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Fix regression introduced in "break *<EXPR>" by explicit location patches.

Browse source 
A relatively recent patch support for explicit locations, and part
of that patch cleaned up the way we parse breakpoint locations.
Unfortunatly, a small regression crept in for "*<EXPR>" breakpoint
locations. In particular, on PIE programs, one can see the issue by
doing the following, with any program:

    (gdb) b *main
    Breakpoint 1 at 0x51a: file hello.c, line 3.
    (gdb) run
    Starting program: /[...]/hello
    Error in re-setting breakpoint 1: Warning:
    Cannot insert breakpoint 1.
    Cannot access memory at address 0x51a

    Warning:
    Cannot insert breakpoint 1.
    Cannot access memory at address 0x51a

Just for the record, this regression was introduced by:

    commit a06efdd6ef
    Date:   Tue Aug 11 17:09:35 2015 -0700
    Subject: Explicit locations: introduce address locations

What happens is that the patch makes the implicit assumption that
the address computed the first time is static, as if it was designed
to only support litteral expressions (Eg. "*0x1234"). This allows
the shortcut of not re-computing the breakpoint location's address
when re-setting breakpoints.

However, this does not work in general, as demonstrated in the example
above.

This patch plugs that hole simply by saving the original expression
used to compute the address as part of the address location, so as
to then re-evaluate that expression during breakpoint re-set.

gdb/ChangeLog:

        * location.h (new_address_location): Add new parameters
        "addr_string" and "addr_string_len".
        (get_address_string_location): Add declaration.
        * location.c (new_address_location): Add new parameters
        "addr_string" and "addr_string_len".  If not NULL, store
        a copy of the addr_string in the new location as well.
        (get_address_string_location): New function.
        (string_to_event_location): Update call to new_address_location.
        * linespec.c (event_location_to_sals) <ADDRESS_LOCATION>:
        Save the event location in the parser's state before
        passing it to convert_address_location_to_sals.
        * breakpoint.c (create_thread_event_breakpoint): Update call
        to new_address_location.
        (init_breakpoint_sal): Get the event location's string, if any,
        and use it to update call to new_address_location.
        * python/py-finishbreakpoint.c (bpfinishpy_init):
        Update call to new_address_location.
        * spu-tdep.c (spu_catch_start): Likewise.

        * config/djgpp/fnchange.lst: Add entries for
        gdb/testsuite/gdb.base/break-fun-addr1.c and
        gdb/testsuite/gdb.base/break-fun-addr2.c.

gdb/testsuite/ChangeLog:

        * gdb.base/break-fun-addr.exp: New file.
        * gdb.base/break-fun-addr1.c: New file.
        * gdb.base/break-fun-addr2.c: New file.
This commit is contained in:
Joel Brobecker 2015-12-08 19:04:56 +01:00
parent 2f340668a9
commit 305e13e67f
12 changed files with 229 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

25
gdb/ChangeLog
View file

@ -1,3 +1,28 @@
2016-01-21 Joel Brobecker <brobecker@adacore.com>
* location.h (new_address_location): Add new parameters
"addr_string" and "addr_string_len".
(get_address_string_location): Add declaration.
* location.c (new_address_location): Add new parameters
"addr_string" and "addr_string_len". If not NULL, store
a copy of the addr_string in the new location as well.
(get_address_string_location): New function.
(string_to_event_location): Update call to new_address_location.
* linespec.c (event_location_to_sals) <ADDRESS_LOCATION>:
Save the event location in the parser's state before
passing it to convert_address_location_to_sals.
* breakpoint.c (create_thread_event_breakpoint): Update call
to new_address_location.
(init_breakpoint_sal): Get the event location's string, if any,
and use it to update call to new_address_location.
* python/py-finishbreakpoint.c (bpfinishpy_init):
Update call to new_address_location.
* spu-tdep.c (spu_catch_start): Likewise.
* config/djgpp/fnchange.lst: Add entries for
gdb/testsuite/gdb.base/break-fun-addr1.c and
gdb/testsuite/gdb.base/break-fun-addr2.c.
2016-01-21 Yao Qi <yao.qi@linaro.org>
* arm-linux-tdep.c (arm_linux_sigreturn_next_pc): Add parameter

15
gdb/breakpoint.c
View file

@ -7798,7 +7798,7 @@ create_thread_event_breakpoint (struct gdbarch *gdbarch, CORE_ADDR address)
b->enable_state = bp_enabled;
/* location has to be used or breakpoint_re_set will delete me. */
b->location = new_address_location (b->loc->address);
b->location = new_address_location (b->loc->address, NULL, 0);
update_global_location_list_nothrow (UGLL_MAY_INSERT);
@ -9369,7 +9369,18 @@ init_breakpoint_sal (struct breakpoint *b, struct gdbarch *gdbarch,
if (location != NULL)
b->location = location;
else
b->location = new_address_location (b->loc->address);
{
const char *addr_string = NULL;
int addr_string_len = 0;
if (location != NULL)
addr_string = event_location_to_string (location);
if (addr_string != NULL)
addr_string_len = strlen (addr_string);
b->location = new_address_location (b->loc->address,
addr_string, addr_string_len);
}
b->filter = filter;
}

2
gdb/config/djgpp/fnchange.lst
View file

@ -407,6 +407,8 @@
@V@/gdb/testsuite/gdb.base/bitfields2.c @V@/gdb/testsuite/gdb.base/bitfiel2.c
@V@/gdb/testsuite/gdb.base/bitfields2.exp @V@/gdb/testsuite/gdb.base/bitfiel2.exp
@V@/gdb/testsuite/gdb.base/break-entry.exp @V@/gdb/testsuite/gdb.base/brkentry.exp
@V@/gdb/testsuite/gdb.base/break-fun-addr1.c @V@/gdb/testsuite/gdb.base/b-f-a1.c
@V@/gdb/testsuite/gdb.base/break-fun-addr2.c @V@/gdb/testsuite/gdb.base/b-f-a2.c
@V@/gdb/testsuite/gdb.base/coremaker2.c @V@/gdb/testsuite/gdb.base/core2maker.c
@V@/gdb/testsuite/gdb.base/hashline1.exp @V@/gdb/testsuite/gdb.base/hash1line.exp
@V@/gdb/testsuite/gdb.base/hashline2.exp @V@/gdb/testsuite/gdb.base/hash2line.exp

24
gdb/linespec.c
View file

@ -2512,9 +2512,27 @@ event_location_to_sals (linespec_parser *parser,
break;
case ADDRESS_LOCATION:
result
= convert_address_location_to_sals (PARSER_STATE (parser),
get_address_location (location));
{
const char *addr_string = get_address_string_location (location);
CORE_ADDR addr = get_address_location (location);
if (addr_string != NULL)
{
char *expr = xstrdup (addr_string);
const char *const_expr = expr;
struct cleanup *cleanup = make_cleanup (xfree, expr);
addr = linespec_expression_to_pc (&const_expr);
if (PARSER_STATE (parser)->canonical != NULL)
PARSER_STATE (parser)->canonical->location
= copy_event_location (location);
do_cleanups (cleanup);
}
result = convert_address_location_to_sals (PARSER_STATE (parser),
addr);
}
break;
case EXPLICIT_LOCATION:

16
gdb/location.c
View file

@ -113,13 +113,16 @@ get_linespec_location (const struct event_location *location)
/* See description in location.h. */
struct event_location *
new_address_location (CORE_ADDR addr)
new_address_location (CORE_ADDR addr, const char *addr_string,
int addr_string_len)
{
struct event_location *location;
location = XCNEW (struct event_location);
EL_TYPE (location) = ADDRESS_LOCATION;
EL_ADDRESS (location) = addr;
if (addr_string != NULL)
EL_STRING (location) = xstrndup (addr_string, addr_string_len);
return location;
}
@ -134,6 +137,15 @@ get_address_location (const struct event_location *location)
/* See description in location.h. */
const char *
get_address_string_location (const struct event_location *location)
{
gdb_assert (EL_TYPE (location) == ADDRESS_LOCATION);
return EL_STRING (location);
}
/* See description in location.h. */
struct event_location *
new_probe_location (const char *probe)
{
@ -635,7 +647,7 @@ string_to_event_location (char **stringp,
orig = arg = *stringp;
addr = linespec_expression_to_pc (&arg);
location = new_address_location (addr);
location = new_address_location (addr, orig, arg - orig);
*stringp += arg - orig;
}
else

15
gdb/location.h
View file

@ -126,11 +126,14 @@ extern struct event_location *
extern const char *
get_linespec_location (const struct event_location *location);
/* Create a new address location. The return result is malloc'd
and should be freed with delete_event_location. */
/* Create a new address location.
ADDR is the address corresponding to this event_location.
ADDR_STRING, a string of ADDR_STRING_LEN characters, is
the expression that was parsed to determine the address ADDR. */
extern struct event_location *
new_address_location (CORE_ADDR addr);
new_address_location (CORE_ADDR addr, const char *addr_string,
int addr_string_len);
/* Return the address location (a CORE_ADDR) of the given event_location
(which must be of type ADDRESS_LOCATION). */
@ -138,6 +141,12 @@ extern struct event_location *
extern CORE_ADDR
get_address_location (const struct event_location *location);
/* Return the expression (a string) that was used to compute the address
of the given event_location (which must be of type ADDRESS_LOCATION). */
extern const char *
get_address_string_location (const struct event_location *location);
/* Create a new probe location. The return result is malloc'd
and should be freed with delete_event_location. */

2
gdb/python/py-finishbreakpoint.c
View file

@ -297,7 +297,7 @@ bpfinishpy_init (PyObject *self, PyObject *args, PyObject *kwargs)
struct cleanup *back_to;
/* Set a breakpoint on the return address. */
location = new_address_location (get_frame_pc (prev_frame));
location = new_address_location (get_frame_pc (prev_frame), NULL, 0);
back_to = make_cleanup_delete_event_location (location);
create_breakpoint (python_gdbarch,
location, NULL, thread, NULL,

2
gdb/spu-tdep.c
View file

@ -2001,7 +2001,7 @@ spu_catch_start (struct objfile *objfile)
/* Use a numerical address for the set_breakpoint command to avoid having
the breakpoint re-set incorrectly. */
location = new_address_location (pc);
location = new_address_location (pc, NULL, 0);
back_to = make_cleanup_delete_event_location (location);
create_breakpoint (get_objfile_arch (objfile), location,
NULL /* cond_string */, -1 /* thread */,

6
gdb/testsuite/ChangeLog
View file

@ -1,3 +1,9 @@
2016-01-21 Joel Brobecker <brobecker@adacore.com>
* gdb.base/break-fun-addr.exp: New file.
* gdb.base/break-fun-addr1.c: New file.
* gdb.base/break-fun-addr2.c: New file.
2016-01-20 Simon Marchi <simon.marchi@polymtl.ca>
* gdb.python/py-pp-maint.exp: Change/add enum flag tests.

84
gdb/testsuite/gdb.base/break-fun-addr.exp Normal file
View file

@ -0,0 +1,84 @@
# Copyright 2016 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/>.
# The purpose of this testcase is to verify that, when using a breakpoint
# location of the form "*<EXPR>" (Eg: "*main"), GDB is able to start
# the program and stop at the correct location. With programs built
# as PIE, this means that GDB needs to re-evaluate the location once
# the program as started, since PIE ensures that the address of all
# symbols have changed after load.
#
# PIE is not always supported by the target system, so instead of
# creating a testcase building executables with PIE, this testcase
# takes a slightly different approach. It builds a first program,
# breaks on *main, and then runs to that breakpoint. It then builds
# a second program, different from the first one, and loads that
# executable within the same GDB session. Similarly to the PIE case,
# the address of main should be different, and therefore GDB should
# recalculate it. We verify that by checking that running to that
# breakpoint still works, and that we land at the first instruction
# of that function in both cases.
set testfile1 "break-fun-addr1"
set srcfile1 ${testfile1}.c
set binfile1 [standard_output_file ${testfile1}]
if { [gdb_compile "${srcdir}/${subdir}/${srcfile1}" "${binfile1}" executable {debug}] != "" } {
untested "Couldn't compile ${srcfile1}"
return -1
}
# Start the debugger with the first executable, put a breakpoint
# on the first instruction of function "main" ("*main"), then
# run to that breakpoint.
clean_restart ${binfile1}
with_test_prefix "${binfile1}" {
gdb_test "break *main" \
"Breakpoint.*at.* file .*$srcfile1, line .*" \
gdb_run_cmd
gdb_test "" \
"Breakpoint.* main \\(\\) at .*$srcfile1:.*" \
"run to breakpoint at *main"
# Verify also that we stopped at the start of the function...
gdb_test "p \$pc == main" " = 1"
}
set testfile2 "break-fun-addr2"
set srcfile2 ${testfile2}.c
set binfile2 [standard_output_file ${testfile2}]
if { [gdb_compile "${srcdir}/${subdir}/${srcfile2}" "${binfile2}" executable {debug}] != "" } {
untested "Couldn't compile ${srcfile2}"
return -1
}
# Now, keeping the same GDB process (so as to keep the same breakpoint),
# start a new debugging session with a different executable.
gdb_load ${binfile2}
with_test_prefix "${binfile2}" {
gdb_run_cmd
gdb_test "" \
"Breakpoint.* main \\(\\) at .*$srcfile2:.*" \
"run to breakpoint at *main"
gdb_test "p \$pc == main" " = 1"
}

22
gdb/testsuite/gdb.base/break-fun-addr1.c Normal file
View file

@ -0,0 +1,22 @@
/* This testcase is part of GDB, the GNU debugger.
Copyright 2016 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
main (void)
{
return 0;
}

28
gdb/testsuite/gdb.base/break-fun-addr2.c Normal file
View file

@ -0,0 +1,28 @@
/* This testcase is part of GDB, the GNU debugger.
Copyright 2016 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
compute_something (int i)
{
return i - 1;
}
int
main (void)
{
return compute_something (1);
}