powerpc/mm: Split mmu_context handling

This splits the mmu_context handling between 32-bit hash based
processors, 64-bit hash based processors and everybody else.  This is
preliminary work for adding SMP support for BookE processors.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 78 insertions, 0 deletions

diff --git a/arch/powerpc/mm/mmu_context_hash64.c b/arch/powerpc/mm/mmu_context_hash64.c
new file mode 100644
index 000000000000..dbeb86ac90cd
--- /dev/null
+++ b/arch/powerpc/mm/mmu_context_hash64.c
@@ -0,0 +1,78 @@
+/*
+ *  MMU context allocation for 64-bit kernels.
+ *
+ *  Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
+ *
+ *  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/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/spinlock.h>
+#include <linux/idr.h>
+
+#include <asm/mmu_context.h>
+
+static DEFINE_SPINLOCK(mmu_context_lock);
+static DEFINE_IDR(mmu_context_idr);
+
+/*
+ * The proto-VSID space has 2^35 - 1 segments available for user mappings.
+ * Each segment contains 2^28 bytes.  Each context maps 2^44 bytes,
+ * so we can support 2^19-1 contexts (19 == 35 + 28 - 44).
+ */
+#define NO_CONTEXT      0
+#define MAX_CONTEXT     ((1UL << 19) - 1)
+
+int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+{
+        int index;
+        int err;
+
+again:
+        if (!idr_pre_get(&mmu_context_idr, GFP_KERNEL))
+                return -ENOMEM;
+
+        spin_lock(&mmu_context_lock);
+        err = idr_get_new_above(&mmu_context_idr, NULL, 1, &index);
+        spin_unlock(&mmu_context_lock);
+
+        if (err == -EAGAIN)
+                goto again;
+        else if (err)
+                return err;
+
+        if (index > MAX_CONTEXT) {
+                spin_lock(&mmu_context_lock);
+                idr_remove(&mmu_context_idr, index);
+                spin_unlock(&mmu_context_lock);
+                return -ENOMEM;
+        }
+
+        /* The old code would re-promote on fork, we don't do that
+         * when using slices as it could cause problem promoting slices
+         * that have been forced down to 4K
+         */
+        if (slice_mm_new_context(mm))
+                slice_set_user_psize(mm, mmu_virtual_psize);
+        mm->context.id = index;
+
+        return 0;
+}
+
+void destroy_context(struct mm_struct *mm)
+{
+        spin_lock(&mmu_context_lock);
+        idr_remove(&mmu_context_idr, mm->context.id);
+        spin_unlock(&mmu_context_lock);
+
+        mm->context.id = NO_CONTEXT;
+}