The following commit has been merged into the sched/core branch of tip: Commit-ID: 0e79823f55de3cff95894fbb40440b17910e7378 Gitweb: https://git.kernel.org/tip/0e79823f55de3cff95894fbb40440b17910e7378 Author: Peter Zijlstra (Intel) <pet...@infradead.org> AuthorDate: Mon, 18 Jan 2021 15:12:23 +01:00 Committer: Peter Zijlstra <pet...@infradead.org> CommitterDate: Tue, 09 Feb 2021 16:30:58 +01:00
preempt/dynamic: Support dynamic preempt with preempt= boot option Support the preempt= boot option and patch the static call sites accordingly. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Signed-off-by: Frederic Weisbecker <frede...@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Link: https://lkml.kernel.org/r/20210118141223.123667-9-frede...@kernel.org --- kernel/sched/core.c | 68 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 67 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index cd0c46f..220393d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5314,9 +5314,75 @@ 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.
