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