From 5e696617c425eb97bd943d781f3941fb1e8f0e5b Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Thu, 18 Dec 2008 19:13:24 +0000 Subject: powerpc/mm: Split mmu_context handling This splits the mmu_context handling between 32-bit hash based processors, 64-bit hash based processors and everybody else. This is preliminary work for adding SMP support for BookE processors. Signed-off-by: Benjamin Herrenschmidt Acked-by: Kumar Gala Signed-off-by: Paul Mackerras --- arch/powerpc/mm/Makefile | 7 +- arch/powerpc/mm/mmu_context_32.c | 84 ------------------ arch/powerpc/mm/mmu_context_64.c | 70 --------------- arch/powerpc/mm/mmu_context_hash32.c | 103 ++++++++++++++++++++++ arch/powerpc/mm/mmu_context_hash64.c | 78 +++++++++++++++++ arch/powerpc/mm/mmu_context_nohash.c | 162 +++++++++++++++++++++++++++++++++++ 6 files changed, 347 insertions(+), 157 deletions(-) delete mode 100644 arch/powerpc/mm/mmu_context_32.c delete mode 100644 arch/powerpc/mm/mmu_context_64.c create mode 100644 arch/powerpc/mm/mmu_context_hash32.c create mode 100644 arch/powerpc/mm/mmu_context_hash64.c create mode 100644 arch/powerpc/mm/mmu_context_nohash.c (limited to 'arch/powerpc/mm') diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile index 148de35c9ee..923bd3fa7d6 100644 --- a/arch/powerpc/mm/Makefile +++ b/arch/powerpc/mm/Makefile @@ -8,15 +8,16 @@ endif obj-y := fault.o mem.o pgtable.o \ init_$(CONFIG_WORD_SIZE).o \ - pgtable_$(CONFIG_WORD_SIZE).o \ - mmu_context_$(CONFIG_WORD_SIZE).o + pgtable_$(CONFIG_WORD_SIZE).o +obj-$(CONFIG_PPC_MMU_NOHASH) += mmu_context_nohash.o hash-$(CONFIG_PPC_NATIVE) := hash_native_64.o obj-$(CONFIG_PPC64) += hash_utils_64.o \ slb_low.o slb.o stab.o \ gup.o mmap.o $(hash-y) obj-$(CONFIG_PPC_STD_MMU_32) += ppc_mmu_32.o obj-$(CONFIG_PPC_STD_MMU) += hash_low_$(CONFIG_WORD_SIZE).o \ - tlb_hash$(CONFIG_WORD_SIZE).o + tlb_hash$(CONFIG_WORD_SIZE).o \ + mmu_context_hash$(CONFIG_WORD_SIZE).o obj-$(CONFIG_40x) += 40x_mmu.o obj-$(CONFIG_44x) += 44x_mmu.o obj-$(CONFIG_FSL_BOOKE) += fsl_booke_mmu.o diff --git a/arch/powerpc/mm/mmu_context_32.c b/arch/powerpc/mm/mmu_context_32.c deleted file mode 100644 index cc32ba41d90..00000000000 --- a/arch/powerpc/mm/mmu_context_32.c +++ /dev/null @@ -1,84 +0,0 @@ -/* - * This file contains the routines for handling the MMU on those - * PowerPC implementations where the MMU substantially follows the - * architecture specification. This includes the 6xx, 7xx, 7xxx, - * 8260, and POWER3 implementations but excludes the 8xx and 4xx. - * -- paulus - * - * Derived from arch/ppc/mm/init.c: - * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) - * - * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au) - * and Cort Dougan (PReP) (cort@cs.nmt.edu) - * Copyright (C) 1996 Paul Mackerras - * - * Derived from "arch/i386/mm/init.c" - * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds - * - * 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. - * - */ - -#include -#include - -#include -#include - -unsigned long next_mmu_context; -unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1]; -#ifdef FEW_CONTEXTS -atomic_t nr_free_contexts; -struct mm_struct *context_mm[LAST_CONTEXT+1]; -void steal_context(void); -#endif /* FEW_CONTEXTS */ - -/* - * Initialize the context management stuff. - */ -void __init -mmu_context_init(void) -{ - /* - * Some processors have too few contexts to reserve one for - * init_mm, and require using context 0 for a normal task. - * Other processors reserve the use of context zero for the kernel. - * This code assumes FIRST_CONTEXT < 32. - */ - context_map[0] = (1 << FIRST_CONTEXT) - 1; - next_mmu_context = FIRST_CONTEXT; -#ifdef FEW_CONTEXTS - atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1); -#endif /* FEW_CONTEXTS */ -} - -#ifdef FEW_CONTEXTS -/* - * Steal a context from a task that has one at the moment. - * This is only used on 8xx and 4xx and we presently assume that - * they don't do SMP. If they do then this will have to check - * whether the MM we steal is in use. - * We also assume that this is only used on systems that don't - * use an MMU hash table - this is true for 8xx and 4xx. - * This isn't an LRU system, it just frees up each context in - * turn (sort-of pseudo-random replacement :). This would be the - * place to implement an LRU scheme if anyone was motivated to do it. - * -- paulus - */ -void -steal_context(void) -{ - struct mm_struct *mm; - - /* free up context `next_mmu_context' */ - /* if we shouldn't free context 0, don't... */ - if (next_mmu_context < FIRST_CONTEXT) - next_mmu_context = FIRST_CONTEXT; - mm = context_mm[next_mmu_context]; - flush_tlb_mm(mm); - destroy_context(mm); -} -#endif /* FEW_CONTEXTS */ diff --git a/arch/powerpc/mm/mmu_context_64.c b/arch/powerpc/mm/mmu_context_64.c deleted file mode 100644 index 1db38ba1f54..00000000000 --- a/arch/powerpc/mm/mmu_context_64.c +++ /dev/null @@ -1,70 +0,0 @@ -/* - * MMU context allocation for 64-bit kernels. - * - * Copyright (C) 2004 Anton Blanchard, 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. - * - */ - -#include -#include -#include -#include -#include -#include -#include -#include - -#include - -static DEFINE_SPINLOCK(mmu_context_lock); -static DEFINE_IDR(mmu_context_idr); - -int init_new_context(struct task_struct *tsk, struct mm_struct *mm) -{ - int index; - int err; - -again: - if (!idr_pre_get(&mmu_context_idr, GFP_KERNEL)) - return -ENOMEM; - - spin_lock(&mmu_context_lock); - err = idr_get_new_above(&mmu_context_idr, NULL, 1, &index); - spin_unlock(&mmu_context_lock); - - if (err == -EAGAIN) - goto again; - else if (err) - return err; - - if (index > MAX_CONTEXT) { - spin_lock(&mmu_context_lock); - idr_remove(&mmu_context_idr, index); - spin_unlock(&mmu_context_lock); - return -ENOMEM; - } - - /* The old code would re-promote on fork, we don't do that - * when using slices as it could cause problem promoting slices - * that have been forced down to 4K - */ - if (slice_mm_new_context(mm)) - slice_set_user_psize(mm, mmu_virtual_psize); - mm->context.id = index; - - return 0; -} - -void destroy_context(struct mm_struct *mm) -{ - spin_lock(&mmu_context_lock); - idr_remove(&mmu_context_idr, mm->context.id); - spin_unlock(&mmu_context_lock); - - mm->context.id = NO_CONTEXT; -} diff --git a/arch/powerpc/mm/mmu_context_hash32.c b/arch/powerpc/mm/mmu_context_hash32.c new file mode 100644 index 00000000000..0dfba2bf7f3 --- /dev/null +++ b/arch/powerpc/mm/mmu_context_hash32.c @@ -0,0 +1,103 @@ +/* + * This file contains the routines for handling the MMU on those + * PowerPC implementations where the MMU substantially follows the + * architecture specification. This includes the 6xx, 7xx, 7xxx, + * 8260, and POWER3 implementations but excludes the 8xx and 4xx. + * -- paulus + * + * Derived from arch/ppc/mm/init.c: + * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) + * + * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au) + * and Cort Dougan (PReP) (cort@cs.nmt.edu) + * Copyright (C) 1996 Paul Mackerras + * + * Derived from "arch/i386/mm/init.c" + * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds + * + * 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. + * + */ + +#include +#include + +#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. + */ +#define NO_CONTEXT ((unsigned long) -1) +#define LAST_CONTEXT 32767 +#define FIRST_CONTEXT 1 + +/* + * 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. + * + * + * CTX_TO_VSID(ctx, va) (((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \ + * & 0xffffff) + */ + +static unsigned long next_mmu_context; +static unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1]; + + +/* + * Set up the context for a new address space. + */ +int init_new_context(struct task_struct *t, struct mm_struct *mm) +{ + unsigned long 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; + + return 0; +} + +/* + * We're finished using the context for an address space. + */ +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; + } + preempt_enable(); +} + +/* + * Initialize the context management stuff. + */ +void __init mmu_context_init(void) +{ + /* Reserve context 0 for kernel use */ + context_map[0] = (1 << FIRST_CONTEXT) - 1; + next_mmu_context = FIRST_CONTEXT; +} diff --git a/arch/powerpc/mm/mmu_context_hash64.c b/arch/powerpc/mm/mmu_context_hash64.c new file mode 100644 index 00000000000..dbeb86ac90c --- /dev/null +++ b/arch/powerpc/mm/mmu_context_hash64.c @@ -0,0 +1,78 @@ +/* + * MMU context allocation for 64-bit kernels. + * + * Copyright (C) 2004 Anton Blanchard, 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. + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +static DEFINE_SPINLOCK(mmu_context_lock); +static DEFINE_IDR(mmu_context_idr); + +/* + * 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) + +int init_new_context(struct task_struct *tsk, struct mm_struct *mm) +{ + int index; + int err; + +again: + if (!idr_pre_get(&mmu_context_idr, GFP_KERNEL)) + return -ENOMEM; + + spin_lock(&mmu_context_lock); + err = idr_get_new_above(&mmu_context_idr, NULL, 1, &index); + spin_unlock(&mmu_context_lock); + + if (err == -EAGAIN) + goto again; + else if (err) + return err; + + if (index > MAX_CONTEXT) { + spin_lock(&mmu_context_lock); + idr_remove(&mmu_context_idr, index); + spin_unlock(&mmu_context_lock); + return -ENOMEM; + } + + /* The old code would re-promote on fork, we don't do that + * when using slices as it could cause problem promoting slices + * that have been forced down to 4K + */ + if (slice_mm_new_context(mm)) + slice_set_user_psize(mm, mmu_virtual_psize); + mm->context.id = index; + + return 0; +} + +void destroy_context(struct mm_struct *mm) +{ + spin_lock(&mmu_context_lock); + idr_remove(&mmu_context_idr, mm->context.id); + spin_unlock(&mmu_context_lock); + + mm->context.id = NO_CONTEXT; +} diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c new file mode 100644 index 00000000000..00e02150abe --- /dev/null +++ b/arch/powerpc/mm/mmu_context_nohash.c @@ -0,0 +1,162 @@ +/* + * This file contains the routines for handling the MMU on those + * PowerPC implementations where the MMU is not using the hash + * table, such as 8xx, 4xx, BookE's etc... + * + * Copyright 2008 Ben Herrenschmidt + * IBM Corp. + * + * Derived from previous arch/powerpc/mm/mmu_context.c + * and arch/powerpc/include/asm/mmu_context.h + * + * 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. + * + */ + +#include +#include + +#include +#include + +/* + * 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 + */ + +#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 +#error Unsupported processor type +#endif + +static unsigned long next_mmu_context; +static unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1]; +static atomic_t nr_free_contexts; +static struct mm_struct *context_mm[LAST_CONTEXT+1]; +static void steal_context(void); + +/* Steal a context from a task that has one at the moment. + * This is only used on 8xx and 4xx and we presently assume that + * they don't do SMP. If they do then this will have to check + * whether the MM we steal is in use. + * We also assume that this is only used on systems that don't + * use an MMU hash table - this is true for 8xx and 4xx. + * This isn't an LRU system, it just frees up each context in + * turn (sort-of pseudo-random replacement :). This would be the + * place to implement an LRU scheme if anyone was motivated to do it. + * -- paulus + */ +static void steal_context(void) +{ + struct mm_struct *mm; + + /* free up context `next_mmu_context' */ + /* if we shouldn't free context 0, don't... */ + if (next_mmu_context < FIRST_CONTEXT) + next_mmu_context = FIRST_CONTEXT; + mm = context_mm[next_mmu_context]; + flush_tlb_mm(mm); + destroy_context(mm); +} + + +/* + * 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; + + while (atomic_dec_if_positive(&nr_free_contexts) < 0) + steal_context(); + + 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; + context_mm[ctx] = mm; +} + +void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next) +{ + get_mmu_context(next); + + set_context(next->context.id, next->pgd); +} + +/* + * Set up the context for a new address space. + */ +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. + */ +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; + atomic_inc(&nr_free_contexts); + } + preempt_enable(); +} + + +/* + * Initialize the context management stuff. + */ +void __init mmu_context_init(void) +{ + /* + * Some processors have too few contexts to reserve one for + * init_mm, and require using context 0 for a normal task. + * Other processors reserve the use of context zero for the kernel. + * This code assumes FIRST_CONTEXT < 32. + */ + context_map[0] = (1 << FIRST_CONTEXT) - 1; + next_mmu_context = FIRST_CONTEXT; + atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1); +} + -- cgit v1.2.3