diff options
Diffstat (limited to 'arch/frv/mm/mmu-context.c')
| -rw-r--r-- | arch/frv/mm/mmu-context.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/arch/frv/mm/mmu-context.c b/arch/frv/mm/mmu-context.c new file mode 100644 index 0000000..f2c6866 --- /dev/null +++ b/arch/frv/mm/mmu-context.c @@ -0,0 +1,208 @@ +/* mmu-context.c: MMU context allocation and management + * + * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * 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 <linux/sched.h> +#include <linux/mm.h> +#include <asm/tlbflush.h> + +#define NR_CXN 4096 + +static unsigned long cxn_bitmap[NR_CXN / (sizeof(unsigned long) * 8)]; +static LIST_HEAD(cxn_owners_lru); +static DEFINE_SPINLOCK(cxn_owners_lock); + +int __nongpreldata cxn_pinned = -1; + + +/*****************************************************************************/ +/* + * initialise a new context + */ +int init_new_context(struct task_struct *tsk, struct mm_struct *mm) +{ + memset(&mm->context, 0, sizeof(mm->context)); + INIT_LIST_HEAD(&mm->context.id_link); + mm->context.itlb_cached_pge = 0xffffffffUL; + mm->context.dtlb_cached_pge = 0xffffffffUL; + + return 0; +} /* end init_new_context() */ + +/*****************************************************************************/ +/* + * make sure a kernel MMU context has a CPU context number + * - call with cxn_owners_lock held + */ +static unsigned get_cxn(mm_context_t *ctx) +{ + struct list_head *_p; + mm_context_t *p; + unsigned cxn; + + if (!list_empty(&ctx->id_link)) { + list_move_tail(&ctx->id_link, &cxn_owners_lru); + } + else { + /* find the first unallocated context number + * - 0 is reserved for the kernel + */ + cxn = find_next_zero_bit(&cxn_bitmap, NR_CXN, 1); + if (cxn < NR_CXN) { + set_bit(cxn, &cxn_bitmap); + } + else { + /* none remaining - need to steal someone else's cxn */ + p = NULL; + list_for_each(_p, &cxn_owners_lru) { + p = list_entry(_p, mm_context_t, id_link); + if (!p->id_busy && p->id != cxn_pinned) + break; + } + + BUG_ON(_p == &cxn_owners_lru); + + cxn = p->id; + p->id = 0; + list_del_init(&p->id_link); + __flush_tlb_mm(cxn); + } + + ctx->id = cxn; + list_add_tail(&ctx->id_link, &cxn_owners_lru); + } + + return ctx->id; +} /* end get_cxn() */ + +/*****************************************************************************/ +/* + * restore the current TLB miss handler mapped page tables into the MMU context and set up a + * mapping for the page directory + */ +void change_mm_context(mm_context_t *old, mm_context_t *ctx, pgd_t *pgd) +{ + unsigned long _pgd; + + _pgd = virt_to_phys(pgd); + + /* save the state of the outgoing MMU context */ + old->id_busy = 0; + + asm volatile("movsg scr0,%0" : "=r"(old->itlb_cached_pge)); + asm volatile("movsg dampr4,%0" : "=r"(old->itlb_ptd_mapping)); + asm volatile("movsg scr1,%0" : "=r"(old->dtlb_cached_pge)); + asm volatile("movsg dampr5,%0" : "=r"(old->dtlb_ptd_mapping)); + + /* select an MMU context number */ + spin_lock(&cxn_owners_lock); + get_cxn(ctx); + ctx->id_busy = 1; + spin_unlock(&cxn_owners_lock); + + asm volatile("movgs %0,cxnr" : : "r"(ctx->id)); + + /* restore the state of the incoming MMU context */ + asm volatile("movgs %0,scr0" : : "r"(ctx->itlb_cached_pge)); + asm volatile("movgs %0,dampr4" : : "r"(ctx->itlb_ptd_mapping)); + asm volatile("movgs %0,scr1" : : "r"(ctx->dtlb_cached_pge)); + asm volatile("movgs %0,dampr5" : : "r"(ctx->dtlb_ptd_mapping)); + + /* map the PGD into uncached virtual memory */ + asm volatile("movgs %0,ttbr" : : "r"(_pgd)); + asm volatile("movgs %0,dampr3" + :: "r"(_pgd | xAMPRx_L | xAMPRx_M | xAMPRx_SS_16Kb | + xAMPRx_S | xAMPRx_C | xAMPRx_V)); + +} /* end change_mm_context() */ + +/*****************************************************************************/ +/* + * finished with an MMU context number + */ +void destroy_context(struct mm_struct *mm) +{ + mm_context_t *ctx = &mm->context; + + spin_lock(&cxn_owners_lock); + + if (!list_empty(&ctx->id_link)) { + if (ctx->id == cxn_pinned) + cxn_pinned = -1; + + list_del_init(&ctx->id_link); + clear_bit(ctx->id, &cxn_bitmap); + __flush_tlb_mm(ctx->id); + ctx->id = 0; + } + + spin_unlock(&cxn_owners_lock); +} /* end destroy_context() */ + +/*****************************************************************************/ +/* + * display the MMU context currently a process is currently using + */ +#ifdef CONFIG_PROC_FS +char *proc_pid_status_frv_cxnr(struct mm_struct *mm, char *buffer) +{ + spin_lock(&cxn_owners_lock); + buffer += sprintf(buffer, "CXNR: %u\n", mm->context.id); + spin_unlock(&cxn_owners_lock); + + return buffer; +} /* end proc_pid_status_frv_cxnr() */ +#endif + +/*****************************************************************************/ +/* + * (un)pin a process's mm_struct's MMU context ID + */ +int cxn_pin_by_pid(pid_t pid) +{ + struct task_struct *tsk; + struct mm_struct *mm = NULL; + int ret; + + /* unpin if pid is zero */ + if (pid == 0) { + cxn_pinned = -1; + return 0; + } + + ret = -ESRCH; + + /* get a handle on the mm_struct */ + read_lock(&tasklist_lock); + tsk = find_task_by_pid(pid); + if (tsk) { + ret = -EINVAL; + + task_lock(tsk); + if (tsk->mm) { + mm = tsk->mm; + atomic_inc(&mm->mm_users); + ret = 0; + } + task_unlock(tsk); + } + read_unlock(&tasklist_lock); + + if (ret < 0) + return ret; + + /* make sure it has a CXN and pin it */ + spin_lock(&cxn_owners_lock); + cxn_pinned = get_cxn(&mm->context); + spin_unlock(&cxn_owners_lock); + + mmput(mm); + return 0; +} /* end cxn_pin_by_pid() */ |
