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