Conditional Z1 breakpoint hangs GDBserver.

While trying to fix hbreak2.exp against GDBserver I noticed this...

 (gdb) hbreak main if 1
 Sending packet: $m400580,40#2e...Packet received: e8d2ffffff5dc3554889e54883ec10c745fc00000000eb0eb800000000e8c1ffffff8345fc01817dfce70300007ee9b800000000c9c3662e0f1f840000000000
 Sending packet: $m40058f,1#31...Packet received: c7
 Hardware assisted breakpoint 1 at 0x40058f: file ../../../src/gdb/testsuite/gdb.base/break-idempotent.c, line 46.
 Sending packet: $Z1,40058f,1;X3,220127#9b...
 *hangs forever*

The issue is that nothing advances the packet pointer if
add_breakpoint_condition either fails to parse the agent expression,
or fails to find the breakpoint, resulting in an infinite loop in
process_point_options.  The latter case should really be fixed by
GDBserver tracking GDB Z1 breakpoints in its breakpoint structures
like Z0 breakpoints are, but the latter case still needs handling.
add_breakpoint_commands has the same issue, though at present I don't
know any way to trigger it other than sending a manually cooked
packet.

Unbelievably, it doesn't look like we have any test that tries setting
a conditional hardware breakpoint.  Looking at cond-eval-mode.exp, it
looks like the file was meant to actually test something, but it's
mostly empty today.  This patch adds tests that tries all sorts of
conditional breakpoints and watchpoints.  The test hangs/fails without
the GDBserver fix.

Tested on x86_64 Fedora 17.

gdb/gdbserver/
2014-04-10  Pedro Alves  <palves@redhat.com>

	* mem-break.c (add_breakpoint_condition, add_breakpoint_commands):
	Check if the condition or command is NULL before checking if the
	breakpoint is known.  On success, return true.
	* mem-break.h (add_breakpoint_condition): Document return.
	(add_breakpoint_commands): Add describing comment.
	* server.c (skip_to_semicolon): New function.
	(process_point_options): Use it.

gdb/testsuite/
2014-04-10  Pedro Alves  <palves@redhat.com>

	* gdb.base/cond-eval-mode.c: New file.
	* gdb.base/cond-eval-mode.exp: Use standard_testfile.  Adjust
	prepare_for_testing to build the new file.  Check result of
	runto_main.
	(test_break, test_watch): New procedures.
	(top level): Use them.
This commit is contained in:
Pedro Alves 2014-04-10 19:22:23 +01:00
parent e4ef1b6c3f
commit d708bcd102
7 changed files with 212 additions and 15 deletions

View File

@ -1,3 +1,13 @@
2014-04-10 Pedro Alves <palves@redhat.com>
* mem-break.c (add_breakpoint_condition, add_breakpoint_commands):
Check if the condition or command is NULL before checking if the
breakpoint is known. On success, return true.
* mem-break.h (add_breakpoint_condition): Document return.
(add_breakpoint_commands): Add describing comment.
* server.c (skip_to_semicolon): New function.
(process_point_options): Use it.
2014-04-09 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_read_loadmap): Pass current_inferior directly

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@ -799,12 +799,12 @@ add_breakpoint_condition (CORE_ADDR addr, char **condition)
char *actparm = *condition;
struct agent_expr *cond;
if (bp == NULL)
return 1;
if (condition == NULL)
return 1;
if (bp == NULL)
return 0;
cond = gdb_parse_agent_expr (&actparm);
if (cond == NULL)
@ -818,7 +818,7 @@ add_breakpoint_condition (CORE_ADDR addr, char **condition)
*condition = actparm;
return 0;
return 1;
}
/* Evaluate condition (if any) at breakpoint BP. Return 1 if
@ -891,12 +891,12 @@ add_breakpoint_commands (CORE_ADDR addr, char **command, int persist)
char *actparm = *command;
struct agent_expr *cmd;
if (bp == NULL)
return 1;
if (command == NULL)
return 1;
if (bp == NULL)
return 0;
cmd = gdb_parse_agent_expr (&actparm);
if (cmd == NULL)
@ -910,7 +910,7 @@ add_breakpoint_commands (CORE_ADDR addr, char **command, int persist)
*command = actparm;
return 0;
return 1;
}
/* Return true if there are no commands to run at this location,

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@ -48,10 +48,17 @@ int breakpoint_inserted_here (CORE_ADDR addr);
void clear_gdb_breakpoint_conditions (CORE_ADDR addr);
/* Set target-side condition CONDITION to the breakpoint at ADDR. */
/* Set target-side condition CONDITION to the breakpoint at ADDR.
Returns false on failure. On success, advances CONDITION pointer
past the condition and returns true. */
int add_breakpoint_condition (CORE_ADDR addr, char **condition);
/* Set target-side commands COMMANDS to the breakpoint at ADDR.
Returns false on failure. On success, advances COMMANDS past the
commands and returns true. If PERSIST, the commands should run
even while GDB is disconnected. */
int add_breakpoint_commands (CORE_ADDR addr, char **commands, int persist);
int any_persistent_commands (void);

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@ -3350,6 +3350,15 @@ main (int argc, char *argv[])
}
}
/* Skip PACKET until the next semi-colon (or end of string). */
static void
skip_to_semicolon (char **packet)
{
while (**packet != '\0' && **packet != ';')
(*packet)++;
}
/* Process options coming from Z packets for *point at address
POINT_ADDR. PACKET is the packet buffer. *PACKET is updated
to point to the first char after the last processed option. */
@ -3376,7 +3385,8 @@ process_point_options (CORE_ADDR point_addr, char **packet)
/* Conditional expression. */
if (debug_threads)
debug_printf ("Found breakpoint condition.\n");
add_breakpoint_condition (point_addr, &dataptr);
if (!add_breakpoint_condition (point_addr, &dataptr))
skip_to_semicolon (&dataptr);
}
else if (strncmp (dataptr, "cmds:", strlen ("cmds:")) == 0)
{
@ -3385,15 +3395,15 @@ process_point_options (CORE_ADDR point_addr, char **packet)
debug_printf ("Found breakpoint commands %s.\n", dataptr);
persist = (*dataptr == '1');
dataptr += 2;
add_breakpoint_commands (point_addr, &dataptr, persist);
if (add_breakpoint_commands (point_addr, &dataptr, persist))
skip_to_semicolon (&dataptr);
}
else
{
fprintf (stderr, "Unknown token %c, ignoring.\n",
*dataptr);
/* Skip tokens until we find one that we recognize. */
while (*dataptr && *dataptr != ';')
dataptr++;
skip_to_semicolon (&dataptr);
}
}
*packet = dataptr;

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@ -1,3 +1,12 @@
2014-04-10 Pedro Alves <palves@redhat.com>
* gdb.base/cond-eval-mode.c: New file.
* gdb.base/cond-eval-mode.exp: Use standard_testfile. Adjust
prepare_for_testing to build the new file. Check result of
runto_main.
(test_break, test_watch): New procedures.
(top level): Use them.
2014-04-08 Pierre Muller <muller@sourceware.org>
* gdb.base/printcmds.exp (test_artificial_arrays): Disable

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@ -0,0 +1,53 @@
/* This testcase is part of GDB, the GNU debugger.
Copyright 2014 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/>. */
int global;
int cond_global;
int
foo (int i)
{
global++;
return i;
}
int
bar (int i)
{
return i;
}
void
test ()
{
foo (1);
foo (2);
bar (3);
}
int
main ()
{
int i;
for (i = 0; i < 1000; i++)
test ();
return 0;
}

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@ -15,11 +15,16 @@
# Test 'set breakpoint condition-evaluation' settings
if { [prepare_for_testing break.exp "break" {break.c break1.c}] } {
standard_testfile
if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
return -1
}
runto main
if ![runto_main] then {
fail "Can't run to main"
return 0
}
set test_host "set breakpoint condition-evaluation host"
set test_auto "set breakpoint condition-evaluation auto"
@ -42,3 +47,106 @@ gdb_test_multiple $test_target $test_target {
pass $test_target
}
}
# Test setting a condition in a breakpoint. BREAK_COMMAND is the
# break/hwatch command to test.
#
proc test_break { break_command } {
global gdb_prompt
with_test_prefix "$break_command" {
delete_breakpoints
gdb_test "$break_command foo" "reakpoint.* at .*"
# A condition that evals true.
gdb_test "condition \$bpnum cond_global==0" ".*"
set can_do_cmd 0
set test "continue"
gdb_test_multiple $test $test {
-re "You may have requested too many.*$gdb_prompt $" {
pass $test
}
-re "Breakpoint .*, foo .*$gdb_prompt $" {
pass $test
set can_do_cmd 1
}
}
if { !$can_do_cmd } {
unsupported "no target support"
return
}
delete_breakpoints
gdb_test "$break_command foo" ".*reakpoint .* at .*"
# A condition that evals false.
gdb_test "condition \$bpnum cond_global==1" ".*"
gdb_test "b bar" "Breakpoint .* at .*"
gdb_test "continue" "Breakpoint .*, bar .*"
}
}
# Test setting conditions in watchpoints. WATCH_COMMAND is the watch
# command to test.
#
proc test_watch { watch_command } {
global gdb_prompt
with_test_prefix "$watch_command" {
if [target_info exists gdb,no_hardware_watchpoints] {
unsupported "no target support"
return
}
delete_breakpoints
gdb_test "$watch_command global" ".*atchpoint .*: global.*"
# A condition that evals true.
gdb_test "condition \$bpnum cond_global==0" ".*"
set can_do_cmd 0
set test "continue"
gdb_test_multiple $test $test {
-re "You may have requested too many.*$gdb_prompt $" {
pass $test
}
-re "atchpoint .*: global.*$gdb_prompt $" {
pass $test
set can_do_cmd 1
}
}
if { !$can_do_cmd } {
unsupported "no target support"
return
}
delete_breakpoints
gdb_test "$watch_command global" ".*atchpoint .*: global.*"
# A condition that evals false.
gdb_test "condition \$bpnum cond_global==1" ".*"
gdb_test "b bar" "Breakpoint .* at .*"
gdb_test "continue" "Breakpoint .*, bar .*"
}
}
foreach break_command { "break" "hbreak" } {
test_break $break_command
}
foreach watch_command { "watch" "rwatch" "awatch" } {
test_watch $watch_command
}