diff options
Diffstat (limited to 'arch/riscv/include/asm/mmu_context.h')
| -rw-r--r-- | arch/riscv/include/asm/mmu_context.h | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/mmu_context.h b/arch/riscv/include/asm/mmu_context.h index de1fc1631fc4..b15b169e3d22 100644 --- a/arch/riscv/include/asm/mmu_context.h +++ b/arch/riscv/include/asm/mmu_context.h @@ -1,5 +1,6 @@ /* * Copyright (C) 2012 Regents of the University of California + * Copyright (C) 2017 SiFive * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License @@ -19,6 +20,7 @@ #include <linux/mm.h> #include <linux/sched.h> #include <asm/tlbflush.h> +#include <asm/cacheflush.h> static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *task) @@ -46,12 +48,54 @@ static inline void set_pgdir(pgd_t *pgd) csr_write(sptbr, virt_to_pfn(pgd) | SPTBR_MODE); } +/* + * When necessary, performs a deferred icache flush for the given MM context, + * on the local CPU. RISC-V has no direct mechanism for instruction cache + * shoot downs, so instead we send an IPI that informs the remote harts they + * need to flush their local instruction caches. To avoid pathologically slow + * behavior in a common case (a bunch of single-hart processes on a many-hart + * machine, ie 'make -j') we avoid the IPIs for harts that are not currently + * executing a MM context and instead schedule a deferred local instruction + * cache flush to be performed before execution resumes on each hart. This + * actually performs that local instruction cache flush, which implicitly only + * refers to the current hart. + */ +static inline void flush_icache_deferred(struct mm_struct *mm) +{ +#ifdef CONFIG_SMP + unsigned int cpu = smp_processor_id(); + cpumask_t *mask = &mm->context.icache_stale_mask; + + if (cpumask_test_cpu(cpu, mask)) { + cpumask_clear_cpu(cpu, mask); + /* + * Ensure the remote hart's writes are visible to this hart. + * This pairs with a barrier in flush_icache_mm. + */ + smp_mb(); + local_flush_icache_all(); + } +#endif +} + static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *task) { if (likely(prev != next)) { + /* + * Mark the current MM context as inactive, and the next as + * active. This is at least used by the icache flushing + * routines in order to determine who should + */ + unsigned int cpu = smp_processor_id(); + + cpumask_clear_cpu(cpu, mm_cpumask(prev)); + cpumask_set_cpu(cpu, mm_cpumask(next)); + set_pgdir(next->pgd); local_flush_tlb_all(); + + flush_icache_deferred(next); } } |