The scheduler IPI does not need the full interrupt entry handling logic when the entry is from kernel mode.
Even if tracing is enabled the only requirement is that RCU is watching and preempt_count has the hardirq bit on. The NOHZ tick state does not have to be adjusted. If the tick is not running then the CPU is in idle and the idle exit will restore the tick. Softinterrupts are not raised here, so handling them on return is not required either. User mode entry must go through the regular entry path as it will invoke the scheduler on return so context tracking needs to be in the correct state. Use IDTENTRY_SYSVEC_SIMPLE and remove the tracepoint static key conditional which is incomplete vs. tracing anyway because e.g. ack_APIC_irq() calls out into instrumentable code. Signed-off-by: Thomas Gleixner <[email protected]> --- arch/x86/entry/entry_64.S | 4 ---- arch/x86/include/asm/entry_arch.h | 3 --- arch/x86/include/asm/hw_irq.h | 3 --- arch/x86/include/asm/idtentry.h | 1 + arch/x86/include/asm/trace/common.h | 4 ---- arch/x86/include/asm/trace/irq_vectors.h | 17 +---------------- arch/x86/kernel/idt.c | 2 +- arch/x86/kernel/smp.c | 19 ++++--------------- arch/x86/kernel/tracepoint.c | 17 ----------------- 9 files changed, 7 insertions(+), 63 deletions(-) --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -956,10 +956,6 @@ apicinterrupt3 \num \sym \do_sym POP_SECTION_IRQENTRY .endm -#ifdef CONFIG_SMP -apicinterrupt RESCHEDULE_VECTOR reschedule_interrupt smp_reschedule_interrupt -#endif - /* * Reload gs selector with exception handling * edi: new selector --- a/arch/x86/include/asm/entry_arch.h +++ b/arch/x86/include/asm/entry_arch.h @@ -10,6 +10,3 @@ * is no hardware IRQ pin equivalent for them, they are triggered * through the ICC by us (IPIs) */ -#ifdef CONFIG_SMP -BUILD_INTERRUPT(reschedule_interrupt,RESCHEDULE_VECTOR) -#endif --- a/arch/x86/include/asm/hw_irq.h +++ b/arch/x86/include/asm/hw_irq.h @@ -28,9 +28,6 @@ #include <asm/irq.h> #include <asm/sections.h> -/* Interrupt handlers registered during init_IRQ */ -extern asmlinkage void reschedule_interrupt(void); - #ifdef CONFIG_X86_LOCAL_APIC struct irq_data; struct pci_dev; --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -576,6 +576,7 @@ DECLARE_IDTENTRY_SYSVEC(X86_PLATFORM_IPI #endif #ifdef CONFIG_SMP +DECLARE_IDTENTRY(RESCHEDULE_VECTOR, sysvec_reschedule_ipi); DECLARE_IDTENTRY_SYSVEC(IRQ_MOVE_CLEANUP_VECTOR, sysvec_irq_move_cleanup); DECLARE_IDTENTRY_SYSVEC(REBOOT_VECTOR, sysvec_reboot); DECLARE_IDTENTRY_SYSVEC(CALL_FUNCTION_SINGLE_VECTOR, sysvec_call_function_single); --- a/arch/x86/include/asm/trace/common.h +++ b/arch/x86/include/asm/trace/common.h @@ -5,12 +5,8 @@ DECLARE_STATIC_KEY_FALSE(trace_pagefault_key); #define trace_pagefault_enabled() \ static_branch_unlikely(&trace_pagefault_key) -DECLARE_STATIC_KEY_FALSE(trace_resched_ipi_key); -#define trace_resched_ipi_enabled() \ - static_branch_unlikely(&trace_resched_ipi_key) #else static inline bool trace_pagefault_enabled(void) { return false; } -static inline bool trace_resched_ipi_enabled(void) { return false; } #endif #endif --- a/arch/x86/include/asm/trace/irq_vectors.h +++ b/arch/x86/include/asm/trace/irq_vectors.h @@ -10,9 +10,6 @@ #ifdef CONFIG_X86_LOCAL_APIC -extern int trace_resched_ipi_reg(void); -extern void trace_resched_ipi_unreg(void); - DECLARE_EVENT_CLASS(x86_irq_vector, TP_PROTO(int vector), @@ -37,18 +34,6 @@ DEFINE_EVENT_FN(x86_irq_vector, name##_e TP_PROTO(int vector), \ TP_ARGS(vector), NULL, NULL); -#define DEFINE_RESCHED_IPI_EVENT(name) \ -DEFINE_EVENT_FN(x86_irq_vector, name##_entry, \ - TP_PROTO(int vector), \ - TP_ARGS(vector), \ - trace_resched_ipi_reg, \ - trace_resched_ipi_unreg); \ -DEFINE_EVENT_FN(x86_irq_vector, name##_exit, \ - TP_PROTO(int vector), \ - TP_ARGS(vector), \ - trace_resched_ipi_reg, \ - trace_resched_ipi_unreg); - /* * local_timer - called when entering/exiting a local timer interrupt * vector handler @@ -99,7 +84,7 @@ TRACE_EVENT_PERF_PERM(irq_work_exit, is_ /* * reschedule - called when entering/exiting a reschedule vector handler */ -DEFINE_RESCHED_IPI_EVENT(reschedule); +DEFINE_IRQ_VECTOR_EVENT(reschedule); /* * call_function - called when entering/exiting a call function interrupt --- a/arch/x86/kernel/idt.c +++ b/arch/x86/kernel/idt.c @@ -109,7 +109,7 @@ static const __initconst struct idt_data */ static const __initconst struct idt_data apic_idts[] = { #ifdef CONFIG_SMP - INTG(RESCHEDULE_VECTOR, reschedule_interrupt), + INTG(RESCHEDULE_VECTOR, asm_sysvec_reschedule_ipi), INTG(CALL_FUNCTION_VECTOR, asm_sysvec_call_function), INTG(CALL_FUNCTION_SINGLE_VECTOR, asm_sysvec_call_function_single), INTG(IRQ_MOVE_CLEANUP_VECTOR, asm_sysvec_irq_move_cleanup), --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -220,26 +220,15 @@ static void native_stop_other_cpus(int w /* * Reschedule call back. KVM uses this interrupt to force a cpu out of - * guest mode + * guest mode. */ -__visible void __irq_entry smp_reschedule_interrupt(struct pt_regs *regs) +DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_reschedule_ipi) { ack_APIC_irq(); + trace_reschedule_entry(RESCHEDULE_VECTOR); inc_irq_stat(irq_resched_count); - - if (trace_resched_ipi_enabled()) { - /* - * scheduler_ipi() might call irq_enter() as well, but - * nested calls are fine. - */ - irq_enter(); - trace_reschedule_entry(RESCHEDULE_VECTOR); - scheduler_ipi(); - trace_reschedule_exit(RESCHEDULE_VECTOR); - irq_exit(); - return; - } scheduler_ipi(); + trace_reschedule_exit(RESCHEDULE_VECTOR); } DEFINE_IDTENTRY_SYSVEC(sysvec_call_function) --- a/arch/x86/kernel/tracepoint.c +++ b/arch/x86/kernel/tracepoint.c @@ -25,20 +25,3 @@ void trace_pagefault_unreg(void) { static_branch_dec(&trace_pagefault_key); } - -#ifdef CONFIG_SMP - -DEFINE_STATIC_KEY_FALSE(trace_resched_ipi_key); - -int trace_resched_ipi_reg(void) -{ - static_branch_inc(&trace_resched_ipi_key); - return 0; -} - -void trace_resched_ipi_unreg(void) -{ - static_branch_dec(&trace_resched_ipi_key); -} - -#endif
