Linux-2.6.12-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!

1 files changed, 194 insertions, 0 deletions

diff --git a/arch/arm26/mm/small_page.c b/arch/arm26/mm/small_page.c
new file mode 100644
index 00000000000..77be86cca78
--- /dev/null
+++ b/arch/arm26/mm/small_page.c
@@ -0,0 +1,194 @@
+/*
+ *  linux/arch/arm26/mm/small_page.c
+ *
+ *  Copyright (C) 1996  Russell King
+ *  Copyright (C) 2003  Ian Molton
+ *
+ * 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.
+ *
+ *  Changelog:
+ *   26/01/1996	RMK	Cleaned up various areas to make little more generic
+ *   07/02/1999	RMK	Support added for 16K and 32K page sizes
+ *			containing 8K blocks
+ *   23/05/2004 IM	Fixed to use struct page->lru (thanks wli)
+ *
+ */
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/smp.h>
+#include <linux/bitops.h>
+
+#include <asm/pgtable.h>
+
+#define PEDANTIC
+
+/*
+ * Requirement:
+ *  We need to be able to allocate naturally aligned memory of finer
+ *  granularity than the page size.  This is typically used for the
+ *  second level page tables on 32-bit ARMs.
+ *
+ * FIXME - this comment is *out of date*
+ * Theory:
+ *  We "misuse" the Linux memory management system.  We use alloc_page
+ *  to allocate a page and then mark it as reserved.  The Linux memory
+ *  management system will then ignore the "offset", "next_hash" and
+ *  "pprev_hash" entries in the mem_map for this page.
+ *
+ *  We then use a bitstring in the "offset" field to mark which segments
+ *  of the page are in use, and manipulate this as required during the
+ *  allocation and freeing of these small pages.
+ *
+ *  We also maintain a queue of pages being used for this purpose using
+ *  the "next_hash" and "pprev_hash" entries of mem_map;
+ */
+
+struct order {
+	struct list_head queue;
+	unsigned int mask;		/* (1 << shift) - 1		*/
+	unsigned int shift;		/* (1 << shift) size of page	*/
+	unsigned int block_mask;	/* nr_blocks - 1		*/
+	unsigned int all_used;		/* (1 << nr_blocks) - 1		*/
+};
+
+
+static struct order orders[] = {
+#if PAGE_SIZE == 32768
+	{ LIST_HEAD_INIT(orders[0].queue), 2047, 11, 15, 0x0000ffff },
+	{ LIST_HEAD_INIT(orders[1].queue), 8191, 13,  3, 0x0000000f }
+#else
+#error unsupported page size (ARGH!)
+#endif
+};
+
+#define USED_MAP(pg)			((pg)->index)
+#define TEST_AND_CLEAR_USED(pg,off)	(test_and_clear_bit(off, &USED_MAP(pg)))
+#define SET_USED(pg,off)		(set_bit(off, &USED_MAP(pg)))
+
+static DEFINE_SPINLOCK(small_page_lock);
+
+static unsigned long __get_small_page(int priority, struct order *order)
+{
+	unsigned long flags;
+	struct page *page;
+	int offset;
+
+	do {
+		spin_lock_irqsave(&small_page_lock, flags);
+
+		if (list_empty(&order->queue))
+			goto need_new_page;
+
+		page = list_entry(order->queue.next, struct page, lru);
+again:
+#ifdef PEDANTIC
+		if (USED_MAP(page) & ~order->all_used)
+			PAGE_BUG(page);
+#endif
+		offset = ffz(USED_MAP(page));
+		SET_USED(page, offset);
+		if (USED_MAP(page) == order->all_used)
+			list_del_init(&page->lru);
+		spin_unlock_irqrestore(&small_page_lock, flags);
+
+		return (unsigned long) page_address(page) + (offset << order->shift);
+
+need_new_page:
+		spin_unlock_irqrestore(&small_page_lock, flags);
+		page = alloc_page(priority);
+		spin_lock_irqsave(&small_page_lock, flags);
+
+		if (list_empty(&order->queue)) {
+			if (!page)
+				goto no_page;
+			SetPageReserved(page);
+			USED_MAP(page) = 0;
+			list_add(&page->lru, &order->queue);
+			goto again;
+		}
+
+		spin_unlock_irqrestore(&small_page_lock, flags);
+		__free_page(page);
+	} while (1);
+
+no_page:
+	spin_unlock_irqrestore(&small_page_lock, flags);
+	return 0;
+}
+
+static void __free_small_page(unsigned long spage, struct order *order)
+{
+	unsigned long flags;
+	struct page *page;
+
+	if (virt_addr_valid(spage)) {
+		page = virt_to_page(spage);
+
+		/*
+		 * The container-page must be marked Reserved
+		 */
+		if (!PageReserved(page) || spage & order->mask)
+			goto non_small;
+
+#ifdef PEDANTIC
+		if (USED_MAP(page) & ~order->all_used)
+			PAGE_BUG(page);
+#endif
+
+		spage = spage >> order->shift;
+		spage &= order->block_mask;
+
+		/*
+		 * the following must be atomic wrt get_page
+		 */
+		spin_lock_irqsave(&small_page_lock, flags);
+
+		if (USED_MAP(page) == order->all_used)
+			list_add(&page->lru, &order->queue);
+
+		if (!TEST_AND_CLEAR_USED(page, spage))
+			goto already_free;
+
+		if (USED_MAP(page) == 0)
+			goto free_page;
+
+		spin_unlock_irqrestore(&small_page_lock, flags);
+	}
+	return;
+
+free_page:
+	/*
+	 * unlink the page from the small page queue and free it
+	 */
+	list_del_init(&page->lru);
+	spin_unlock_irqrestore(&small_page_lock, flags);
+	ClearPageReserved(page);
+	__free_page(page);
+	return;
+
+non_small:
+	printk("Trying to free non-small page from %p\n", __builtin_return_address(0));
+	return;
+already_free:
+	printk("Trying to free free small page from %p\n", __builtin_return_address(0));
+}
+
+unsigned long get_page_8k(int priority)
+{
+	return __get_small_page(priority, orders+1);
+}
+
+void free_page_8k(unsigned long spage)
+{
+	__free_small_page(spage, orders+1);
+}