forked from Imagelibrary/binutils-gdb
b381c2381c
After building gdb with "-O0 -g -fsanitize=thread" on aarch64-linux, with test-case gdb.reverse/time-reverse.exp I run into: ... (gdb) continue^M Continuing.^M FAIL: $exp: mode=c: continue to breakpoint: marker2 (timeout) ... The problem is that instruction stepping gets stuck in a loop with this call stack: time -> __GI___clock_gettime -> __kernel_clock_gettime -> __cvdso_clock_gettime. This is not specific to fsanitize=thread, it just makes gdb slow, which makes instruction stepping slow, which results in the application getting stuck. I ran into this as well with a regular gdb build on a 32-bit i686 laptop with 1GB of memory, an inherently slow setup. In that instance, I was able to observe that the loop we're stuck in is the outer loop in do_coarse in linux kernel source lib/vdso/gettimeofday.c. Fix this by setting "record full insn-number-max" to 2000, and handling running into the limit. Initially I tried the approach of using "stepi 2000" instead of continue, but that made the issue more likely to show up (for instance, I observed it after building gdb with -O0 on aarch64-linux). Tested on aarch64-linux. Approved-By: Guinevere Larsen <guinevere@redhat.com> PR testsuite/32678 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32678
111 lines
3.4 KiB
Plaintext
111 lines
3.4 KiB
Plaintext
# Copyright 2015-2025 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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# This file is part of the gdb testsuite.
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#
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# This test tests time syscall for reverse execution.
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#
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require supports_reverse
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require supports_process_record
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standard_testfile
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# MODE is either "syscall" for testing the time syscall explicitly, or
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# "c" for testing the C time(2) function.
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proc test {mode} {
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set options {debug}
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if {$mode == "syscall"} {
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lappend options additional_flags=-DUSE_SYSCALL
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} elseif {$mode != "c"} {
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error "unrecognized mode: $mode"
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}
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if { [prepare_for_testing "failed to prepare" $::testfile-$mode $::srcfile $options] } {
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return
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}
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if { ![runto marker1] } {
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return
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}
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# Activate process record/replay
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gdb_test_no_output "record" "turn on process record"
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gdb_test_no_output "set record full stop-at-limit on"
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gdb_test_no_output "set record full insn-number-max 2000"
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set re_srcfile [string_to_regexp $::srcfile]
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gdb_test "break marker2" \
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"Breakpoint $::decimal at $::hex: file .*$re_srcfile, line $::decimal.*" \
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"set breakpoint at marker2"
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set re_question \
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[string_list_to_regexp \
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"Do you want to auto delete previous execution log entries when" \
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" record/replay buffer becomes full" \
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{ (record full stop-at-limit)?([y] or n)}]
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set re_program_stopped \
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[multi_line \
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[string_to_regexp "Process record: stopped by user."] \
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"" \
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[string_to_regexp "Program stopped."]]
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set re_marker2 [string_to_regexp "marker2 ()"]
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gdb_test_multiple "continue" "continue to breakpoint: marker2" {
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-re "$re_question " {
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send_gdb "n\n"
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exp_continue
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}
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-re -wrap "Breakpoint $::decimal, $re_marker2 .*" {
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pass $gdb_test_name
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}
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-re -wrap "\r\n$re_program_stopped\r\n.*" {
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unsupported $gdb_test_name
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}
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}
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# Show how many instructions we've recorded.
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gdb_test "info record" "Active record target: .*"
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gdb_test "reverse-continue" ".*$re_srcfile:$::decimal.*" "reverse to marker1"
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# If the variable was recorded properly, the old contents (-1)
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# will be remembered. If not, new contents (current time) will be
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# used, and the test will fail.
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gdb_test "print time_global" ".* = -1" "check time record"
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}
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# Test both using the syscall explicitly, and using the time(2) C
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# function.
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#
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# The C variant ensures that if some platform uses some syscall we are
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# not aware of yet, we'll still exercise it (and likely fail).
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#
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# The explicit syscall variant is useful on platforms where the C
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# function does not call a syscall at all by default, e.g., on some
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# systems the C time function wraps an implementation provided by the
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# vDSO.
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foreach_with_prefix mode {syscall c} {
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if {$mode == "syscall" && ![have_syscall time]} {
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continue
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}
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test $mode
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}
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