From 71995e4d004f6afbc86cc4a80c4a281f6c00b07f Mon Sep 17 00:00:00 2001 From: Ley Foon Tan Date: Thu, 6 Nov 2014 15:19:47 +0800 Subject: nios2: Process management This patch adds support for thread creation and context switching. Signed-off-by: Ley Foon Tan --- arch/nios2/mm/mmu_context.c | 116 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+) create mode 100644 arch/nios2/mm/mmu_context.c (limited to 'arch/nios2/mm/mmu_context.c') diff --git a/arch/nios2/mm/mmu_context.c b/arch/nios2/mm/mmu_context.c new file mode 100644 index 000000000000..45d6b9c58d67 --- /dev/null +++ b/arch/nios2/mm/mmu_context.c @@ -0,0 +1,116 @@ +/* + * MMU context handling. + * + * Copyright (C) 2011 Tobias Klauser + * 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 + +#include +#include +#include + +/* 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)); +} -- cgit