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authorMiroslav Benes <mbenes@suse.cz>2019-10-16 14:33:13 +0300
committerSteven Rostedt <rostedt@goodmis.org>2019-11-04 17:33:15 +0300
commit7162431dcf72032835d369c8d7b51311df407938 (patch)
tree194454e629a477bba5410fc5eab3303c5c089de4 /include/linux/ftrace.h
parenta99d8080aaf358d5d23581244e5da23b35e340b9 (diff)
downloadlinux-7162431dcf72032835d369c8d7b51311df407938.tar.xz
ftrace: Introduce PERMANENT ftrace_ops flag
Livepatch uses ftrace for redirection to new patched functions. It means that if ftrace is disabled, all live patched functions are disabled as well. Toggling global 'ftrace_enabled' sysctl thus affect it directly. It is not a problem per se, because only administrator can set sysctl values, but it still may be surprising. Introduce PERMANENT ftrace_ops flag to amend this. If the FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be disabled by disabling ftrace_enabled. Equally, a callback with the flag set cannot be registered if ftrace_enabled is disabled. Link: http://lkml.kernel.org/r/20191016113316.13415-2-mbenes@suse.cz Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/ftrace.h')
-rw-r--r--include/linux/ftrace.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 8a8cb3c401b2..8385cafe4f9f 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -142,6 +142,8 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
* PID - Is affected by set_ftrace_pid (allows filtering on those pids)
* RCU - Set when the ops can only be called when RCU is watching.
* TRACE_ARRAY - The ops->private points to a trace_array descriptor.
+ * PERMANENT - Set when the ops is permanent and should not be affected by
+ * ftrace_enabled.
*/
enum {
FTRACE_OPS_FL_ENABLED = 1 << 0,
@@ -160,6 +162,7 @@ enum {
FTRACE_OPS_FL_PID = 1 << 13,
FTRACE_OPS_FL_RCU = 1 << 14,
FTRACE_OPS_FL_TRACE_ARRAY = 1 << 15,
+ FTRACE_OPS_FL_PERMANENT = 1 << 16,
};
#ifdef CONFIG_DYNAMIC_FTRACE