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[patch] step over permanent breakpoint
- From: Aleksandar Ristovski <aristovski at qnx dot com>
- To: gdb-patches at sources dot redhat dot com
- Date: Wed, 06 Aug 2008 10:11:12 -0400
- Subject: [patch] step over permanent breakpoint
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
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.
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);
+}
+
+
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;
}
2008-08-05 Aleksandar Ristovski <aristovski@qnx.com>
* i386-bp_permanent.exp: New test.
# 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."