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Message-ID: <20191015145801.GA9922@redhat.com>
Date: Tue, 15 Oct 2019 10:58:01 -0400
From: Joe Lawrence <joe.lawrence@...hat.com>
To: Miroslav Benes <mbenes@...e.cz>
Cc: rostedt@...dmis.org, mingo@...hat.com, jpoimboe@...hat.com,
jikos@...nel.org, pmladek@...e.com, linux-kernel@...r.kernel.org,
live-patching@...r.kernel.org
Subject: Re: [PATCH v2] ftrace: Introduce PERMANENT ftrace_ops flag
On Tue, Oct 15, 2019 at 01:23:10PM +0200, Miroslav Benes wrote:
> > Hi Miroslav,
> >
> > Maybe we should add a test to verify this new behavior? See sample
> > version below (lightly tested). We can add to this one, or patch
> > seperately if you prefer.
>
> Thanks a lot, Joe. It looks nice. I'll include it in v3. One question
> below.
>
> [ ... snip ... ]
>
> Shouldn't we call push_ftrace_enabled() somewhere at the beginning of the
> test script? set_dynamic_debug() calls its push_dynamic_debug() directly,
> but set_ftrace_enabled() is different, because it is called more than once
> in the script.
>
> One could argue that ftrace_enabled has to be true at the beginning of
> testing anyway, but I think it would be cleaner. Btw, we should probably
> guarantee that ftrace_enabled is true when livepatch selftests are
> invoked.
>
Here's a new version that combines the ftrace_enabled configuration with
the debugfs stuff (so its only pushed/pop once per test) and updates all
the tests accordingly. Feel free to any tweaks or flourishes when
adding to v3.
Thanks,
-- Joe
-->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8-- -->8--
>From a22ca55b3f429b7c9ceed6be87a571f77520994c Mon Sep 17 00:00:00 2001
From: Joe Lawrence <joe.lawrence@...hat.com>
Date: Tue, 15 Oct 2019 10:33:18 -0400
Subject: [PATCH] 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.
Signed-off-by: Joe Lawrence <joe.lawrence@...hat.com>
---
tools/testing/selftests/livepatch/Makefile | 3 +-
.../testing/selftests/livepatch/functions.sh | 34 +++++++---
.../selftests/livepatch/test-callbacks.sh | 2 +-
.../selftests/livepatch/test-ftrace.sh | 65 +++++++++++++++++++
.../selftests/livepatch/test-livepatch.sh | 2 +-
.../selftests/livepatch/test-shadow-vars.sh | 2 +-
6 files changed, 95 insertions(+), 13 deletions(-)
create mode 100755 tools/testing/selftests/livepatch/test-ftrace.sh
diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
index fd405402c3ff..1886d9d94b88 100644
--- a/tools/testing/selftests/livepatch/Makefile
+++ b/tools/testing/selftests/livepatch/Makefile
@@ -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
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index 79b0affd21fb..31eb09e38729 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -29,29 +29,45 @@ function die() {
exit 1
}
-function push_dynamic_debug() {
- DYNAMIC_DEBUG=$(grep '^kernel/livepatch' /sys/kernel/debug/dynamic_debug/control | \
- awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}')
+function push_config() {
+ DYNAMIC_DEBUG=$(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_dynamic_debug() {
+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
}
-# set_dynamic_debug() - save the current dynamic debug config and tweak
-# it for the self-tests. Set a script exit trap
-# that restores the original config.
function set_dynamic_debug() {
- push_dynamic_debug
- trap pop_dynamic_debug EXIT INT TERM HUP
cat <<-EOF > /sys/kernel/debug/dynamic_debug/control
file kernel/livepatch/* +p
func klp_try_switch_task -p
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 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
+}
+
# loop_until(cmd) - loop a command until it is successful or $MAX_RETRIES,
# sleep $RETRY_INTERVAL between attempts
# cmd - command and its arguments to run
diff --git a/tools/testing/selftests/livepatch/test-callbacks.sh b/tools/testing/selftests/livepatch/test-callbacks.sh
index e97a9dcb73c7..a35289b13c9c 100755
--- a/tools/testing/selftests/livepatch/test-callbacks.sh
+++ b/tools/testing/selftests/livepatch/test-callbacks.sh
@@ -9,7 +9,7 @@ MOD_LIVEPATCH2=test_klp_callbacks_demo2
MOD_TARGET=test_klp_callbacks_mod
MOD_TARGET_BUSY=test_klp_callbacks_busy
-set_dynamic_debug
+setup_config
# TEST: target module before livepatch
diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh
new file mode 100755
index 000000000000..e2a76887f40a
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test-ftrace.sh
@@ -0,0 +1,65 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2019 Joe Lawrence <joe.lawrence@...hat.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
diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index f05268aea859..493e3df415a1 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -7,7 +7,7 @@
MOD_LIVEPATCH=test_klp_livepatch
MOD_REPLACE=test_klp_atomic_replace
-set_dynamic_debug
+setup_config
# TEST: basic function patching
diff --git a/tools/testing/selftests/livepatch/test-shadow-vars.sh b/tools/testing/selftests/livepatch/test-shadow-vars.sh
index 04a37831e204..1aae73299114 100755
--- a/tools/testing/selftests/livepatch/test-shadow-vars.sh
+++ b/tools/testing/selftests/livepatch/test-shadow-vars.sh
@@ -6,7 +6,7 @@
MOD_TEST=test_klp_shadow_vars
-set_dynamic_debug
+setup_config
# TEST: basic shadow variable API
--
2.21.0
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