noinline)); 264static uint32_t GetFP() { 265 uint32_t fp; 266 __asm__ __volatile__( 267 "ld [%%fp+56], %0" 268 : "=r" (fp) 269 ); 270 return fp; 271} 272 273// GetPC returns the program counter identifying the next instruction to 274// execute after GetPC returns. It obtains this information from the 275// link register, where it was placed by the branch instruction that called 276// GetPC. Because this function depends on the caller's use of a branch 277// instruction, inlining is disabled. 278static uint32_t GetPC() __attribute__((noinline)); 279static uint32_t GetPC() { 280 uint32_t pc; 281 __asm__ __volatile__( 282 "mov %%i7, %0" 283 : "=r" (pc) 284 ); 285 return pc + 8; 286} 287 288#endif // __i386__ || __ppc__ || __sparc__ 289 290#elif defined(__SUNPRO_CC) 291 292#if defined(__i386__) 293extern "C" { 294extern uint32_t GetEIP(); 295extern uint32_t GetEBP(); 296extern uint32_t GetESP(); 297} 298#elif defined(__sparc__) 299extern "C" { 300extern uint32_t GetPC(); 301extern uint32_t GetFP(); 302extern uint32_t GetSP(); 303} 304#endif // __i386__ || __sparc__ 305 306#endif // __GNUC__ || __SUNPRO_CC 307 308// CountCallerFrames returns the number of stack frames beneath the function 309// that called CountCallerFrames. Because this function's return value 310// is dependent on the size of the stack beneath it, inlining is disabled, 311// and any function that calls this should not be inlined either. 312#if defined(__GNUC__) 313static unsigned int CountCallerFrames() __attribute__((noinline)); 314#elif defined(__SUNPRO_CC) 315static unsigned int CountCallerFrames(); 316#endif 317static unsigned int CountCallerFrames() { 318 SelfMemoryRegion memory; 319 BasicSourceLineResolver resolver; 320 321#if defined(__i386__) 322 MDRawContextX86 context = MDRawContextX86(); 323 context.eip = GetEIP(); 324 context.ebp = GetEBP(); 325 context.esp = GetESP(); 326 327 StackwalkerX86 stackwalker = StackwalkerX86(NULL, &context, &memory, NULL, 328 NULL, &resolver); 329#elif defined(__ppc__) 330 MDRawContextPPC context = MDRawContextPPC(); 331 context.srr0 = GetPC(); 332 context.gpr[1] = GetSP(); 333 334 StackwalkerPPC stackwalker = StackwalkerPPC(NULL, &context, &memory, NULL, 335 NULL, &resolver); 336#elif defined(__sparc__) 337 MDRawContextSPARC context = MDRawContextSPARC(); 338 context.pc = GetPC(); 339 context.g_r[14] = GetSP(); 340 context.g_r[30] = GetFP(); 341 342 StackwalkerSPARC stackwalker = StackwalkerSPARC(NULL, &context, &memory, 343 NULL, NULL, &resolver); 344#endif // __i386__ || __ppc__ || __sparc__ 345 346 CallStack stack; 347 vector<const CodeModule*> modules_without_symbols; 348 stackwalker.Walk(&stack, &modules_without_symbols); 349 350#ifdef PRINT_STACKS 351 printf("\n"); 352 for (unsigned int frame_index = 0; 353 frame_index < stack.frames()->size(); 354 ++frame_index) { 355 StackFrame *frame = stack.frames()->at(frame_index); 356 printf("frame %-3d instruction = 0x%08" PRIx64, 357 frame_index, frame->instruction); 358#if defined(__i386__) 359 StackFrameX86 *frame_x86 = reinterpret_cast<StackFrameX86*>(frame); 360 printf(" esp = 0x%08x ebp = 0x%08x\n", 361 frame_x86->context.esp, frame_x86->context.ebp); 362#elif defined(__ppc__) 363 StackFramePPC *frame_ppc = reinterpret_cast<StackFramePPC*>(frame); 364 printf(" gpr[1] = 0x%08x\n", frame_ppc->context.gpr[1]); 365#elif defined(__sparc__) 366 StackFrameSPARC *frame_sparc = reinterpret_cast<StackFrameSPARC*>(frame); 367 printf(" sp = 0x%08x fp = 0x%08x\n", 368 frame_sparc->context.g_r[14], frame_sparc->context.g_r[30]); 369#endif // __i386__ || __ppc__ || __sparc__ 370 } 371#endif // PRINT_STACKS 372 373 // Subtract 1 because the caller wants the number of frames beneath 374 // itself. Because the caller called us, subract two for our frame and its 375 // frame, which are included in stack.size(). 376 return stack.frames()->size() - 2; 377} 378 379 380// Recursor verifies that the number stack frames beneath itself is one more 381// than the number of stack frames beneath its parent. When depth frames 382// have been reached, Recursor stops checking and returns success. If the 383// frame count check fails at any depth, Recursor will stop and return false. 384// Because this calls CountCallerFrames, inlining is disabled. 385#if defined(__GNUC__) 386static bool Recursor(unsigned int depth, unsigned int parent_callers) 387 __attribute__((noinline)); 388#elif defined(__SUNPRO_CC) 389static bool Recursor(unsigned int depth, unsigned int parent_callers); 390#endif 391static bool Recursor(unsigned int depth, unsigned int parent_callers) { 392 unsigned int callers = CountCallerFrames(); 393 if (callers != parent_callers + 1) 394 return false; 395 396 if (depth) 397 return Recursor(depth - 1, callers); 398 399 // depth == 0 400 return true; 401} 402 403 404// Because this calls CountCallerFrames, inlining is disabled - but because 405// it's main (and nobody calls it other than the entry point), it wouldn't 406// be inlined anyway. 407#if defined(__GNUC__) 408int main(int argc, char** argv) __attribute__((noinline)); 409#elif defined(__SUNPRO_CC) 410int main(int argc, char** argv); 411#endif 412int main(int argc, char** argv) { 413 BPLOG_INIT(&argc, &argv); 414 415 return Recursor(RECURSION_DEPTH, CountCallerFrames()) ? 0 : 1; 416} 417 418 419#else 420// Not i386 or ppc or sparc? We can only test stacks we know how to walk. 421 422 423int main(int argc, char **argv) { 424 BPLOG_INIT(&argc, &argv); 425 426 // "make check" interprets an exit status of 77 to mean that the test is 427 // not supported. 428 BPLOG(ERROR) << "Selftest not supported here"; 429 return 77; 430} 431 432 433#endif // (__GNUC__ || __SUNPRO_CC) && (__i386__ || __ppc__ || __sparc__) 434