Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757436AbZD0Jzm (ORCPT ); Mon, 27 Apr 2009 05:55:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755106AbZD0Jsv (ORCPT ); Mon, 27 Apr 2009 05:48:51 -0400 Received: from 178-47-31-89.wifiinternet.cz ([89.31.47.178]:60685 "EHLO monstr.eu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754927AbZD0Jsu (ORCPT ); Mon, 27 Apr 2009 05:48:50 -0400 From: monstr@monstr.eu To: linux-kernel@vger.kernel.org Cc: john.williams@petalogix.com, Michal Simek Subject: [PATCH 10/30] microblaze_mmu_v1: Context handling - mmu_context.c/h Date: Mon, 27 Apr 2009 10:31:59 +0200 Message-Id: <1240821139-7247-11-git-send-email-monstr@monstr.eu> X-Mailer: git-send-email 1.5.5.1 In-Reply-To: <1240821139-7247-10-git-send-email-monstr@monstr.eu> References: <1240821139-7247-1-git-send-email-monstr@monstr.eu> <1240821139-7247-2-git-send-email-monstr@monstr.eu> <1240821139-7247-3-git-send-email-monstr@monstr.eu> <1240821139-7247-4-git-send-email-monstr@monstr.eu> <1240821139-7247-5-git-send-email-monstr@monstr.eu> <1240821139-7247-6-git-send-email-monstr@monstr.eu> <1240821139-7247-7-git-send-email-monstr@monstr.eu> <1240821139-7247-8-git-send-email-monstr@monstr.eu> <1240821139-7247-9-git-send-email-monstr@monstr.eu> <1240821139-7247-10-git-send-email-monstr@monstr.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7573 Lines: 248 From: Michal Simek Signed-off-by: Michal Simek --- arch/microblaze/include/asm/mmu_context.h | 134 +++++++++++++++++++++++++++++ arch/microblaze/mm/mmu_context.c | 70 +++++++++++++++ 2 files changed, 204 insertions(+), 0 deletions(-) create mode 100644 arch/microblaze/mm/mmu_context.c diff --git a/arch/microblaze/include/asm/mmu_context.h b/arch/microblaze/include/asm/mmu_context.h index 150ca01..2f49649 100644 --- a/arch/microblaze/include/asm/mmu_context.h +++ b/arch/microblaze/include/asm/mmu_context.h @@ -1,4 +1,6 @@ /* + * Copyright (C) 2008-2009 Michal Simek + * Copyright (C) 2008-2009 PetaLogix * Copyright (C) 2006 Atmark Techno, Inc. * * This file is subject to the terms and conditions of the GNU General Public @@ -9,6 +11,7 @@ #ifndef _ASM_MICROBLAZE_MMU_CONTEXT_H #define _ASM_MICROBLAZE_MMU_CONTEXT_H +# ifndef CONFIG_MMU # define init_new_context(tsk, mm) ({ 0; }) # define enter_lazy_tlb(mm, tsk) do {} while (0) @@ -18,4 +21,135 @@ # define switch_mm(prev, next, tsk) do {} while (0) # define activate_mm(prev, next) do {} while (0) +# else /* CONFIG_MMU */ + +# include +# include +# include +# include + +# ifdef __KERNEL__ +/* + * 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) + +/* + MicroBlaze 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. + */ + +static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) +{ +} + +# define NO_CONTEXT 256 +# define LAST_CONTEXT 255 +# define FIRST_CONTEXT 1 + +/* + * Set the current MMU context. + * This is done byloading 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(mm_context_t context, 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 mm_context_t next_mmu_context; + +/* + * Since 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. + */ +extern atomic_t nr_free_contexts; +extern struct mm_struct *context_mm[LAST_CONTEXT+1]; +extern void steal_context(void); + +/* + * Get a new mmu context for the address space described by `mm'. + */ +static inline void get_mmu_context(struct mm_struct *mm) +{ + mm_context_t ctx; + + if (mm->context != 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 = ctx; + context_mm[ctx] = mm; +} + +/* + * Set up the context for a new address space. + */ +# define init_new_context(tsk, mm) (((mm)->context = NO_CONTEXT), 0) + +/* + * We're finished using the context for an address space. + */ +static inline void destroy_context(struct mm_struct *mm) +{ + if (mm->context != NO_CONTEXT) { + clear_bit(mm->context, context_map); + mm->context = NO_CONTEXT; + atomic_inc(&nr_free_contexts); + } +} + +static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, + struct task_struct *tsk) +{ + tsk->thread.pgdir = next->pgd; + get_mmu_context(next); + set_context(next->context, next->pgd); +} + +/* + * 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 *active_mm, + struct mm_struct *mm) +{ + current->thread.pgdir = mm->pgd; + get_mmu_context(mm); + set_context(mm->context, mm->pgd); +} + +extern void mmu_context_init(void); + +# endif /* __KERNEL__ */ +# endif /* CONFIG_MMU */ #endif /* _ASM_MICROBLAZE_MMU_CONTEXT_H */ diff --git a/arch/microblaze/mm/mmu_context.c b/arch/microblaze/mm/mmu_context.c new file mode 100644 index 0000000..26ff82f --- /dev/null +++ b/arch/microblaze/mm/mmu_context.c @@ -0,0 +1,70 @@ +/* + * This file contains the routines for handling the MMU. + * + * Copyright (C) 2007 Xilinx, Inc. All rights reserved. + * + * Derived from arch/ppc/mm/4xx_mmu.c: + * -- 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 + * Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk). + * + * 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 + +mm_context_t next_mmu_context; +unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1]; +atomic_t nr_free_contexts; +struct mm_struct *context_mm[LAST_CONTEXT+1]; + +/* + * Initialize the context management stuff. + */ +void __init mmu_context_init(void) +{ + /* + * The use of context zero is reserved 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); +} + +/* + * Steal a context from a task that has one at the moment. + * + * 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 were motivated to do it. + */ +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); +} -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/