Disable displaced stepping if trying it fails
Running the testsuite with "maint set target-non-stop on" shows:
(gdb) PASS: gdb.base/valgrind-infcall.exp: continue #98 (false warning)
continue
Continuing.
dl_main (phdr=<optimized out>..., auxv=<optimized out>) at rtld.c:2302
2302 LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);
Cannot access memory at address 0x400532
(gdb) PASS: gdb.base/valgrind-infcall.exp: continue #99 (false warning)
p gdb_test_infcall ()
$1 = 1
(gdb) FAIL: gdb.base/valgrind-infcall.exp: p gdb_test_infcall ()
Even though that was a native GNU/Linux test run, this test spawns
Valgrind and connects to it with "target remote". The error above is
actually orthogonal to target-non-stop. The real issue is that that
enables displaced stepping, and displaced stepping doesn't work with
Valgrind, because we can't write to the inferior memory (thus can't
copy the instruction to the scratch pad area).
I'm sure there will be other targets with the same issue, so trying to
identify Valgrind wouldn't be sufficient. The fix is to try setting
up the displaced step anyway. If we get a MEMORY_ERROR, we disable
displaced stepping for that inferior, and fall back to doing an
in-line step-over. If "set displaced-stepping" is "on" (as opposed to
"auto), GDB warns displaced stepping failed ("on" is mainly useful for
the testsuite, not for users).
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* inferior.h (struct inferior) <displaced_stepping_failed>: New
field.
* infrun.c (use_displaced_stepping_now_p): New parameter 'inf'.
Return false if dispaced stepping failed before.
(resume): Pass the current inferior to
use_displaced_stepping_now_p. Wrap displaced_step_prepare in
TRY/CATCH. If we get a MEMORY_ERROR, set the inferior's
displaced_stepping_failed flag, and fall back to an in-line
step-over.
gdb/testsuite/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* gdb.base/valgrind-disp-step.c: New file.
* gdb.base/valgrind-disp-step.exp: New file.
2015-08-06 19:22:59 +02:00
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/* This testcase is part of GDB, the GNU debugger.
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2017-01-01 07:50:51 +01:00
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Copyright 2015-2017 Free Software Foundation, Inc.
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Disable displaced stepping if trying it fails
Running the testsuite with "maint set target-non-stop on" shows:
(gdb) PASS: gdb.base/valgrind-infcall.exp: continue #98 (false warning)
continue
Continuing.
dl_main (phdr=<optimized out>..., auxv=<optimized out>) at rtld.c:2302
2302 LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);
Cannot access memory at address 0x400532
(gdb) PASS: gdb.base/valgrind-infcall.exp: continue #99 (false warning)
p gdb_test_infcall ()
$1 = 1
(gdb) FAIL: gdb.base/valgrind-infcall.exp: p gdb_test_infcall ()
Even though that was a native GNU/Linux test run, this test spawns
Valgrind and connects to it with "target remote". The error above is
actually orthogonal to target-non-stop. The real issue is that that
enables displaced stepping, and displaced stepping doesn't work with
Valgrind, because we can't write to the inferior memory (thus can't
copy the instruction to the scratch pad area).
I'm sure there will be other targets with the same issue, so trying to
identify Valgrind wouldn't be sufficient. The fix is to try setting
up the displaced step anyway. If we get a MEMORY_ERROR, we disable
displaced stepping for that inferior, and fall back to doing an
in-line step-over. If "set displaced-stepping" is "on" (as opposed to
"auto), GDB warns displaced stepping failed ("on" is mainly useful for
the testsuite, not for users).
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* inferior.h (struct inferior) <displaced_stepping_failed>: New
field.
* infrun.c (use_displaced_stepping_now_p): New parameter 'inf'.
Return false if dispaced stepping failed before.
(resume): Pass the current inferior to
use_displaced_stepping_now_p. Wrap displaced_step_prepare in
TRY/CATCH. If we get a MEMORY_ERROR, set the inferior's
displaced_stepping_failed flag, and fall back to an in-line
step-over.
gdb/testsuite/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* gdb.base/valgrind-disp-step.c: New file.
* gdb.base/valgrind-disp-step.exp: New file.
2015-08-06 19:22:59 +02:00
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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static int
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foo (void)
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{
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}
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int
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main (void)
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{
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foo (); /* stop 0 */
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foo (); /* stop 1 */
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foo (); /* stop 2 */
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foo (); /* stop 3 */
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foo (); /* stop 4 */
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return 0;
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}
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