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McKenney" , Ingo Molnar , Michal Hocko Subject: [RFC PATCH 5/7] preempt/dynamic: Provide preempt_schedule[_notrace]() static calls Date: Tue, 10 Nov 2020 01:56:07 +0100 Message-Id: <20201110005609.40989-6-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201110005609.40989-1-frederic@kernel.org> References: <20201110005609.40989-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Peter Zijlstra (Intel)" 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) Cc: Thomas Gleixner Cc: Mel Gorman Cc: Ingo Molnar Cc: Michal Hocko Cc: Paul E. McKenney [only define static calls when PREEMPT_DYNAMIC, make it less dependent on x86 with __preempt_schedule_func()] Signed-off-by: Frederic Weisbecker --- 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 #include #include +#include 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