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Linux/arch/ia64/kernel/uncached.c

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  1 /*
  2  * Copyright (C) 2001-2008 Silicon Graphics, Inc.  All rights reserved.
  3  *
  4  * This program is free software; you can redistribute it and/or modify it
  5  * under the terms of version 2 of the GNU General Public License
  6  * as published by the Free Software Foundation.
  7  *
  8  * A simple uncached page allocator using the generic allocator. This
  9  * allocator first utilizes the spare (spill) pages found in the EFI
 10  * memmap and will then start converting cached pages to uncached ones
 11  * at a granule at a time. Node awareness is implemented by having a
 12  * pool of pages per node.
 13  */
 14 
 15 #include <linux/types.h>
 16 #include <linux/kernel.h>
 17 #include <linux/module.h>
 18 #include <linux/init.h>
 19 #include <linux/errno.h>
 20 #include <linux/string.h>
 21 #include <linux/efi.h>
 22 #include <linux/genalloc.h>
 23 #include <linux/gfp.h>
 24 #include <asm/page.h>
 25 #include <asm/pal.h>
 26 #include <asm/pgtable.h>
 27 #include <linux/atomic.h>
 28 #include <asm/tlbflush.h>
 29 #include <asm/sn/arch.h>
 30 
 31 
 32 extern void __init efi_memmap_walk_uc(efi_freemem_callback_t, void *);
 33 
 34 struct uncached_pool {
 35         struct gen_pool *pool;
 36         struct mutex add_chunk_mutex;   /* serialize adding a converted chunk */
 37         int nchunks_added;              /* #of converted chunks added to pool */
 38         atomic_t status;                /* smp called function's return status*/
 39 };
 40 
 41 #define MAX_CONVERTED_CHUNKS_PER_NODE   2
 42 
 43 struct uncached_pool uncached_pools[MAX_NUMNODES];
 44 
 45 
 46 static void uncached_ipi_visibility(void *data)
 47 {
 48         int status;
 49         struct uncached_pool *uc_pool = (struct uncached_pool *)data;
 50 
 51         status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
 52         if ((status != PAL_VISIBILITY_OK) &&
 53             (status != PAL_VISIBILITY_OK_REMOTE_NEEDED))
 54                 atomic_inc(&uc_pool->status);
 55 }
 56 
 57 
 58 static void uncached_ipi_mc_drain(void *data)
 59 {
 60         int status;
 61         struct uncached_pool *uc_pool = (struct uncached_pool *)data;
 62 
 63         status = ia64_pal_mc_drain();
 64         if (status != PAL_STATUS_SUCCESS)
 65                 atomic_inc(&uc_pool->status);
 66 }
 67 
 68 
 69 /*
 70  * Add a new chunk of uncached memory pages to the specified pool.
 71  *
 72  * @pool: pool to add new chunk of uncached memory to
 73  * @nid: node id of node to allocate memory from, or -1
 74  *
 75  * This is accomplished by first allocating a granule of cached memory pages
 76  * and then converting them to uncached memory pages.
 77  */
 78 static int uncached_add_chunk(struct uncached_pool *uc_pool, int nid)
 79 {
 80         struct page *page;
 81         int status, i, nchunks_added = uc_pool->nchunks_added;
 82         unsigned long c_addr, uc_addr;
 83 
 84         if (mutex_lock_interruptible(&uc_pool->add_chunk_mutex) != 0)
 85                 return -1;      /* interrupted by a signal */
 86 
 87         if (uc_pool->nchunks_added > nchunks_added) {
 88                 /* someone added a new chunk while we were waiting */
 89                 mutex_unlock(&uc_pool->add_chunk_mutex);
 90                 return 0;
 91         }
 92 
 93         if (uc_pool->nchunks_added >= MAX_CONVERTED_CHUNKS_PER_NODE) {
 94                 mutex_unlock(&uc_pool->add_chunk_mutex);
 95                 return -1;
 96         }
 97 
 98         /* attempt to allocate a granule's worth of cached memory pages */
 99 
100         page = alloc_pages_exact_node(nid,
101                                 GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
102                                 IA64_GRANULE_SHIFT-PAGE_SHIFT);
103         if (!page) {
104                 mutex_unlock(&uc_pool->add_chunk_mutex);
105                 return -1;
106         }
107 
108         /* convert the memory pages from cached to uncached */
109 
110         c_addr = (unsigned long)page_address(page);
111         uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET;
112 
113         /*
114          * There's a small race here where it's possible for someone to
115          * access the page through /dev/mem halfway through the conversion
116          * to uncached - not sure it's really worth bothering about
117          */
118         for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
119                 SetPageUncached(&page[i]);
120 
121         flush_tlb_kernel_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);
122 
123         status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
124         if (status == PAL_VISIBILITY_OK_REMOTE_NEEDED) {
125                 atomic_set(&uc_pool->status, 0);
126                 status = smp_call_function(uncached_ipi_visibility, uc_pool, 1);
127                 if (status || atomic_read(&uc_pool->status))
128                         goto failed;
129         } else if (status != PAL_VISIBILITY_OK)
130                 goto failed;
131 
132         preempt_disable();
133 
134         if (ia64_platform_is("sn2"))
135                 sn_flush_all_caches(uc_addr, IA64_GRANULE_SIZE);
136         else
137                 flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);
138 
139         /* flush the just introduced uncached translation from the TLB */
140         local_flush_tlb_all();
141 
142         preempt_enable();
143 
144         status = ia64_pal_mc_drain();
145         if (status != PAL_STATUS_SUCCESS)
146                 goto failed;
147         atomic_set(&uc_pool->status, 0);
148         status = smp_call_function(uncached_ipi_mc_drain, uc_pool, 1);
149         if (status || atomic_read(&uc_pool->status))
150                 goto failed;
151 
152         /*
153          * The chunk of memory pages has been converted to uncached so now we
154          * can add it to the pool.
155          */
156         status = gen_pool_add(uc_pool->pool, uc_addr, IA64_GRANULE_SIZE, nid);
157         if (status)
158                 goto failed;
159 
160         uc_pool->nchunks_added++;
161         mutex_unlock(&uc_pool->add_chunk_mutex);
162         return 0;
163 
164         /* failed to convert or add the chunk so give it back to the kernel */
165 failed:
166         for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
167                 ClearPageUncached(&page[i]);
168 
169         free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT);
170         mutex_unlock(&uc_pool->add_chunk_mutex);
171         return -1;
172 }
173 
174 
175 /*
176  * uncached_alloc_page
177  *
178  * @starting_nid: node id of node to start with, or -1
179  * @n_pages: number of contiguous pages to allocate
180  *
181  * Allocate the specified number of contiguous uncached pages on the
182  * the requested node. If not enough contiguous uncached pages are available
183  * on the requested node, roundrobin starting with the next higher node.
184  */
185 unsigned long uncached_alloc_page(int starting_nid, int n_pages)
186 {
187         unsigned long uc_addr;
188         struct uncached_pool *uc_pool;
189         int nid;
190 
191         if (unlikely(starting_nid >= MAX_NUMNODES))
192                 return 0;
193 
194         if (starting_nid < 0)
195                 starting_nid = numa_node_id();
196         nid = starting_nid;
197 
198         do {
199                 if (!node_state(nid, N_HIGH_MEMORY))
200                         continue;
201                 uc_pool = &uncached_pools[nid];
202                 if (uc_pool->pool == NULL)
203                         continue;
204                 do {
205                         uc_addr = gen_pool_alloc(uc_pool->pool,
206                                                  n_pages * PAGE_SIZE);
207                         if (uc_addr != 0)
208                                 return uc_addr;
209                 } while (uncached_add_chunk(uc_pool, nid) == 0);
210 
211         } while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid);
212 
213         return 0;
214 }
215 EXPORT_SYMBOL(uncached_alloc_page);
216 
217 
218 /*
219  * uncached_free_page
220  *
221  * @uc_addr: uncached address of first page to free
222  * @n_pages: number of contiguous pages to free
223  *
224  * Free the specified number of uncached pages.
225  */
226 void uncached_free_page(unsigned long uc_addr, int n_pages)
227 {
228         int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET);
229         struct gen_pool *pool = uncached_pools[nid].pool;
230 
231         if (unlikely(pool == NULL))
232                 return;
233 
234         if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET)
235                 panic("uncached_free_page invalid address %lx\n", uc_addr);
236 
237         gen_pool_free(pool, uc_addr, n_pages * PAGE_SIZE);
238 }
239 EXPORT_SYMBOL(uncached_free_page);
240 
241 
242 /*
243  * uncached_build_memmap,
244  *
245  * @uc_start: uncached starting address of a chunk of uncached memory
246  * @uc_end: uncached ending address of a chunk of uncached memory
247  * @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc())
248  *
249  * Called at boot time to build a map of pages that can be used for
250  * memory special operations.
251  */
252 static int __init uncached_build_memmap(u64 uc_start, u64 uc_end, void *arg)
253 {
254         int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET);
255         struct gen_pool *pool = uncached_pools[nid].pool;
256         size_t size = uc_end - uc_start;
257 
258         touch_softlockup_watchdog();
259 
260         if (pool != NULL) {
261                 memset((char *)uc_start, 0, size);
262                 (void) gen_pool_add(pool, uc_start, size, nid);
263         }
264         return 0;
265 }
266 
267 
268 static int __init uncached_init(void)
269 {
270         int nid;
271 
272         for_each_node_state(nid, N_ONLINE) {
273                 uncached_pools[nid].pool = gen_pool_create(PAGE_SHIFT, nid);
274                 mutex_init(&uncached_pools[nid].add_chunk_mutex);
275         }
276 
277         efi_memmap_walk_uc(uncached_build_memmap, NULL);
278         return 0;
279 }
280 
281 __initcall(uncached_init);
282 

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