From: "Peter Zijlstra (Intel)" <pet...@infradead.org>
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.
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Mel Gorman <mgor...@suse.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Michal Hocko <mho...@kernel.org>
Cc: Paul E. McKenney <paul...@kernel.org>
[only define static calls when PREEMPT_DYNAMIC, make it less dependent
on x86 with __preempt_schedule_func()]
Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
---
arch/x86/include/asm/preempt.h | 34 ++++++++++++++++++++++++++--------
kernel/sched/core.c | 12 ++++++++++++
2 files changed, 38 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index 69485ca13665..3db9cb8b1a25 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -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 */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6432d0079510..6715caa17ea7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4709,6 +4709,12 @@ 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
*
@@ -4761,6 +4767,12 @@ 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 */
/*
--
2.25.1
