Skip unwritable frames in command "finish"

Nowadays, GDB can't insert breakpoint on the return address of the
exception handler on ARM M-profile, because the address is a magic
one 0xfffffff9,

 (gdb) bt
 #0  CT32B1_IRQHandler () at ../src/timer.c:67
 #1  <signal handler called>
 #2  main () at ../src/timer.c:127

(gdb) info frame
Stack level 0, frame at 0x200ffa8:
 pc = 0x4ec in CT32B1_IRQHandler (../src/timer.c:67); saved pc = 0xfffffff9
 called by frame at 0x200ffc8
 source language c.
 Arglist at 0x200ffa0, args:
 Locals at 0x200ffa0, Previous frame's sp is 0x200ffa8
 Saved registers:
  r7 at 0x200ffa0, lr at 0x200ffa4

(gdb) x/x 0xfffffff9
0xfffffff9:     Cannot access memory at address 0xfffffff9

(gdb) finish
Run till exit from #0  CT32B1_IRQHandler () at ../src/timer.c:67
Ed:15: Target error from Set break/watch: Et:96: Pseudo-address (0xFFFFFFxx) for EXC_RETURN is invalid (GDB error?)

Warning:
Cannot insert hardware breakpoint 0.
Could not insert hardware breakpoints:
You may have requested too many hardware breakpoints/watchpoints.

Command aborted.

even some debug probe can't set hardware breakpoint on the magic
address too,

(gdb) hbreak *0xfffffff9
Hardware assisted breakpoint 2 at 0xfffffff9
(gdb) c
Continuing.
Ed:15: Target error from Set break/watch: Et:96: Pseudo-address (0xFFFFFFxx) for EXC_RETURN is invalid (GDB error?)

Warning:
Cannot insert hardware breakpoint 2.
Could not insert hardware breakpoints:
You may have requested too many hardware breakpoints/watchpoints.

Command aborted.

The problem described above is quite similar to PR 8841, in which GDB
can't set breakpoint on signal trampoline, which is mapped to a read-only
page by kernel.  The rationale of this patch is to skip "unwritable"
frames when looking for caller frames in command "finish", and a new
gdbarch method code_of_frame_writable is added.  This patch fixes
the problem on ARM cortex-m target, but it can be used to fix
PR 8841 too.

gdb:

2016-05-10  Yao Qi  <yao.qi@arm.com>

	* arch-utils.c (default_code_of_frame_writable): New function.
	* arch-utils.h (default_code_of_frame_writable): Declare.
	* arm-tdep.c (arm_code_of_frame_writable): New function.
	(arm_gdbarch_init): Install gdbarch method
	code_of_frame_writable if the target is M-profile.
	* frame.c (skip_unwritable_frames): New function.
	* frame.h (skip_unwritable_frames): Declare.
	* gdbarch.sh (code_of_frame_writable): New.
	* gdbarch.c, gdbarch.h: Re-generated.
	* infcmd.c (finish_command): Call skip_unwritable_frames.
This commit is contained in:
Yao Qi 2016-05-23 17:32:56 +01:00 committed by Yao Qi
parent 0f6ed0e0ef
commit 7eb895307f
10 changed files with 94 additions and 0 deletions

View File

@ -1,3 +1,16 @@
2016-05-23 Yao Qi <yao.qi@arm.com>
* arch-utils.c (default_code_of_frame_writable): New function.
* arch-utils.h (default_code_of_frame_writable): Declare.
* arm-tdep.c (arm_code_of_frame_writable): New function.
(arm_gdbarch_init): Install gdbarch method
code_of_frame_writable if the target is M-profile.
* frame.c (skip_unwritable_frames): New function.
* frame.h (skip_unwritable_frames): Declare.
* gdbarch.sh (code_of_frame_writable): New.
* gdbarch.c, gdbarch.h: Re-generated.
* infcmd.c (finish_command): Call skip_unwritable_frames.
2016-05-23 Tom Tromey <tom@tromey.com>
PR python/19438, PR python/18393:

View File

@ -132,6 +132,13 @@ generic_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
return 0;
}
int
default_code_of_frame_writable (struct gdbarch *gdbarch,
struct frame_info *frame)
{
return 1;
}
/* Helper functions for gdbarch_inner_than */
int

View File

@ -107,6 +107,9 @@ extern int generic_in_solib_return_trampoline (struct gdbarch *gdbarch,
extern int generic_stack_frame_destroyed_p (struct gdbarch *gdbarch,
CORE_ADDR pc);
extern int default_code_of_frame_writable (struct gdbarch *gdbarch,
struct frame_info *frame);
/* By default, registers are not convertible. */
extern int generic_convert_register_p (struct gdbarch *gdbarch, int regnum,
struct type *type);

View File

@ -8862,6 +8862,22 @@ arm_register_g_packet_guesses (struct gdbarch *gdbarch)
/* Otherwise we don't have a useful guess. */
}
/* Implement the code_of_frame_writable gdbarch method. */
static int
arm_code_of_frame_writable (struct gdbarch *gdbarch, struct frame_info *frame)
{
if (gdbarch_tdep (gdbarch)->is_m
&& get_frame_type (frame) == SIGTRAMP_FRAME)
{
/* M-profile exception frames return to some magic PCs, where
isn't writable at all. */
return 0;
}
else
return 1;
}
/* Initialize the current architecture based on INFO. If possible,
re-use an architecture from ARCHES, which is a list of
@ -9312,6 +9328,9 @@ arm_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
set_gdbarch_push_dummy_call (gdbarch, arm_push_dummy_call);
set_gdbarch_frame_align (gdbarch, arm_frame_align);
if (is_m)
set_gdbarch_code_of_frame_writable (gdbarch, arm_code_of_frame_writable);
set_gdbarch_write_pc (gdbarch, arm_write_pc);
/* Frame handling. */

View File

@ -444,6 +444,19 @@ skip_artificial_frames (struct frame_info *frame)
return frame;
}
struct frame_info *
skip_unwritable_frames (struct frame_info *frame)
{
while (gdbarch_code_of_frame_writable (get_frame_arch (frame), frame) == 0)
{
frame = get_prev_frame (frame);
if (frame == NULL)
break;
}
return frame;
}
/* See frame.h. */
struct frame_info *

View File

@ -826,4 +826,9 @@ extern enum language get_frame_language (struct frame_info *frame);
extern struct frame_info *skip_tailcall_frames (struct frame_info *frame);
/* Return the first frame above FRAME or FRAME of which the code is
writable. */
extern struct frame_info *skip_unwritable_frames (struct frame_info *frame);
#endif /* !defined (FRAME_H) */

View File

@ -205,6 +205,7 @@ struct gdbarch
gdbarch_push_dummy_call_ftype *push_dummy_call;
int call_dummy_location;
gdbarch_push_dummy_code_ftype *push_dummy_code;
gdbarch_code_of_frame_writable_ftype *code_of_frame_writable;
gdbarch_print_registers_info_ftype *print_registers_info;
gdbarch_print_float_info_ftype *print_float_info;
gdbarch_print_vector_info_ftype *print_vector_info;
@ -387,6 +388,7 @@ gdbarch_alloc (const struct gdbarch_info *info,
gdbarch->dwarf2_reg_to_regnum = no_op_reg_to_regnum;
gdbarch->deprecated_fp_regnum = -1;
gdbarch->call_dummy_location = AT_ENTRY_POINT;
gdbarch->code_of_frame_writable = default_code_of_frame_writable;
gdbarch->print_registers_info = default_print_registers_info;
gdbarch->print_float_info = default_print_float_info;
gdbarch->register_sim_regno = legacy_register_sim_regno;
@ -552,6 +554,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
/* Skip verify of push_dummy_call, has predicate. */
/* Skip verify of call_dummy_location, invalid_p == 0 */
/* Skip verify of push_dummy_code, has predicate. */
/* Skip verify of code_of_frame_writable, invalid_p == 0 */
/* Skip verify of print_registers_info, invalid_p == 0 */
/* Skip verify of print_float_info, invalid_p == 0 */
/* Skip verify of print_vector_info, has predicate. */
@ -803,6 +806,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
fprintf_unfiltered (file,
"gdbarch_dump: char_signed = %s\n",
plongest (gdbarch->char_signed));
fprintf_unfiltered (file,
"gdbarch_dump: code_of_frame_writable = <%s>\n",
host_address_to_string (gdbarch->code_of_frame_writable));
fprintf_unfiltered (file,
"gdbarch_dump: coff_make_msymbol_special = <%s>\n",
host_address_to_string (gdbarch->coff_make_msymbol_special));
@ -2314,6 +2320,23 @@ set_gdbarch_push_dummy_code (struct gdbarch *gdbarch,
gdbarch->push_dummy_code = push_dummy_code;
}
int
gdbarch_code_of_frame_writable (struct gdbarch *gdbarch, struct frame_info *frame)
{
gdb_assert (gdbarch != NULL);
gdb_assert (gdbarch->code_of_frame_writable != NULL);
if (gdbarch_debug >= 2)
fprintf_unfiltered (gdb_stdlog, "gdbarch_code_of_frame_writable called\n");
return gdbarch->code_of_frame_writable (gdbarch, frame);
}
void
set_gdbarch_code_of_frame_writable (struct gdbarch *gdbarch,
gdbarch_code_of_frame_writable_ftype code_of_frame_writable)
{
gdbarch->code_of_frame_writable = code_of_frame_writable;
}
void
gdbarch_print_registers_info (struct gdbarch *gdbarch, struct ui_file *file, struct frame_info *frame, int regnum, int all)
{

View File

@ -395,6 +395,12 @@ typedef CORE_ADDR (gdbarch_push_dummy_code_ftype) (struct gdbarch *gdbarch, CORE
extern CORE_ADDR gdbarch_push_dummy_code (struct gdbarch *gdbarch, CORE_ADDR sp, CORE_ADDR funaddr, struct value **args, int nargs, struct type *value_type, CORE_ADDR *real_pc, CORE_ADDR *bp_addr, struct regcache *regcache);
extern void set_gdbarch_push_dummy_code (struct gdbarch *gdbarch, gdbarch_push_dummy_code_ftype *push_dummy_code);
/* Return true if the code of FRAME is writable. */
typedef int (gdbarch_code_of_frame_writable_ftype) (struct gdbarch *gdbarch, struct frame_info *frame);
extern int gdbarch_code_of_frame_writable (struct gdbarch *gdbarch, struct frame_info *frame);
extern void set_gdbarch_code_of_frame_writable (struct gdbarch *gdbarch, gdbarch_code_of_frame_writable_ftype *code_of_frame_writable);
typedef void (gdbarch_print_registers_info_ftype) (struct gdbarch *gdbarch, struct ui_file *file, struct frame_info *frame, int regnum, int all);
extern void gdbarch_print_registers_info (struct gdbarch *gdbarch, struct ui_file *file, struct frame_info *frame, int regnum, int all);
extern void set_gdbarch_print_registers_info (struct gdbarch *gdbarch, gdbarch_print_registers_info_ftype *print_registers_info);

View File

@ -485,6 +485,9 @@ M:CORE_ADDR:push_dummy_call:struct value *function, struct regcache *regcache, C
v:int:call_dummy_location::::AT_ENTRY_POINT::0
M:CORE_ADDR:push_dummy_code:CORE_ADDR sp, CORE_ADDR funaddr, struct value **args, int nargs, struct type *value_type, CORE_ADDR *real_pc, CORE_ADDR *bp_addr, struct regcache *regcache:sp, funaddr, args, nargs, value_type, real_pc, bp_addr, regcache
# Return true if the code of FRAME is writable.
m:int:code_of_frame_writable:struct frame_info *frame:frame::default_code_of_frame_writable::0
m:void:print_registers_info:struct ui_file *file, struct frame_info *frame, int regnum, int all:file, frame, regnum, all::default_print_registers_info::0
m:void:print_float_info:struct ui_file *file, struct frame_info *frame, const char *args:file, frame, args::default_print_float_info::0
M:void:print_vector_info:struct ui_file *file, struct frame_info *frame, const char *args:file, frame, args

View File

@ -2029,6 +2029,8 @@ finish_command (char *arg, int from_tty)
entering THISFRAME. */
frame = skip_tailcall_frames (frame);
frame = skip_unwritable_frames (frame);
if (frame == NULL)
error (_("Cannot find the caller frame."));