1 /* mmu-context.c: MMU context allocation and management
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
12 #include <linux/sched.h>
14 #include <linux/vs_cvirt.h>
15 #include <asm/tlbflush.h>
19 static unsigned long cxn_bitmap[NR_CXN / (sizeof(unsigned long) * 8)];
20 static LIST_HEAD(cxn_owners_lru);
21 static DEFINE_SPINLOCK(cxn_owners_lock);
23 int __nongpreldata cxn_pinned = -1;
26 /*****************************************************************************/
28 * initialise a new context
30 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
32 memset(&mm->context, 0, sizeof(mm->context));
33 INIT_LIST_HEAD(&mm->context.id_link);
34 mm->context.itlb_cached_pge = 0xffffffffUL;
35 mm->context.dtlb_cached_pge = 0xffffffffUL;
38 } /* end init_new_context() */
40 /*****************************************************************************/
42 * make sure a kernel MMU context has a CPU context number
43 * - call with cxn_owners_lock held
45 static unsigned get_cxn(mm_context_t *ctx)
51 if (!list_empty(&ctx->id_link)) {
52 list_move_tail(&ctx->id_link, &cxn_owners_lru);
55 /* find the first unallocated context number
56 * - 0 is reserved for the kernel
58 cxn = find_next_zero_bit(cxn_bitmap, NR_CXN, 1);
60 set_bit(cxn, cxn_bitmap);
63 /* none remaining - need to steal someone else's cxn */
65 list_for_each(_p, &cxn_owners_lru) {
66 p = list_entry(_p, mm_context_t, id_link);
67 if (!p->id_busy && p->id != cxn_pinned)
71 BUG_ON(_p == &cxn_owners_lru);
75 list_del_init(&p->id_link);
80 list_add_tail(&ctx->id_link, &cxn_owners_lru);
86 /*****************************************************************************/
88 * restore the current TLB miss handler mapped page tables into the MMU context and set up a
89 * mapping for the page directory
91 void change_mm_context(mm_context_t *old, mm_context_t *ctx, pgd_t *pgd)
95 _pgd = virt_to_phys(pgd);
97 /* save the state of the outgoing MMU context */
100 asm volatile("movsg scr0,%0" : "=r"(old->itlb_cached_pge));
101 asm volatile("movsg dampr4,%0" : "=r"(old->itlb_ptd_mapping));
102 asm volatile("movsg scr1,%0" : "=r"(old->dtlb_cached_pge));
103 asm volatile("movsg dampr5,%0" : "=r"(old->dtlb_ptd_mapping));
105 /* select an MMU context number */
106 spin_lock(&cxn_owners_lock);
109 spin_unlock(&cxn_owners_lock);
111 asm volatile("movgs %0,cxnr" : : "r"(ctx->id));
113 /* restore the state of the incoming MMU context */
114 asm volatile("movgs %0,scr0" : : "r"(ctx->itlb_cached_pge));
115 asm volatile("movgs %0,dampr4" : : "r"(ctx->itlb_ptd_mapping));
116 asm volatile("movgs %0,scr1" : : "r"(ctx->dtlb_cached_pge));
117 asm volatile("movgs %0,dampr5" : : "r"(ctx->dtlb_ptd_mapping));
119 /* map the PGD into uncached virtual memory */
120 asm volatile("movgs %0,ttbr" : : "r"(_pgd));
121 asm volatile("movgs %0,dampr3"
122 :: "r"(_pgd | xAMPRx_L | xAMPRx_M | xAMPRx_SS_16Kb |
123 xAMPRx_S | xAMPRx_C | xAMPRx_V));
125 } /* end change_mm_context() */
127 /*****************************************************************************/
129 * finished with an MMU context number
131 void destroy_context(struct mm_struct *mm)
133 mm_context_t *ctx = &mm->context;
135 spin_lock(&cxn_owners_lock);
137 if (!list_empty(&ctx->id_link)) {
138 if (ctx->id == cxn_pinned)
141 list_del_init(&ctx->id_link);
142 clear_bit(ctx->id, cxn_bitmap);
143 __flush_tlb_mm(ctx->id);
147 spin_unlock(&cxn_owners_lock);
148 } /* end destroy_context() */
150 /*****************************************************************************/
152 * display the MMU context currently a process is currently using
154 #ifdef CONFIG_PROC_FS
155 char *proc_pid_status_frv_cxnr(struct mm_struct *mm, char *buffer)
157 spin_lock(&cxn_owners_lock);
158 buffer += sprintf(buffer, "CXNR: %u\n", mm->context.id);
159 spin_unlock(&cxn_owners_lock);
162 } /* end proc_pid_status_frv_cxnr() */
165 /*****************************************************************************/
167 * (un)pin a process's mm_struct's MMU context ID
169 int cxn_pin_by_pid(pid_t pid)
171 struct task_struct *tsk;
172 struct mm_struct *mm = NULL;
175 /* unpin if pid is zero */
183 /* get a handle on the mm_struct */
184 read_lock(&tasklist_lock);
185 tsk = find_task_by_pid(pid);
192 atomic_inc(&mm->mm_users);
197 read_unlock(&tasklist_lock);
202 /* make sure it has a CXN and pin it */
203 spin_lock(&cxn_owners_lock);
204 cxn_pinned = get_cxn(&mm->context);
205 spin_unlock(&cxn_owners_lock);
209 } /* end cxn_pin_by_pid() */