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[PING] [PATCH 1/2] Display ExceptionRecord for $_siginfo


 Ping.

Am Freitag, 17. Januar 2020, 16:32:28 MEZ hat Hannes Domani via gdb-patches <gdb-patches@sourceware.org> Folgendes geschrieben:

> Uses the $_siginfo convenience variable to show the last exception.
>
> The type looks like this:
>
> (gdb) pt $_siginfo
> type = struct EXCEPTION_RECORD {
>     unsigned int ExceptionCode;
>     unsigned int ExceptionFlags;
>     struct EXCEPTION_RECORD *ExceptionRecord;
>     void *ExceptionAddress;
>     unsigned int NumberParameters;
>     void *ExceptionInformation[15];
> }
>
> EXCEPTION_RECORD is documented at [1].
>
> Example:
>
> Program received signal SIGSEGV, Segmentation fault.
> main () at crasher.c:4
> 4        *(int*)0x123 = 0;
> (gdb) p $_siginfo
> $1 = {
>   ExceptionCode = 3221225477,
>   ExceptionFlags = 0,
>   ExceptionRecord = 0x0,
>   ExceptionAddress = 0x401632 <main+18>,
>   NumberParameters = 2,
>   ExceptionInformation = {0x1, 0x123, 0x0 <repeats 13 times>}
> }
> (gdb) p/x $_siginfo.ExceptionCode
> $2 = 0xc0000005
>
> And 0xc0000005 is the value of EXCEPTION_ACCESS_VIOLATION.
>
> [1] https://docs.microsoft.com/en-us/windows/win32/api/winnt/ns-winnt-exception_record
>
> gdb/ChangeLog:
>
> 2020-01-17  Hannes Domani  <ssbssa@yahoo.de>
>
>     * windows-nat.c (handle_exception): Set siginfo_er.
>     (windows_nat_target::mourn_inferior): Reset siginfo_er.
>     (windows_xfer_siginfo): New function.
>     (windows_nat_target::xfer_partial): Call windows_xfer_siginfo.
>     * windows-tdep.c (struct windows_gdbarch_data): New struct.
>     (init_windows_gdbarch_data): New function.
>     (get_windows_gdbarch_data): New function.
>     (windows_get_siginfo_type): New function.
>     (windows_init_abi): Register windows_get_siginfo_type.
>     (_initialize_windows_tdep): Register init_windows_gdbarch_data.
>
> gdb/gdbserver/ChangeLog:
>
> 2020-01-17  Hannes Domani  <ssbssa@yahoo.de>
>
>     * win32-low.c (win32_clear_inferiors): Reset siginfo_er.
>     (handle_exception): Set siginfo_er.
>     (win32_xfer_siginfo): New function.
> ---
> gdb/gdbserver/win32-low.c | 28 +++++++++++++++++-
> gdb/windows-nat.c        | 29 ++++++++++++++++++
> gdb/windows-tdep.c        | 62 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 118 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/gdbserver/win32-low.c b/gdb/gdbserver/win32-low.c
> index 2c4a9b1074..223561be54 100644
> --- a/gdb/gdbserver/win32-low.c
> +++ b/gdb/gdbserver/win32-low.c
> @@ -75,6 +75,7 @@ static int attaching = 0;
> static HANDLE current_process_handle = NULL;
> static DWORD current_process_id = 0;
> static DWORD main_thread_id = 0;
> +static EXCEPTION_RECORD siginfo_er;    /* Contents of $_siginfo */
> static enum gdb_signal last_sig = GDB_SIGNAL_0;
>
> /* The current debug event from WaitForDebugEvent.  */
> @@ -801,6 +802,7 @@ win32_clear_inferiors (void)
>     CloseHandle (current_process_handle);
>
>   for_each_thread (delete_thread_info);
> +  siginfo_er.ExceptionCode = 0;
>   clear_inferiors ();
> }
>
> @@ -1230,6 +1232,9 @@ handle_exception (struct target_waitstatus *ourstatus)
> {
>   DWORD code = current_event.u.Exception.ExceptionRecord.ExceptionCode;
>
> +  memcpy (&siginfo_er, &current_event.u.Exception.ExceptionRecord,
> +      sizeof siginfo_er);
> +
>   ourstatus->kind = TARGET_WAITKIND_STOPPED;
>
>   switch (code)
> @@ -1772,6 +1777,27 @@ wince_hostio_last_error (char *buf)
> }
> #endif
>
> +static int
> +win32_xfer_siginfo (const char *annex, unsigned char *readbuf,
> +            unsigned const char *writebuf, CORE_ADDR offset, int len)
> +{
> +  if (!siginfo_er.ExceptionCode)
> +    return -1;
> +
> +  if (!readbuf)
> +    return -1;
> +
> +  if (offset > sizeof (siginfo_er))
> +    return -1;
> +
> +  if (offset + len > sizeof (siginfo_er))
> +    len = sizeof (siginfo_er) - offset;
> +
> +  memcpy (readbuf, (char *) &siginfo_er + offset, len);
> +
> +  return len;
> +}
> +
> /* Write Windows OS Thread Information Block address.  */
>
> static int
> @@ -1833,7 +1859,7 @@ static process_stratum_target win32_target_ops = {
>   hostio_last_error_from_errno,
> #endif
>   NULL, /* qxfer_osdata */
> -  NULL, /* qxfer_siginfo */
> +  win32_xfer_siginfo,
>   NULL, /* supports_non_stop */
>   NULL, /* async */
>   NULL, /* start_non_stop */
> diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
> index 901e64263c..824ff4b322 100644
> --- a/gdb/windows-nat.c
> +++ b/gdb/windows-nat.c
> @@ -236,6 +236,7 @@ static DEBUG_EVENT current_event;    /* The current debug event from
>                       WaitForDebugEvent */
> static HANDLE current_process_handle;    /* Currently executing process */
> static windows_thread_info *current_thread;    /* Info on currently selected thread */
> +static EXCEPTION_RECORD siginfo_er;    /* Contents of $_siginfo */
>
> /* Counts of things.  */
> static int exception_count = 0;
> @@ -1166,6 +1167,8 @@ handle_exception (struct target_waitstatus *ourstatus)
>   DWORD code = rec->ExceptionCode;
>   handle_exception_result result = HANDLE_EXCEPTION_HANDLED;
>
> +  memcpy (&siginfo_er, rec, sizeof siginfo_er);
> +
>   ourstatus->kind = TARGET_WAITKIND_STOPPED;
>
>   /* Record the context of the current thread.  */
> @@ -2862,6 +2865,7 @@ windows_nat_target::mourn_inferior ()
>       CHECK (CloseHandle (current_process_handle));
>       open_process_used = 0;
>     }
> +  siginfo_er.ExceptionCode = 0;
>   inf_child_target::mourn_inferior ();
> }
>
> @@ -2994,6 +2998,28 @@ windows_xfer_shared_libraries (struct target_ops *ops,
>   return len != 0 ? TARGET_XFER_OK : TARGET_XFER_EOF;
> }
>
> +static enum target_xfer_status
> +windows_xfer_siginfo (gdb_byte *readbuf, ULONGEST offset, ULONGEST len,
> +              ULONGEST *xfered_len)
> +{
> +  if (!siginfo_er.ExceptionCode)
> +    return TARGET_XFER_E_IO;
> +
> +  if (!readbuf)
> +    return TARGET_XFER_E_IO;
> +
> +  if (offset > sizeof (siginfo_er))
> +    return TARGET_XFER_E_IO;
> +
> +  if (offset + len > sizeof (siginfo_er))
> +    len = sizeof (siginfo_er) - offset;
> +
> +  memcpy (readbuf, (char *) &siginfo_er + offset, len);
> +  *xfered_len = len;
> +
> +  return TARGET_XFER_OK;
> +}
> +
> enum target_xfer_status
> windows_nat_target::xfer_partial (enum target_object object,
>                   const char *annex, gdb_byte *readbuf,
> @@ -3009,6 +3035,9 @@ windows_nat_target::xfer_partial (enum target_object object,
>       return windows_xfer_shared_libraries (this, object, annex, readbuf,
>                         writebuf, offset, len, xfered_len);
>
> +    case TARGET_OBJECT_SIGNAL_INFO:
> +      return windows_xfer_siginfo (readbuf, offset, len, xfered_len);
> +
>     default:
>       if (beneath () == NULL)
>     {
> diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c
> index 1fc2748581..50efa31709 100644
> --- a/gdb/windows-tdep.c
> +++ b/gdb/windows-tdep.c
> @@ -153,6 +153,26 @@ static const int FULL_TIB_SIZE = 0x1000;
>
> static bool maint_display_all_tib = false;
>
> +static struct gdbarch_data *windows_gdbarch_data_handle;
> +
> +struct windows_gdbarch_data
> +  {
> +    struct type *siginfo_type;
> +  };
> +
> +static void *
> +init_windows_gdbarch_data (struct gdbarch *gdbarch)
> +{
> +  return GDBARCH_OBSTACK_ZALLOC (gdbarch, struct windows_gdbarch_data);
> +}
> +
> +static struct windows_gdbarch_data *
> +get_windows_gdbarch_data (struct gdbarch *gdbarch)
> +{
> +  return ((struct windows_gdbarch_data *)
> +      gdbarch_data (gdbarch, windows_gdbarch_data_handle));
> +}
> +
> /* Define Thread Local Base pointer type.  */
>
> static struct type *
> @@ -648,6 +668,43 @@ windows_gdb_signal_to_target (struct gdbarch *gdbarch, enum gdb_signal signal)
>   return -1;
> }
>
> +static struct type *
> +windows_get_siginfo_type (struct gdbarch *gdbarch)
> +{
> +  struct windows_gdbarch_data *windows_gdbarch_data;
> +  struct type *uint_type, *void_ptr_type;
> +  struct type *siginfo_ptr_type, *siginfo_type;
> +
> +  windows_gdbarch_data = get_windows_gdbarch_data (gdbarch);
> +  if (windows_gdbarch_data->siginfo_type != NULL)
> +    return windows_gdbarch_data->siginfo_type;
> +
> +  uint_type = arch_integer_type (gdbarch, gdbarch_int_bit (gdbarch),
> +                1, "unsigned int");
> +  void_ptr_type = lookup_pointer_type (builtin_type (gdbarch)->builtin_void);
> +
> +  siginfo_type = arch_composite_type (gdbarch, "EXCEPTION_RECORD",
> +                      TYPE_CODE_STRUCT);
> +  siginfo_ptr_type = arch_pointer_type (gdbarch, gdbarch_ptr_bit (gdbarch),
> +                    NULL, siginfo_type);
> +
> +  append_composite_type_field (siginfo_type, "ExceptionCode", uint_type);
> +  append_composite_type_field (siginfo_type, "ExceptionFlags", uint_type);
> +  append_composite_type_field (siginfo_type, "ExceptionRecord",
> +                  siginfo_ptr_type);
> +  append_composite_type_field (siginfo_type, "ExceptionAddress",
> +                  void_ptr_type);
> +  append_composite_type_field (siginfo_type, "NumberParameters", uint_type);
> +  append_composite_type_field_aligned (siginfo_type, "ExceptionInformation",
> +                      lookup_array_range_type (void_ptr_type,
> +                                0, 14),
> +                      TYPE_LENGTH (void_ptr_type));
> +
> +  windows_gdbarch_data->siginfo_type = siginfo_type;
> +
> +  return siginfo_type;
> +}
> +
> /* To be called from the various GDB_OSABI_CYGWIN handlers for the
>     various Windows architectures and machine types.  */
>
> @@ -667,6 +724,8 @@ windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
>   set_gdbarch_gdb_signal_to_target (gdbarch, windows_gdb_signal_to_target);
>
>   set_solib_ops (gdbarch, &solib_target_so_ops);
> +
> +  set_gdbarch_get_siginfo_type (gdbarch, windows_get_siginfo_type);
> }
>
> /* Implementation of `tlb' variable.  */
> @@ -682,6 +741,9 @@ void _initialize_windows_tdep ();
> void
> _initialize_windows_tdep ()
> {
> +  windows_gdbarch_data_handle =
> +    gdbarch_data_register_post_init (init_windows_gdbarch_data);
> +
>   init_w32_command_list ();
>   add_cmd ("thread-information-block", class_info, display_tib,
>       _("Display thread information block."),
> --
> 2.25.0


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