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Subject[PATCH 3/3 v7] livepatch: function,sympos scheme in livepatch sysfs directory
Date
The following directory structure will allow for cases when the same
function name exists in a single object.
/sys/kernel/livepatch/<patch>/<object>/<function,sympos>

The sympos number corresponds to the nth occurrence of the symbol name in
kallsyms for the patched object.

An example of patching multiple symbols can be found here:
https://github.com/dynup/kpatch/issues/493

Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
---
Documentation/ABI/testing/sysfs-kernel-livepatch | 6 +++++-
kernel/livepatch/core.c | 10 ++++++++--
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
index 5bf42a8..da87f43 100644
--- a/Documentation/ABI/testing/sysfs-kernel-livepatch
+++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
@@ -33,7 +33,7 @@ Description:
The object directory contains subdirectories for each function
that is patched within the object.

-What: /sys/kernel/livepatch/<patch>/<object>/<function>
+What: /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
Date: Nov 2014
KernelVersion: 3.19.0
Contact: live-patching@vger.kernel.org
@@ -41,4 +41,8 @@ Description:
The function directory contains attributes regarding the
properties and state of the patched function.

+ The directory name contains the patched function name and a
+ sympos number corresponding to the nth occurrence of the symbol
+ name in kallsyms for the patched object.
+
There are currently no such attributes.
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 9d98c7b..2a1fd1f 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -534,7 +534,7 @@ EXPORT_SYMBOL_GPL(klp_enable_patch);
* /sys/kernel/livepatch/<patch>
* /sys/kernel/livepatch/<patch>/enabled
* /sys/kernel/livepatch/<patch>/<object>
- * /sys/kernel/livepatch/<patch>/<object>/<func>
+ * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
*/

static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
@@ -679,8 +679,14 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
INIT_LIST_HEAD(&func->stack_node);
func->state = KLP_DISABLED;

+ /* The format for the sysfs directory is <function,sympos> where sympos
+ * is the nth occurrence of this symbol in kallsyms for the patched
+ * object. If the user selects 0 for old_sympos, then 1 will be used
+ * since a unique symbol will be the first occurrence.
+ */
return kobject_init_and_add(&func->kobj, &klp_ktype_func,
- &obj->kobj, "%s", func->old_name);
+ &obj->kobj, "%s,%lu", func->old_name,
+ func->old_sympos ? func->old_sympos : 1);
}

/* parts of the initialization that is done only when the object is loaded */
--
1.9.1


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