diff options
| author | Peter Zijlstra | 2021-01-18 15:12:16 +0100 |
|---|---|---|
| committer | Ingo Molnar | 2021-02-17 14:08:43 +0100 |
| commit | 3f2a8fc4b15de18644e8a80a09edda168676e22c (patch) | |
| tree | ecceaeff23b07b1e7e7e611fdd64d9646b04e099 /include | |
| parent | 880cfed3a012d7863f42251791cea7fe78c39390 (diff) | |
static_call/x86: Add __static_call_return0()
Provide a stub function that return 0 and wire up the static call site
patching to replace the CALL with a single 5 byte instruction that
clears %RAX, the return value register.
The function can be cast to any function pointer type that has a
single %RAX return (including pointers). Also provide a version that
returns an int for convenience. We are clearing the entire %RAX register
in any case, whether the return value is 32 or 64 bits, since %RAX is
always a scratch register anyway.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-2-frederic@kernel.org
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/static_call.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/static_call.h b/include/linux/static_call.h index a2c064585c03..bd6735d10e2e 100644 --- a/include/linux/static_call.h +++ b/include/linux/static_call.h @@ -142,6 +142,8 @@ extern void __static_call_update(struct static_call_key *key, void *tramp, void extern int static_call_mod_init(struct module *mod); extern int static_call_text_reserved(void *start, void *end); +extern long __static_call_return0(void); + #define DEFINE_STATIC_CALL(name, _func) \ DECLARE_STATIC_CALL(name, _func); \ struct static_call_key STATIC_CALL_KEY(name) = { \ @@ -206,6 +208,11 @@ static inline int static_call_text_reserved(void *start, void *end) return 0; } +static inline long __static_call_return0(void) +{ + return 0; +} + #define EXPORT_STATIC_CALL(name) \ EXPORT_SYMBOL(STATIC_CALL_KEY(name)); \ EXPORT_SYMBOL(STATIC_CALL_TRAMP(name)) @@ -222,6 +229,11 @@ struct static_call_key { void *func; }; +static inline long __static_call_return0(void) +{ + return 0; +} + #define DEFINE_STATIC_CALL(name, _func) \ DECLARE_STATIC_CALL(name, _func); \ struct static_call_key STATIC_CALL_KEY(name) = { \ |