arch/ia64/kernel/uncached.c

   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_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);