Commit-ID: 21e450d21ccad4cb7c7984c29ff145012b47736d Gitweb: https://git.kernel.org/tip/21e450d21ccad4cb7c7984c29ff145012b47736d Author: Jan Kiszka <jan.kis...@siemens.com> AuthorDate: Tue, 18 Jun 2019 09:32:11 +0200 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Wed, 24 Jul 2019 14:43:37 +0200
x86/mm: Avoid redundant interrupt disable in load_mm_cr4() load_mm_cr4() is always called with interrupts disabled from: - switch_mm_irqs_off() - refresh_pce(), which is a on_each_cpu() callback Thus, disabling interrupts in cr4_set/clear_bits() is redundant. Implement cr4_set/clear_bits_irqsoff() helpers, rename load_mm_cr4() to load_mm_cr4_irqsoff() and use the new helpers. The new helpers do not need a lockdep assert as __cr4_set() has one already. The renaming in combination with the checks in __cr4_set() ensure that any changes in the boundary conditions at the call sites will be detected. [ tglx: Massaged change log ] Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Link: https://lkml.kernel.org/r/0fbbcb64-5f26-4ffb-1bb9-4f5f48426...@siemens.com --- arch/x86/events/core.c | 2 +- arch/x86/include/asm/mmu_context.h | 8 ++++---- arch/x86/include/asm/tlbflush.h | 30 +++++++++++++++++++++++------- arch/x86/mm/tlb.c | 2 +- 4 files changed, 29 insertions(+), 13 deletions(-) diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 81b005e4c7d9..cfe256ca76df 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2087,7 +2087,7 @@ static int x86_pmu_event_init(struct perf_event *event) static void refresh_pce(void *ignored) { - load_mm_cr4(this_cpu_read(cpu_tlbstate.loaded_mm)); + load_mm_cr4_irqsoff(this_cpu_read(cpu_tlbstate.loaded_mm)); } static void x86_pmu_event_mapped(struct perf_event *event, struct mm_struct *mm) diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 9024236693d2..16ae821483c8 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -28,16 +28,16 @@ static inline void paravirt_activate_mm(struct mm_struct *prev, DECLARE_STATIC_KEY_FALSE(rdpmc_always_available_key); -static inline void load_mm_cr4(struct mm_struct *mm) +static inline void load_mm_cr4_irqsoff(struct mm_struct *mm) { if (static_branch_unlikely(&rdpmc_always_available_key) || atomic_read(&mm->context.perf_rdpmc_allowed)) - cr4_set_bits(X86_CR4_PCE); + cr4_set_bits_irqsoff(X86_CR4_PCE); else - cr4_clear_bits(X86_CR4_PCE); + cr4_clear_bits_irqsoff(X86_CR4_PCE); } #else -static inline void load_mm_cr4(struct mm_struct *mm) {} +static inline void load_mm_cr4_irqsoff(struct mm_struct *mm) {} #endif #ifdef CONFIG_MODIFY_LDT_SYSCALL diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index dee375831962..6f66d841262d 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -290,26 +290,42 @@ static inline void __cr4_set(unsigned long cr4) } /* Set in this cpu's CR4. */ -static inline void cr4_set_bits(unsigned long mask) +static inline void cr4_set_bits_irqsoff(unsigned long mask) { - unsigned long cr4, flags; + unsigned long cr4; - local_irq_save(flags); cr4 = this_cpu_read(cpu_tlbstate.cr4); if ((cr4 | mask) != cr4) __cr4_set(cr4 | mask); - local_irq_restore(flags); } /* Clear in this cpu's CR4. */ -static inline void cr4_clear_bits(unsigned long mask) +static inline void cr4_clear_bits_irqsoff(unsigned long mask) { - unsigned long cr4, flags; + unsigned long cr4; - local_irq_save(flags); cr4 = this_cpu_read(cpu_tlbstate.cr4); if ((cr4 & ~mask) != cr4) __cr4_set(cr4 & ~mask); +} + +/* Set in this cpu's CR4. */ +static inline void cr4_set_bits(unsigned long mask) +{ + unsigned long flags; + + local_irq_save(flags); + cr4_set_bits_irqsoff(mask); + local_irq_restore(flags); +} + +/* Clear in this cpu's CR4. */ +static inline void cr4_clear_bits(unsigned long mask) +{ + unsigned long flags; + + local_irq_save(flags); + cr4_clear_bits_irqsoff(mask); local_irq_restore(flags); } diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 4de9704c4aaf..e6a9edc5baaf 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -440,7 +440,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, this_cpu_write(cpu_tlbstate.loaded_mm_asid, new_asid); if (next != real_prev) { - load_mm_cr4(next); + load_mm_cr4_irqsoff(next); switch_ldt(real_prev, next); } }
