Commit ef767455 authored by Peter Zijlstra (Intel)'s avatar Peter Zijlstra (Intel) Committed by Zheng Zengkai
Browse files

preempt/dynamic: Support dynamic preempt with preempt= boot option 

mainline inclusion
from mainline-5.12-rc1
commit 826bfeb3
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I410UT
CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=826bfeb37bb4302ee6042f330c4c0c757152bdb8



---------------------------

Support the preempt= boot option and patch the static call sites
accordingly.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-9-frederic@kernel.org


Signed-off-by: default avatarMa Junhai <majunhai2@huawei.com>
Reviewed-by: default avatarChen Hui <judy.chenhui@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 11744274

kernel/sched/core.c

+67 −1
Original line number Diff line number Diff line
@@ -4766,9 +4766,75 @@ DEFINE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func); 
EXPORT_STATIC_CALL(preempt_schedule_notrace);

#endif





#endif /* CONFIG_PREEMPTION */



#ifdef CONFIG_PREEMPT_DYNAMIC



#include <linux/entry-common.h>



/*

 * SC:cond_resched

 * SC:might_resched

 * SC:preempt_schedule

 * SC:preempt_schedule_notrace

 * SC:irqentry_exit_cond_resched

 *

 *

 * NONE:

 *   cond_resched               <- __cond_resched

 *   might_resched              <- RET0

 *   preempt_schedule           <- NOP

 *   preempt_schedule_notrace   <- NOP

 *   irqentry_exit_cond_resched <- NOP

 *

 * VOLUNTARY:

 *   cond_resched               <- __cond_resched

 *   might_resched              <- __cond_resched

 *   preempt_schedule           <- NOP

 *   preempt_schedule_notrace   <- NOP

 *   irqentry_exit_cond_resched <- NOP

 *

 * FULL:

 *   cond_resched               <- RET0

 *   might_resched              <- RET0

 *   preempt_schedule           <- preempt_schedule

 *   preempt_schedule_notrace   <- preempt_schedule_notrace

 *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched

 */

static int __init setup_preempt_mode(char *str)

{

	if (!strcmp(str, "none")) {

		static_call_update(cond_resched, __cond_resched);

		static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);

		static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);

		static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);

		static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);

		pr_info("Dynamic Preempt: %s\n", str);

	} else if (!strcmp(str, "voluntary")) {

		static_call_update(cond_resched, __cond_resched);

		static_call_update(might_resched, __cond_resched);

		static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);

		static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);

		static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);

		pr_info("Dynamic Preempt: %s\n", str);

	} else if (!strcmp(str, "full")) {

		static_call_update(cond_resched, (typeof(&__cond_resched)) __static_call_return0);

		static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);

		static_call_update(preempt_schedule, __preempt_schedule_func);

		static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);

		static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);

		pr_info("Dynamic Preempt: %s\n", str);

	} else {

		pr_warn("Dynamic Preempt: Unsupported preempt mode %s, default to full\n", str);

		return 1;

	}

	return 0;

}

__setup("preempt=", setup_preempt_mode);



#endif /* CONFIG_PREEMPT_DYNAMIC */





/*

 * This is the entry point to schedule() from kernel preemption

 * off of irq context.