| /* |
| * MMU context handling. |
| * |
| * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch> |
| * Copyright (C) 2009 Wind River Systems Inc |
| * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com |
| * |
| * This file is subject to the terms and conditions of the GNU General Public |
| * License. See the file "COPYING" in the main directory of this archive |
| * for more details. |
| */ |
| |
| #include <linux/mm.h> |
| |
| #include <asm/cpuinfo.h> |
| #include <asm/mmu_context.h> |
| #include <asm/tlb.h> |
| |
| /* The pids position and mask in context */ |
| #define PID_SHIFT 0 |
| #define PID_BITS (cpuinfo.tlb_pid_num_bits) |
| #define PID_MASK ((1UL << PID_BITS) - 1) |
| |
| /* The versions position and mask in context */ |
| #define VERSION_BITS (32 - PID_BITS) |
| #define VERSION_SHIFT (PID_SHIFT + PID_BITS) |
| #define VERSION_MASK ((1UL << VERSION_BITS) - 1) |
| |
| /* Return the version part of a context */ |
| #define CTX_VERSION(c) (((c) >> VERSION_SHIFT) & VERSION_MASK) |
| |
| /* Return the pid part of a context */ |
| #define CTX_PID(c) (((c) >> PID_SHIFT) & PID_MASK) |
| |
| /* Value of the first context (version 1, pid 0) */ |
| #define FIRST_CTX ((1UL << VERSION_SHIFT) | (0 << PID_SHIFT)) |
| |
| static mm_context_t next_mmu_context; |
| |
| /* |
| * Initialize MMU context management stuff. |
| */ |
| void __init mmu_context_init(void) |
| { |
| /* We need to set this here because the value depends on runtime data |
| * from cpuinfo */ |
| next_mmu_context = FIRST_CTX; |
| } |
| |
| /* |
| * Set new context (pid), keep way |
| */ |
| static void set_context(mm_context_t context) |
| { |
| set_mmu_pid(CTX_PID(context)); |
| } |
| |
| static mm_context_t get_new_context(void) |
| { |
| /* Return the next pid */ |
| next_mmu_context += (1UL << PID_SHIFT); |
| |
| /* If the pid field wraps around we increase the version and |
| * flush the tlb */ |
| if (unlikely(CTX_PID(next_mmu_context) == 0)) { |
| /* Version is incremented since the pid increment above |
| * overflows info version */ |
| flush_cache_all(); |
| flush_tlb_all(); |
| } |
| |
| /* If the version wraps we start over with the first generation, we do |
| * not need to flush the tlb here since it's always done above */ |
| if (unlikely(CTX_VERSION(next_mmu_context) == 0)) |
| next_mmu_context = FIRST_CTX; |
| |
| return next_mmu_context; |
| } |
| |
| void switch_mm(struct mm_struct *prev, struct mm_struct *next, |
| struct task_struct *tsk) |
| { |
| unsigned long flags; |
| |
| local_irq_save(flags); |
| |
| /* If the process context we are swapping in has a different context |
| * generation then we have it should get a new generation/pid */ |
| if (unlikely(CTX_VERSION(next->context) != |
| CTX_VERSION(next_mmu_context))) |
| next->context = get_new_context(); |
| |
| /* Save the current pgd so the fast tlb handler can find it */ |
| pgd_current = next->pgd; |
| |
| /* Set the current context */ |
| set_context(next->context); |
| |
| local_irq_restore(flags); |
| } |
| |
| /* |
| * After we have set current->mm to a new value, this activates |
| * the context for the new mm so we see the new mappings. |
| */ |
| void activate_mm(struct mm_struct *prev, struct mm_struct *next) |
| { |
| next->context = get_new_context(); |
| set_context(next->context); |
| pgd_current = next->pgd; |
| } |
| |
| unsigned long get_pid_from_context(mm_context_t *context) |
| { |
| return CTX_PID((*context)); |
| } |