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

["Hannes Domani via gdb-patches" <gdb-patches at sourceware dot org>]

 Ping.

Am Freitag, 31. Januar 2020, 13:12:15 MEZ hat Hannes Domani via gdb-patches <gdb-patches@sourceware.org> Folgendes geschrieben:

> 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