diff options
Diffstat (limited to 'arch/powerpc/include/asm/mmu_context.h')
| -rw-r--r-- | arch/powerpc/include/asm/mmu_context.h | 257 |
1 files changed, 34 insertions, 223 deletions
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h index 6b993ef452ff..ab4f19263c42 100644 --- a/arch/powerpc/include/asm/mmu_context.h +++ b/arch/powerpc/include/asm/mmu_context.h @@ -2,237 +2,26 @@ #define __ASM_POWERPC_MMU_CONTEXT_H #ifdef __KERNEL__ +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/sched.h> +#include <linux/spinlock.h> #include <asm/mmu.h> #include <asm/cputable.h> #include <asm-generic/mm_hooks.h> - -#ifndef CONFIG_PPC64 -#include <asm/atomic.h> -#include <linux/bitops.h> - -/* - * On 32-bit PowerPC 6xx/7xx/7xxx CPUs, we use a set of 16 VSIDs - * (virtual segment identifiers) for each context. Although the - * hardware supports 24-bit VSIDs, and thus >1 million contexts, - * we only use 32,768 of them. That is ample, since there can be - * at most around 30,000 tasks in the system anyway, and it means - * that we can use a bitmap to indicate which contexts are in use. - * Using a bitmap means that we entirely avoid all of the problems - * that we used to have when the context number overflowed, - * particularly on SMP systems. - * -- paulus. - */ - -/* - * This function defines the mapping from contexts to VSIDs (virtual - * segment IDs). We use a skew on both the context and the high 4 bits - * of the 32-bit virtual address (the "effective segment ID") in order - * to spread out the entries in the MMU hash table. Note, if this - * function is changed then arch/ppc/mm/hashtable.S will have to be - * changed to correspond. - */ -#define CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \ - & 0xffffff) - -/* - The MPC8xx has only 16 contexts. We rotate through them on each - task switch. A better way would be to keep track of tasks that - own contexts, and implement an LRU usage. That way very active - tasks don't always have to pay the TLB reload overhead. The - kernel pages are mapped shared, so the kernel can run on behalf - of any task that makes a kernel entry. Shared does not mean they - are not protected, just that the ASID comparison is not performed. - -- Dan - - The IBM4xx has 256 contexts, so we can just rotate through these - as a way of "switching" contexts. If the TID of the TLB is zero, - the PID/TID comparison is disabled, so we can use a TID of zero - to represent all kernel pages as shared among all contexts. - -- Dan - */ - -static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) -{ -} - -#ifdef CONFIG_8xx -#define NO_CONTEXT 16 -#define LAST_CONTEXT 15 -#define FIRST_CONTEXT 0 - -#elif defined(CONFIG_4xx) -#define NO_CONTEXT 256 -#define LAST_CONTEXT 255 -#define FIRST_CONTEXT 1 - -#elif defined(CONFIG_E200) || defined(CONFIG_E500) -#define NO_CONTEXT 256 -#define LAST_CONTEXT 255 -#define FIRST_CONTEXT 1 - -#else - -/* PPC 6xx, 7xx CPUs */ -#define NO_CONTEXT ((unsigned long) -1) -#define LAST_CONTEXT 32767 -#define FIRST_CONTEXT 1 -#endif - -/* - * Set the current MMU context. - * On 32-bit PowerPCs (other than the 8xx embedded chips), this is done by - * loading up the segment registers for the user part of the address space. - * - * Since the PGD is immediately available, it is much faster to simply - * pass this along as a second parameter, which is required for 8xx and - * can be used for debugging on all processors (if you happen to have - * an Abatron). - */ -extern void set_context(unsigned long contextid, pgd_t *pgd); - -/* - * Bitmap of contexts in use. - * The size of this bitmap is LAST_CONTEXT + 1 bits. - */ -extern unsigned long context_map[]; - -/* - * This caches the next context number that we expect to be free. - * Its use is an optimization only, we can't rely on this context - * number to be free, but it usually will be. - */ -extern unsigned long next_mmu_context; - -/* - * If we don't have sufficient contexts to give one to every task - * that could be in the system, we need to be able to steal contexts. - * These variables support that. - */ -#if LAST_CONTEXT < 30000 -#define FEW_CONTEXTS 1 -extern atomic_t nr_free_contexts; -extern struct mm_struct *context_mm[LAST_CONTEXT+1]; -extern void steal_context(void); -#endif - -/* - * Get a new mmu context for the address space described by `mm'. - */ -static inline void get_mmu_context(struct mm_struct *mm) -{ - unsigned long ctx; - - if (mm->context.id != NO_CONTEXT) - return; -#ifdef FEW_CONTEXTS - while (atomic_dec_if_positive(&nr_free_contexts) < 0) - steal_context(); -#endif - ctx = next_mmu_context; - while (test_and_set_bit(ctx, context_map)) { - ctx = find_next_zero_bit(context_map, LAST_CONTEXT+1, ctx); - if (ctx > LAST_CONTEXT) - ctx = 0; - } - next_mmu_context = (ctx + 1) & LAST_CONTEXT; - mm->context.id = ctx; -#ifdef FEW_CONTEXTS - context_mm[ctx] = mm; -#endif -} - -/* - * Set up the context for a new address space. - */ -static inline int init_new_context(struct task_struct *t, struct mm_struct *mm) -{ - mm->context.id = NO_CONTEXT; - return 0; -} - -/* - * We're finished using the context for an address space. - */ -static inline void destroy_context(struct mm_struct *mm) -{ - preempt_disable(); - if (mm->context.id != NO_CONTEXT) { - clear_bit(mm->context.id, context_map); - mm->context.id = NO_CONTEXT; -#ifdef FEW_CONTEXTS - atomic_inc(&nr_free_contexts); -#endif - } - preempt_enable(); -} - -static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, - struct task_struct *tsk) -{ -#ifdef CONFIG_ALTIVEC - if (cpu_has_feature(CPU_FTR_ALTIVEC)) - asm volatile ("dssall;\n" -#ifndef CONFIG_POWER4 - "sync;\n" /* G4 needs a sync here, G5 apparently not */ -#endif - : : ); -#endif /* CONFIG_ALTIVEC */ - - tsk->thread.pgdir = next->pgd; - - /* No need to flush userspace segments if the mm doesnt change */ - if (prev == next) - return; - - /* Setup new userspace context */ - get_mmu_context(next); - set_context(next->context.id, next->pgd); -} - -#define deactivate_mm(tsk,mm) do { } while (0) +#include <asm/cputhreads.h> /* - * After we have set current->mm to a new value, this activates - * the context for the new mm so we see the new mappings. + * Most if the context management is out of line */ -#define activate_mm(active_mm, mm) switch_mm(active_mm, mm, current) - extern void mmu_context_init(void); - - -#else - -#include <linux/kernel.h> -#include <linux/mm.h> -#include <linux/sched.h> - -/* - * Copyright (C) 2001 PPC 64 Team, IBM Corp - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * as published by the Free Software Foundation; either version - * 2 of the License, or (at your option) any later version. - */ - -static inline void enter_lazy_tlb(struct mm_struct *mm, - struct task_struct *tsk) -{ -} - -/* - * The proto-VSID space has 2^35 - 1 segments available for user mappings. - * Each segment contains 2^28 bytes. Each context maps 2^44 bytes, - * so we can support 2^19-1 contexts (19 == 35 + 28 - 44). - */ -#define NO_CONTEXT 0 -#define MAX_CONTEXT ((1UL << 19) - 1) - extern int init_new_context(struct task_struct *tsk, struct mm_struct *mm); extern void destroy_context(struct mm_struct *mm); +extern void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next); extern void switch_stab(struct task_struct *tsk, struct mm_struct *mm); extern void switch_slb(struct task_struct *tsk, struct mm_struct *mm); +extern void set_context(unsigned long id, pgd_t *pgd); /* * switch_mm is the entry point called from the architecture independent @@ -241,22 +30,39 @@ extern void switch_slb(struct task_struct *tsk, struct mm_struct *mm); static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk) { - if (!cpu_isset(smp_processor_id(), next->cpu_vm_mask)) - cpu_set(smp_processor_id(), next->cpu_vm_mask); + /* Mark this context has been used on the new CPU */ + cpu_set(smp_processor_id(), next->cpu_vm_mask); + + /* 32-bit keeps track of the current PGDIR in the thread struct */ +#ifdef CONFIG_PPC32 + tsk->thread.pgdir = next->pgd; +#endif /* CONFIG_PPC32 */ - /* No need to flush userspace segments if the mm doesnt change */ + /* Nothing else to do if we aren't actually switching */ if (prev == next) return; + /* We must stop all altivec streams before changing the HW + * context + */ #ifdef CONFIG_ALTIVEC if (cpu_has_feature(CPU_FTR_ALTIVEC)) asm volatile ("dssall"); #endif /* CONFIG_ALTIVEC */ + /* The actual HW switching method differs between the various + * sub architectures. + */ +#ifdef CONFIG_PPC_STD_MMU_64 if (cpu_has_feature(CPU_FTR_SLB)) switch_slb(tsk, next); else switch_stab(tsk, next); +#else + /* Out of line for now */ + switch_mmu_context(prev, next); +#endif + } #define deactivate_mm(tsk,mm) do { } while (0) @@ -274,6 +80,11 @@ static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next) local_irq_restore(flags); } -#endif /* CONFIG_PPC64 */ +/* We don't currently use enter_lazy_tlb() for anything */ +static inline void enter_lazy_tlb(struct mm_struct *mm, + struct task_struct *tsk) +{ +} + #endif /* __KERNEL__ */ #endif /* __ASM_POWERPC_MMU_CONTEXT_H */ |