[PATCH v2 0/2] add sysfs entry "patched" for each klp_object

[PATCH v2 0/2] add sysfs entry "patched" for each klp_object

[Song Liu]

I was debugging an issue that a livepatch appears to be attached, but
actually not. It turns out that there is a mismatch in module name
(abc-xyz vs. abc_xyz), klp_find_object_module failed to find the module.

Changes v1 => v2:
1. Add selftest. (Petr Mladek)
2. Update documentation. (Petr Mladek)
3. Use sysfs_emit. (Petr Mladek)

Song Liu (2):
  livepatch: add sysfs entry "patched" for each klp_object
  selftests/livepatch: add sysfs test

 .../ABI/testing/sysfs-kernel-livepatch        |  8 ++++
 kernel/livepatch/core.c                       | 18 +++++++++
 tools/testing/selftests/livepatch/Makefile    |  3 +-
 .../testing/selftests/livepatch/test-sysfs.sh | 40 +++++++++++++++++++
 4 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/livepatch/test-sysfs.sh

--
2.30.2

[PATCH v2 1/2] livepatch: add sysfs entry "patched" for each klp_object

[Song Liu]

Add per klp_object sysfs entry "patched". It makes it easier to debug
typos in the module name.

Signed-off-by: Song Liu <song@kernel.org>
---
I was debugging an issue that a livepatch appears to be attached, but
actually not. It turns out that there is a mismatch in module name
(abc-xyz vs. abc_xyz), klp_find_object_module failed to find the module.
---
 .../ABI/testing/sysfs-kernel-livepatch         |  8 ++++++++
 kernel/livepatch/core.c                        | 18 ++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
index bea7bd5a1d5f..ebe39a3cea39 100644
--- a/Documentation/ABI/testing/sysfs-kernel-livepatch
+++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
@@ -55,6 +55,14 @@ Description:
 		The object directory contains subdirectories for each function
 		that is patched within the object.
 
+What:		/sys/kernel/livepatch/<patch>/<object>/patched
+Date:		August 2022
+KernelVersion:	6.0.0
+Contact:	live-patching@vger.kernel.org
+Description:
+		An attribute which indicates whether the object is currently
+		patched.
+
 What:		/sys/kernel/livepatch/<patch>/<object>/<function,sympos>
 Date:		Nov 2014
 KernelVersion:	3.19.0
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index bc475e62279d..67eb9f9168f3 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -325,6 +325,7 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
  * /sys/kernel/livepatch/<patch>/transition
  * /sys/kernel/livepatch/<patch>/force
  * /sys/kernel/livepatch/<patch>/<object>
+ * /sys/kernel/livepatch/<patch>/<object>/patched
  * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
  */
 static int __klp_disable_patch(struct klp_patch *patch);
@@ -431,6 +432,22 @@ static struct attribute *klp_patch_attrs[] = {
 };
 ATTRIBUTE_GROUPS(klp_patch);
 
+static ssize_t patched_show(struct kobject *kobj,
+			    struct kobj_attribute *attr, char *buf)
+{
+	struct klp_object *obj;
+
+	obj = container_of(kobj, struct klp_object, kobj);
+	return sysfs_emit(buf, "%d\n", obj->patched);
+}
+
+static struct kobj_attribute patched_kobj_attr = __ATTR_RO(patched);
+static struct attribute *klp_object_attrs[] = {
+	&patched_kobj_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(klp_object);
+
 static void klp_free_object_dynamic(struct klp_object *obj)
 {
 	kfree(obj->name);
@@ -576,6 +593,7 @@ static void klp_kobj_release_object(struct kobject *kobj)
 static struct kobj_type klp_ktype_object = {
 	.release = klp_kobj_release_object,
 	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = klp_object_groups,
 };
 
 static void klp_kobj_release_func(struct kobject *kobj)
-- 
2.30.2

[PATCH v2 2/2] selftests/livepatch: add sysfs test

[Song Liu]

Add a test for livepatch sysfs entries.

Signed-off-by: Song Liu <song@kernel.org>
---
 tools/testing/selftests/livepatch/Makefile    |  3 +-
 .../testing/selftests/livepatch/test-sysfs.sh | 40 +++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100755 tools/testing/selftests/livepatch/test-sysfs.sh

diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
index 1acc9e1fa3fb..02fadc9d55e0 100644
--- a/tools/testing/selftests/livepatch/Makefile
+++ b/tools/testing/selftests/livepatch/Makefile
@@ -6,7 +6,8 @@ TEST_PROGS := \
 	test-callbacks.sh \
 	test-shadow-vars.sh \
 	test-state.sh \
-	test-ftrace.sh
+	test-ftrace.sh \
+	test-sysfs.sh
 
 TEST_FILES := settings
 
diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
new file mode 100755
index 000000000000..eb4a69ba1c2c
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test-sysfs.sh
@@ -0,0 +1,40 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2022 Song Liu <song@kernel.org>
+
+. $(dirname $0)/functions.sh
+
+MOD_LIVEPATCH=test_klp_livepatch
+
+setup_config
+
+# - load a livepatch and verifies the sysfs entries work as expected
+
+start_test "sysfs test"
+
+load_lp $MOD_LIVEPATCH
+
+grep . "/sys/kernel/livepatch/$MOD_LIVEPATCH"/* > /dev/kmsg
+grep . "/sys/kernel/livepatch/$MOD_LIVEPATCH"/*/* > /dev/kmsg
+
+disable_lp $MOD_LIVEPATCH
+
+unload_lp $MOD_LIVEPATCH
+
+check_result "% 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
+/sys/kernel/livepatch/test_klp_livepatch/enabled:1
+/sys/kernel/livepatch/test_klp_livepatch/transition:0
+/sys/kernel/livepatch/test_klp_livepatch/vmlinux/patched:1
+% 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
-- 
2.30.2

Re: [PATCH v2 2/2] selftests/livepatch: add sysfs test

[Joe Lawrence]

On Mon, Aug 01, 2022 at 06:08:57PM -0700, Song Liu wrote:
> Add a test for livepatch sysfs entries.
> 
> Signed-off-by: Song Liu <song@kernel.org>
> ---
>  tools/testing/selftests/livepatch/Makefile    |  3 +-
>  .../testing/selftests/livepatch/test-sysfs.sh | 40 +++++++++++++++++++
>  2 files changed, 42 insertions(+), 1 deletion(-)
>  create mode 100755 tools/testing/selftests/livepatch/test-sysfs.sh
> 
> diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
> index 1acc9e1fa3fb..02fadc9d55e0 100644
> --- a/tools/testing/selftests/livepatch/Makefile
> +++ b/tools/testing/selftests/livepatch/Makefile
> @@ -6,7 +6,8 @@ TEST_PROGS := \
>  	test-callbacks.sh \
>  	test-shadow-vars.sh \
>  	test-state.sh \
> -	test-ftrace.sh
> +	test-ftrace.sh \
> +	test-sysfs.sh
>  
>  TEST_FILES := settings
>  
> diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
> new file mode 100755
> index 000000000000..eb4a69ba1c2c
> --- /dev/null
> +++ b/tools/testing/selftests/livepatch/test-sysfs.sh
> @@ -0,0 +1,40 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2022 Song Liu <song@kernel.org>
> +
> +. $(dirname $0)/functions.sh
> +
> +MOD_LIVEPATCH=test_klp_livepatch
> +
> +setup_config
> +
> +# - load a livepatch and verifies the sysfs entries work as expected
> +
> +start_test "sysfs test"
> +
> +load_lp $MOD_LIVEPATCH
> +
> +grep . "/sys/kernel/livepatch/$MOD_LIVEPATCH"/* > /dev/kmsg
> +grep . "/sys/kernel/livepatch/$MOD_LIVEPATCH"/*/* > /dev/kmsg

Clever grep.  I like to use `head -n100 <pattern>` to dump debugging
filenames and content, but this "grep anything" is nice for one liner
files :)

> +
> +disable_lp $MOD_LIVEPATCH
> +
> +unload_lp $MOD_LIVEPATCH
> +
> +check_result "% 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
> +/sys/kernel/livepatch/test_klp_livepatch/enabled:1
> +/sys/kernel/livepatch/test_klp_livepatch/transition:0
> +/sys/kernel/livepatch/test_klp_livepatch/vmlinux/patched:1
> +% 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
> -- 
> 2.30.2
> 

The patch and test look fine.  I wonder how we'll modify these type of
tests if we can decouple the selftests from the kernel version.  In that
case we may need to individually verify files only if they exist.  The
upside to this version is that it will remind anyone who adds another
file to update the expected check_result value.

Also, I believe Red Hat QE has a few internal tests that verify sysfs
values during transitions, etc.  I'll inquire about those in case we can
follow up with even more sysfs verification.

--
Joe

Re: [PATCH v2 0/2] add sysfs entry "patched" for each klp_object

[Joe Lawrence]

On Mon, Aug 01, 2022 at 06:08:55PM -0700, Song Liu wrote:
> I was debugging an issue that a livepatch appears to be attached, but
> actually not. It turns out that there is a mismatch in module name
> (abc-xyz vs. abc_xyz), klp_find_object_module failed to find the module.
> 
> Changes v1 => v2:
> 1. Add selftest. (Petr Mladek)
> 2. Update documentation. (Petr Mladek)
> 3. Use sysfs_emit. (Petr Mladek)
> 
> Song Liu (2):
>   livepatch: add sysfs entry "patched" for each klp_object
>   selftests/livepatch: add sysfs test
> 
>  .../ABI/testing/sysfs-kernel-livepatch        |  8 ++++
>  kernel/livepatch/core.c                       | 18 +++++++++
>  tools/testing/selftests/livepatch/Makefile    |  3 +-
>  .../testing/selftests/livepatch/test-sysfs.sh | 40 +++++++++++++++++++
>  4 files changed, 68 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/livepatch/test-sysfs.sh
> 
> --
> 2.30.2
> 

For both,

Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com>

--
Joe

Re: [PATCH v2 0/2] add sysfs entry "patched" for each klp_object

[Song Liu]

On Tue, Aug 2, 2022 at 2:37 PM Joe Lawrence <joe.lawrence@redhat.com> wrote:
>
> On Mon, Aug 01, 2022 at 06:08:55PM -0700, Song Liu wrote:
> > I was debugging an issue that a livepatch appears to be attached, but
> > actually not. It turns out that there is a mismatch in module name
> > (abc-xyz vs. abc_xyz), klp_find_object_module failed to find the module.
> >
> > Changes v1 => v2:
> > 1. Add selftest. (Petr Mladek)
> > 2. Update documentation. (Petr Mladek)
> > 3. Use sysfs_emit. (Petr Mladek)
> >
> > Song Liu (2):
> >   livepatch: add sysfs entry "patched" for each klp_object
> >   selftests/livepatch: add sysfs test
> >
> >  .../ABI/testing/sysfs-kernel-livepatch        |  8 ++++
> >  kernel/livepatch/core.c                       | 18 +++++++++
> >  tools/testing/selftests/livepatch/Makefile    |  3 +-
> >  .../testing/selftests/livepatch/test-sysfs.sh | 40 +++++++++++++++++++
> >  4 files changed, 68 insertions(+), 1 deletion(-)
> >  create mode 100644 tools/testing/selftests/livepatch/test-sysfs.sh
> >
> > --
> > 2.30.2
> >
>
> For both,
>
> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com>

Hi folks,

Do we need more work for this set?

Thanks,
Song

Re: [PATCH v2 1/2] livepatch: add sysfs entry "patched" for each klp_object

[Petr Mladek]

On Mon 2022-08-01 18:08:56, Song Liu wrote:
> Add per klp_object sysfs entry "patched". It makes it easier to debug
> typos in the module name.
> 
> Signed-off-by: Song Liu <song@kernel.org>

Looks good to me:

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

Re: [PATCH v2 2/2] selftests/livepatch: add sysfs test

[Petr Mladek]

On Mon 2022-08-01 18:08:57, Song Liu wrote:
> Add a test for livepatch sysfs entries.
> 
> Signed-off-by: Song Liu <song@kernel.org>
> ---
>  tools/testing/selftests/livepatch/Makefile    |  3 +-
>  .../testing/selftests/livepatch/test-sysfs.sh | 40 +++++++++++++++++++
>  2 files changed, 42 insertions(+), 1 deletion(-)
>  create mode 100755 tools/testing/selftests/livepatch/test-sysfs.sh
> 
> diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
> index 1acc9e1fa3fb..02fadc9d55e0 100644
> --- a/tools/testing/selftests/livepatch/Makefile
> +++ b/tools/testing/selftests/livepatch/Makefile
> @@ -6,7 +6,8 @@ TEST_PROGS := \
>  	test-callbacks.sh \
>  	test-shadow-vars.sh \
>  	test-state.sh \
> -	test-ftrace.sh
> +	test-ftrace.sh \
> +	test-sysfs.sh
>  
>  TEST_FILES := settings
>  
> diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
> new file mode 100755
> index 000000000000..eb4a69ba1c2c
> --- /dev/null
> +++ b/tools/testing/selftests/livepatch/test-sysfs.sh
> @@ -0,0 +1,40 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2022 Song Liu <song@kernel.org>
> +
> +. $(dirname $0)/functions.sh
> +
> +MOD_LIVEPATCH=test_klp_livepatch
> +
> +setup_config
> +
> +# - load a livepatch and verifies the sysfs entries work as expected
> +
> +start_test "sysfs test"
> +
> +load_lp $MOD_LIVEPATCH
> +
> +grep . "/sys/kernel/livepatch/$MOD_LIVEPATCH"/* > /dev/kmsg
> +grep . "/sys/kernel/livepatch/$MOD_LIVEPATCH"/*/* > /dev/kmsg
> +

I see the following when I run the test:

host:kernel/linux/tools/testing/selftests/livepatch # ./test-sysfs.sh 
TEST: sysfs test ... grep: /sys/kernel/livepatch/test_klp_livepatch/force: Permission denied
grep: /sys/kernel/livepatch/test_klp_livepatch/vmlinux: Is a directory
grep: /sys/kernel/livepatch/test_klp_livepatch/vmlinux/cmdline_proc_show,1: Is a directory
ok

The errors are expected. A solution would be to redirect 2>&1 or
2>/dev/null. Both looks a bit ugly to me.

Instead, I would suggest to create some helper scripts in functions.sh,
for example:

# check_sysfs_exists(modname, rel_path, expected_rights) - check sysfs interface
#	modname - livepatch module creating the sysfs interface
#	rel_patch - relative patch of the sysfs interface
#	expected_rights - expected access rights
function check_sysfs_rights() {
	local mod="$1"; shift
	local rel_path="$1"; shift
	local expected_rights="$1"; shift

	local path="$KLP_SYSFS_DIR/$mod/$rel_path"
	local rights=`ls -l -d $path | cut -d " " -f 1`

	if test "$rights" != "$expected_rights" ; then
	    die "Unexpected access rights of $path: $expected_rights vs. $rights"
	fi
}

# check_sysfs_exists(modname, rel_path, expected_value) - check sysfs interface
#	modname - livepatch module creating the sysfs interface
#	rel_patch - relative patch of the sysfs interface
#	expected_value - expected value read from the file
function check_sysfs_value() {
	local mod="$1"; shift
	local rel_path="$1"; shift
	local expected_value="$1"; shift

	local path="$KLP_SYSFS_DIR/$mod/$rel_path"
	local value=`cat $path`

	if test "$value" != "$expected_value" ; then
	    die "Unexpected value in $path: $expected_value vs. $value"
	fi
}

It would allow to create a fine tuned tests, for example:

check_sysfs_rights "$MOD_LIVEPATCH" "" "drwxr-xr-x"
check_sysfs_rights "$MOD_LIVEPATCH" "enabled" "-rw-r--r--"

check_sysfs_value  "$MOD_LIVEPATCH" "enabled" "1"



Also it would be great to test that the "patched" value is "0"
when the object is not patched. I would require to create
a test module that might be livepatched. I mean something like:


check_sysfs_value  $MOD_LIVEPATCH "$TEST_MODULE/patched" "0"
load_mod $TEST_MODULE
check_sysfs_value  $MOD_LIVEPATCH "$TEST_MODULE/patched" "1"
unload_mod $TEST_MODULE
check_sysfs_value  $MOD_LIVEPATCH "$TEST_MODULE/patched" "0"


Best Regards,
Petr

Re: [PATCH v2 2/2] selftests/livepatch: add sysfs test

[Joe Lawrence]

On 9/2/22 8:37 AM, Petr Mladek wrote:
> On Mon 2022-08-01 18:08:57, Song Liu wrote:
>> Add a test for livepatch sysfs entries.
>>
>> Signed-off-by: Song Liu <song@kernel.org>
>> ---
>>  tools/testing/selftests/livepatch/Makefile    |  3 +-
>>  .../testing/selftests/livepatch/test-sysfs.sh | 40 +++++++++++++++++++
>>  2 files changed, 42 insertions(+), 1 deletion(-)
>>  create mode 100755 tools/testing/selftests/livepatch/test-sysfs.sh
>>
>> diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile
>> index 1acc9e1fa3fb..02fadc9d55e0 100644
>> --- a/tools/testing/selftests/livepatch/Makefile
>> +++ b/tools/testing/selftests/livepatch/Makefile
>> @@ -6,7 +6,8 @@ TEST_PROGS := \
>>  	test-callbacks.sh \
>>  	test-shadow-vars.sh \
>>  	test-state.sh \
>> -	test-ftrace.sh
>> +	test-ftrace.sh \
>> +	test-sysfs.sh
>>  
>>  TEST_FILES := settings
>>  
>> diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
>> new file mode 100755
>> index 000000000000..eb4a69ba1c2c
>> --- /dev/null
>> +++ b/tools/testing/selftests/livepatch/test-sysfs.sh
>> @@ -0,0 +1,40 @@
>> +#!/bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +# Copyright (C) 2022 Song Liu <song@kernel.org>
>> +
>> +. $(dirname $0)/functions.sh
>> +
>> +MOD_LIVEPATCH=test_klp_livepatch
>> +
>> +setup_config
>> +
>> +# - load a livepatch and verifies the sysfs entries work as expected
>> +
>> +start_test "sysfs test"
>> +
>> +load_lp $MOD_LIVEPATCH
>> +
>> +grep . "/sys/kernel/livepatch/$MOD_LIVEPATCH"/* > /dev/kmsg
>> +grep . "/sys/kernel/livepatch/$MOD_LIVEPATCH"/*/* > /dev/kmsg
>> +
> 
> I see the following when I run the test:
> 
> host:kernel/linux/tools/testing/selftests/livepatch # ./test-sysfs.sh 
> TEST: sysfs test ... grep: /sys/kernel/livepatch/test_klp_livepatch/force: Permission denied
> grep: /sys/kernel/livepatch/test_klp_livepatch/vmlinux: Is a directory
> grep: /sys/kernel/livepatch/test_klp_livepatch/vmlinux/cmdline_proc_show,1: Is a directory
> ok
> 
> The errors are expected. A solution would be to redirect 2>&1 or
> 2>/dev/null. Both looks a bit ugly to me.
> 
> Instead, I would suggest to create some helper scripts in functions.sh,
> for example:
> 

I realize this was just a code sketch, but a few ideas before
copy/pasting the functions :)

> # check_sysfs_exists(modname, rel_path, expected_rights) - check sysfs interface

# check_sysfs_rights(modname, rel_path, expected_rights) - check sysfs
path permissions

> #	modname - livepatch module creating the sysfs interface
> #	rel_patch - relative patch of the sysfs interface

s/patch/path

> #	expected_rights - expected access rights
> function check_sysfs_rights() {
> 	local mod="$1"; shift
> 	local rel_path="$1"; shift
> 	local expected_rights="$1"; shift
> 
> 	local path="$KLP_SYSFS_DIR/$mod/$rel_path"

Checking for existence here might be cleaner than failing later.  Unless
the caller is going to do it first.  Or should we just have a
check_sysfs_exists() like your function comments hint at?

> 	local rights=`ls -l -d $path | cut -d " " -f 1`

$(/bin/stat --format '%A' "$path") easier?

> 
> 	if test "$rights" != "$expected_rights" ; then
> 	    die "Unexpected access rights of $path: $expected_rights vs. $rights"
> 	fi
> }
> 
> # check_sysfs_exists(modname, rel_path, expected_value) - check sysfs interface

# check_sysfs_value(modname, rel_path, expected_value) - check sysfs value

> #	modname - livepatch module creating the sysfs interface
> #	rel_patch - relative patch of the sysfs interface

s/patch/path

> #	expected_value - expected value read from the file
> function check_sysfs_value() {
> 	local mod="$1"; shift
> 	local rel_path="$1"; shift
> 	local expected_value="$1"; shift
> 
> 	local path="$KLP_SYSFS_DIR/$mod/$rel_path"
> 	local value=`cat $path`
> 
> 	if test "$value" != "$expected_value" ; then
> 	    die "Unexpected value in $path: $expected_value vs. $value"
> 	fi
> }
> 
> It would allow to create a fine tuned tests, for example:
> 
> check_sysfs_rights "$MOD_LIVEPATCH" "" "drwxr-xr-x"
> check_sysfs_rights "$MOD_LIVEPATCH" "enabled" "-rw-r--r--"
> 
> check_sysfs_value  "$MOD_LIVEPATCH" "enabled" "1"
> 
> 
> 
> Also it would be great to test that the "patched" value is "0"
> when the object is not patched. I would require to create
> a test module that might be livepatched. I mean something like:
> 
> 
> check_sysfs_value  $MOD_LIVEPATCH "$TEST_MODULE/patched" "0"
> load_mod $TEST_MODULE
> check_sysfs_value  $MOD_LIVEPATCH "$TEST_MODULE/patched" "1"
> unload_mod $TEST_MODULE
> check_sysfs_value  $MOD_LIVEPATCH "$TEST_MODULE/patched" "0"
> 
> 

Yes, these helpers would be nice to have to better verify the sysfs
structure and values.

Regards,
-- 
Joe