arch/ia64/kernel/uncached.c - maze/linux - Git at Google

 /*
  * Copyright (C) 2001-2008 Silicon Graphics, Inc.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of version 2 of the GNU General Public License
  * as published by the Free Software Foundation.
  *
  * A simple uncached page allocator using the generic allocator. This
  * allocator first utilizes the spare (spill) pages found in the EFI
  * memmap and will then start converting cached pages to uncached ones
  * at a granule at a time. Node awareness is implemented by having a
  * pool of pages per node.
  */

 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/efi.h>
 #include <linux/genalloc.h>
 #include <linux/gfp.h>
 #include <asm/page.h>
 #include <asm/pal.h>
 #include <asm/pgtable.h>
 #include <linux/atomic.h>
 #include <asm/tlbflush.h>
 #include <asm/sn/arch.h>


 extern void __init efi_memmap_walk_uc(efi_freemem_callback_t, void *);

 struct uncached_pool {
 	struct gen_pool *pool;
 	struct mutex add_chunk_mutex;	/* serialize adding a converted chunk */
 	int nchunks_added;		/* #of converted chunks added to pool */
 	atomic_t status;		/* smp called function's return status*/
 };

 #define MAX_CONVERTED_CHUNKS_PER_NODE	2

 struct uncached_pool uncached_pools[MAX_NUMNODES];


 static void uncached_ipi_visibility(void *data)
 {
 	int status;
 	struct uncached_pool *uc_pool = (struct uncached_pool *)data;

 	status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
 	if ((status != PAL_VISIBILITY_OK) &&
 	    (status != PAL_VISIBILITY_OK_REMOTE_NEEDED))
 		atomic_inc(&uc_pool->status);
 }


 static void uncached_ipi_mc_drain(void *data)
 {
 	int status;
 	struct uncached_pool *uc_pool = (struct uncached_pool *)data;

 	status = ia64_pal_mc_drain();
 	if (status != PAL_STATUS_SUCCESS)
 		atomic_inc(&uc_pool->status);
 }


 /*
  * Add a new chunk of uncached memory pages to the specified pool.
  *
  * @pool: pool to add new chunk of uncached memory to
  * @nid: node id of node to allocate memory from, or -1
  *
  * This is accomplished by first allocating a granule of cached memory pages
  * and then converting them to uncached memory pages.
  */
 static int uncached_add_chunk(struct uncached_pool *uc_pool, int nid)
 {
 	struct page *page;
 	int status, i, nchunks_added = uc_pool->nchunks_added;
 	unsigned long c_addr, uc_addr;

 	if (mutex_lock_interruptible(&uc_pool->add_chunk_mutex) != 0)
 		return -1;	/* interrupted by a signal */

 	if (uc_pool->nchunks_added > nchunks_added) {
 		/* someone added a new chunk while we were waiting */
 		mutex_unlock(&uc_pool->add_chunk_mutex);
 		return 0;
 	}

 	if (uc_pool->nchunks_added >= MAX_CONVERTED_CHUNKS_PER_NODE) {
 		mutex_unlock(&uc_pool->add_chunk_mutex);
 		return -1;
 	}

 	/* attempt to allocate a granule's worth of cached memory pages */

 	page = alloc_pages_exact_node(nid,
 				GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
 				IA64_GRANULE_SHIFT-PAGE_SHIFT);
 	if (!page) {
 		mutex_unlock(&uc_pool->add_chunk_mutex);
 		return -1;
 	}

 	/* convert the memory pages from cached to uncached */

 	c_addr = (unsigned long)page_address(page);
 	uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET;

 	/*
 	 * There's a small race here where it's possible for someone to
 	 * access the page through /dev/mem halfway through the conversion
 	 * to uncached - not sure it's really worth bothering about
 	 */
 	for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
 		SetPageUncached(&page[i]);

 	flush_tlb_kernel_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);

 	status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
 	if (status == PAL_VISIBILITY_OK_REMOTE_NEEDED) {
 		atomic_set(&uc_pool->status, 0);
 		status = smp_call_function(uncached_ipi_visibility, uc_pool, 1);
 		if (status || atomic_read(&uc_pool->status))
 			goto failed;
 	} else if (status != PAL_VISIBILITY_OK)
 		goto failed;

 	preempt_disable();

 	if (ia64_platform_is("sn2"))
 		sn_flush_all_caches(uc_addr, IA64_GRANULE_SIZE);
 	else
 		flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);

 	/* flush the just introduced uncached translation from the TLB */
 	local_flush_tlb_all();

 	preempt_enable();

 	status = ia64_pal_mc_drain();
 	if (status != PAL_STATUS_SUCCESS)
 		goto failed;
 	atomic_set(&uc_pool->status, 0);
 	status = smp_call_function(uncached_ipi_mc_drain, uc_pool, 1);
 	if (status || atomic_read(&uc_pool->status))
 		goto failed;

 	/*
 	 * The chunk of memory pages has been converted to uncached so now we
 	 * can add it to the pool.
 	 */
 	status = gen_pool_add(uc_pool->pool, uc_addr, IA64_GRANULE_SIZE, nid);
 	if (status)
 		goto failed;

 	uc_pool->nchunks_added++;
 	mutex_unlock(&uc_pool->add_chunk_mutex);
 	return 0;

 	/* failed to convert or add the chunk so give it back to the kernel */
 failed:
 	for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
 		ClearPageUncached(&page[i]);

 	free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT);
 	mutex_unlock(&uc_pool->add_chunk_mutex);
 	return -1;
 }


 /*
  * uncached_alloc_page
  *
  * @starting_nid: node id of node to start with, or -1
  * @n_pages: number of contiguous pages to allocate
  *
  * Allocate the specified number of contiguous uncached pages on the
  * the requested node. If not enough contiguous uncached pages are available
  * on the requested node, roundrobin starting with the next higher node.
  */
 unsigned long uncached_alloc_page(int starting_nid, int n_pages)
 {
 	unsigned long uc_addr;
 	struct uncached_pool *uc_pool;
 	int nid;

 	if (unlikely(starting_nid >= MAX_NUMNODES))
 		return 0;

 	if (starting_nid < 0)
 		starting_nid = numa_node_id();
 	nid = starting_nid;

 	do {
 		if (!node_state(nid, N_HIGH_MEMORY))
 			continue;
 		uc_pool = &uncached_pools[nid];
 		if (uc_pool->pool == NULL)
 			continue;
 		do {
 			uc_addr = gen_pool_alloc(uc_pool->pool,
 						 n_pages * PAGE_SIZE);
 			if (uc_addr != 0)
 				return uc_addr;
 		} while (uncached_add_chunk(uc_pool, nid) == 0);

 	} while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid);

 	return 0;
 }
 EXPORT_SYMBOL(uncached_alloc_page);


 /*
  * uncached_free_page
  *
  * @uc_addr: uncached address of first page to free
  * @n_pages: number of contiguous pages to free
  *
  * Free the specified number of uncached pages.
  */
 void uncached_free_page(unsigned long uc_addr, int n_pages)
 {
 	int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET);
 	struct gen_pool *pool = uncached_pools[nid].pool;

 	if (unlikely(pool == NULL))
 		return;

 	if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET)
 		panic("uncached_free_page invalid address %lx\n", uc_addr);

 	gen_pool_free(pool, uc_addr, n_pages * PAGE_SIZE);
 }
 EXPORT_SYMBOL(uncached_free_page);


 /*
  * uncached_build_memmap,
  *
  * @uc_start: uncached starting address of a chunk of uncached memory
  * @uc_end: uncached ending address of a chunk of uncached memory
  * @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc())
  *
  * Called at boot time to build a map of pages that can be used for
  * memory special operations.
  */
 static int __init uncached_build_memmap(u64 uc_start, u64 uc_end, void *arg)
 {
 	int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET);
 	struct gen_pool *pool = uncached_pools[nid].pool;
 	size_t size = uc_end - uc_start;

 	touch_softlockup_watchdog();

 	if (pool != NULL) {
 		memset((char *)uc_start, 0, size);
 		(void) gen_pool_add(pool, uc_start, size, nid);
 	}
 	return 0;
 }


 static int __init uncached_init(void)
 {
 	int nid;

 	for_each_node_state(nid, N_ONLINE) {
 		uncached_pools[nid].pool = gen_pool_create(PAGE_SHIFT, nid);
 		mutex_init(&uncached_pools[nid].add_chunk_mutex);
 	}

 	efi_memmap_walk_uc(uncached_build_memmap, NULL);
 	return 0;
 }

 __initcall(uncached_init);
	/*
	* Copyright (C) 2001-2008 Silicon Graphics, Inc. All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of version 2 of the GNU General Public License
	* as published by the Free Software Foundation.
	*
	* A simple uncached page allocator using the generic allocator. This
	* allocator first utilizes the spare (spill) pages found in the EFI
	* memmap and will then start converting cached pages to uncached ones
	* at a granule at a time. Node awareness is implemented by having a
	* pool of pages per node.
	*/

	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/errno.h>
	#include <linux/string.h>
	#include <linux/efi.h>
	#include <linux/genalloc.h>
	#include <linux/gfp.h>
	#include <asm/page.h>
	#include <asm/pal.h>
	#include <asm/pgtable.h>
	#include <linux/atomic.h>
	#include <asm/tlbflush.h>
	#include <asm/sn/arch.h>


	extern void __init efi_memmap_walk_uc(efi_freemem_callback_t, void *);

	struct uncached_pool {
	struct gen_pool *pool;
	struct mutex add_chunk_mutex; /* serialize adding a converted chunk */
	int nchunks_added; /* #of converted chunks added to pool */
	atomic_t status; /* smp called function's return status*/
	};

	#define MAX_CONVERTED_CHUNKS_PER_NODE 2

	struct uncached_pool uncached_pools[MAX_NUMNODES];


	static void uncached_ipi_visibility(void *data)
	{
	int status;
	struct uncached_pool uc_pool = (struct uncached_pool )data;

	status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
	if ((status != PAL_VISIBILITY_OK) &&
	(status != PAL_VISIBILITY_OK_REMOTE_NEEDED))
	atomic_inc(&uc_pool->status);
	}


	static void uncached_ipi_mc_drain(void *data)
	{
	int status;
	struct uncached_pool uc_pool = (struct uncached_pool )data;

	status = ia64_pal_mc_drain();
	if (status != PAL_STATUS_SUCCESS)
	atomic_inc(&uc_pool->status);
	}


	/*
	* Add a new chunk of uncached memory pages to the specified pool.
	*
	* @pool: pool to add new chunk of uncached memory to
	* @nid: node id of node to allocate memory from, or -1
	*
	* This is accomplished by first allocating a granule of cached memory pages
	* and then converting them to uncached memory pages.
	*/
	static int uncached_add_chunk(struct uncached_pool *uc_pool, int nid)
	{
	struct page *page;
	int status, i, nchunks_added = uc_pool->nchunks_added;
	unsigned long c_addr, uc_addr;

	if (mutex_lock_interruptible(&uc_pool->add_chunk_mutex) != 0)
	return -1; /* interrupted by a signal */

	if (uc_pool->nchunks_added > nchunks_added) {
	/* someone added a new chunk while we were waiting */
	mutex_unlock(&uc_pool->add_chunk_mutex);
	return 0;
	}

	if (uc_pool->nchunks_added >= MAX_CONVERTED_CHUNKS_PER_NODE) {
	mutex_unlock(&uc_pool->add_chunk_mutex);
	return -1;
	}

	/* attempt to allocate a granule's worth of cached memory pages */

	page = alloc_pages_exact_node(nid,
	GFP_KERNEL \| __GFP_ZERO \| GFP_THISNODE,
	IA64_GRANULE_SHIFT-PAGE_SHIFT);
	if (!page) {
	mutex_unlock(&uc_pool->add_chunk_mutex);
	return -1;
	}

	/* convert the memory pages from cached to uncached */

	c_addr = (unsigned long)page_address(page);
	uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET;

	/*
	* There's a small race here where it's possible for someone to
	* access the page through /dev/mem halfway through the conversion
	* to uncached - not sure it's really worth bothering about
	*/
	for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
	SetPageUncached(&page[i]);

	flush_tlb_kernel_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);

	status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
	if (status == PAL_VISIBILITY_OK_REMOTE_NEEDED) {
	atomic_set(&uc_pool->status, 0);
	status = smp_call_function(uncached_ipi_visibility, uc_pool, 1);
	if (status \|\| atomic_read(&uc_pool->status))
	goto failed;
	} else if (status != PAL_VISIBILITY_OK)
	goto failed;

	preempt_disable();

	if (ia64_platform_is("sn2"))
	sn_flush_all_caches(uc_addr, IA64_GRANULE_SIZE);
	else
	flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);

	/* flush the just introduced uncached translation from the TLB */
	local_flush_tlb_all();

	preempt_enable();

	status = ia64_pal_mc_drain();
	if (status != PAL_STATUS_SUCCESS)
	goto failed;
	atomic_set(&uc_pool->status, 0);
	status = smp_call_function(uncached_ipi_mc_drain, uc_pool, 1);
	if (status \|\| atomic_read(&uc_pool->status))
	goto failed;

	/*
	* The chunk of memory pages has been converted to uncached so now we
	* can add it to the pool.
	*/
	status = gen_pool_add(uc_pool->pool, uc_addr, IA64_GRANULE_SIZE, nid);
	if (status)
	goto failed;

	uc_pool->nchunks_added++;
	mutex_unlock(&uc_pool->add_chunk_mutex);
	return 0;

	/* failed to convert or add the chunk so give it back to the kernel */
	failed:
	for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
	ClearPageUncached(&page[i]);

	free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT);
	mutex_unlock(&uc_pool->add_chunk_mutex);
	return -1;
	}


	/*
	* uncached_alloc_page
	*
	* @starting_nid: node id of node to start with, or -1
	* @n_pages: number of contiguous pages to allocate
	*
	* Allocate the specified number of contiguous uncached pages on the
	* the requested node. If not enough contiguous uncached pages are available
	* on the requested node, roundrobin starting with the next higher node.
	*/
	unsigned long uncached_alloc_page(int starting_nid, int n_pages)
	{
	unsigned long uc_addr;
	struct uncached_pool *uc_pool;
	int nid;

	if (unlikely(starting_nid >= MAX_NUMNODES))
	return 0;

	if (starting_nid < 0)
	starting_nid = numa_node_id();
	nid = starting_nid;

	do {
	if (!node_state(nid, N_HIGH_MEMORY))
	continue;
	uc_pool = &uncached_pools[nid];
	if (uc_pool->pool == NULL)
	continue;
	do {
	uc_addr = gen_pool_alloc(uc_pool->pool,
	n_pages * PAGE_SIZE);
	if (uc_addr != 0)
	return uc_addr;
	} while (uncached_add_chunk(uc_pool, nid) == 0);

	} while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid);

	return 0;
	}
	EXPORT_SYMBOL(uncached_alloc_page);


	/*
	* uncached_free_page
	*
	* @uc_addr: uncached address of first page to free
	* @n_pages: number of contiguous pages to free
	*
	* Free the specified number of uncached pages.
	*/
	void uncached_free_page(unsigned long uc_addr, int n_pages)
	{
	int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET);
	struct gen_pool *pool = uncached_pools[nid].pool;

	if (unlikely(pool == NULL))
	return;

	if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET)
	panic("uncached_free_page invalid address %lx\n", uc_addr);

	gen_pool_free(pool, uc_addr, n_pages * PAGE_SIZE);
	}
	EXPORT_SYMBOL(uncached_free_page);


	/*
	* uncached_build_memmap,
	*
	* @uc_start: uncached starting address of a chunk of uncached memory
	* @uc_end: uncached ending address of a chunk of uncached memory
	* @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc())
	*
	* Called at boot time to build a map of pages that can be used for
	* memory special operations.
	*/
	static int __init uncached_build_memmap(u64 uc_start, u64 uc_end, void *arg)
	{
	int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET);
	struct gen_pool *pool = uncached_pools[nid].pool;
	size_t size = uc_end - uc_start;

	touch_softlockup_watchdog();

	if (pool != NULL) {
	memset((char *)uc_start, 0, size);
	(void) gen_pool_add(pool, uc_start, size, nid);
	}
	return 0;
	}


	static int __init uncached_init(void)
	{
	int nid;

	for_each_node_state(nid, N_ONLINE) {
	uncached_pools[nid].pool = gen_pool_create(PAGE_SHIFT, nid);
	mutex_init(&uncached_pools[nid].add_chunk_mutex);
	}

	efi_memmap_walk_uc(uncached_build_memmap, NULL);
	return 0;
	}

	__initcall(uncached_init);