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Fix PR19548: Breakpoint re-set inserts breakpoints when it shouldn't

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PR19548 shows that we still have problems related to 13fd3ff343:

 [PR17431: following execs with "breakpoint always-inserted on"]
 https://sourceware.org/ml/gdb-patches/2014-09/msg00733.html

The problem this time is that we currently update the global location
list and try to insert breakpoint locations after re-setting _each_
breakpoint in turn.

Say:

 - We have _more_ than one breakpoint set.  Let's assume 2.

 - There's a breakpoint with a pre-exec address that ends up being an
   unmapped address after the exec.

 - That breakpoint is NOT the first in the breakpoint list.

Then when handling an exec, and we re-set the first breakpoint in the
breakpoint list, we mistakently try to install the old pre-exec /
un-re-set locations of the other breakpoint, which fails:

 (gdb) continue
 Continuing.
 process 28295 is executing new program: (...)/execl-update-breakpoints2
 Error in re-setting breakpoint 1: Warning:
 Cannot insert breakpoint 2.
 Cannot access memory at address 0x1000764

 Breakpoint 1, main (argc=1, argv=0x7fffffffd368) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/execl-update-breakpoints.c:34
 34        len = strlen (argv[0]);
 (gdb)

Fix this by deferring the global location list update till after all
breakpoints are re-set.

Tested on x86_64 Fedora 20, native and gdbserver.

gdb/ChangeLog:
2016-02-09  Pedro Alves  <palves@redhat.com>

	PR breakpoints/19548
	* breakpoint.c (create_overlay_event_breakpoint): Don't update
	global location list here.
	(create_longjmp_master_breakpoint)
	(create_std_terminate_master_breakpoint)
	(create_exception_master_breakpoint, create_jit_event_breakpoint)
	(update_breakpoint_locations):
	(breakpoint_re_set): Update global location list after all
	breakpoints are re-set.

gdb/testsuite/ChangeLog:
2016-02-09  Pedro Alves  <palves@redhat.com>

	PR breakpoints/19548
	* gdb.base/execl-update-breakpoints.c (some_function): New
	function.
	(main): Call it.
	* gdb.base/execl-update-breakpoints.exp: Add a second breakpoint.
	Tighten expected GDB output.
This commit is contained in:
Pedro Alves 2016-02-09 12:12:17 +00:00
parent 8adce0342f
commit 2a7f3dffce
5 changed files with 66 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

25
gdb/breakpoint.c
View file

@ -3488,7 +3488,6 @@ create_overlay_event_breakpoint (void)
overlay_events_enabled = 0;
}
}
update_global_location_list (UGLL_MAY_INSERT);
}
static void
@ -3602,7 +3601,6 @@ create_longjmp_master_breakpoint (void)
}
}
}
update_global_location_list (UGLL_MAY_INSERT);
do_cleanups (old_chain);
}
@ -3661,8 +3659,6 @@ create_std_terminate_master_breakpoint (void)
}
}
update_global_location_list (UGLL_MAY_INSERT);
do_cleanups (old_chain);
}
@ -3766,8 +3762,6 @@ create_exception_master_breakpoint (void)
b->location = new_explicit_location (&explicit_loc);
b->enable_state = bp_disabled;
}
update_global_location_list (UGLL_MAY_INSERT);
}
void
@ -7807,12 +7801,8 @@ struct lang_and_radix
struct breakpoint *
create_jit_event_breakpoint (struct gdbarch *gdbarch, CORE_ADDR address)
{
struct breakpoint *b;
b = create_internal_breakpoint (gdbarch, address, bp_jit_event,
&internal_breakpoint_ops);
update_global_location_list_nothrow (UGLL_MAY_INSERT);
return b;
return create_internal_breakpoint (gdbarch, address, bp_jit_event,
&internal_breakpoint_ops);
}
/* Remove JIT code registration and unregistration breakpoint(s). */
@ -14278,7 +14268,6 @@ update_breakpoint_locations (struct breakpoint *b,
/* Ranged breakpoints have only one start location and one end
location. */
b->enable_state = bp_disabled;
update_global_location_list (UGLL_MAY_INSERT);
printf_unfiltered (_("Could not reset ranged breakpoint %d: "
"multiple locations found\n"),
b->number);
@ -14376,8 +14365,6 @@ update_breakpoint_locations (struct breakpoint *b,
if (!locations_are_equal (existing_locations, b->loc))
observer_notify_breakpoint_modified (b);
update_global_location_list (UGLL_MAY_INSERT);
}
/* Find the SaL locations corresponding to the given LOCATION.
@ -14617,6 +14604,11 @@ breakpoint_re_set (void)
save_input_radix = input_radix;
old_chain = save_current_space_and_thread ();
/* Note: we must not try to insert locations until after all
breakpoints have been re-set. Otherwise, e.g., when re-setting
breakpoint 1, we'd insert the locations of breakpoint 2, which
hadn't been re-set yet, and thus may have stale locations. */
ALL_BREAKPOINTS_SAFE (b, b_tmp)
{
/* Format possible error msg. */
@ -14637,6 +14629,9 @@ breakpoint_re_set (void)
create_longjmp_master_breakpoint ();
create_std_terminate_master_breakpoint ();
create_exception_master_breakpoint ();
/* Now we can insert. */
update_global_location_list (UGLL_MAY_INSERT);
}
/* Reset the thread number of this breakpoint: