From b8b572e1015f81b4e748417be2629dfe51ab99f9 Mon Sep 17 00:00:00 2001 From: Stephen Rothwell Date: Fri, 1 Aug 2008 15:20:30 +1000 Subject: powerpc: Move include files to arch/powerpc/include/asm from include/asm-powerpc. This is the result of a mkdir arch/powerpc/include/asm git mv include/asm-powerpc/* arch/powerpc/include/asm Followed by a few documentation/comment fixups and a couple of places where was being used explicitly. Of the latter only one was outside the arch code and it is a driver only built for powerpc. Signed-off-by: Stephen Rothwell Signed-off-by: Paul Mackerras --- arch/powerpc/include/asm/mmu_context.h | 280 +++++++++++++++++++++++++++++++++ 1 file changed, 280 insertions(+) create mode 100644 arch/powerpc/include/asm/mmu_context.h (limited to 'arch/powerpc/include/asm/mmu_context.h') diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h new file mode 100644 index 000000000000..9102b8bf0ead --- /dev/null +++ b/arch/powerpc/include/asm/mmu_context.h @@ -0,0 +1,280 @@ +#ifndef __ASM_POWERPC_MMU_CONTEXT_H +#define __ASM_POWERPC_MMU_CONTEXT_H +#ifdef __KERNEL__ + +#include +#include +#include + +#ifndef CONFIG_PPC64 +#include +#include + +/* + * 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; + mm->context.vdso_base = 0; + 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) + +/* + * After we have set current->mm to a new value, this activates + * the context for the new mm so we see the new mappings. + */ +#define activate_mm(active_mm, mm) switch_mm(active_mm, mm, current) + +extern void mmu_context_init(void); + + +#else + +#include +#include +#include + +/* + * 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_stab(struct task_struct *tsk, struct mm_struct *mm); +extern void switch_slb(struct task_struct *tsk, struct mm_struct *mm); + +/* + * switch_mm is the entry point called from the architecture independent + * code in kernel/sched.c + */ +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); + + /* No need to flush userspace segments if the mm doesnt change */ + if (prev == next) + return; + +#ifdef CONFIG_ALTIVEC + if (cpu_has_feature(CPU_FTR_ALTIVEC)) + asm volatile ("dssall"); +#endif /* CONFIG_ALTIVEC */ + + if (cpu_has_feature(CPU_FTR_SLB)) + switch_slb(tsk, next); + else + switch_stab(tsk, next); +} + +#define deactivate_mm(tsk,mm) do { } while (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_mm(struct mm_struct *prev, struct mm_struct *next) +{ + unsigned long flags; + + local_irq_save(flags); + switch_mm(prev, next, current); + local_irq_restore(flags); +} + +#endif /* CONFIG_PPC64 */ +#endif /* __KERNEL__ */ +#endif /* __ASM_POWERPC_MMU_CONTEXT_H */ -- cgit v1.2.3