--- /dev/null
+/* 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_vpid(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() */
Code Review / kvmfornfv.git / blobdiff