f3770638ca
Both PRs are triggered by the same use case. PR18214 is about software single-step targets. On those, the 'resume' code that detects that we're stepping over a breakpoint and delivering a signal at the same time: /* Currently, our software single-step implementation leads to different results than hardware single-stepping in one situation: when stepping into delivering a signal which has an associated signal handler, hardware single-step will stop at the first instruction of the handler, while software single-step will simply skip execution of the handler. ... Fortunately, we can at least fix this particular issue. We detect here the case where we are about to deliver a signal while software single-stepping with breakpoints removed. In this situation, we revert the decisions to remove all breakpoints and insert single- step breakpoints, and instead we install a step-resume breakpoint at the current address, deliver the signal without stepping, and once we arrive back at the step-resume breakpoint, actually step over the breakpoint we originally wanted to step over. */ doesn't handle the case of _another_ thread also needing to step over a breakpoint. Because the other thread is just resumed at the PC where it had stopped and a breakpoint is still inserted there, the thread immediately re-traps the same breakpoint. This test exercises that. On software single-step targets, it fails like this: KFAIL: gdb.threads/multiple-step-overs.exp: displaced=off: signal thr3: continue to sigusr1_handler KFAIL: gdb.threads/multiple-step-overs.exp: displaced=off: signal thr2: continue to sigusr1_handler gdb.log (simplified): (gdb) continue Continuing. Breakpoint 4, child_function_2 (arg=0x0) at src/gdb/testsuite/gdb.threads/multiple-step-overs.c:66 66 callme (); /* set breakpoint thread 2 here */ (gdb) thread 3 (gdb) queue-signal SIGUSR1 (gdb) thread 1 [Switching to thread 1 (Thread 0x7ffff7fc1740 (LWP 24824))] #0 main () at src/gdb/testsuite/gdb.threads/multiple-step-overs.c:106 106 wait_threads (); /* set wait-threads breakpoint here */ (gdb) break sigusr1_handler Breakpoint 5 at 0x400837: file src/gdb/testsuite/gdb.threads/multiple-step-overs.c, line 31. (gdb) continue Continuing. [Switching to Thread 0x7ffff7fc0700 (LWP 24828)] Breakpoint 4, child_function_2 (arg=0x0) at src/gdb/testsuite/gdb.threads/multiple-step-overs.c:66 66 callme (); /* set breakpoint thread 2 here */ (gdb) KFAIL: gdb.threads/multiple-step-overs.exp: displaced=off: signal thr3: continue to sigusr1_handler For good measure, I made the test try displaced stepping too. And then I found it crashes GDB on x86-64 (a hardware step target), but only when displaced stepping... : KFAIL: gdb.threads/multiple-step-overs.exp: displaced=on: signal thr1: continue to sigusr1_handler (PRMS: gdb/18216) KFAIL: gdb.threads/multiple-step-overs.exp: displaced=on: signal thr2: continue to sigusr1_handler (PRMS: gdb/18216) KFAIL: gdb.threads/multiple-step-overs.exp: displaced=on: signal thr3: continue to sigusr1_handler (PRMS: gdb/18216) Program terminated with signal SIGSEGV, Segmentation fault. #0 0x000000000062a83a in process_event_stop_test (ecs=0x7fff847eeee0) at src/gdb/infrun.c:4964 4964 if (sr_bp->loc->permanent Setting up the environment for debugging gdb. Breakpoint 1 at 0x79fcfc: file src/gdb/common/errors.c, line 54. Breakpoint 2 at 0x50a26c: file src/gdb/cli/cli-cmds.c, line 217. (top-gdb) p sr_bp $1 = (struct breakpoint *) 0x0 (top-gdb) bt #0 0x000000000062a83a in process_event_stop_test (ecs=0x7fff847eeee0) at src/gdb/infrun.c:4964 #1 0x000000000062a1af in handle_signal_stop (ecs=0x7fff847eeee0) at src/gdb/infrun.c:4715 #2 0x0000000000629097 in handle_inferior_event (ecs=0x7fff847eeee0) at src/gdb/infrun.c:4165 #3 0x0000000000627482 in fetch_inferior_event (client_data=0x0) at src/gdb/infrun.c:3298 #4 0x000000000064ad7b in inferior_event_handler (event_type=INF_REG_EVENT, client_data=0x0) at src/gdb/inf-loop.c:56 #5 0x00000000004c375f in handle_target_event (error=0, client_data=0x0) at src/gdb/linux-nat.c:4658 #6 0x0000000000648c47 in handle_file_event (file_ptr=0x2e0eaa0, ready_mask=1) at src/gdb/event-loop.c:658 The all-stop-non-stop series fixes this, but meanwhile, this augments the multiple-step-overs.exp test to cover this, KFAILed. gdb/testsuite/ChangeLog: 2015-04-08 Pedro Alves <palves@redhat.com> PR gdb/18214 PR gdb/18216 * gdb.threads/multiple-step-overs.c (sigusr1_handler): New function. (main): Install it as SIGUSR1 handler. * gdb.threads/multiple-step-overs.exp (setup): Remove 'prefix' parameter. Always use "setup" as prefix. Toggle "set displaced-stepping" off/on depending on global. Don't switch to thread 1 here. (top level): Add displaced stepping "off/on" test axis. Update "setup" calls. Wrap each subtest with with_test_prefix. Test continuing with a queued signal in each thread.
132 lines
3.8 KiB
Text
132 lines
3.8 KiB
Text
# Copyright (C) 2011-2015 Free Software Foundation, Inc.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# Test that GDB steps over all breakpoints of threads not the stepping
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# thread, before actually proceeding with the stepped thread.
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standard_testfile
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set executable ${testfile}
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if [target_info exists gdb,nosignals] {
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verbose "Skipping ${testfile}.exp because of nosignals."
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return -1
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}
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if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
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executable [list debug "incdir=${objdir}"]] != "" } {
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return -1
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}
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# Prepare environment for test.
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proc setup {} {
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global executable
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global displaced
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with_test_prefix "setup" {
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clean_restart $executable
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if ![runto_main] {
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return -1
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}
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gdb_test_no_output "set displaced-stepping $displaced"
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gdb_breakpoint [gdb_get_line_number "set wait-threads breakpoint here"]
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gdb_continue_to_breakpoint "run to breakpoint"
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gdb_test "info threads" "3 .* 2 .*\\\* 1.*" "info threads shows all threads"
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gdb_test_no_output "set scheduler-locking on"
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gdb_breakpoint [gdb_get_line_number "set breakpoint thread 3 here"]
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gdb_breakpoint [gdb_get_line_number "set breakpoint thread 2 here"]
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gdb_test "thread 3" "Switching.*"
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gdb_continue_to_breakpoint "run to breakpoint in thread 3"
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gdb_test "p *myp = 0" " = 0" "unbreak loop in thread 3"
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gdb_test "thread 2" "Switching.*"
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gdb_continue_to_breakpoint "run to breakpoint in thread 2"
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gdb_test "p *myp = 0" " = 0" "unbreak loop in thread 2"
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# Disable scheduler locking.
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gdb_test_no_output "set scheduler-locking off"
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# Now all 3 threads are stopped for a breakpoint that needs to
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# be stepped over before thread 1 is resumed.
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}
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}
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foreach displaced { "off" "on" } {
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with_test_prefix "displaced=$displaced" {
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with_test_prefix "step" {
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setup
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gdb_test "thread 1" "Switching.*"
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gdb_test "step" "in wait_threads .*"
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}
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with_test_prefix "next" {
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setup
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gdb_test "thread 1" "Switching.*"
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gdb_test "next" "pthread_join.*"
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}
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with_test_prefix "continue" {
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setup
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gdb_breakpoint [gdb_get_line_number "EXIT_SUCCESS"]
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gdb_test "thread 1" "Switching.*"
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gdb_test "continue" "EXIT_SUCCESS.*"
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}
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# Try continuing with a queued signal in each of the threads
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# (one at a time). Should stop at the signal handler, instead
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# of re-trapping the breakpoint the threads were already
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# stopped at.
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foreach thread {1 2 3} {
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with_test_prefix "signal thr$thread" {
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setup
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# Queue a signal in THREAD.
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gdb_test "thread $thread" "Switching.*"
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gdb_test_no_output "queue-signal SIGUSR1"
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# Switch back to thread 1, and continue.
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gdb_test "thread 1" "Switching.*" "switch back to thread 1"
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gdb_breakpoint "sigusr1_handler" "set break at sigusr1_handler"
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set msg "continue to sigusr1_handler"
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gdb_test_multiple "continue" $msg {
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-re "Breakpoint .* sigusr1_handler .*$gdb_prompt $" {
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pass $msg
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}
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-re "Breakpoint .*$gdb_prompt $" {
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if {![can_single_step_to_signal_handler]
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&& $thread != 1 && $displaced == "off"} {
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setup_kfail "gdb/18214" "*-*-*"
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}
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fail $msg
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}
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eof {
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if {[can_single_step_to_signal_handler]
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&& $displaced == "on"} {
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setup_kfail "gdb/18216" "*-*-*"
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}
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fail $msg
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}
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}
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}
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}
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}
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}
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