From 91a1d97ef482c1e4c9d4c1c656a53b0f6b16d0ed Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 13 Mar 2024 19:01:03 +0100 Subject: jump_label,module: Don't alloc static_key_mod for __ro_after_init keys When a static_key is marked ro_after_init, its state will never change (after init), therefore jump_label_update() will never need to iterate the entries, and thus module load won't actually need to track this -- avoiding the static_key::next write. Therefore, mark these keys such that jump_label_add_module() might recognise them and avoid the modification. Use the special state: 'static_key_linked(key) && !static_key_mod(key)' to denote such keys. jump_label_add_module() does not exist under CONFIG_JUMP_LABEL=n, so the newly-introduced jump_label_init_ro() can be defined as a nop for that configuration. [ mingo: Renamed jump_label_ro() to jump_label_init_ro() ] Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Valentin Schneider Signed-off-by: Ingo Molnar Acked-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20240313180106.2917308-2-vschneid@redhat.com --- include/linux/jump_label.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/jump_label.h') diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index f0a949b7c973..f5a2727ca4a9 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -216,6 +216,7 @@ extern struct jump_entry __start___jump_table[]; extern struct jump_entry __stop___jump_table[]; extern void jump_label_init(void); +extern void jump_label_init_ro(void); extern void jump_label_lock(void); extern void jump_label_unlock(void); extern void arch_jump_label_transform(struct jump_entry *entry, @@ -265,6 +266,8 @@ static __always_inline void jump_label_init(void) static_key_initialized = true; } +static __always_inline void jump_label_init_ro(void) { } + static __always_inline bool static_key_false(struct static_key *key) { if (unlikely_notrace(static_key_count(key) > 0)) -- cgit v1.2.3