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Diffstat (limited to 'include/asm-ppc64/mmu_context.h')
| -rw-r--r-- | include/asm-ppc64/mmu_context.h | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/include/asm-ppc64/mmu_context.h b/include/asm-ppc64/mmu_context.h new file mode 100644 index 000000000000..c2e8e0466383 --- /dev/null +++ b/include/asm-ppc64/mmu_context.h @@ -0,0 +1,169 @@ +#ifndef __PPC64_MMU_CONTEXT_H +#define __PPC64_MMU_CONTEXT_H + +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <asm/mmu.h> +#include <asm/cputable.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. + */ + +/* + * Every architecture must define this function. It's the fastest + * way of searching a 140-bit bitmap where the first 100 bits are + * unlikely to be set. It's guaranteed that at least one of the 140 + * bits is cleared. + */ +static inline int sched_find_first_bit(unsigned long *b) +{ + if (unlikely(b[0])) + return __ffs(b[0]); + if (unlikely(b[1])) + return __ffs(b[1]) + 64; + return __ffs(b[2]) + 128; +} + +static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) +{ +} + +#define NO_CONTEXT 0 +#define MAX_CONTEXT (0x100000-1) + +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); +} + +/* VSID allocation + * =============== + * + * We first generate a 36-bit "proto-VSID". For kernel addresses this + * is equal to the ESID, for user addresses it is: + * (context << 15) | (esid & 0x7fff) + * + * The two forms are distinguishable because the top bit is 0 for user + * addresses, whereas the top two bits are 1 for kernel addresses. + * Proto-VSIDs with the top two bits equal to 0b10 are reserved for + * now. + * + * The proto-VSIDs are then scrambled into real VSIDs with the + * multiplicative hash: + * + * VSID = (proto-VSID * VSID_MULTIPLIER) % VSID_MODULUS + * where VSID_MULTIPLIER = 268435399 = 0xFFFFFC7 + * VSID_MODULUS = 2^36-1 = 0xFFFFFFFFF + * + * This scramble is only well defined for proto-VSIDs below + * 0xFFFFFFFFF, so both proto-VSID and actual VSID 0xFFFFFFFFF are + * reserved. VSID_MULTIPLIER is prime, so in particular it is + * co-prime to VSID_MODULUS, making this a 1:1 scrambling function. + * Because the modulus is 2^n-1 we can compute it efficiently without + * a divide or extra multiply (see below). + * + * This scheme has several advantages over older methods: + * + * - We have VSIDs allocated for every kernel address + * (i.e. everything above 0xC000000000000000), except the very top + * segment, which simplifies several things. + * + * - We allow for 15 significant bits of ESID and 20 bits of + * context for user addresses. i.e. 8T (43 bits) of address space for + * up to 1M contexts (although the page table structure and context + * allocation will need changes to take advantage of this). + * + * - The scramble function gives robust scattering in the hash + * table (at least based on some initial results). The previous + * method was more susceptible to pathological cases giving excessive + * hash collisions. + */ + +/* + * WARNING - If you change these you must make sure the asm + * implementations in slb_allocate(), do_stab_bolted and mmu.h + * (ASM_VSID_SCRAMBLE macro) are changed accordingly. + * + * You'll also need to change the precomputed VSID values in head.S + * which are used by the iSeries firmware. + */ + +static inline unsigned long vsid_scramble(unsigned long protovsid) +{ +#if 0 + /* The code below is equivalent to this function for arguments + * < 2^VSID_BITS, which is all this should ever be called + * with. However gcc is not clever enough to compute the + * modulus (2^n-1) without a second multiply. */ + return ((protovsid * VSID_MULTIPLIER) % VSID_MODULUS); +#else /* 1 */ + unsigned long x; + + x = protovsid * VSID_MULTIPLIER; + x = (x >> VSID_BITS) + (x & VSID_MODULUS); + return (x + ((x+1) >> VSID_BITS)) & VSID_MODULUS; +#endif /* 1 */ +} + +/* This is only valid for addresses >= KERNELBASE */ +static inline unsigned long get_kernel_vsid(unsigned long ea) +{ + return vsid_scramble(ea >> SID_SHIFT); +} + +/* This is only valid for user addresses (which are below 2^41) */ +static inline unsigned long get_vsid(unsigned long context, unsigned long ea) +{ + return vsid_scramble((context << USER_ESID_BITS) + | (ea >> SID_SHIFT)); +} + +#endif /* __PPC64_MMU_CONTEXT_H */ |