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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 /kernel/livepatch
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 'kernel/livepatch')
-rw-r--r--kernel/livepatch/patch.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
index bd43537702bd..b552cf2d85f8 100644
--- a/kernel/livepatch/patch.c
+++ b/kernel/livepatch/patch.c
@@ -196,7 +196,8 @@ static int klp_patch_func(struct klp_func *func)
ops->fops.func = klp_ftrace_handler;
ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS |
FTRACE_OPS_FL_DYNAMIC |
- FTRACE_OPS_FL_IPMODIFY;
+ FTRACE_OPS_FL_IPMODIFY |
+ FTRACE_OPS_FL_PERMANENT;
list_add(&ops->node, &klp_ops);