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//===-- sanitizer_unwind_linux_libcdep.cpp --------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains the unwind.h-based (aka "slow") stack unwinding routines
// available to the tools on Linux, Android, NetBSD, FreeBSD, and Solaris.
//===----------------------------------------------------------------------===//
#include "sanitizer_platform.h"
#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
SANITIZER_SOLARIS
#include "sanitizer_common.h"
#include "sanitizer_stacktrace.h"
#if SANITIZER_ANDROID
#include <dlfcn.h> // for dlopen()
#endif
#if SANITIZER_FREEBSD
#define _GNU_SOURCE // to declare _Unwind_Backtrace() from <unwind.h>
#endif
#include <unwind.h>
namespace __sanitizer {
namespace {
//---------------------------- UnwindSlow --------------------------------------
typedef struct {
uptr absolute_pc;
uptr stack_top;
uptr stack_size;
} backtrace_frame_t;
extern "C" {
typedef void *(*acquire_my_map_info_list_func)();
typedef void (*release_my_map_info_list_func)(void *map);
typedef sptr (*unwind_backtrace_signal_arch_func)(
void *siginfo, void *sigcontext, void *map_info_list,
backtrace_frame_t *backtrace, uptr ignore_depth, uptr max_depth);
acquire_my_map_info_list_func acquire_my_map_info_list;
release_my_map_info_list_func release_my_map_info_list;
unwind_backtrace_signal_arch_func unwind_backtrace_signal_arch;
} // extern "C"
#if defined(__arm__) && !SANITIZER_NETBSD
// NetBSD uses dwarf EH
#define UNWIND_STOP _URC_END_OF_STACK
#define UNWIND_CONTINUE _URC_NO_REASON
#else
#define UNWIND_STOP _URC_NORMAL_STOP
#define UNWIND_CONTINUE _URC_NO_REASON
#endif
uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
#if defined(__arm__) && !SANITIZER_APPLE
uptr val;
_Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
15 /* r15 = PC */, _UVRSD_UINT32, &val);
CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
// Clear the Thumb bit.
return val & ~(uptr)1;
#else
return (uptr)_Unwind_GetIP(ctx);
#endif
}
struct UnwindTraceArg {
BufferedStackTrace *stack;
u32 max_depth;
};
_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
UnwindTraceArg *arg = (UnwindTraceArg*)param;
CHECK_LT(arg->stack->size, arg->max_depth);
uptr pc = Unwind_GetIP(ctx);
const uptr kPageSize = GetPageSizeCached();
// Let's assume that any pointer in the 0th page (i.e. <0x1000 on i386 and
// x86_64) is invalid and stop unwinding here. If we're adding support for
// a platform where this isn't true, we need to reconsider this check.
if (pc < kPageSize) return UNWIND_STOP;
arg->stack->trace_buffer[arg->stack->size++] = pc;
if (arg->stack->size == arg->max_depth) return UNWIND_STOP;
return UNWIND_CONTINUE;
}
} // namespace
#if SANITIZER_ANDROID
void SanitizerInitializeUnwinder() {
if (AndroidGetApiLevel() >= ANDROID_LOLLIPOP_MR1) return;
// Pre-lollipop Android can not unwind through signal handler frames with
// libgcc unwinder, but it has a libcorkscrew.so library with the necessary
// workarounds.
void *p = dlopen("libcorkscrew.so", RTLD_LAZY);
if (!p) {
VReport(1,
"Failed to open libcorkscrew.so. You may see broken stack traces "
"in SEGV reports.");
return;
}
acquire_my_map_info_list =
(acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list");
release_my_map_info_list =
(release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list");
unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym(
p, "unwind_backtrace_signal_arch");
if (!acquire_my_map_info_list || !release_my_map_info_list ||
!unwind_backtrace_signal_arch) {
VReport(1,
"Failed to find one of the required symbols in libcorkscrew.so. "
"You may see broken stack traces in SEGV reports.");
acquire_my_map_info_list = 0;
unwind_backtrace_signal_arch = 0;
release_my_map_info_list = 0;
}
}
#endif
void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
CHECK_GE(max_depth, 2);
size = 0;
UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
_Unwind_Backtrace(Unwind_Trace, &arg);
// We need to pop a few frames so that pc is on top.
uptr to_pop = LocatePcInTrace(pc);
// trace_buffer[0] belongs to the current function so we always pop it,
// unless there is only 1 frame in the stack trace (1 frame is always better
// than 0!).
// 1-frame stacks don't normally happen, but this depends on the actual
// unwinder implementation (libgcc, libunwind, etc) which is outside of our
// control.
if (to_pop == 0 && size > 1)
to_pop = 1;
PopStackFrames(to_pop);
#if defined(__GNUC__) && defined(__sparc__)
// __builtin_return_address returns the address of the call instruction
// on the SPARC and not the return address, so we need to compensate.
trace_buffer[0] = GetNextInstructionPc(pc);
#else
trace_buffer[0] = pc;
#endif
}
void BufferedStackTrace::UnwindSlow(uptr pc, void *context, u32 max_depth) {
CHECK(context);
CHECK_GE(max_depth, 2);
if (!unwind_backtrace_signal_arch) {
UnwindSlow(pc, max_depth);
return;
}
void *map = acquire_my_map_info_list();
CHECK(map);
InternalMmapVector<backtrace_frame_t> frames(kStackTraceMax);
// siginfo argument appears to be unused.
sptr res = unwind_backtrace_signal_arch(/* siginfo */ 0, context, map,
frames.data(),
/* ignore_depth */ 0, max_depth);
release_my_map_info_list(map);
if (res < 0) return;
CHECK_LE((uptr)res, kStackTraceMax);
size = 0;
// +2 compensate for libcorkscrew unwinder returning addresses of call
// instructions instead of raw return addresses.
for (sptr i = 0; i < res; ++i)
trace_buffer[size++] = frames[i].absolute_pc + 2;
}
} // namespace __sanitizer
#endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||
// SANITIZER_SOLARIS
|
