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preempt/dynamic: Provide preempt_schedule[_notrace]() static calls

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Provide static calls to control preempt_schedule[_notrace]()
(called in CONFIG_PREEMPT) so that we can override their behaviour when
preempt= is overriden.

Since the default behaviour is full preemption, both their calls are
initialized to the arch provided wrapper, if any.

[fweisbec: only define static calls when PREEMPT_DYNAMIC, make it less
           dependent on x86 with __preempt_schedule_func]
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/20210118141223.123667-7-frederic@kernel.org
This commit is contained in:
Peter Zijlstra (Intel) 2021-01-18 15:12:21 +01:00 committed by Ingo Molnar
parent b965f1ddb4
commit 2c9a98d3bc
2 changed files with 38 additions and 8 deletions
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34
arch/x86/include/asm/preempt.h
View file

@ -5,6 +5,7 @@
#include <asm/rmwcc.h>
#include <asm/percpu.h>
#include <linux/thread_info.h>
#include <linux/static_call_types.h>
DECLARE_PER_CPU(int, __preempt_count);
@ -103,16 +104,33 @@ static __always_inline bool should_resched(int preempt_offset)
}
#ifdef CONFIG_PREEMPTION
extern asmlinkage void preempt_schedule_thunk(void);
# define __preempt_schedule() \
asm volatile ("call preempt_schedule_thunk" : ASM_CALL_CONSTRAINT)
extern asmlinkage void preempt_schedule(void);
extern asmlinkage void preempt_schedule_notrace_thunk(void);
# define __preempt_schedule_notrace() \
asm volatile ("call preempt_schedule_notrace_thunk" : ASM_CALL_CONSTRAINT)
extern asmlinkage void preempt_schedule(void);
extern asmlinkage void preempt_schedule_thunk(void);
#define __preempt_schedule_func preempt_schedule_thunk
DECLARE_STATIC_CALL(preempt_schedule, __preempt_schedule_func);
#define __preempt_schedule() \
do { \
__ADDRESSABLE(STATIC_CALL_KEY(preempt_schedule)); \
asm volatile ("call " STATIC_CALL_TRAMP_STR(preempt_schedule) : ASM_CALL_CONSTRAINT); \
} while (0)
extern asmlinkage void preempt_schedule_notrace(void);
extern asmlinkage void preempt_schedule_notrace_thunk(void);
#define __preempt_schedule_notrace_func preempt_schedule_notrace_thunk
DECLARE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func);
#define __preempt_schedule_notrace() \
do { \
__ADDRESSABLE(STATIC_CALL_KEY(preempt_schedule_notrace)); \
asm volatile ("call " STATIC_CALL_TRAMP_STR(preempt_schedule_notrace) : ASM_CALL_CONSTRAINT); \
} while (0)
extern asmlinkage void preempt_schedule_notrace(void);
#endif
#endif /* __ASM_PREEMPT_H */

12
kernel/sched/core.c
View file

@ -5265,6 +5265,12 @@ asmlinkage __visible void __sched notrace preempt_schedule(void)
NOKPROBE_SYMBOL(preempt_schedule);
EXPORT_SYMBOL(preempt_schedule);
#ifdef CONFIG_PREEMPT_DYNAMIC
DEFINE_STATIC_CALL(preempt_schedule, __preempt_schedule_func);
EXPORT_STATIC_CALL(preempt_schedule);
#endif
/**
* preempt_schedule_notrace - preempt_schedule called by tracing
*
@ -5317,6 +5323,12 @@ asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
}
EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
#ifdef CONFIG_PREEMPT_DYNAMIC
DEFINE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func);
EXPORT_STATIC_CALL(preempt_schedule_notrace);
#endif
#endif /* CONFIG_PREEMPTION */
/*