From 7cfa8d93cbbe16424fe2190cb3d27fc94c59f39b Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Wed, 10 Nov 2021 12:55:55 +0100 Subject: [PATCH] [gdb/testsuite] Add gdb.opt/break-on-_exit.exp Add a test-case to excercise the problem scenario reported in PR28527 and fixed in commit a50bdb99afe "[gdb/tdep, rs6000] Don't skip system call in skip_prologue": - set a breakpoint on _exit, and - verify that it triggers. Note that this is not a regression test for that commit. Since the actual code in _exit may vary across os instances, we cannot guarantee that the problem will always trigger with this test-case. Rather, this test-case is a version of the original test-case (gdb.threads/process-dies-while-detaching.exp) that is minimal while still reproducing the problem reported in PR28527, in that same setting. The benefit of this test-case is that it exercise real-life code and may expose similar problems in other settings. Also, it provides a much easier test-case to investigate in case a similar problem occurs. Tested on x86_64-linux and ppc64le-linux. --- gdb/testsuite/gdb.opt/break-on-_exit.c | 26 ++++++++++ gdb/testsuite/gdb.opt/break-on-_exit.exp | 66 ++++++++++++++++++++++++ 2 files changed, 92 insertions(+) create mode 100644 gdb/testsuite/gdb.opt/break-on-_exit.c create mode 100644 gdb/testsuite/gdb.opt/break-on-_exit.exp diff --git a/gdb/testsuite/gdb.opt/break-on-_exit.c b/gdb/testsuite/gdb.opt/break-on-_exit.c new file mode 100644 index 00000000000..d8da66193a8 --- /dev/null +++ b/gdb/testsuite/gdb.opt/break-on-_exit.c @@ -0,0 +1,26 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2021 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 . */ + +#include + +int +main (void) +{ + _exit (0); + + return 0; +} diff --git a/gdb/testsuite/gdb.opt/break-on-_exit.exp b/gdb/testsuite/gdb.opt/break-on-_exit.exp new file mode 100644 index 00000000000..38476412862 --- /dev/null +++ b/gdb/testsuite/gdb.opt/break-on-_exit.exp @@ -0,0 +1,66 @@ +# Copyright 2021 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 . */ + +# Set a breakpoint on libc's _exit, and verify that it triggers. The function +# tends to do a syscall immediately after the prologue, and if the breakpoint is +# set past the syscall due to faulty prologue skipping, the breakpoint will not +# trigger. +# +# In particular, we're trying to excercise the instruction analysis +# functionality of prologue skipping. If the non-minimal symbols are +# read for libc, then that functionality might not be used because f.i. +# line-info is used instead. Also, if the minimal symbols are not read +# for libc, then the breakpoint is set on the exec-local _exit@plt instead, +# and that functionality will also not be used. +# +# We may get the required setup in case of a libc with misssing separate +# debuginfo, but we want the same effect if that debuginfo is installed. +# +# So, we use -readnever to read minimal symbols, but not non-miminal symbols. +# +# Because the code at _exit may be and usually is optimized, the test is in +# the gdb.opt directory. + +standard_testfile + +# See if we have target board readnow.exp or similar. +if { [lsearch -exact $GDBFLAGS -readnow] != -1 \ + || [lsearch -exact $GDBFLAGS --readnow] != -1 } { + untested "--readnever not allowed in combination with --readnow" + return -1 +} + +save_vars { GDBFLAGS } { + append GDBFLAGS " -readnever" + + if {[prepare_for_testing "failed to prepare" $testfile $srcfile nodebug]} { + return -1 + } +} + +if ![runto_main] then { + return 0 +} + +gdb_breakpoint "_exit" + +# Give some background information about the breakpoint(s) and corresponding +# the shared lib(s). +gdb_test "info breakpoints" +gdb_test "info shared" + +# If the skip_prologue analysis of _exit is too eager, we may not hit the +# breakpoint. +gdb_continue_to_breakpoint "_exit" "_exit \\(\\) .*" -- 2.30.2