[RFA/RFC 2] Remove hardware break and watchpoints at program exit.

Pierre Muller
2002-01-11T12:01:07Z

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At 10:20 09/01/2002 , vous avez Ã©crit:

>On Wed, 9 Jan 2002, Pierre Muller wrote:
>
> > The patch simply calls i386_cleanup_dregs
> > in breakpoint_init_inferior if context is inf_exited.

I finally change completely my patch to
another (more correct, in my opinion) strategy.

In breakpoint_init_inferior
I added code that conditionally removes hardware watch and breakpoint
if the context is inf_exited, i.e. at exit of the debugged program.

This leads to a much cleaner removal of the watchpoints.
I still kept the call to a generic hardware removal function
and testing the i386 case, I could see that even though the dr_mirror
array is zeored out, the dr_control_mirror and
dr_status_mirror still aren't set to zero.
For dr_control_register, this is due to an error in the I386_DR_DISABLE
because that macro only resets the active bit, but not the size and type bits
associated to that debug register.

I suspect that before this patch,
the hardware watchpoint code that was in s390-nat.c
didn't reset the area_base to nil when a program was exited.
Could DJ Barrow please test this and see if the patch below does
fix this.
(I can't test this as I ave no acces to s390 machine,
but it appears to me that this might cause certain
watchpoints to still show up after removal, if
the debuggee was run several times).
After the patch, probably no HARDWARE_REGISTER_RESET
function is needed anymore, but I didn't inspect the code entirely.

I have a little doubt about the default value of the
HARDWARE_REGISTER_RESET macro.
What should be used as a no-op default ?

2002-01-09 Pierre Muller <muller@ics.u-strasbg.fr>

* breakpoint.c (REMOVE_HARDWARE_BREAKPOINT_AT_EXIT):
Define to 0 if not defined.
(REMOVE_HARDWARE_WATCHPOINT_AT_EXIT):
Define to 0 if not defined.
(HARDWARE_REGISTER_RESET): Default to no-op.
(breakpoint_init_inferior): Use REMOVE_HARDWARE_BREAKPOINT_AT_EXIT
and REMOVE_HARDWARE_WATCHPOINT_AT_EXIT to conditionally
remove hardware break and watchpoints at exit.
Call HARDWARE_REGISTER_RESET macro if defined at exit.

* config/i386/nm-i386.h: Define HARDWARE_REGISTER_RESET
macro to call i386_cleanup_dregs().
Set REMOVE_HARDWARE_BREAKPOINT_AT_EXIT to 1.
Set REMOVE_HARDWARE_WATCHPOINT_AT_EXIT to 1.

* go32-nat.c (go32_mourn_inferior): Remove call to i386_cleanup_dregs
as this is done in breakpoint_init_inferior().

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Index: breakpoint.c
===================================================================
RCS file: /cvs/src/src/gdb/breakpoint.c,v
retrieving revision 1.57
diff -u -p -r1.57 breakpoint.c
--- breakpoint.c 2001/11/11 16:39:59 1.57
+++ breakpoint.c 2002/01/11 11:34:08
@@ -234,6 +234,19 @@ static int executing_breakpoint_commands
B ? (TMP=B->next, 1): 0; \
B = TMP)

+#ifndef REMOVE_HARDWARE_BREAKPOINT_AT_EXIT
+#define REMOVE_HARDWARE_BREAKPOINT_AT_EXIT 0
+#endif
+
+#ifndef REMOVE_HARDWARE_WATCHPOINT_AT_EXIT
+#define REMOVE_HARDWARE_WATCHPOINT_AT_EXIT 0
+#endif
+
+
+#ifndef HARDWARE_REGISTERS_RESET
+#define HARDWARE_REGISTERS_RESET {}
+#endif
+
/* True if SHIFT_INST_REGS defined, false otherwise. */

int must_shift_inst_regs =
@@ -1440,7 +1453,17 @@ breakpoint_init_inferior (enum inf_conte

ALL_BREAKPOINTS_SAFE (b, temp)
{
- b->inserted = 0;
+ if ((((REMOVE_HARDWARE_BREAKPOINT_AT_EXIT)
+ && b->type == bp_hardware_breakpoint)
+ ||((REMOVE_HARDWARE_WATCHPOINT_AT_EXIT)
+ && (b->type == bp_hardware_watchpoint
+ || b->type == bp_access_watchpoint
+ || b->type == bp_read_watchpoint)))
+ && b->inserted
+ && context == inf_exited)
+ remove_breakpoint (b, mark_uninserted);
+
+ b->inserted = 0;

switch (b->type)
{
@@ -1487,6 +1510,8 @@ breakpoint_init_inferior (enum inf_conte
warning ("You must reinsert them explicitly.");
warning_needed = 0;
}
+ if (context == inf_exited)
+ HARDWARE_REGISTER_RESET;
}

/* breakpoint_here_p (PC) returns non-zero if an enabled breakpoint
Index: go32-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/go32-nat.c,v
retrieving revision 1.26
diff -u -p -r1.26 go32-nat.c
--- go32-nat.c 2001/12/06 08:15:37 1.26
+++ go32-nat.c 2002/01/11 11:34:08
@@ -670,7 +670,7 @@ go32_mourn_inferior (void)
be nice if GDB itself would take care to remove all breakpoints
at all times, but it doesn't, probably under an assumption that
the OS cleans up when the debuggee exits. */
- i386_cleanup_dregs ();
+ // i386_cleanup_dregs ();
go32_kill_inferior ();
generic_mourn_inferior ();
}
Index: config/i386/nm-i386.h
===================================================================
RCS file: /cvs/src/src/gdb/config/i386/nm-i386.h,v
retrieving revision 1.2
diff -u -p -r1.2 nm-i386.h
--- nm-i386.h 2001/03/23 16:17:45 1.2
+++ nm-i386.h 2002/01/11 11:34:08
@@ -115,6 +115,12 @@ extern int i386_remove_hw_breakpoint (C

#define DECR_PC_AFTER_HW_BREAK 0

+#define REMOVE_HARDWARE_WATCHPOINT_AT_EXIT 1
+
+#define REMOVE_HARDWARE_BREAKPOINT_AT_EXIT 1
+
+#define HARDWARE_REGISTERS_RESET i386_cleanup_dregs ()
+
#endif /* I386_USE_GENERIC_WATCHPOINTS */

#endif /* NM_I386_H */

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Pierre Muller
Institut Charles Sadron
6,rue Boussingault
F 67083 STRASBOURG CEDEX (France)
mailto:muller@ics.u-strasbg.fr
Phone : (33)-3-88-41-40-07 Fax : (33)-3-88-41-40-99