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| author | Peter Zijlstra <peterz@infradead.org> | 2021-01-18 15:12:16 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2021-02-17 14:08:43 +0100 |
| commit | 3f2a8fc4b15de18644e8a80a09edda168676e22c (patch) | |
| tree | ecceaeff23b07b1e7e7e611fdd64d9646b04e099 /kernel/static_call.c | |
| parent | 880cfed3a012d7863f42251791cea7fe78c39390 (diff) | |
| download | lwn-3f2a8fc4b15de18644e8a80a09edda168676e22c.tar.gz lwn-3f2a8fc4b15de18644e8a80a09edda168676e22c.zip | |
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 'kernel/static_call.c')
| -rw-r--r-- | kernel/static_call.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/static_call.c b/kernel/static_call.c index 84565c2a41b8..0bc11b5ce681 100644 --- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -438,6 +438,11 @@ int __init static_call_init(void) } early_initcall(static_call_init); +long __static_call_return0(void) +{ + return 0; +} + #ifdef CONFIG_STATIC_CALL_SELFTEST static int func_a(int x) |