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| author | Kees Cook <keescook@chromium.org> | 2021-04-01 16:23:42 -0700 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2021-04-08 14:05:19 +0200 |
| commit | 0d66ccc1627013c95f1e7ef10b95b8451cd7834e (patch) | |
| tree | e313d2e817100022f160bad42e2fd8e7eab3c4bf /include/linux/jump_label.h | |
| parent | e49d033bddf5b565044e2abe4241353959bc9120 (diff) | |
| download | linux-0d66ccc1627013c95f1e7ef10b95b8451cd7834e.tar.gz linux-0d66ccc1627013c95f1e7ef10b95b8451cd7834e.tar.bz2 linux-0d66ccc1627013c95f1e7ef10b95b8451cd7834e.zip | |
jump_label: Provide CONFIG-driven build state defaults
As shown in the comment in jump_label.h, choosing the initial state of
static branches changes the assembly layout. If the condition is expected
to be likely it's inline, and if unlikely it is out of line via a jump.
A few places in the kernel use (or could be using) a CONFIG to choose the
default state, which would give a small performance benefit to their
compile-time declared default. Provide the infrastructure to do this.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210401232347.2791257-2-keescook@chromium.org
Diffstat (limited to 'include/linux/jump_label.h')
| -rw-r--r-- | include/linux/jump_label.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index d92691262f51..05f5554d860f 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -382,6 +382,21 @@ struct static_key_false { [0 ... (count) - 1] = STATIC_KEY_FALSE_INIT, \ } +#define _DEFINE_STATIC_KEY_1(name) DEFINE_STATIC_KEY_TRUE(name) +#define _DEFINE_STATIC_KEY_0(name) DEFINE_STATIC_KEY_FALSE(name) +#define DEFINE_STATIC_KEY_MAYBE(cfg, name) \ + __PASTE(_DEFINE_STATIC_KEY_, IS_ENABLED(cfg))(name) + +#define _DEFINE_STATIC_KEY_RO_1(name) DEFINE_STATIC_KEY_TRUE_RO(name) +#define _DEFINE_STATIC_KEY_RO_0(name) DEFINE_STATIC_KEY_FALSE_RO(name) +#define DEFINE_STATIC_KEY_MAYBE_RO(cfg, name) \ + __PASTE(_DEFINE_STATIC_KEY_RO_, IS_ENABLED(cfg))(name) + +#define _DECLARE_STATIC_KEY_1(name) DECLARE_STATIC_KEY_TRUE(name) +#define _DECLARE_STATIC_KEY_0(name) DECLARE_STATIC_KEY_FALSE(name) +#define DECLARE_STATIC_KEY_MAYBE(cfg, name) \ + __PASTE(_DECLARE_STATIC_KEY_, IS_ENABLED(cfg))(name) + extern bool ____wrong_branch_error(void); #define static_key_enabled(x) \ @@ -482,6 +497,10 @@ extern bool ____wrong_branch_error(void); #endif /* CONFIG_JUMP_LABEL */ +#define static_branch_maybe(config, x) \ + (IS_ENABLED(config) ? static_branch_likely(x) \ + : static_branch_unlikely(x)) + /* * Advanced usage; refcount, branch is enabled when: count != 0 */ |