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binutils-gdb/gdb/testsuite/gdb.base/watchpoint-unaligned.exp
Tom de Vries 9a03f21853 [gdb/tdep] Fix gdb.base/watchpoint-unaligned.exp on aarch64
On aarch64-linux, with test-case gdb.base/watchpoint-unaligned.exp I run into:
...
(gdb) watch data.u.size8twice[1]^M
Hardware watchpoint 241: data.u.size8twice[1]^M
(gdb) PASS: gdb.base/watchpoint-unaligned.exp: watch data.u.size8twice[1]
continue^M
Continuing.^M
FAIL: gdb.base/watchpoint-unaligned.exp: continue (timeout)
FAIL: gdb.base/watchpoint-unaligned.exp: size8twice write
...

This happens as follows.

We start the exec and set an 8-byte hardware watchpoint on
data.u.size8twice[1] at address 0x440048:
...
(gdb) p sizeof (data.u.size8twice[1])
$1 = 8
(gdb) p &data.u.size8twice[1]
$2 = (uint64_t *) 0x440048 <data+16>
...

We continue execution, and a 16-byte write at address 0x440040 triggers the
hardware watchpoint:
...
  4101c8:       a9000801        stp     x1, x2, [x0]
...

When checking whether a watchpoint has triggered in
aarch64_stopped_data_address, we check against address 0x440040 (passed in
parameter addr_trap).  This behaviour is documented:
...
	  /* ADDR_TRAP reports the first address of the memory range
	     accessed by the CPU, regardless of what was the memory
	     range watched.  ...  */
...
and consequently the matching logic compares against an addr_watch_aligned:
...
	  && addr_trap >= addr_watch_aligned
	  && addr_trap < addr_watch + len)
...

However, the comparison fails:
...
(gdb) p /x addr_watch_aligned
$3 = 0x440048
(gdb) p addr_trap >= addr_watch_aligned
$4 = false
...

Consequently, aarch64_stopped_data_address returns false, and
stopped_by_watchpoint returns false, and watchpoints_triggered returns 0,
which make infrun think it's looking at a delayed hardware
breakpoint/watchpoint trap:
...
  [infrun] handle_signal_stop: stop_pc=0x4101c8
  [infrun] handle_signal_stop: delayed hardware breakpoint/watchpoint trap, ignoring
...
Infrun then ignores the trap and continues, but runs into the same situation
again and again, causing a hang which then causes the test timeout.

Fix this by allowing a match 8 bytes below addr_watch_aligned.  This
introduces the possibility for false positives, so we only do this for regular
"value changed" watchpoints.

An earlier version of this patch worked by aligning addr_watch_aligned to 16
instead of 8:
...
-  const CORE_ADDR addr_watch_aligned = align_down (state->dr_addr_wp[i], 8);
+  const CORE_ADDR addr_watch_aligned = align_down (state->dr_addr_wp[i], 16);
...
but while that fixed the test-case, it didn't fix the problem completely, so
extend the test-case to check more scenarios.

Tested on aarch64-linux.

Tested-By: Luis Machado <luis.machado@arm.com>
Approved-By: Luis Machado <luis.machado@arm.com>

PR tdep/29423
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29423
2024-03-14 11:25:10 +01:00

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# Copyright 2017-2024 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 is part of the gdb testsuite.
# Test inserting read watchpoints on unaligned addresses.
require allow_hw_watchpoint_tests
standard_testfile
if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
return -1
}
if ![runto_main] {
return -1
}
gdb_breakpoint [gdb_get_line_number "start_again"] "Breakpoint $decimal at $hex" "start_again"
set sizes {1 2 4 8}
array set alignedend {1 1 2 2 3 4 4 4 5 8 6 8 7 8 8 8}
set rwatch "rwatch"
set rwatch_exp "Hardware read watchpoint"
if {[istarget "s390*-*-*"]} {
# Target does not support this type of hardware watchpoint."
set rwatch "watch"
set rwatch_exp "Hardware watchpoint"
}
foreach wpsize $sizes {
for {set wpoffset 0} {$wpoffset < 8 / $wpsize} {incr wpoffset} {
set wpstart [expr $wpoffset * $wpsize]
set wpend [expr ($wpoffset + 1) * $wpsize]
set wpendaligned $alignedend($wpend)
foreach rdsize $sizes {
for {set rdoffset 0} {$rdoffset < 8 / $rdsize} {incr rdoffset} {
set rdstart [expr $rdoffset * $rdsize]
set rdend [expr ($rdoffset + 1) * $rdsize]
set expect_hit [expr max ($wpstart, $rdstart) < min ($wpend, $rdend)]
set test "$rwatch data.u.size$wpsize\[$wpoffset\]"
set wpnum ""
gdb_test_multiple $test $test {
-re "$rwatch_exp (\[0-9\]+): .*\r\n$gdb_prompt $" {
set wpnum $expect_out(1,string)
}
-re "Expression cannot be implemented with read/access watchpoint.\r\n$gdb_prompt $" {
if {$wpsize == 8 && [istarget "arm*-*-*"]} {
untested $test
continue
}
fail $test
}
}
gdb_test_no_output -nopass "set variable size = $rdsize"
gdb_test_no_output -nopass "set variable offset = $rdoffset"
set test "continue"
set got_hit 0
gdb_test_multiple $test $test {
-re "$rwatch_exp $wpnum:.*alue = .*\r\n$gdb_prompt $" {
set got_hit 1
send_gdb "continue\n"
exp_continue
}
-re " start_again .*\r\n$gdb_prompt $" {
}
}
gdb_test_no_output -nopass "delete $wpnum"
set test "wp(size=$wpsize offset=$wpoffset) rd(size=$rdsize offset=$rdoffset) expect=$expect_hit"
if {$expect_hit == $got_hit} {
pass $test
} else {
# We do not know if we run on a fixed Linux kernel
# or not. Report XFAIL only in the FAIL case.
if {$expect_hit == 0 && $rdstart < $wpendaligned} {
setup_xfail external/20207 "aarch64*-*-linux*"
}
if {!$expect_hit && [expr max ($wpstart / 8, $rdstart / 8) < min (($wpend + 7) / 8, ($rdend + 7) / 8)]} {
setup_xfail breakpoints/23131 "powerpc*-*-*"
}
fail $test
}
}
}
}
}
foreach wpcount {4 7} {
array set wpoffset_to_wpnum {}
for {set wpoffset 1} {$wpoffset <= $wpcount} {incr wpoffset} {
set test "$rwatch data.u.size1\[$wpoffset\]"
set wpnum ""
# Initialize the result incase the test fails.
set wpoffset_to_wpnum($wpoffset) 0
gdb_test_multiple $test $test {
-re "$rwatch_exp (\[0-9\]+): .*\r\n$gdb_prompt $" {
set wpoffset_to_wpnum($wpoffset) $expect_out(1,string)
}
-re "There are not enough available hardware resources for this watchpoint.\r\n$gdb_prompt $" {
if {$wpoffset > 1} {
setup_xfail breakpoints/23131 "powerpc*-*-*"
setup_xfail breakpoints/23131 "arm*-*-*"
}
fail $test
}
}
}
gdb_test_no_output -nopass "set variable size = 1"
gdb_test_no_output -nopass "set variable offset = 1"
set test "continue"
set got_hit 0
gdb_test_multiple $test $test {
-re "\r\nCould not insert hardware watchpoint .*\r\n$gdb_prompt $" {
}
-re "$rwatch_exp $wpoffset_to_wpnum(1):.*alue = .*\r\n$gdb_prompt $" {
set got_hit 1
send_gdb "continue\n"
exp_continue
}
-re " start_again .*\r\n$gdb_prompt $" {
}
}
for {set wpoffset 1} {$wpoffset <= $wpcount} {incr wpoffset} {
if {$wpoffset_to_wpnum($wpoffset)} {
gdb_test_no_output "delete $wpoffset_to_wpnum($wpoffset)" ""
}
}
set test "wpcount($wpcount)"
if {!$wpoffset_to_wpnum([expr $wpcount - 1])} {
untested $test
continue
}
if {$wpcount > 4} {
if {![istarget "s390*-*-*"]} {
setup_kfail tdep/22389 *-*-*
}
}
gdb_assert $got_hit $test
}
# We've got an array with 3 8-byte elements. Do a store of 16 bytes,
# to:
# - elements 0 and 1 (offset == 0), and
# - elements 1 and 2 (offset == 1).
# For each case, check setting a watchpoint at:
# - the first written element (index == 0), and
# - the second element (index == 1).
foreach_with_prefix offset { 0 1 } {
foreach_with_prefix index { 0 1 } {
clean_restart $binfile
if ![runto_main] {
return -1
}
gdb_test_no_output "set var offset = $offset"
gdb_breakpoint [gdb_get_line_number "final_return"] \
"Breakpoint $decimal at $hex" "final_return"
set watch_index [expr $offset + $index]
set test "watch data.u.size8twice\[$watch_index\]"
set wpnum 0
gdb_test_multiple $test $test {
-re "Hardware watchpoint (\[0-9\]+): .*\r\n$gdb_prompt $" {
set wpnum $expect_out(1,string)
pass $gdb_test_name
}
-re "Watchpoint (\[0-9\]+): .*\r\n$gdb_prompt $" {
if {[istarget "arm*-*-*"]} {
untested $gdb_test_name
} else {
fail $gdb_test_name
}
}
}
if {$wpnum} {
set test "continue"
set got_hit 0
gdb_test_multiple $test $test {
-re "\r\nCould not insert hardware watchpoint .*\r\n$gdb_prompt $" {
}
-re "Hardware watchpoint $wpnum:.*New value = .*\r\n$gdb_prompt $" {
set got_hit 1
send_gdb "continue\n"
exp_continue
}
-re " final_return .*\r\n$gdb_prompt $" {
}
}
gdb_assert $got_hit "size8twice write"
}
}
}