1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2001-2008 Silicon Graphics, Inc. All rights reserved.
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.
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>
26 #include <linux/atomic.h>
27 #include <asm/tlbflush.h>
29 struct uncached_pool {
30 struct gen_pool *pool;
31 struct mutex add_chunk_mutex; /* serialize adding a converted chunk */
32 int nchunks_added; /* #of converted chunks added to pool */
33 atomic_t status; /* smp called function's return status*/
36 #define MAX_CONVERTED_CHUNKS_PER_NODE 2
38 struct uncached_pool uncached_pools[MAX_NUMNODES];
41 static void uncached_ipi_visibility(void *data)
44 struct uncached_pool *uc_pool = (struct uncached_pool *)data;
46 status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
47 if ((status != PAL_VISIBILITY_OK) &&
48 (status != PAL_VISIBILITY_OK_REMOTE_NEEDED))
49 atomic_inc(&uc_pool->status);
53 static void uncached_ipi_mc_drain(void *data)
56 struct uncached_pool *uc_pool = (struct uncached_pool *)data;
58 status = ia64_pal_mc_drain();
59 if (status != PAL_STATUS_SUCCESS)
60 atomic_inc(&uc_pool->status);
65 * Add a new chunk of uncached memory pages to the specified pool.
67 * @pool: pool to add new chunk of uncached memory to
68 * @nid: node id of node to allocate memory from, or -1
70 * This is accomplished by first allocating a granule of cached memory pages
71 * and then converting them to uncached memory pages.
73 static int uncached_add_chunk(struct uncached_pool *uc_pool, int nid)
76 int status, i, nchunks_added = uc_pool->nchunks_added;
77 unsigned long c_addr, uc_addr;
79 if (mutex_lock_interruptible(&uc_pool->add_chunk_mutex) != 0)
80 return -1; /* interrupted by a signal */
82 if (uc_pool->nchunks_added > nchunks_added) {
83 /* someone added a new chunk while we were waiting */
84 mutex_unlock(&uc_pool->add_chunk_mutex);
88 if (uc_pool->nchunks_added >= MAX_CONVERTED_CHUNKS_PER_NODE) {
89 mutex_unlock(&uc_pool->add_chunk_mutex);
93 /* attempt to allocate a granule's worth of cached memory pages */
95 page = __alloc_pages_node(nid,
96 GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
97 IA64_GRANULE_SHIFT-PAGE_SHIFT);
99 mutex_unlock(&uc_pool->add_chunk_mutex);
103 /* convert the memory pages from cached to uncached */
105 c_addr = (unsigned long)page_address(page);
106 uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET;
109 * There's a small race here where it's possible for someone to
110 * access the page through /dev/mem halfway through the conversion
111 * to uncached - not sure it's really worth bothering about
113 for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
114 SetPageUncached(&page[i]);
116 flush_tlb_kernel_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);
118 status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
119 if (status == PAL_VISIBILITY_OK_REMOTE_NEEDED) {
120 atomic_set(&uc_pool->status, 0);
121 smp_call_function(uncached_ipi_visibility, uc_pool, 1);
122 if (atomic_read(&uc_pool->status))
124 } else if (status != PAL_VISIBILITY_OK)
129 flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);
131 /* flush the just introduced uncached translation from the TLB */
132 local_flush_tlb_all();
136 status = ia64_pal_mc_drain();
137 if (status != PAL_STATUS_SUCCESS)
139 atomic_set(&uc_pool->status, 0);
140 smp_call_function(uncached_ipi_mc_drain, uc_pool, 1);
141 if (atomic_read(&uc_pool->status))
145 * The chunk of memory pages has been converted to uncached so now we
146 * can add it to the pool.
148 status = gen_pool_add(uc_pool->pool, uc_addr, IA64_GRANULE_SIZE, nid);
152 uc_pool->nchunks_added++;
153 mutex_unlock(&uc_pool->add_chunk_mutex);
156 /* failed to convert or add the chunk so give it back to the kernel */
158 for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
159 ClearPageUncached(&page[i]);
161 free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT);
162 mutex_unlock(&uc_pool->add_chunk_mutex);
168 * uncached_alloc_page
170 * @starting_nid: node id of node to start with, or -1
171 * @n_pages: number of contiguous pages to allocate
173 * Allocate the specified number of contiguous uncached pages on the
174 * requested node. If not enough contiguous uncached pages are available
175 * on the requested node, roundrobin starting with the next higher node.
177 unsigned long uncached_alloc_page(int starting_nid, int n_pages)
179 unsigned long uc_addr;
180 struct uncached_pool *uc_pool;
183 if (unlikely(starting_nid >= MAX_NUMNODES))
186 if (starting_nid < 0)
187 starting_nid = numa_node_id();
191 if (!node_state(nid, N_HIGH_MEMORY))
193 uc_pool = &uncached_pools[nid];
194 if (uc_pool->pool == NULL)
197 uc_addr = gen_pool_alloc(uc_pool->pool,
198 n_pages * PAGE_SIZE);
201 } while (uncached_add_chunk(uc_pool, nid) == 0);
203 } while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid);
207 EXPORT_SYMBOL(uncached_alloc_page);
213 * @uc_addr: uncached address of first page to free
214 * @n_pages: number of contiguous pages to free
216 * Free the specified number of uncached pages.
218 void uncached_free_page(unsigned long uc_addr, int n_pages)
220 int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET);
221 struct gen_pool *pool = uncached_pools[nid].pool;
223 if (unlikely(pool == NULL))
226 if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET)
227 panic("uncached_free_page invalid address %lx\n", uc_addr);
229 gen_pool_free(pool, uc_addr, n_pages * PAGE_SIZE);
231 EXPORT_SYMBOL(uncached_free_page);
235 * uncached_build_memmap,
237 * @uc_start: uncached starting address of a chunk of uncached memory
238 * @uc_end: uncached ending address of a chunk of uncached memory
239 * @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc())
241 * Called at boot time to build a map of pages that can be used for
242 * memory special operations.
244 static int __init uncached_build_memmap(u64 uc_start, u64 uc_end, void *arg)
246 int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET);
247 struct gen_pool *pool = uncached_pools[nid].pool;
248 size_t size = uc_end - uc_start;
250 touch_softlockup_watchdog();
253 memset((char *)uc_start, 0, size);
254 (void) gen_pool_add(pool, uc_start, size, nid);
260 static int __init uncached_init(void)
264 for_each_online_node(nid) {
265 uncached_pools[nid].pool = gen_pool_create(PAGE_SHIFT, nid);
266 mutex_init(&uncached_pools[nid].add_chunk_mutex);
269 efi_memmap_walk_uc(uncached_build_memmap, NULL);
273 __initcall(uncached_init);