[RFA/RFC 3] Remove hardware break and watchpoints at program exit.

[Pierre Muller <muller@cerbere.u-strasbg.fr>]

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After the  previous discussion about  the 
hardware watch and breakpoint removal 
about the debuggee exited. I slightly modifed my patch
by adding a test to avoid calling ptrace
in i386-linux-nat.c, i386bsd-nat.c and x86-64-linux-nat.c
i386_linux_dr_set, i386bsd_dr_set and x86_64_linux_dr_set functions
if taget_has_execution is 0.


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().
	* i386-linux-nat.c (i386_linux_dr_set): Don't call ptrace if target_has_execution is zero.
	* i386bsd-nat.c (i386bsd_dr_set): Likewise.
	* x86-64-linux-nat.c (x86_64_linux_dr_set): Likewise.

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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 16:19:11
@@ -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 16:19:11
@@ -663,14 +663,6 @@ go32_create_inferior (char *exec_file, c
 static void
 go32_mourn_inferior (void)
 {
-  /* We need to make sure all the breakpoint enable bits in the DR7
-     register are reset when the inferior exits.  Otherwise, if they
-     rerun the inferior, the uncleared bits may cause random SIGTRAPs,
-     failure to set more watchpoints, and other calamities.  It would
-     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 ();
   go32_kill_inferior ();
   generic_mourn_inferior ();
 }
Index: i386-linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/i386-linux-nat.c,v
retrieving revision 1.34
diff -u -p -r1.34 i386-linux-nat.c
--- i386-linux-nat.c	2002/01/09 22:32:16	1.34
+++ i386-linux-nat.c	2002/01/11 16:19:12
@@ -738,8 +738,9 @@ i386_linux_dr_set (int regnum, unsigned 
   tid = PIDGET (inferior_ptid);
 
   errno = 0;
-  ptrace (PT_WRITE_U, tid,
-	  offsetof (struct user, u_debugreg[regnum]), value);
+  if (target_has_execution)
+    ptrace (PT_WRITE_U, tid,
+	    offsetof (struct user, u_debugreg[regnum]), value);
   if (errno != 0)
     perror_with_name ("Couldn't write debug register");
 }
Index: i386bsd-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/i386bsd-nat.c,v
retrieving revision 1.11
diff -u -p -r1.11 i386bsd-nat.c
--- i386bsd-nat.c	2002/01/05 18:36:32	1.11
+++ i386bsd-nat.c	2002/01/11 16:19:12
@@ -298,8 +298,9 @@ i386bsd_dr_set (int regnum, unsigned int
 {
   struct dbreg dbregs;
 
-  if (ptrace (PT_GETDBREGS, PIDGET (inferior_ptid),
-              (PTRACE_ARG3_TYPE) &dbregs, 0) == -1)
+  if (target_has_execution
+      && ptrace (PT_GETDBREGS, PIDGET (inferior_ptid),
+                (PTRACE_ARG3_TYPE) &dbregs, 0) == -1))
     perror_with_name ("Couldn't get debug registers");
 
   /* For some mysterious reason, some of the reserved bits in the
@@ -309,8 +310,9 @@ i386bsd_dr_set (int regnum, unsigned int
 
   DBREG_DRX ((&dbregs), regnum) = value;
 
-  if (ptrace (PT_SETDBREGS, PIDGET (inferior_ptid),
-              (PTRACE_ARG3_TYPE) &dbregs, 0) == -1)
+  if (target_has_execution
+      && ptrace (PT_SETDBREGS, PIDGET (inferior_ptid),
+                (PTRACE_ARG3_TYPE) &dbregs, 0) == -1))
     perror_with_name ("Couldn't write debug registers");
 }
 
Index: x86-64-linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/x86-64-linux-nat.c,v
retrieving revision 1.2
diff -u -p -r1.2 x86-64-linux-nat.c
--- x86-64-linux-nat.c	2002/01/08 00:59:31	1.2
+++ x86-64-linux-nat.c	2002/01/11 16:19:12
@@ -73,8 +73,9 @@ x86_64_linux_dr_set (int regnum, unsigne
   tid = PIDGET (inferior_ptid);
 
   errno = 0;
-  ptrace (PT_WRITE_U, tid,
-	  offsetof (struct user, u_debugreg[regnum]), value);
+  if (target_has_execution)
+    ptrace (PT_WRITE_U, tid,
+	    offsetof (struct user, u_debugreg[regnum]), value);
   if (errno != 0)
     perror_with_name ("Couldn't write debug register");
 }
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 16:19:12
@@ -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