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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/mm/minicache.c
downloadconfigs-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/arm/mm/minicache.c')
-rw-r--r--arch/arm/mm/minicache.c73
1 files changed, 73 insertions, 0 deletions
diff --git a/arch/arm/mm/minicache.c b/arch/arm/mm/minicache.c
new file mode 100644
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+++ b/arch/arm/mm/minicache.c
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+/*
+ * linux/arch/arm/mm/minicache.c
+ *
+ * Copyright (C) 2001 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This handles the mini data cache, as found on SA11x0 and XScale
+ * processors. When we copy a user page page, we map it in such a way
+ * that accesses to this page will not touch the main data cache, but
+ * will be cached in the mini data cache. This prevents us thrashing
+ * the main data cache on page faults.
+ */
+#include <linux/init.h>
+#include <linux/mm.h>
+
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+
+/*
+ * 0xffff8000 to 0xffffffff is reserved for any ARM architecture
+ * specific hacks for copying pages efficiently.
+ */
+#define minicache_address (0xffff8000)
+#define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
+ L_PTE_CACHEABLE)
+
+static pte_t *minicache_pte;
+
+/*
+ * Note that this is intended to be called only from the copy_user_page
+ * asm code; anything else will require special locking to prevent the
+ * mini-cache space being re-used. (Note: probably preempt unsafe).
+ *
+ * We rely on the fact that the minicache is 2K, and we'll be pushing
+ * 4K of data through it, so we don't actually have to specifically
+ * flush the minicache when we change the mapping.
+ *
+ * Note also: assert(PAGE_OFFSET <= virt < high_memory).
+ * Unsafe: preempt, kmap.
+ */
+unsigned long map_page_minicache(unsigned long virt)
+{
+ set_pte(minicache_pte, pfn_pte(__pa(virt) >> PAGE_SHIFT, minicache_pgprot));
+ flush_tlb_kernel_page(minicache_address);
+
+ return minicache_address;
+}
+
+static int __init minicache_init(void)
+{
+ pgd_t *pgd;
+ pmd_t *pmd;
+
+ spin_lock(&init_mm.page_table_lock);
+
+ pgd = pgd_offset_k(minicache_address);
+ pmd = pmd_alloc(&init_mm, pgd, minicache_address);
+ if (!pmd)
+ BUG();
+ minicache_pte = pte_alloc_kernel(&init_mm, pmd, minicache_address);
+ if (!minicache_pte)
+ BUG();
+
+ spin_unlock(&init_mm.page_table_lock);
+
+ return 0;
+}
+
+core_initcall(minicache_init);