arch/ia64/kernel/uncached.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2001-2008 Silicon Graphics, Inc.  All rights reserved.
   4  *
   5  * A simple uncached page allocator using the generic allocator. This
   6  * allocator first utilizes the spare (spill) pages found in the EFI
   7  * memmap and will then start converting cached pages to uncached ones
   8  * at a granule at a time. Node awareness is implemented by having a
   9  * pool of pages per node.
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/errno.h>
  17 #include <linux/string.h>
  18 #include <linux/efi.h>
  19 #include <linux/nmi.h>
  20 #include <linux/genalloc.h>
  21 #include <linux/gfp.h>
  22 #include <linux/pgtable.h>
  23 #include <asm/page.h>
  24 #include <asm/pal.h>
  25 #include <linux/atomic.h>
  26 #include <asm/tlbflush.h>
  27
  28
  29 extern void __init efi_memmap_walk_uc(efi_freemem_callback_t, void *);
  30
  31 struct uncached_pool {
  32         struct gen_pool *pool;
  33         struct mutex add_chunk_mutex;   /* serialize adding a converted chunk */
  34         int nchunks_added;              /* #of converted chunks added to pool */
  35         atomic_t status;                /* smp called function's return status*/
  36 };
  37
  38 #define MAX_CONVERTED_CHUNKS_PER_NODE   2
  39
  40 struct uncached_pool uncached_pools[MAX_NUMNODES];
  41
  42
  43 static void uncached_ipi_visibility(void *data)
  44 {
  45         int status;
  46         struct uncached_pool *uc_pool = (struct uncached_pool *)data;
  47
  48         status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
  49         if ((status != PAL_VISIBILITY_OK) &&
  50             (status != PAL_VISIBILITY_OK_REMOTE_NEEDED))
  51                 atomic_inc(&uc_pool->status);
  52 }
  53
  54
  55 static void uncached_ipi_mc_drain(void *data)
  56 {
  57         int status;
  58         struct uncached_pool *uc_pool = (struct uncached_pool *)data;
  59
  60         status = ia64_pal_mc_drain();
  61         if (status != PAL_STATUS_SUCCESS)
  62                 atomic_inc(&uc_pool->status);
  63 }
  64
  65
  66 /*
  67  * Add a new chunk of uncached memory pages to the specified pool.
  68  *
  69  * @pool: pool to add new chunk of uncached memory to
  70  * @nid: node id of node to allocate memory from, or -1
  71  *
  72  * This is accomplished by first allocating a granule of cached memory pages
  73  * and then converting them to uncached memory pages.
  74  */
  75 static int uncached_add_chunk(struct uncached_pool *uc_pool, int nid)
  76 {
  77         struct page *page;
  78         int status, i, nchunks_added = uc_pool->nchunks_added;
  79         unsigned long c_addr, uc_addr;
  80
  81         if (mutex_lock_interruptible(&uc_pool->add_chunk_mutex) != 0)
  82                 return -1;      /* interrupted by a signal */
  83
  84         if (uc_pool->nchunks_added > nchunks_added) {
  85                 /* someone added a new chunk while we were waiting */
  86                 mutex_unlock(&uc_pool->add_chunk_mutex);
  87                 return 0;
  88         }
  89
  90         if (uc_pool->nchunks_added >= MAX_CONVERTED_CHUNKS_PER_NODE) {
  91                 mutex_unlock(&uc_pool->add_chunk_mutex);
  92                 return -1;
  93         }
  94
  95         /* attempt to allocate a granule's worth of cached memory pages */
  96
  97         page = __alloc_pages_node(nid,
  98                                 GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
  99                                 IA64_GRANULE_SHIFT-PAGE_SHIFT);
 100         if (!page) {
 101                 mutex_unlock(&uc_pool->add_chunk_mutex);
 102                 return -1;
 103         }
 104
 105         /* convert the memory pages from cached to uncached */
 106
 107         c_addr = (unsigned long)page_address(page);
 108         uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET;
 109
 110         /*
 111          * There's a small race here where it's possible for someone to
 112          * access the page through /dev/mem halfway through the conversion
 113          * to uncached - not sure it's really worth bothering about
 114          */
 115         for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
 116                 SetPageUncached(&page[i]);
 117
 118         flush_tlb_kernel_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);
 119
 120         status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
 121         if (status == PAL_VISIBILITY_OK_REMOTE_NEEDED) {
 122                 atomic_set(&uc_pool->status, 0);
 123                 smp_call_function(uncached_ipi_visibility, uc_pool, 1);
 124                 if (atomic_read(&uc_pool->status))
 125                         goto failed;
 126         } else if (status != PAL_VISIBILITY_OK)
 127                 goto failed;
 128
 129         preempt_disable();
 130
 131         flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);
 132
 133         /* flush the just introduced uncached translation from the TLB */
 134         local_flush_tlb_all();
 135
 136         preempt_enable();
 137
 138         status = ia64_pal_mc_drain();
 139         if (status != PAL_STATUS_SUCCESS)
 140                 goto failed;
 141         atomic_set(&uc_pool->status, 0);
 142         smp_call_function(uncached_ipi_mc_drain, uc_pool, 1);
 143         if (atomic_read(&uc_pool->status))
 144                 goto failed;
 145
 146         /*
 147          * The chunk of memory pages has been converted to uncached so now we
 148          * can add it to the pool.
 149          */
 150         status = gen_pool_add(uc_pool->pool, uc_addr, IA64_GRANULE_SIZE, nid);
 151         if (status)
 152                 goto failed;
 153
 154         uc_pool->nchunks_added++;
 155         mutex_unlock(&uc_pool->add_chunk_mutex);
 156         return 0;
 157
 158         /* failed to convert or add the chunk so give it back to the kernel */
 159 failed:
 160         for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
 161                 ClearPageUncached(&page[i]);
 162
 163         free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT);
 164         mutex_unlock(&uc_pool->add_chunk_mutex);
 165         return -1;
 166 }
 167
 168
 169 /*
 170  * uncached_alloc_page
 171  *
 172  * @starting_nid: node id of node to start with, or -1
 173  * @n_pages: number of contiguous pages to allocate
 174  *
 175  * Allocate the specified number of contiguous uncached pages on the
 176  * the requested node. If not enough contiguous uncached pages are available
 177  * on the requested node, roundrobin starting with the next higher node.
 178  */
 179 unsigned long uncached_alloc_page(int starting_nid, int n_pages)
 180 {
 181         unsigned long uc_addr;
 182         struct uncached_pool *uc_pool;
 183         int nid;
 184
 185         if (unlikely(starting_nid >= MAX_NUMNODES))
 186                 return 0;
 187
 188         if (starting_nid < 0)
 189                 starting_nid = numa_node_id();
 190         nid = starting_nid;
 191
 192         do {
 193                 if (!node_state(nid, N_HIGH_MEMORY))
 194                         continue;
 195                 uc_pool = &uncached_pools[nid];
 196                 if (uc_pool->pool == NULL)
 197                         continue;
 198                 do {
 199                         uc_addr = gen_pool_alloc(uc_pool->pool,
 200                                                  n_pages * PAGE_SIZE);
 201                         if (uc_addr != 0)
 202                                 return uc_addr;
 203                 } while (uncached_add_chunk(uc_pool, nid) == 0);
 204
 205         } while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid);
 206
 207         return 0;
 208 }
 209 EXPORT_SYMBOL(uncached_alloc_page);
 210
 211
 212 /*
 213  * uncached_free_page
 214  *
 215  * @uc_addr: uncached address of first page to free
 216  * @n_pages: number of contiguous pages to free
 217  *
 218  * Free the specified number of uncached pages.
 219  */
 220 void uncached_free_page(unsigned long uc_addr, int n_pages)
 221 {
 222         int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET);
 223         struct gen_pool *pool = uncached_pools[nid].pool;
 224
 225         if (unlikely(pool == NULL))
 226                 return;
 227
 228         if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET)
 229                 panic("uncached_free_page invalid address %lx\n", uc_addr);
 230
 231         gen_pool_free(pool, uc_addr, n_pages * PAGE_SIZE);
 232 }
 233 EXPORT_SYMBOL(uncached_free_page);
 234
 235
 236 /*
 237  * uncached_build_memmap,
 238  *
 239  * @uc_start: uncached starting address of a chunk of uncached memory
 240  * @uc_end: uncached ending address of a chunk of uncached memory
 241  * @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc())
 242  *
 243  * Called at boot time to build a map of pages that can be used for
 244  * memory special operations.
 245  */
 246 static int __init uncached_build_memmap(u64 uc_start, u64 uc_end, void *arg)
 247 {
 248         int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET);
 249         struct gen_pool *pool = uncached_pools[nid].pool;
 250         size_t size = uc_end - uc_start;
 251
 252         touch_softlockup_watchdog();
 253
 254         if (pool != NULL) {
 255                 memset((char *)uc_start, 0, size);
 256                 (void) gen_pool_add(pool, uc_start, size, nid);
 257         }
 258         return 0;
 259 }
 260
 261
 262 static int __init uncached_init(void)
 263 {
 264         int nid;
 265
 266         for_each_node_state(nid, N_ONLINE) {
 267                 uncached_pools[nid].pool = gen_pool_create(PAGE_SHIFT, nid);
 268                 mutex_init(&uncached_pools[nid].add_chunk_mutex);
 269         }
 270
 271         efi_memmap_walk_uc(uncached_build_memmap, NULL);
 272         return 0;
 273 }
 274
 275 __initcall(uncached_init);