TakeV/dxx-rebirth
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity

Fix Windows exception log short stack

Browse source 
The Windows exception handler probes the stack to determine how much can
be safely dumped, up to a fixed maximum number of bytes.  A logic error
caused the probe function to start its stack probe lower than intended,
so the eventual dump code logs fewer pre-exception bytes than intended.
Fix that error so that the dump shows more pre-exception bytes.

Also, log the address of the ud2 instruction, so that the effective load
address of the module can be determined.  Without this, ASLR makes
reading the dumps needlessly difficult.
This commit is contained in:
Kp 2017-11-18 04:45:50 +00:00
parent e5496d3aaf
commit d42fff397b
1 changed files with 12 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
common/arch/win32/except.cpp
View file

@ -93,7 +93,7 @@ struct dxx_trap_context
}
#define DXX_REPORT_TEXT_FORMAT_UUID "Format UUID: dfd09b9c-8caa-428c-a294-7d12cbd6cd89"
#define DXX_REPORT_TEXT_FORMAT_UUID "Format UUID: 0f7deda4-1122-4be8-97d5-afc91b7803d6"
#define DXX_REPORT_TEXT_LEADER_VERSION_PREFIX "Rebirth version: x"
#define DXX_REPORT_TEXT_LEADER_BUILD_DATETIME "Rebirth built: "
#define DXX_REPORT_TEXT_LEADER_EXCEPTION_MESSAGE "Exception message: "
@ -186,11 +186,12 @@ static LONG CALLBACK vectored_exception_handler(EXCEPTION_POINTERS *const ep)
/* Ensure gcc does not clone the inline labels */
__attribute__((__noinline__,__noclone__,__warn_unused_result__))
static void *capture_exception_context(dxx_trap_context &dtc)
static void *capture_exception_context(dxx_trap_context &dtc, const uint8_t *const sp)
{
const auto handler = AddVectoredExceptionHandler(1, &vectored_exception_handler);
if (handler)
{
dtc = {};
/*
* This block guarantees at least one and at most two faults to
* occur. Run it only if an exception handler was successfully
@ -213,7 +214,7 @@ DXX_ASM_LABEL("dxx_rebirth_veh_ud2") ":\n"
" ud2\n"
:: "a" (&dtc) : "memory"
);
auto p = dtc.ContextRecord.DXX_NT_CONTEXT_REGISTER(sp);
auto p = reinterpret_cast<uintptr_t>(sp);
for (auto e = p + dump_stack_bytes; p != e; ++p)
asm volatile(
DXX_ASM_LABEL("dxx_rebirth_veh_sp") ":\n"
@ -244,7 +245,6 @@ DXX_ASM_LABEL("dxx_rebirth_veh_sp") ":\n"
return handler;
}
#undef DXX_ASM_LABEL
#undef DXX_NT_CONTEXT_REGISTER
/*
* Initialize `path` with a path suitable to be used to write a minidump
@ -361,7 +361,7 @@ static void write_exception_dump(dxx_trap_context &dtc, const unsigned pid, cons
* Write a plain text dump of metadata and a hex dump of the faulting
* stack.
*/
static void write_exception_stack(const wchar_t *const filename, const unsigned pid, const uint8_t *const begin_sp, const uint8_t *const end_sp, const std::string &what, const HANDLE h)
static void write_exception_stack(const wchar_t *const filename, const unsigned pid, const uint8_t *const begin_sp, const dxx_trap_context &dtc, const std::string &what, const HANDLE h)
{
std::array<char, 4096> buf;
buf = {};
@ -374,9 +374,10 @@ DXX_REPORT_TEXT_LEADER_BUILD_DATETIME "%s\n"
"Rebirth PID: %u\n"
"Report date-time: %.19ls\n"
DXX_REPORT_TEXT_LEADER_EXCEPTION_MESSAGE "\"%s\"\n"
"UD2 IP: %p\n"
"SP: %p\n"
"\n"
, g_strctxuuid.data(), g_descent_version, g_descent_build_datetime, pid, filename, what.c_str(), begin_sp
, g_strctxuuid.data(), g_descent_version, g_descent_build_datetime, pid, filename, what.c_str(), reinterpret_cast<const uint8_t *>(dtc.ContextRecord.DXX_NT_CONTEXT_REGISTER(ip)), begin_sp
);
/*
* end_sp is rounded down to a paragraph boundary.
@ -386,6 +387,7 @@ DXX_REPORT_TEXT_LEADER_EXCEPTION_MESSAGE "\"%s\"\n"
const auto sp = reinterpret_cast<const uint8_t *>(reinterpret_cast<uintptr_t>(begin_sp) & -dump_stack_stride);
DWORD dwWritten;
WriteFile(h, buf.data(), len_header_text, &dwWritten, 0);
const auto end_sp = dtc.end_sp;
for (unsigned i = 0; i < dump_stack_bytes; i += dump_stack_stride)
{
char hexdump[dump_stack_stride + 1];
@ -410,10 +412,10 @@ DXX_REPORT_TEXT_LEADER_EXCEPTION_MESSAGE "\"%s\"\n"
}
}
static void write_exception_stack(const wchar_t *const filename, const unsigned pid, const uint8_t *const sp, const uint8_t *const end_sp, const std::string &what, path_buffer &path)
static void write_exception_stack(const wchar_t *const filename, const unsigned pid, const uint8_t *const sp, const dxx_trap_context &dtc, const std::string &what, path_buffer &path)
{
if (RAII_Windows_FILE_HANDLE h{CreateFileW(path.data(), GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)})
write_exception_stack(filename, pid, sp, end_sp, what, h);
write_exception_stack(filename, pid, sp, dtc, what, h);
else
path.front() = 0;
}
@ -453,7 +455,7 @@ static void write_exception_logs(const uint8_t *const sp)
#endif
path_buffer path_stack;
dxx_trap_context dtc;
if (capture_exception_context(dtc))
if (capture_exception_context(dtc, sp))
{
const unsigned pid = GetCurrentProcessId();
wchar_t *filename;
@ -468,7 +470,7 @@ static void write_exception_logs(const uint8_t *const sp)
#else
(void)pl;
#endif
write_exception_stack(filename, pid, sp, dtc.end_sp, what, path_stack);
write_exception_stack(filename, pid, sp, dtc, what, path_stack);
}
else
{