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static_call: Add function to query current function

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Some users of paravirtualized functions need to query which function
has been specified in a pv_ops vector element. In order to be able to
switch such paravirtualized functions to static_calls instead, there
needs to be a function to query the function which will be called via
static_call().

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-4-jgross@suse.com
This commit is contained in:
Juergen Gross 2021-03-11 15:23:08 +01:00 committed by Borislav Petkov
parent b046664872
commit 6ea312d95e
1 changed files with 8 additions and 0 deletions
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8
include/linux/static_call.h
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@ -20,6 +20,7 @@
* static_call(name)(args...);
* static_call_cond(name)(args...);
* static_call_update(name, func);
* static_call_query(name);
*
* Usage example:
*
@ -91,6 +92,10 @@
*
* which will include the required value tests to avoid NULL-pointer
* dereferences.
*
* To query which function is currently set to be called, use:
*
* func = static_call_query(name);
*/
#include <linux/types.h>
@ -118,6 +123,8 @@ extern void arch_static_call_transform(void *site, void *tramp, void *func, bool
STATIC_CALL_TRAMP_ADDR(name), func); \
})
#define static_call_query(name) (READ_ONCE(STATIC_CALL_KEY(name).func))
#ifdef CONFIG_HAVE_STATIC_CALL_INLINE
extern int __init static_call_init(void);
@ -191,6 +198,7 @@ static inline int static_call_init(void) { return 0; }
}; \
ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name)
#define static_call_cond(name) (void)__static_call(name)
static inline