105 lines
3.5 KiB
Text
105 lines
3.5 KiB
Text
# Copyright 2018-2022 Free Software Foundation, Inc.
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#
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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 test script tries to expose a bug in some of the uses of
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# waitpid in the Linux native support within GDB. The problem was
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# spotted on systems which were heavily loaded when attaching to
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# threaded test programs. What happened was that during the initial
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# attach, the loop of waitpid calls that normally received the stop
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# events from each of the threads in the inferior was not receiving a
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# stop event for some threads (the kernel just hadn't sent the stop
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# event yet).
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#
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# GDB would then trigger a call to stop_all_threads which would
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# continue to wait for all of the outstanding threads to stop, when
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# the outstanding stop events finally arrived GDB would then
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# (incorrectly) discard the stop event, resume the thread, and
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# continue to wait for the thread to stop.... which it now never
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# would.
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#
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# In order to try and expose this issue reliably, this test preloads a
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# library that intercepts waitpid calls. All waitpid calls targeting
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# pid -1 with the WNOHANG flag are rate limited so that only 1 per
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# second can complete. Additional calls are forced to return 0
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# indicating no event waiting. This is enough to trigger the bug
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# during the attach phase.
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# This test only works on Linux
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if { ![isnative] || [is_remote host] || [use_gdb_stub]
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|| ![istarget *-linux*] } {
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return
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}
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standard_testfile
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set libfile slow-waitpid
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set libsrc "${srcdir}/${subdir}/${libfile}.c"
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set libobj [standard_output_file ${libfile}.so]
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with_test_prefix "compile preload library" {
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# Compile the preload library. We only get away with this as we
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# limit this test to running when ISNATIVE is true.
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if { [gdb_compile_shlib_pthreads \
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$libsrc $libobj {debug}] != "" } then {
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return -1
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}
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}
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with_test_prefix "compile test executable" {
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# Compile the test program
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if { [gdb_compile_pthreads \
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"${srcdir}/${subdir}/${srcfile}" "${binfile}" \
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executable {debug}] != "" } {
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return -1
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}
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}
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# Spawn GDB with LIB preloaded with LD_PRELOAD.
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proc gdb_spawn_with_ld_preload {lib} {
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global env
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save_vars { env(LD_PRELOAD) } {
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if { ![info exists env(LD_PRELOAD) ]
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|| $env(LD_PRELOAD) == "" } {
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set env(LD_PRELOAD) "$lib"
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} else {
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append env(LD_PRELOAD) ":$lib"
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}
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gdb_start
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}
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}
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# Run test program in the background.
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set test_spawn_id [spawn_wait_for_attach $binfile]
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set testpid [spawn_id_get_pid $test_spawn_id]
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# Start GDB with preload library in place.
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if { [gdb_spawn_with_ld_preload $libobj] == -1 } {
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# Make sure we get UNTESTED rather than UNRESOLVED.
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set errcnt 0
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untested "Couldn't start GDB with preloaded lib"
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return -1
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}
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# Load binary, and attach to running program.
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gdb_load ${binfile}
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gdb_test "attach $testpid" "Attaching to program.*" "attach to target"
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gdb_exit
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# Kill of test program.
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kill_wait_spawned_process $test_spawn_id
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