+2010-02-22 Pedro Alves <pedro@codesourcery.com>
+
+ PR9605
+
+ gdb/
+ * breakpoint.c (insert_bp_location): If inserting the read
+ watchpoint failed, fallback to an access watchpoint.
+ (bpstat_check_watchpoint): Stop for read watchpoint triggers even
+ if the value changed, if not watching the same memory for writes.
+ (watchpoint_locations_match): Add comment.
+ (update_global_location_list): Copy the location's watchpoint type.
+ * i386-nat.c (i386_length_and_rw_bits): It's an internal error to
+ handle read watchpoints here.
+ (i386_insert_watchpoint): Read watchpoints aren't supported.
+ * remote.c (remote_insert_watchpoint): Return 1 for unsupported
+ packets.
+ * target.h (target_insert_watchpoint): Update description.
+
2010-02-19 Tom Tromey <tromey@redhat.com>
* p-typeprint.c (pascal_type_print_varspec_prefix): Update.
struct address_space *aspace2,
CORE_ADDR addr2);
+static int watchpoint_locations_match (struct bp_location *loc1,
+ struct bp_location *loc2);
+
static void breakpoints_info (char *, int);
static void breakpoint_1 (int, int);
watchpoints. It's not clear that it's necessary... */
&& bpt->owner->disposition != disp_del_at_next_stop)
{
- val = target_insert_watchpoint (bpt->address,
+ val = target_insert_watchpoint (bpt->address,
bpt->length,
bpt->watchpoint_type);
- bpt->inserted = (val != -1);
+
+ /* If trying to set a read-watchpoint, and it turns out it's not
+ supported, try emulating one with an access watchpoint. */
+ if (val == 1 && bpt->watchpoint_type == hw_read)
+ {
+ struct bp_location *loc, **loc_temp;
+
+ /* But don't try to insert it, if there's already another
+ hw_access location that would be considered a duplicate
+ of this one. */
+ ALL_BP_LOCATIONS (loc, loc_temp)
+ if (loc != bpt
+ && loc->watchpoint_type == hw_access
+ && watchpoint_locations_match (bpt, loc))
+ {
+ bpt->duplicate = 1;
+ bpt->inserted = 1;
+ bpt->target_info = loc->target_info;
+ bpt->watchpoint_type = hw_access;
+ val = 0;
+ break;
+ }
+
+ if (val == 1)
+ {
+ val = target_insert_watchpoint (bpt->address,
+ bpt->length,
+ hw_access);
+ if (val == 0)
+ bpt->watchpoint_type = hw_access;
+ }
+ }
+
+ bpt->inserted = (val == 0);
}
else if (bpt->owner->type == bp_catchpoint)
case WP_VALUE_CHANGED:
if (b->type == bp_read_watchpoint)
{
- /* Don't stop: read watchpoints shouldn't fire if
- the value has changed. This is for targets
- which cannot set read-only watchpoints. */
- bs->print_it = print_it_noop;
- bs->stop = 0;
+ /* There are two cases to consider here:
+
+ 1. we're watching the triggered memory for reads.
+ In that case, trust the target, and always report
+ the watchpoint hit to the user. Even though
+ reads don't cause value changes, the value may
+ have changed since the last time it was read, and
+ since we're not trapping writes, we will not see
+ those, and as such we should ignore our notion of
+ old value.
+
+ 2. we're watching the triggered memory for both
+ reads and writes. There are two ways this may
+ happen:
+
+ 2.1. this is a target that can't break on data
+ reads only, but can break on accesses (reads or
+ writes), such as e.g., x86. We detect this case
+ at the time we try to insert read watchpoints.
+
+ 2.2. otherwise, the target supports read
+ watchpoints, but, the user set an access or write
+ watchpoint watching the same memory as this read
+ watchpoint.
+
+ If we're watching memory writes as well as reads,
+ ignore watchpoint hits when we find that the
+ value hasn't changed, as reads don't cause
+ changes. This still gives false positives when
+ the program writes the same value to memory as
+ what there was already in memory (we will confuse
+ it for a read), but it's much better than
+ nothing. */
+
+ int other_write_watchpoint = 0;
+
+ if (bl->watchpoint_type == hw_read)
+ {
+ struct breakpoint *other_b;
+
+ ALL_BREAKPOINTS (other_b)
+ if ((other_b->type == bp_hardware_watchpoint
+ || other_b->type == bp_access_watchpoint)
+ && (other_b->watchpoint_triggered
+ == watch_triggered_yes))
+ {
+ other_write_watchpoint = 1;
+ break;
+ }
+ }
+
+ if (other_write_watchpoint
+ || bl->watchpoint_type == hw_access)
+ {
+ /* We're watching the same memory for writes,
+ and the value changed since the last time we
+ updated it, so this trap must be for a write.
+ Ignore it. */
+ bs->print_it = print_it_noop;
+ bs->stop = 0;
+ }
}
break;
case WP_VALUE_NOT_CHANGED:
static int
watchpoint_locations_match (struct bp_location *loc1, struct bp_location *loc2)
{
+ /* Note that this checks the owner's type, not the location's. In
+ case the target does not support read watchpoints, but does
+ support access watchpoints, we'll have bp_read_watchpoint
+ watchpoints with hw_access locations. Those should be considered
+ duplicates of hw_read locations. The hw_read locations will
+ become hw_access locations later. */
return (loc1->owner->type == loc2->owner->type
&& loc1->pspace->aspace == loc2->pspace->aspace
&& loc1->address == loc2->address
/* For the sake of should_be_inserted.
Duplicates check below will fix up this later. */
loc2->duplicate = 0;
+
+ /* Read watchpoint locations are switched to
+ access watchpoints, if the former are not
+ supported, but the latter are. */
+ if (is_hardware_watchpoint (old_loc->owner))
+ {
+ gdb_assert (is_hardware_watchpoint (loc2->owner));
+ loc2->watchpoint_type = old_loc->watchpoint_type;
+ }
+
if (loc2 != old_loc && should_be_inserted (loc2))
{
loc2->inserted = 1;
+2010-02-22 Pedro Alves <pedro@codesourcery.com>
+
+ PR9605
+
+ * i386-low.c (i386_length_and_rw_bits): Throw a fatal error if
+ handing a read watchpoint.
+ (i386_low_insert_watchpoint): Read watchpoints aren't supported.
+
2010-02-12 Doug Evans <dje@google.com>
* linux-low.c (linux_supports_tracefork_flag): Document.
rw = DR_RW_WRITE;
break;
case hw_read:
- /* The i386 doesn't support data-read watchpoints. */
+ fatal ("The i386 doesn't support data-read watchpoints.\n");
case hw_access:
rw = DR_RW_READ;
break;
int retval;
enum target_hw_bp_type type = Z_packet_to_hw_type (type_from_packet);
+ if (type == hw_read)
+ return 1; /* unsupported */
+
if (((len != 1 && len != 2 && len != 4)
&& !(TARGET_HAS_DR_LEN_8 && len == 8))
|| addr % len != 0)
rw = DR_RW_WRITE;
break;
case hw_read:
- /* The i386 doesn't support data-read watchpoints. */
+ internal_error (__FILE__, __LINE__,
+ _("The i386 doesn't support data-read watchpoints.\n"));
case hw_access:
rw = DR_RW_READ;
break;
{
int retval;
+ if (type == hw_read)
+ return 1; /* unsupported */
+
if (((len != 1 && len !=2 && len !=4) && !(TARGET_HAS_DR_LEN_8 && len == 8))
|| addr % len != 0)
retval = i386_handle_nonaligned_watchpoint (WP_INSERT, addr, len, type);
enum Z_packet_type packet = watchpoint_to_Z_packet (type);
if (remote_protocol_packets[PACKET_Z0 + packet].support == PACKET_DISABLE)
- return -1;
+ return 1;
sprintf (rs->buf, "Z%x,", packet);
p = strchr (rs->buf, '\0');
switch (packet_ok (rs->buf, &remote_protocol_packets[PACKET_Z0 + packet]))
{
case PACKET_ERROR:
- case PACKET_UNKNOWN:
return -1;
+ case PACKET_UNKNOWN:
+ return 1;
case PACKET_OK:
return 0;
}
(*current_target.to_region_ok_for_hw_watchpoint) (addr, len)
-/* Set/clear a hardware watchpoint starting at ADDR, for LEN bytes. TYPE is 0
- for write, 1 for read, and 2 for read/write accesses. Returns 0 for
- success, non-zero for failure. */
+/* Set/clear a hardware watchpoint starting at ADDR, for LEN bytes.
+ TYPE is 0 for write, 1 for read, and 2 for read/write accesses.
+ Returns 0 for success, 1 if the watchpoint type is not supported,
+ -1 for failure. */
#define target_insert_watchpoint(addr, len, type) \
(*current_target.to_insert_watchpoint) (addr, len, type)
+2010-02-22 Pedro Alves <pedro@codesourcery.com>
+
+ PR9605
+
+ * gdb.base/watch-read.c, gdb.base/watch-read.exp: New files.
+
2010-02-19 Tom Tromey <tromey@redhat.com>
PR c++/8693, PR c++/9496:
--- /dev/null
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2009, 2010 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/>. */
+
+volatile int global;
+
+int
+main (void)
+{
+ int foo = -1;
+
+ while (1)
+ {
+ foo = global; /* read line */
+
+ global = foo + 1; /* write line */
+ }
+
+ return 0;
+}
--- /dev/null
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2010 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/>.
+
+# This file was written by Pedro Alves <pedro@codesourcery.com>
+
+# This file is part of the gdb testsuite.
+
+#
+# Tests involving read watchpoints, and other kinds of watchpoints
+# watching the same memory as read watchpoints.
+#
+
+set testfile "watch-read"
+set srcfile ${testfile}.c
+
+if { [target_info exists gdb,no_hardware_watchpoints] } {
+ untested ${testfile}.exp
+ return -1
+}
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+ untested ${testfile}.exp
+ return -1
+}
+
+if { ![runto main] } then {
+ fail "run to main"
+ return
+}
+
+set read_line [gdb_get_line_number "read line" $srcfile]
+
+# Test running to a read of `global', with a read watchpoint set
+# watching it.
+
+gdb_test "rwatch global" \
+ "Hardware read watchpoint .*: global" \
+ "set hardware read watchpoint on global variable"
+
+# The first read is on entry to the loop.
+
+gdb_test "continue" \
+ "read watchpoint .*: global.*.*Value = 0.*in main.*$srcfile:$read_line.*" \
+ "read watchpoint triggers on first read"
+
+# The second read happens on second loop iteration, after `global'
+# having been incremented. On architectures where gdb has to emulate
+# read watchpoints with access watchpoints, this tests the
+# only-report-if-value-changed logic. On targets that support real
+# read watchpoints, this tests that GDB ignores the watchpoint's old
+# value, knowing that some untrapped write could have changed it, and
+# so reports the read watchpoint unconditionally.
+
+gdb_test "continue" \
+ "read watchpoint .*: global.*.*Value = 1.*in main.*$srcfile:$read_line.*" \
+ "read watchpoint triggers on read after value changed"
+
+# The following tests check that when the user sets a write or access
+# watchpoint watching the same memory as a read watchpoint, GDB also
+# applies the only-report-if-value-changed logic even on targets that
+# support real read watchpoints.
+
+# The program should be stopped at the read line. Set a write
+# watchpoint (leaving the read watchpoint) and continue. Only the
+# write watchpoint should be reported as triggering.
+
+gdb_test "watch global" \
+ "atchpoint .*: global" \
+ "set write watchpoint on global variable"
+
+gdb_test "continue" \
+ "atchpoint .*: global.*Old value = 1.*New value = 2.*" \
+ "write watchpoint triggers"
+
+set exp ""
+set exp "${exp}2.*read watchpoint.*keep y.*global.*breakpoint already hit 2 times.*"
+set exp "${exp}3.*watchpoint.*keep y.*global.*breakpoint already hit 1 time.*"
+gdb_test "info watchpoints" \
+ "$exp" \
+ "only write watchpoint triggers when value changes"
+
+# The program is now stopped at the write line. Continuing should
+# stop at the read line, and only the read watchpoint should be
+# reported as triggering.
+
+gdb_test "continue" \
+ "read watchpoint .*: global.*Value = 2.*in main.*$srcfile:$read_line.*" \
+ "read watchpoint triggers when value doesn't change, trapping reads and writes"
+
+set exp ""
+set exp "${exp}2.*read watchpoint.*keep y.*global.*breakpoint already hit 3 times.*"
+set exp "${exp}3.*watchpoint.*keep y.*global.*breakpoint already hit 1 time.*"
+gdb_test "info watchpoints" \
+ "$exp" \
+ "only read watchpoint triggers when value doesn't change"
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