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* [patch] step over permanent breakpoint
@ 2008-08-06 14:12 Aleksandar Ristovski
  2008-08-18 11:08 ` Joel Brobecker
  0 siblings, 1 reply; 7+ messages in thread
From: Aleksandar Ristovski @ 2008-08-06 14:12 UTC (permalink / raw)
  To: gdb-patches

[-- Attachment #1: Type: text/plain, Size: 355 bytes --]

Hello,

I encountered a problem when setting a breakpoint over a permanent breakpoint. GDB did not handle this situation correctly.

The attached test demonstrates the problem, and the patch fixes it for i386 architecture.

For other architectures, skip_permanent_breakpoint needs to be implemented. 


Thanks,

Aleksandar Ristovski
QNX Software Systems


[-- Attachment #2: i386_permanent_breakpoints-20080805.diff.ChangeLog --]
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2008-08-05  Aleksandar Ristovski  <aristovski@qnx.com>

	* breakpoint.c (breakpoint_init_inferior): Mark as not inserted only
	non-permanent breakpoints.
	(create_breakpoint): Check if the location points to a permanent
	breakpoint.
	(update_breakpoint_locations): Make sure new locations of permanent
	breakpoints are properly initialized.
	* i386-tdep.c (i386_skip_permanent_breakpoint): New function.
	(i386_gdbarch_init): Set gdbarch_skip_permanent_breakpoint.


[-- Attachment #3: i386_permanent_breakpoints-20080805.diff --]
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Index: gdb/breakpoint.c
===================================================================
RCS file: /cvs/src/src/gdb/breakpoint.c,v
retrieving revision 1.338
diff -u -p -r1.338 breakpoint.c
--- gdb/breakpoint.c	28 Jul 2008 17:53:52 -0000	1.338
+++ gdb/breakpoint.c	5 Aug 2008 20:32:55 -0000
@@ -1720,7 +1720,10 @@ breakpoint_init_inferior (enum inf_conte
   struct bp_location *bpt;
 
   ALL_BP_LOCATIONS (bpt)
-    bpt->inserted = 0;
+    {
+      if (bpt->owner->enable_state != bp_permanent)
+	bpt->inserted = 0;
+    }
 
   ALL_BREAKPOINTS_SAFE (b, temp)
   {
@@ -3058,7 +3061,8 @@ bpstat_stop_status (CORE_ADDR bp_addr, p
 	/* We will stop here */
 	if (b->disposition == disp_disable)
 	  {
-	    b->enable_state = bp_disabled;
+	    if (b->enable_state != bp_permanent)
+	      b->enable_state = bp_disabled;
 	    update_global_location_list (0);
 	  }
 	if (b->silent)
@@ -5100,6 +5104,22 @@ create_breakpoint (struct symtabs_and_li
 	  loc = add_location_to_breakpoint (b, type, &sal);
 	}
 
+      /* Check if the location points to permanent breakpoint.  */
+      if (loc != NULL)
+	{
+	  int len;
+	  CORE_ADDR addr = loc->address;
+	  const gdb_byte *brk = gdbarch_breakpoint_from_pc (current_gdbarch,
+							    &addr, &len);
+	  gdb_byte target_mem[32];
+	  if (!target_read_memory (loc->address, target_mem, len))
+	    {
+	      /* We have the target memory here.  */
+	      if (memcmp (target_mem, brk, len) == 0)
+		make_breakpoint_permanent (b);
+	    }
+	}
+
       if (b->cond_string)
 	{
 	  char *arg = b->cond_string;
@@ -7437,6 +7457,10 @@ update_breakpoint_locations (struct brea
 	b->line_number = sals.sals[i].line;
     }
 
+  /* Update locationos of permanent breakpoints.  */
+  if (b->enable_state == bp_permanent)
+    make_breakpoint_permanent (b);
+
   /* If possible, carry over 'disable' status from existing breakpoints.  */
   {
     struct bp_location *e = existing_locations;
Index: gdb/i386-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/i386-tdep.c,v
retrieving revision 1.261
diff -u -p -r1.261 i386-tdep.c
--- gdb/i386-tdep.c	3 Jul 2008 00:19:58 -0000	1.261
+++ gdb/i386-tdep.c	5 Aug 2008 20:32:55 -0000
@@ -2550,6 +2550,17 @@ i386_fetch_pointer_argument (struct fram
   return read_memory_unsigned_integer (sp + (4 * (argi + 1)), 4);
 }
 
+/* On i386, breakpoint is exactly 1 byte long, so we just
+   adjust the PC in the regcache.  */
+static void
+i386_skip_permanent_breakpoint (struct regcache *regcache)
+{
+  CORE_ADDR current_pc = regcache_read_pc (regcache);
+  current_pc += 1;
+  regcache_write_pc (regcache, current_pc);
+}
+
+
 \f
 static struct gdbarch *
 i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
@@ -2738,6 +2749,9 @@ i386_gdbarch_init (struct gdbarch_info i
   if (tdep->mm0_regnum == 0)
     tdep->mm0_regnum = gdbarch_num_regs (gdbarch);
 
+  set_gdbarch_skip_permanent_breakpoint (gdbarch,
+					 i386_skip_permanent_breakpoint);
+
   return gdbarch;
 }
 


[-- Attachment #4: i386-bp_permanent.exp.ChangeLog --]
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2008-08-05  Aleksandar Ristovski  <aristovski@qnx.com>

	* i386-bp_permanent.exp: New test.


[-- Attachment #5: i386-bp_permanent.exp --]
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# Copyright (C) 2003, 2004, 2006, 2007, 2008 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Please email any bugs, comments, and/or additions to this file to:
# bug-gdb@gnu.org

# This file is part of the gdb testsuite.

if $tracelevel {
    strace $tracelevel
}

# Test i386 prologue analyzer.

set prms_id 0
set bug_id 0

if ![istarget "i?86-*-*"] then {
    verbose "Skipping i386 prologue tests."
    return
}

set testfile "i386-prologue"
set srcfile ${testfile}.c
set binfile ${objdir}/${subdir}/${testfile}

# some targets have leading underscores on assembly symbols.
# TODO: detect this automatically
set additional_flags ""
if [istarget "i?86-*-cygwin*"] then {
  set additional_flags "additional_flags=-DSYMBOL_PREFIX=\"_\""
}   

# Don't use "debug", so that we don't have line information for the assembly
# fragments.
if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable [list $additional_flags]] != "" } {
    untested i386-prologue.exp
    return -1
}


gdb_exit
gdb_start
gdb_reinitialize_dir $srcdir/$subdir
gdb_load ${binfile}

#
# Run to `main' where we begin our tests.
#

if ![runto_main] then {
    gdb_suppress_tests
}

# Testcase for standard prologue.

send_gdb "disassemble standard\n";
gdb_expect 60 {
    -re ".*($hex) <standard\\+0>.*($hex) <standard\\+4>.*($hex) <standard\\+5>.*($hex) <standard\\+6>.*" {
      set standard_start $expect_out(1,string);
      set address $expect_out(2,string);
      set address1 $expect_out(3,string);
      set address2 $expect_out(4,string);
    }
    default {
      send_user "Oops, can't find address\n"
      gdb_supress_tests
    }
}

gdb_breakpoint "*$standard_start"

gdb_breakpoint "*$address"

gdb_test "continue" "Breakpoint .*, $standard_start in standard.*" \
	 "Stop at the standard start breakpoint (fetching esp)."

# We want to fetch esp at the start of 'standard' function to make sure
# skip_permanent_breakpoint implementation really skips only the perm. 
# breakpoint. If, for whatever reason, 'leave' instruction doesn't get
# executed, esp will not have this value.
send_gdb "print \$esp\n"
gdb_expect 60 {
    -re ".1.*($hex).*" {
      set start_esp $expect_out(1,string);
    }
    default {
      gdb_fail "Fetching esp failed."
    }
}

gdb_test "continue" "Breakpoint .*, $address in standard.*" \
	 "Stop at permanent breakpoint."

gdb_test "stepi" "$address1|$address2 in standard.*" \
	 "Single stepping past permanent breakpoint."

gdb_test "print \$esp" ".*$start_esp.*" \
	 "ESP value does not match - step_permanent_breakpoint wrong."


^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2008-09-03 13:46 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2008-08-06 14:12 [patch] step over permanent breakpoint Aleksandar Ristovski
2008-08-18 11:08 ` Joel Brobecker
2008-08-19 15:39   ` Aleksandar Ristovski
2008-08-25 16:36     ` Joel Brobecker
2008-09-02 15:37       ` Aleksandar Ristovski
2008-09-02 20:54         ` Joel Brobecker
2008-09-03 13:46           ` Aleksandar Ristovski

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