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authorJosh Poimboeuf <jpoimboe@redhat.com>2015-01-20 18:26:19 +0300
committerJiri Kosina <jkosina@suse.cz>2015-01-20 22:09:41 +0300
commit3c33f5b99d688deafd21d4a770303691c7c3a320 (patch)
tree1b133a30910364c15190202616f65c08d306f55e /include/linux/livepatch.h
parent83a90bb1345767f0cb96d242fd8b9db44b2b0e17 (diff)
downloadlinux-3c33f5b99d688deafd21d4a770303691c7c3a320.tar.xz
livepatch: support for repatching a function
Add support for patching a function multiple times. If multiple patches affect a function, the function in the most recently enabled patch "wins". This enables a cumulative patch upgrade path, where each patch is a superset of previous patches. This requires restructuring the data a little bit. With the current design, where each klp_func struct has its own ftrace_ops, we'd have to unregister the old ops and then register the new ops, because FTRACE_OPS_FL_IPMODIFY prevents us from having two ops registered for the same function at the same time. That would leave a regression window where the function isn't patched at all (not good for a patch upgrade path). This patch replaces the per-klp_func ftrace_ops with a global klp_ops list, with one ftrace_ops per original function. A single ftrace_ops is shared between all klp_funcs which have the same old_addr. This allows the switch between function versions to happen instantaneously by updating the klp_ops struct's func_stack list. The winner is the klp_func at the top of the func_stack (front of the list). [ jkosina@suse.cz: turn WARN_ON() into WARN_ON_ONCE() in ftrace handler to avoid storm in pathological cases ] Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'include/linux/livepatch.h')
-rw-r--r--include/linux/livepatch.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 950bc615842f..f14c6fb262b4 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -40,8 +40,8 @@ enum klp_state {
* @old_addr: a hint conveying at what address the old function
* can be found (optional, vmlinux patches only)
* @kobj: kobject for sysfs resources
- * @fops: ftrace operations structure
* @state: tracks function-level patch application state
+ * @stack_node: list node for klp_ops func_stack list
*/
struct klp_func {
/* external */
@@ -59,8 +59,8 @@ struct klp_func {
/* internal */
struct kobject kobj;
- struct ftrace_ops *fops;
enum klp_state state;
+ struct list_head stack_node;
};
/**