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selftests/livepatch: Test interaction with ftrace_enabled 

Since livepatching depends upon ftrace handlers to implement "patched"
code functionality, verify that the ftrace_enabled sysctl value
interacts with livepatch registration as expected.  At the same time,
ensure that ftrace_enabled is set and part of the test environment
configuration that is saved and restored when running the selftests.

Link: http://lkml.kernel.org/r/20191016113316.13415-4-mbenes@suse.cz

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Joe Lawrence 2019-10-16 13:33:15 +02:00 committed by Steven Rostedt
parent 35c9e74cff
commit 8c666d2ab5
3 changed files with 80 additions and 2 deletions
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3
tools/testing/selftests/livepatch/Makefile
View File

@ -4,6 +4,7 @@ TEST_PROGS_EXTENDED := functions.sh
TEST_PROGS := \
test-livepatch.sh \
test-callbacks.sh \
test-shadow-vars.sh
test-shadow-vars.sh \
test-ftrace.sh
include ../lib.mk

14
tools/testing/selftests/livepatch/functions.sh
View File

@ -32,12 +32,16 @@ function die() {
function push_config() {
DYNAMIC_DEBUG=$(grep '^kernel/livepatch' /sys/kernel/debug/dynamic_debug/control | \
awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}')
FTRACE_ENABLED=$(sysctl --values kernel.ftrace_enabled)
}
function pop_config() {
if [[ -n "$DYNAMIC_DEBUG" ]]; then
echo -n "$DYNAMIC_DEBUG" > /sys/kernel/debug/dynamic_debug/control
fi
if [[ -n "$FTRACE_ENABLED" ]]; then
sysctl kernel.ftrace_enabled="$FTRACE_ENABLED" &> /dev/null
fi
}
function set_dynamic_debug() {
@ -47,12 +51,20 @@ function set_dynamic_debug() {
EOF
}
function set_ftrace_enabled() {
local sysctl="$1"
result=$(sysctl kernel.ftrace_enabled="$1" 2>&1 | paste --serial --delimiters=' ')
echo "livepatch: $result" > /dev/kmsg
}
# setup_config - save the current config and set a script exit trap that
# restores the original config. Setup the dynamic debug
# for verbose livepatching output.
# for verbose livepatching output and turn on
# the ftrace_enabled sysctl.
function setup_config() {
push_config
set_dynamic_debug
set_ftrace_enabled 1
trap pop_config EXIT INT TERM HUP
}

65
tools/testing/selftests/livepatch/test-ftrace.sh Executable file
View File

@ -0,0 +1,65 @@
#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
. $(dirname $0)/functions.sh
MOD_LIVEPATCH=test_klp_livepatch
setup_config
# TEST: livepatch interaction with ftrace_enabled sysctl
# - turn ftrace_enabled OFF and verify livepatches can't load
# - turn ftrace_enabled ON and verify livepatch can load
# - verify that ftrace_enabled can't be turned OFF while a livepatch is loaded
echo -n "TEST: livepatch interaction with ftrace_enabled sysctl ... "
dmesg -C
set_ftrace_enabled 0
load_failing_mod $MOD_LIVEPATCH
set_ftrace_enabled 1
load_lp $MOD_LIVEPATCH
if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
echo -e "FAIL\n\n"
die "livepatch kselftest(s) failed"
fi
set_ftrace_enabled 0
if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
echo -e "FAIL\n\n"
die "livepatch kselftest(s) failed"
fi
disable_lp $MOD_LIVEPATCH
unload_lp $MOD_LIVEPATCH
check_result "livepatch: kernel.ftrace_enabled = 0
% modprobe $MOD_LIVEPATCH
livepatch: enabling patch '$MOD_LIVEPATCH'
livepatch: '$MOD_LIVEPATCH': initializing patching transition
livepatch: failed to register ftrace handler for function 'cmdline_proc_show' (-16)
livepatch: failed to patch object 'vmlinux'
livepatch: failed to enable patch '$MOD_LIVEPATCH'
livepatch: '$MOD_LIVEPATCH': canceling patching transition, going to unpatch
livepatch: '$MOD_LIVEPATCH': completing unpatching transition
livepatch: '$MOD_LIVEPATCH': unpatching complete
modprobe: ERROR: could not insert '$MOD_LIVEPATCH': Device or resource busy
livepatch: kernel.ftrace_enabled = 1
% modprobe $MOD_LIVEPATCH
livepatch: enabling patch '$MOD_LIVEPATCH'
livepatch: '$MOD_LIVEPATCH': initializing patching transition
livepatch: '$MOD_LIVEPATCH': starting patching transition
livepatch: '$MOD_LIVEPATCH': completing patching transition
livepatch: '$MOD_LIVEPATCH': patching complete
livepatch: sysctl: setting key \"kernel.ftrace_enabled\": Device or resource busy kernel.ftrace_enabled = 0
% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled
livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
livepatch: '$MOD_LIVEPATCH': starting unpatching transition
livepatch: '$MOD_LIVEPATCH': completing unpatching transition
livepatch: '$MOD_LIVEPATCH': unpatching complete
% rmmod $MOD_LIVEPATCH"
exit 0