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Diffstat (limited to 'kernel/arch/mn10300/include/asm/mmu_context.h')
| -rw-r--r-- | kernel/arch/mn10300/include/asm/mmu_context.h | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/kernel/arch/mn10300/include/asm/mmu_context.h b/kernel/arch/mn10300/include/asm/mmu_context.h new file mode 100644 index 000000000..75dbe696f --- /dev/null +++ b/kernel/arch/mn10300/include/asm/mmu_context.h @@ -0,0 +1,161 @@ +/* MN10300 MMU context management + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Modified by David Howells (dhowells@redhat.com) + * - Derived from include/asm-m32r/mmu_context.h + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + * + * + * This implements an algorithm to provide TLB PID mappings to provide + * selective access to the TLB for processes, thus reducing the number of TLB + * flushes required. + * + * Note, however, that the M32R algorithm is technically broken as it does not + * handle version wrap-around, and could, theoretically, have a problem with a + * very long lived program that sleeps long enough for the version number to + * wrap all the way around so that its TLB mappings appear valid once again. + */ +#ifndef _ASM_MMU_CONTEXT_H +#define _ASM_MMU_CONTEXT_H + +#include <linux/atomic.h> +#include <asm/pgalloc.h> +#include <asm/tlbflush.h> +#include <asm-generic/mm_hooks.h> + +#define MMU_CONTEXT_TLBPID_NR 256 +#define MMU_CONTEXT_TLBPID_MASK 0x000000ffUL +#define MMU_CONTEXT_VERSION_MASK 0xffffff00UL +#define MMU_CONTEXT_FIRST_VERSION 0x00000100UL +#define MMU_NO_CONTEXT 0x00000000UL +#define MMU_CONTEXT_TLBPID_LOCK_NR 0 + +#define enter_lazy_tlb(mm, tsk) do {} while (0) + +static inline void cpu_ran_vm(int cpu, struct mm_struct *mm) +{ +#ifdef CONFIG_SMP + cpumask_set_cpu(cpu, mm_cpumask(mm)); +#endif +} + +static inline bool cpu_maybe_ran_vm(int cpu, struct mm_struct *mm) +{ +#ifdef CONFIG_SMP + return cpumask_test_and_set_cpu(cpu, mm_cpumask(mm)); +#else + return true; +#endif +} + +#ifdef CONFIG_MN10300_TLB_USE_PIDR +extern unsigned long mmu_context_cache[NR_CPUS]; +#define mm_context(mm) (mm->context.tlbpid[smp_processor_id()]) + +/** + * allocate_mmu_context - Allocate storage for the arch-specific MMU data + * @mm: The userspace VM context being set up + */ +static inline unsigned long allocate_mmu_context(struct mm_struct *mm) +{ + unsigned long *pmc = &mmu_context_cache[smp_processor_id()]; + unsigned long mc = ++(*pmc); + + if (!(mc & MMU_CONTEXT_TLBPID_MASK)) { + /* we exhausted the TLB PIDs of this version on this CPU, so we + * flush this CPU's TLB in its entirety and start new cycle */ + local_flush_tlb_all(); + + /* fix the TLB version if needed (we avoid version #0 so as to + * distinguish MMU_NO_CONTEXT) */ + if (!mc) + *pmc = mc = MMU_CONTEXT_FIRST_VERSION; + } + mm_context(mm) = mc; + return mc; +} + +/* + * get an MMU context if one is needed + */ +static inline unsigned long get_mmu_context(struct mm_struct *mm) +{ + unsigned long mc = MMU_NO_CONTEXT, cache; + + if (mm) { + cache = mmu_context_cache[smp_processor_id()]; + mc = mm_context(mm); + + /* if we have an old version of the context, replace it */ + if ((mc ^ cache) & MMU_CONTEXT_VERSION_MASK) + mc = allocate_mmu_context(mm); + } + return mc; +} + +/* + * initialise the context related info for a new mm_struct instance + */ +static inline int init_new_context(struct task_struct *tsk, + struct mm_struct *mm) +{ + int num_cpus = NR_CPUS, i; + + for (i = 0; i < num_cpus; i++) + mm->context.tlbpid[i] = MMU_NO_CONTEXT; + return 0; +} + +/* + * after we have set current->mm to a new value, this activates the context for + * the new mm so we see the new mappings. + */ +static inline void activate_context(struct mm_struct *mm) +{ + PIDR = get_mmu_context(mm) & MMU_CONTEXT_TLBPID_MASK; +} +#else /* CONFIG_MN10300_TLB_USE_PIDR */ + +#define init_new_context(tsk, mm) (0) +#define activate_context(mm) local_flush_tlb() + +#endif /* CONFIG_MN10300_TLB_USE_PIDR */ + +/** + * destroy_context - Destroy mm context information + * @mm: The MM being destroyed. + * + * Destroy context related info for an mm_struct that is about to be put to + * rest + */ +#define destroy_context(mm) do {} while (0) + +/** + * switch_mm - Change between userspace virtual memory contexts + * @prev: The outgoing MM context. + * @next: The incoming MM context. + * @tsk: The incoming task. + */ +static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, + struct task_struct *tsk) +{ + int cpu = smp_processor_id(); + + if (prev != next) { +#ifdef CONFIG_SMP + per_cpu(cpu_tlbstate, cpu).active_mm = next; +#endif + cpu_ran_vm(cpu, next); + PTBR = (unsigned long) next->pgd; + activate_context(next); + } +} + +#define deactivate_mm(tsk, mm) do {} while (0) +#define activate_mm(prev, next) switch_mm((prev), (next), NULL) + +#endif /* _ASM_MMU_CONTEXT_H */ |