binutils-gdb/gdb/testsuite/gdb.base/hbreak-unmapped.c

/* 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
main (void)
{
  return 0;
}
Don't suppress errors inserting/removing hardware breakpoints in shared libraries. As explained in https://sourceware.org/ml/gdb-patches/2008-08/msg00361.html, after a shared library was unloaded, we can no longer insert or remove breakpoints into/from its (no longer present) code segment. That'll fail with memory errors. However, that concern does not apply to hardware breakpoints. By definition, hardware breakpoints are implemented using a mechanism that is not dependent on being able to modify the target's memory. Usually, by setting up CPU debug registers. IOW, we should be able to set hw breakpoints in an unmapped address. We don't seem to have a test that exercises that, so this patch adds one. I noticed the error supression because of a related issue -- the target_insert_hw_breakpoint/target_remove_hw_breakpoint interfaces don't really distinguish "not supported" from "error" return, and so remote.c returns -1 in both cases. This results in hardware breakpoints set in shared libraries silently ending up pending forever even though the target doesn't actually support hw breakpoints. (gdb) set breakpoint always-inserted on (gdb) set remote Z-packet off (gdb) info breakpoints No breakpoints or watchpoints. (gdb) hbreak shrfunc Hardware assisted breakpoint 3 at 0x7ffff7dfb657: file ../../../src/gdb/testsuite/gdb.base/hbreak-in-shr-unsupported-shr.c, line 21. (gdb) info break Num Type Disp Enb Address What 3 hw breakpoint keep y <PENDING> shrfunc After the patch we get the expected: (gdb) hbreak shrfunc Hardware assisted breakpoint 3 at 0x7ffff7dfb657: file ../../../src/gdb/testsuite/gdb.base/hbreak-in-shr-unsupported-shr.c, line 21. Warning: Cannot insert hardware breakpoint 3. Could not insert hardware breakpoints: You may have requested too many hardware breakpoints/watchpoints. (gdb) info break Num Type Disp Enb Address What 3 hw breakpoint keep y 0x00007ffff7dfb657 in shrfunc at ../../../src/gdb/testsuite/gdb.base/hbreak-in-shr-unsupported-shr.c:21 (HW breakpoints set in the main executable, when the target doesn't support HW breakpoints always resulted in the latter output.) We probably should improve the insert/remove interface to return a different error code for unsupported. But I chose to fix the error supression first, as it's a deeper and wider issue. Tested on x86_64 Fedora 17, native and gdbserver. gdb/ 2014-04-23 Pedro Alves <palves@redhat.com> * breakpoint.c (insert_bp_location, remove_breakpoint_1): If the breakpoint is set in a shared library, only suppress errors for software breakpoints, not hardware breakpoints. gdb/testsuite/ 2014-04-23 Pedro Alves <palves@redhat.com> * gdb.base/hbreak-in-shr-unsupported-shr.c: New file. * gdb.base/hbreak-in-shr-unsupported.c: New file. * gdb.base/hbreak-in-shr-unsupported.exp: New file. * gdb.base/hbreak-unmapped.c: New file. * gdb.base/hbreak-unmapped.exp: New file. * gdb.trace/qtro.exp (gdb_is_target_remote): Move ... * lib/gdb.exp (gdb_is_target_remote): ... here. 2014-04-23 22:06:47 +08:00			`/* 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`
			`main (void)`
			`{`
			`return 0;`
			`}`