Re: gdbserver

Daniel Jacobowitz
2002-08-30T22:22:30Z

[Bart, please try this patch.]

List folks,

I think the time has come for generic_prepare_to_proceed to actually be
used. The problem addressed by this patch is that PREPARE_TO_PROCEED
is not a native-only macro (and not part of the target stack). So
lin_lwp_prepare_to_proceed would be called when using gdbserver, and of
course trap_ptid would be null_ptid or stale.
generic_prepare_to_proceed works correctly for lin-lwp native
debugging, and for remote debugging. This patch fixes an incorrect
breakpoint hit after manually switching threads; i.e. the same
breakpoint would be hit a second time. I'll try to write an
independent test case.

Patch look OK?

On Fri, Aug 23, 2002 at 08:35:17AM +0200, Van Assche, Bart wrote:
> Hello Dan,
>
> Thanks for your response. I tried with the latest snapshot, and debugging
> threads has indeed improved. However, I still get a SIGSEGV reported when I
> use remote debugging (that I do not get with native debugging -- see also
> below).

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer

2002-08-30 Daniel Jacobowitz <drow@mvista.com>

* arch-utils.c (default_prepare_to_proceed): Remove.
* arch-utils.h (default_prepare_to_proceed): Remove prototype.
* gdbarch.sh (PREPARE_TO_PROCEED): Change default to
generic_prepare_to_proceed.
* gdbarch.c: Regenerated.
* gdbarch.h: Regenerated.
* lin-lwp.c (lin_lwp_prepare_to_proceed): Remove.
* config/nm-linux.h (PREPARE_TO_PROCEED): Don't define.
(lin_lwp_prepare_to_proceed): Remove prototype.

Index: arch-utils.c
===================================================================
RCS file: /cvs/src/src/gdb/arch-utils.c,v
retrieving revision 1.67
diff -u -p -r1.67 arch-utils.c
--- arch-utils.c 24 Aug 2002 00:21:34 -0000 1.67
+++ arch-utils.c 30 Aug 2002 22:13:11 -0000
@@ -320,13 +320,6 @@ default_frame_address (struct frame_info
return fi->frame;
}

-/* Default prepare_to_procced(). */
-int
-default_prepare_to_proceed (int select_it)
-{
- return 0;
-}
-
/* Generic prepare_to_proceed(). This one should be suitable for most
targets that support threads. */
int
Index: gdbarch.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbarch.c,v
retrieving revision 1.146
diff -u -p -r1.146 gdbarch.c
--- gdbarch.c 24 Aug 2002 00:21:34 -0000 1.146
+++ gdbarch.c 30 Aug 2002 22:13:12 -0000
@@ -530,7 +530,7 @@ gdbarch_alloc (const struct gdbarch_info
current_gdbarch->memory_insert_breakpoint = default_memory_insert_breakpoint;
current_gdbarch->memory_remove_breakpoint = default_memory_remove_breakpoint;
current_gdbarch->decr_pc_after_break = -1;
- current_gdbarch->prepare_to_proceed = default_prepare_to_proceed;
+ current_gdbarch->prepare_to_proceed = generic_prepare_to_proceed;
current_gdbarch->function_start_offset = -1;
current_gdbarch->remote_translate_xfer_address = generic_remote_translate_xfer_address;
current_gdbarch->frame_args_skip = -1;
Index: gdbarch.h
===================================================================
RCS file: /cvs/src/src/gdb/gdbarch.h,v
retrieving revision 1.114
diff -u -p -r1.114 gdbarch.h
--- gdbarch.h 24 Aug 2002 00:21:34 -0000 1.114
+++ gdbarch.h 30 Aug 2002 22:13:13 -0000
@@ -1809,7 +1809,7 @@ extern void set_gdbarch_decr_pc_after_br

/* Default (function) for non- multi-arch platforms. */
#if (!GDB_MULTI_ARCH) && !defined (PREPARE_TO_PROCEED)
-#define PREPARE_TO_PROCEED(select_it) (default_prepare_to_proceed (select_it))
+#define PREPARE_TO_PROCEED(select_it) (generic_prepare_to_proceed (select_it))
#endif

typedef int (gdbarch_prepare_to_proceed_ftype) (int select_it);
Index: gdbarch.sh
===================================================================
RCS file: /cvs/src/src/gdb/gdbarch.sh,v
retrieving revision 1.158
diff -u -p -r1.158 gdbarch.sh
--- gdbarch.sh 24 Aug 2002 00:21:34 -0000 1.158
+++ gdbarch.sh 30 Aug 2002 22:13:14 -0000
@@ -549,7 +549,7 @@ f:2:BREAKPOINT_FROM_PC:const unsigned ch
f:2:MEMORY_INSERT_BREAKPOINT:int:memory_insert_breakpoint:CORE_ADDR addr, char *contents_cache:addr, contents_cache::0:default_memory_insert_breakpoint::0
f:2:MEMORY_REMOVE_BREAKPOINT:int:memory_remove_breakpoint:CORE_ADDR addr, char *contents_cache:addr, contents_cache::0:default_memory_remove_breakpoint::0
v:2:DECR_PC_AFTER_BREAK:CORE_ADDR:decr_pc_after_break::::0:-1
-f::PREPARE_TO_PROCEED:int:prepare_to_proceed:int select_it:select_it::0:default_prepare_to_proceed::0
+f::PREPARE_TO_PROCEED:int:prepare_to_proceed:int select_it:select_it::0:generic_prepare_to_proceed::0
v:2:FUNCTION_START_OFFSET:CORE_ADDR:function_start_offset::::0:-1
#
f:2:REMOTE_TRANSLATE_XFER_ADDRESS:void:remote_translate_xfer_address:CORE_ADDR gdb_addr, int gdb_len, CORE_ADDR *rem_addr, int *rem_len:gdb_addr, gdb_len, rem_addr, rem_len:::generic_remote_translate_xfer_address::0
Index: lin-lwp.c
===================================================================
RCS file: /cvs/src/src/gdb/lin-lwp.c,v
retrieving revision 1.35
diff -u -p -r1.35 lin-lwp.c
--- lin-lwp.c 27 Aug 2002 22:37:06 -0000 1.35
+++ lin-lwp.c 30 Aug 2002 22:13:14 -0000
@@ -294,46 +294,6 @@ iterate_over_lwps (int (*callback) (stru
}
\f

-/* Implementation of the PREPARE_TO_PROCEED hook for the GNU/Linux LWP
- layer.
-
- Note that this implementation is potentially redundant now that
- default_prepare_to_proceed() has been added.
-
- FIXME This may not support switching threads after Ctrl-C
- correctly. The default implementation does support this. */
-
-int
-lin_lwp_prepare_to_proceed (void)
-{
- if (! ptid_equal (trap_ptid, null_ptid)
- && ! ptid_equal (inferior_ptid, trap_ptid))
- {
- /* Switched over from TRAP_PID. */
- CORE_ADDR stop_pc = read_pc ();
- CORE_ADDR trap_pc;
-
- /* Avoid switching where it wouldn't do any good, i.e. if both
- threads are at the same breakpoint. */
- trap_pc = read_pc_pid (trap_ptid);
- if (trap_pc != stop_pc && breakpoint_here_p (trap_pc))
- {
- /* User hasn't deleted the breakpoint. Return non-zero, and
- switch back to TRAP_PID. */
- inferior_ptid = trap_ptid;
-
- /* FIXME: Is this stuff really necessary? */
- flush_cached_frames ();
- registers_changed ();
-
- return 1;
- }
- }
-
- return 0;
-}
-\f
-
#if 0
static void
lin_lwp_open (char *args, int from_tty)
Index: config/nm-linux.h
===================================================================
RCS file: /cvs/src/src/gdb/config/nm-linux.h,v
retrieving revision 1.12
diff -u -p -r1.12 nm-linux.h
--- config/nm-linux.h 24 Feb 2002 22:56:04 -0000 1.12
+++ config/nm-linux.h 30 Aug 2002 22:13:14 -0000
@@ -49,9 +49,6 @@ struct target_waitstatus;
extern ptid_t child_wait (ptid_t ptid, struct target_waitstatus *ourstatus);
#define CHILD_WAIT

-extern int lin_lwp_prepare_to_proceed (void);
-#define PREPARE_TO_PROCEED(select_it) lin_lwp_prepare_to_proceed ()
-
extern void lin_lwp_attach_lwp (ptid_t ptid, int verbose);
#define ATTACH_LWP(ptid, verbose) lin_lwp_attach_lwp ((ptid), (verbose))

Index: arch-utils.h
===================================================================
RCS file: /cvs/src/src/gdb/arch-utils.h,v
retrieving revision 1.41
diff -u -p -r1.41 arch-utils.h
--- arch-utils.h 24 Aug 2002 00:21:34 -0000 1.41
+++ arch-utils.h 30 Aug 2002 22:15:25 -0000
@@ -115,8 +115,6 @@ extern CORE_ADDR default_frame_address (

/* Default prepare_to_procced. */

-extern int default_prepare_to_proceed (int select_it);
-
extern int generic_prepare_to_proceed (int select_it);

/* Versions of init_frame_pc(). Do nothing; do the default. */