old-cross-binutils/gdb/testsuite/gdb.threads/step-bg-decr-pc-switch-thread.exp

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Fix adjust_pc_after_break, remove still current thread check On decr_pc_after_break targets, GDB adjusts the PC incorrectly if a background single-step stops somewhere where PC-$decr_pc has a breakpoint, and the thread that finishes the step is not the current thread, like: ADDR1 nop <-- breakpoint here ADDR2 jmp PC IOW, say thread A is stepping ADDR2's line in the background (an infinite loop), and the user switches focus to thread B. GDB's adjust_pc_after_break logic confuses the single-step stop of thread A for a hit of the breakpoint at ADDR1, and thus adjusts thread A's PC to point at ADDR1 when it should not, and reports a breakpoint hit, when thread A did not execute the instruction at ADDR1 at all. The test added by this patch exercises exactly that. I can't find any reason we'd need the "thread to be examined is still the current thread" condition in adjust_pc_after_break, at least nowadays; it might have made sense in the past. Best just remove it, and rely on currently_stepping(). Here's the test's log of a run with an unpatched GDB: 35 while (1); (gdb) PASS: gdb.threads/step-bg-decr-pc-switch-thread.exp: next over nop next& (gdb) PASS: gdb.threads/step-bg-decr-pc-switch-thread.exp: next& over inf loop thread 1 [Switching to thread 1 (Thread 0x7ffff7fc2740 (LWP 29027))](running) (gdb) PASS: gdb.threads/step-bg-decr-pc-switch-thread.exp: switch to main thread Breakpoint 2, thread_function (arg=0x0) at ...src/gdb/testsuite/gdb.threads/step-bg-decr-pc-switch-thread.c:34 34 NOP; /* set breakpoint here */ FAIL: gdb.threads/step-bg-decr-pc-switch-thread.exp: no output while stepping gdb/ChangeLog: 2015-02-11 Pedro Alves <pedro@codesourcery.com> * infrun.c (adjust_pc_after_break): Don't adjust the PC just because the event thread is not the current thread. gdb/testsuite/ChangeLog: 2015-02-11 Pedro Alves <pedro@codesourcery.com> * gdb.threads/step-bg-decr-pc-switch-thread.c: New file. * gdb.threads/step-bg-decr-pc-switch-thread.exp: New file.
2015-02-11 09:45:41 +00:00
# Copyright (C) 2014-2015 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/>.
# On decr_pc_after_break targets, GDB used to adjust the PC
# incorrectly if a background single-step stopped somewhere where
# PC-$decr_pc had a breakpoint, and the thread was not the current
# thread, like:
#
# ADDR1 nop <-- breakpoint here
# ADDR2 jmp PC
#
# IOW, say thread A is stepping ADDR2's line in the background (an
# infinite loop), and the user switches focus to thread B. GDB's
# adjust_pc_after_break logic would confuse the single-step stop of
# thread A for a hit of the breakpoint at ADDR1, and thus adjust
# thread A's PC to point at ADDR1 when it should not: the thread had
# been single-stepped, not continued.
standard_testfile
if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug pthreads}] == -1} {
return -1
}
clean_restart $binfile
if ![runto_main] {
continue
}
# Make sure it's GDB's decr_pc logic that's being tested, not the
# target's.
gdb_test_no_output "set range-stepping off"
delete_breakpoints
gdb_breakpoint [gdb_get_line_number "set breakpoint here"]
gdb_continue_to_breakpoint "run to nop breakpoint"
List inferiors/threads/pspaces in ascending order Before: (gdb) info threads Id Target Id Frame 3 Thread 0x7ffff77c3700 (LWP 29035) callme () at foo.c:30 2 Thread 0x7ffff7fc4700 (LWP 29034) 0x000000000040087b in child_function_2 (arg=0x0) at foo.c:60 * 1 Thread 0x7ffff7fc5740 (LWP 29030) 0x0000003b37209237 in pthread_join (threadid=140737353893632, thread_return=0x0) at pthread_join.c:92 After: (gdb) info threads Id Target Id Frame * 1 Thread 0x7ffff7fc5740 (LWP 29030) 0x0000003b37209237 in pthread_join (threadid=140737353893632, thread_return=0x0) at pthread_join.c:92 2 Thread 0x7ffff7fc4700 (LWP 29034) 0x000000000040087b in child_function_2 (arg=0x0) at foo.c:60 3 Thread 0x7ffff77c3700 (LWP 29035) callme () at foo.c:30 gdb/doc/ChangeLog: 2015-11-24 Pedro Alves <palves@redhat.com> PR 17539 * gdb.texinfo (Inferiors and Programs): Adjust "maint info program-spaces" example to ascending order listing. (Threads): Adjust "info threads" example to ascending order listing. (Forks): Adjust "info inferiors" example to ascending order listing. gdb/ChangeLog: 2015-11-24 Pedro Alves <palves@redhat.com> PR 17539 * inferior.c (add_inferior_silent): Append the new inferior to the end of the list. * progspace.c (add_program_space): Append the new pspace to the end of the list. * thread.c (new_thread): Append the new thread to the end of the list. gdb/testsuite/ChangeLog: 2015-11-24 Pedro Alves <palves@redhat.com> PR 17539 * gdb.base/foll-exec-mode.exp: Adjust to GDB listing inferiors and threads in ascending order. * gdb.base/foll-fork.exp: Likewise. * gdb.base/foll-vfork.exp: Likewise. * gdb.base/multi-forks.exp: Likewise. * gdb.mi/mi-nonstop.exp: Likewise. * gdb.mi/mi-nsintrall.exp: Likewise. * gdb.multi/base.exp: Likewise. * gdb.multi/multi-arch.exp: Likewise. * gdb.python/py-inferior.exp: Likewise. * gdb.threads/break-while-running.exp: Likewise. * gdb.threads/execl.exp: Likewise. * gdb.threads/gcore-thread.exp: Likewise. * gdb.threads/info-threads-cur-sal.exp: Likewise. * gdb.threads/kill.exp: Likewise. * gdb.threads/linux-dp.exp: Likewise. * gdb.threads/multiple-step-overs.exp: Likewise. * gdb.threads/next-bp-other-thread.exp: Likewise. * gdb.threads/step-bg-decr-pc-switch-thread.exp: Likewise. * gdb.threads/step-over-lands-on-breakpoint.exp: Likewise. * gdb.threads/step-over-trips-on-watchpoint.exp: Likewise. * gdb.threads/thread-find.exp: Likewise. * gdb.threads/tls.exp: Likewise. * lib/mi-support.exp (mi_reverse_list): Delete. (mi_check_thread_states): No longer reverse list.
2015-11-24 18:11:21 +00:00
gdb_test "info threads" " 1 .*\\\* 2 .*" "info threads shows all threads"
Fix adjust_pc_after_break, remove still current thread check On decr_pc_after_break targets, GDB adjusts the PC incorrectly if a background single-step stops somewhere where PC-$decr_pc has a breakpoint, and the thread that finishes the step is not the current thread, like: ADDR1 nop <-- breakpoint here ADDR2 jmp PC IOW, say thread A is stepping ADDR2's line in the background (an infinite loop), and the user switches focus to thread B. GDB's adjust_pc_after_break logic confuses the single-step stop of thread A for a hit of the breakpoint at ADDR1, and thus adjusts thread A's PC to point at ADDR1 when it should not, and reports a breakpoint hit, when thread A did not execute the instruction at ADDR1 at all. The test added by this patch exercises exactly that. I can't find any reason we'd need the "thread to be examined is still the current thread" condition in adjust_pc_after_break, at least nowadays; it might have made sense in the past. Best just remove it, and rely on currently_stepping(). Here's the test's log of a run with an unpatched GDB: 35 while (1); (gdb) PASS: gdb.threads/step-bg-decr-pc-switch-thread.exp: next over nop next& (gdb) PASS: gdb.threads/step-bg-decr-pc-switch-thread.exp: next& over inf loop thread 1 [Switching to thread 1 (Thread 0x7ffff7fc2740 (LWP 29027))](running) (gdb) PASS: gdb.threads/step-bg-decr-pc-switch-thread.exp: switch to main thread Breakpoint 2, thread_function (arg=0x0) at ...src/gdb/testsuite/gdb.threads/step-bg-decr-pc-switch-thread.c:34 34 NOP; /* set breakpoint here */ FAIL: gdb.threads/step-bg-decr-pc-switch-thread.exp: no output while stepping gdb/ChangeLog: 2015-02-11 Pedro Alves <pedro@codesourcery.com> * infrun.c (adjust_pc_after_break): Don't adjust the PC just because the event thread is not the current thread. gdb/testsuite/ChangeLog: 2015-02-11 Pedro Alves <pedro@codesourcery.com> * gdb.threads/step-bg-decr-pc-switch-thread.c: New file. * gdb.threads/step-bg-decr-pc-switch-thread.exp: New file.
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gdb_test "next" "while.*" "next over nop"
gdb_test_no_output "next&" "next& over inf loop"
set test "switch to main thread"
gdb_test_multiple "thread 1" $test {
-re "Cannot execute this command while the target is running.*$gdb_prompt $" {
unsupported $test
# With remote targets, we can't send any other remote packet
# until the target stops. Switching thread wants to ask the
# remote side whether the thread is alive.
return
}
-re "Switching to thread 1.*\\(running\\)\r\n$gdb_prompt " {
# Prefer to match the prompt without an anchor. If there's a
# bug and output comes after the prompt immediately, it's
# faster to handle that in the following test, instead of
# waiting for a timeout here.
pass $test
}
}
# Wait a bit. Use gdb_expect instead of sleep so that any (bad) GDB
# output is visible in the log.
gdb_expect 4 {}
set test "no output while stepping"
gdb_test_multiple "" $test {
-timeout 1
timeout {
pass $test
}
-re "." {
# If we see any output, it's a failure. On the original bug,
# this would be a breakpoint hit.
fail $test
}
}