Re: gdbserver

[Daniel Jacobowitz <drow at mvista dot com>]

[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
 }
 
 
-/* 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;
-}
-
-
 #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. */