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Re: [rfc, rfa/doc] Multi-threaded watchpoint improvements
Andreas Schwab <schwab@suse.de> writes:
> Daniel Jacobowitz <drow@false.org> writes:
>
>> On Thu, Apr 17, 2008 at 11:52:31AM +0200, Andreas Schwab wrote:
>>> Looking closer, it is actually a kernel bug. PTRACE_GETSIGINFO is not
>>> emulated for 32-bit processes, so that si_addr is set to the upper half
>>> of the address, which is of course zero.
>>
>> Glad you could track that down. Yes, my patch made GDB less tolerant
>> of targets which claim they can report the stopped data address, but
>> actually fail. It will only report watchpoints when the target
>> doesn't know what address has changed, or report a changed address
>> that falls on a particular watchpoint. This lets us keep track of
>> which thread hit each watchpoint.
>
> There is still a problem with that: if the watchpoint granularity is
> bigger than the size of the data then gdb can still get this wrong.
Here's a patch. OK?
Andreas.
2008-04-23 Andreas Schwab <schwab@suse.de>
* target.h (struct target_ops): Add
to_watchpoint_addr_within_range.
(target_watchpoint_addr_within_range): New function.
* target.c (update_current_target): Inherit
to_watchpoint_addr_within_range, defaulting to
default_watchpoint_addr_within_range.
(default_watchpoint_addr_within_range): New function.
(debug_to_watchpoint_addr_within_range): New function.
(setup_target_debug): Set to_watchpoint_addr_within_range.
* ppc-linux-nat.c (ppc_linux_watchpoint_addr_within_range):
New function.
(_initialize_ppc_linux_nat): Set to_watchpoint_addr_within_range.
* breakpoint.c (watchpoints_triggered): Use
target_watchpoint_addr_within_range.
doc/:
* gdbint.texinfo (Algorithms): Describe
target_watchpoint_addr_within_range.
Index: breakpoint.c
===================================================================
RCS file: /cvs/src/src/gdb/breakpoint.c,v
retrieving revision 1.310
diff -u -a -p -a -u -p -r1.310 breakpoint.c
--- breakpoint.c 18 Apr 2008 00:41:28 -0000 1.310
+++ breakpoint.c 23 Apr 2008 11:00:51 -0000
@@ -2552,8 +2552,9 @@ watchpoints_triggered (struct target_wai
for (loc = b->loc; loc; loc = loc->next)
/* Exact match not required. Within range is
sufficient. */
- if (addr >= loc->address
- && addr < loc->address + loc->length)
+ if (target_watchpoint_addr_within_range (¤t_target,
+ addr, loc->address,
+ loc->length))
{
b->watchpoint_triggered = watch_triggered_yes;
break;
Index: ppc-linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/ppc-linux-nat.c,v
retrieving revision 1.78
diff -u -a -p -a -u -p -r1.78 ppc-linux-nat.c
--- ppc-linux-nat.c 16 Jan 2008 04:48:55 -0000 1.78
+++ ppc-linux-nat.c 23 Apr 2008 11:00:52 -0000
@@ -889,6 +889,16 @@ ppc_linux_stopped_by_watchpoint (void)
return ppc_linux_stopped_data_address (¤t_target, &addr);
}
+static int
+ppc_linux_watchpoint_addr_within_range (struct target_ops *target,
+ CORE_ADDR addr,
+ CORE_ADDR start, int length)
+{
+ addr &= ~7;
+ /* Check whether [start, start+length-1] intersects [addr, addr+7]. */
+ return start <= addr + 7 && start + length - 1 >= addr;
+}
+
static void
ppc_linux_store_inferior_registers (struct regcache *regcache, int regno)
{
@@ -997,6 +1007,7 @@ _initialize_ppc_linux_nat (void)
t->to_remove_watchpoint = ppc_linux_remove_watchpoint;
t->to_stopped_by_watchpoint = ppc_linux_stopped_by_watchpoint;
t->to_stopped_data_address = ppc_linux_stopped_data_address;
+ t->to_watchpoint_addr_within_range = ppc_linux_watchpoint_addr_within_range;
t->to_read_description = ppc_linux_read_description;
Index: target.c
===================================================================
RCS file: /cvs/src/src/gdb/target.c,v
retrieving revision 1.159
diff -u -a -p -a -u -p -r1.159 target.c
--- target.c 28 Mar 2008 16:37:08 -0000 1.159
+++ target.c 23 Apr 2008 11:00:52 -0000
@@ -49,6 +49,9 @@ static void kill_or_be_killed (int);
static void default_terminal_info (char *, int);
+static int default_watchpoint_addr_within_range (struct target_ops *,
+ CORE_ADDR, CORE_ADDR, int);
+
static int default_region_ok_for_hw_watchpoint (CORE_ADDR, int);
static int nosymbol (char *, CORE_ADDR *);
@@ -131,6 +134,9 @@ static int debug_to_stopped_by_watchpoin
static int debug_to_stopped_data_address (struct target_ops *, CORE_ADDR *);
+static int debug_to_watchpoint_addr_within_range (struct target_ops *,
+ CORE_ADDR, CORE_ADDR, int);
+
static int debug_to_region_ok_for_hw_watchpoint (CORE_ADDR, int);
static void debug_to_terminal_init (void);
@@ -416,9 +422,10 @@ update_current_target (void)
INHERIT (to_insert_watchpoint, t);
INHERIT (to_remove_watchpoint, t);
INHERIT (to_stopped_data_address, t);
- INHERIT (to_stopped_by_watchpoint, t);
INHERIT (to_have_steppable_watchpoint, t);
INHERIT (to_have_continuable_watchpoint, t);
+ INHERIT (to_stopped_by_watchpoint, t);
+ INHERIT (to_watchpoint_addr_within_range, t);
INHERIT (to_region_ok_for_hw_watchpoint, t);
INHERIT (to_terminal_init, t);
INHERIT (to_terminal_inferior, t);
@@ -544,6 +551,8 @@ update_current_target (void)
de_fault (to_stopped_data_address,
(int (*) (struct target_ops *, CORE_ADDR *))
return_zero);
+ de_fault (to_watchpoint_addr_within_range,
+ default_watchpoint_addr_within_range);
de_fault (to_region_ok_for_hw_watchpoint,
default_region_ok_for_hw_watchpoint);
de_fault (to_terminal_init,
@@ -1873,6 +1882,14 @@ default_region_ok_for_hw_watchpoint (COR
}
static int
+default_watchpoint_addr_within_range (struct target_ops *target,
+ CORE_ADDR addr,
+ CORE_ADDR start, int length)
+{
+ return addr >= start && addr < start + length;
+}
+
+static int
return_zero (void)
{
return 0;
@@ -2440,6 +2457,23 @@ debug_to_stopped_data_address (struct ta
}
static int
+debug_to_watchpoint_addr_within_range (struct target_ops *target,
+ CORE_ADDR addr,
+ CORE_ADDR start, int length)
+{
+ int retval;
+
+ retval = debug_target.to_watchpoint_addr_within_range (target, addr,
+ start, length);
+
+ fprintf_filtered (gdb_stdlog,
+ "target_watchpoint_addr_within_range (0x%lx, 0x%lx, %d) = %d\n",
+ (unsigned long) addr, (unsigned long) start, length,
+ retval);
+ return retval;
+}
+
+static int
debug_to_insert_hw_breakpoint (struct bp_target_info *bp_tgt)
{
int retval;
@@ -2782,6 +2816,7 @@ setup_target_debug (void)
current_target.to_remove_watchpoint = debug_to_remove_watchpoint;
current_target.to_stopped_by_watchpoint = debug_to_stopped_by_watchpoint;
current_target.to_stopped_data_address = debug_to_stopped_data_address;
+ current_target.to_watchpoint_addr_within_range = debug_to_watchpoint_addr_within_range;
current_target.to_region_ok_for_hw_watchpoint = debug_to_region_ok_for_hw_watchpoint;
current_target.to_terminal_init = debug_to_terminal_init;
current_target.to_terminal_inferior = debug_to_terminal_inferior;
Index: target.h
===================================================================
RCS file: /cvs/src/src/gdb/target.h,v
retrieving revision 1.116
diff -u -a -p -a -u -p -r1.116 target.h
--- target.h 8 Apr 2008 17:02:23 -0000 1.116
+++ target.h 23 Apr 2008 11:00:52 -0000
@@ -367,6 +367,8 @@ struct target_ops
int to_have_steppable_watchpoint;
int to_have_continuable_watchpoint;
int (*to_stopped_data_address) (struct target_ops *, CORE_ADDR *);
+ int (*to_watchpoint_addr_within_range) (struct target_ops *,
+ CORE_ADDR, CORE_ADDR, int);
int (*to_region_ok_for_hw_watchpoint) (CORE_ADDR, int);
void (*to_terminal_init) (void);
void (*to_terminal_inferior) (void);
@@ -1093,6 +1095,9 @@ extern int target_stopped_data_address_p
#define target_stopped_data_address_p(CURRENT_TARGET) (1)
#endif
+#define target_watchpoint_addr_within_range(target, addr, start, length) \
+ (*target.to_watchpoint_addr_within_range) (target, addr, start, length)
+
extern const struct target_desc *target_read_description (struct target_ops *);
/* Command logging facility. */
--- doc/gdbint.texinfo.~1.281.~ 2008-04-22 11:46:53.000000000 +0200
+++ doc/gdbint.texinfo 2008-04-23 12:01:04.000000000 +0200
@@ -9,7 +9,7 @@
@ifinfo
This file documents the internals of the GNU debugger @value{GDBN}.
Copyright (C) 1990, 1991, 1992, 1993, 1994, 1996, 1998, 1999, 2000, 2001,
- 2002, 2003, 2004, 2005, 2006
+ 2002, 2003, 2004, 2005, 2006, 2008
Free Software Foundation, Inc.
Contributed by Cygnus Solutions. Written by John Gilmore.
Second Edition by Stan Shebs.
@@ -743,10 +743,19 @@ target's watchpoint indication is sticky
resuming, this method should clear it. For instance, the x86 debug
control register has sticky triggered flags.
+@findex target_watchpoint_addr_within_range
+@item target_watchpoint_addr_within_range (@var{target}, @var{addr}, @var{start}, @var{length})
+Check whether @var{addr} (as returned by target_stopped_data_address)
+lies within the hardware-defined watchpoint region described by
+@var{start} and @var{length}. This only needs to be provided if the
+granularity of a watchpoint is greater than one byte, i.e., if the
+watchpoint can also trigger on nearby addresses outside of the watched
+region.
+
@findex HAVE_STEPPABLE_WATCHPOINT
@item HAVE_STEPPABLE_WATCHPOINT
If defined to a non-zero value, it is not necessary to disable a
-watchpoint to step over it. Like @code{gdbarch_have_nonsteppable_watchpoint},
+watchpoint to step over it. Like @code{gdbarch_have_nonsteppable_watchpoint},
this is usually set when watchpoints trigger at the instruction
which will perform an interesting read or write. It should be
set if there is a temporary disable bit which allows the processor
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."