summaryrefslogtreecommitdiffstats
path: root/arch/ia64/kernel/uncached.c
blob: 20e8a9b21d7519ebf7d506e4825d83c05629ba37 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
/*
 * Copyright (C) 2001-2008 Silicon Graphics, Inc.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 *
 * A simple uncached page allocator using the generic allocator. This
 * allocator first utilizes the spare (spill) pages found in the EFI
 * memmap and will then start converting cached pages to uncached ones
 * at a granule at a time. Node awareness is implemented by having a
 * pool of pages per node.
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/efi.h>
#include <linux/genalloc.h>
#include <linux/gfp.h>
#include <asm/page.h>
#include <asm/pal.h>
#include <asm/pgtable.h>
#include <linux/atomic.h>
#include <asm/tlbflush.h>
#include <asm/sn/arch.h>


extern void __init efi_memmap_walk_uc(efi_freemem_callback_t, void *);

struct uncached_pool {
	struct gen_pool *pool;
	struct mutex add_chunk_mutex;	/* serialize adding a converted chunk */
	int nchunks_added;		/* #of converted chunks added to pool */
	atomic_t status;		/* smp called function's return status*/
};

#define MAX_CONVERTED_CHUNKS_PER_NODE	2

struct uncached_pool uncached_pools[MAX_NUMNODES];


static void uncached_ipi_visibility(void *data)
{
	int status;
	struct uncached_pool *uc_pool = (struct uncached_pool *)data;

	status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
	if ((status != PAL_VISIBILITY_OK) &&
	    (status != PAL_VISIBILITY_OK_REMOTE_NEEDED))
		atomic_inc(&uc_pool->status);
}


static void uncached_ipi_mc_drain(void *data)
{
	int status;
	struct uncached_pool *uc_pool = (struct uncached_pool *)data;

	status = ia64_pal_mc_drain();
	if (status != PAL_STATUS_SUCCESS)
		atomic_inc(&uc_pool->status);
}


/*
 * Add a new chunk of uncached memory pages to the specified pool.
 *
 * @pool: pool to add new chunk of uncached memory to
 * @nid: node id of node to allocate memory from, or -1
 *
 * This is accomplished by first allocating a granule of cached memory pages
 * and then converting them to uncached memory pages.
 */
static int uncached_add_chunk(struct uncached_pool *uc_pool, int nid)
{
	struct page *page;
	int status, i, nchunks_added = uc_pool->nchunks_added;
	unsigned long c_addr, uc_addr;

	if (mutex_lock_interruptible(&uc_pool->add_chunk_mutex) != 0)
		return -1;	/* interrupted by a signal */

	if (uc_pool->nchunks_added > nchunks_added) {
		/* someone added a new chunk while we were waiting */
		mutex_unlock(&uc_pool->add_chunk_mutex);
		return 0;
	}

	if (uc_pool->nchunks_added >= MAX_CONVERTED_CHUNKS_PER_NODE) {
		mutex_unlock(&uc_pool->add_chunk_mutex);
		return -1;
	}

	/* attempt to allocate a granule's worth of cached memory pages */

	page = alloc_pages_exact_node(nid,
				GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
				IA64_GRANULE_SHIFT-PAGE_SHIFT);
	if (!page) {
		mutex_unlock(&uc_pool->add_chunk_mutex);
		return -1;
	}

	/* convert the memory pages from cached to uncached */

	c_addr = (unsigned long)page_address(page);
	uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET;

	/*
	 * There's a small race here where it's possible for someone to
	 * access the page through /dev/mem halfway through the conversion
	 * to uncached - not sure it's really worth bothering about
	 */
	for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
		SetPageUncached(&page[i]);

	flush_tlb_kernel_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);

	status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
	if (status == PAL_VISIBILITY_OK_REMOTE_NEEDED) {
		atomic_set(&uc_pool->status, 0);
		status = smp_call_function(uncached_ipi_visibility, uc_pool, 1);
		if (status || atomic_read(&uc_pool->status))
			goto failed;
	} else if (status != PAL_VISIBILITY_OK)
		goto failed;

	preempt_disable();

	if (ia64_platform_is("sn2"))
		sn_flush_all_caches(uc_addr, IA64_GRANULE_SIZE);
	else
		flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);

	/* flush the just introduced uncached translation from the TLB */
	local_flush_tlb_all();

	preempt_enable();

	status = ia64_pal_mc_drain();
	if (status != PAL_STATUS_SUCCESS)
		goto failed;
	atomic_set(&uc_pool->status, 0);
	status = smp_call_function(uncached_ipi_mc_drain, uc_pool, 1);
	if (status || atomic_read(&uc_pool->status))
		goto failed;

	/*
	 * The chunk of memory pages has been converted to uncached so now we
	 * can add it to the pool.
	 */
	status = gen_pool_add(uc_pool->pool, uc_addr, IA64_GRANULE_SIZE, nid);
	if (status)
		goto failed;

	uc_pool->nchunks_added++;
	mutex_unlock(&uc_pool->add_chunk_mutex);
	return 0;

	/* failed to convert or add the chunk so give it back to the kernel */
failed:
	for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
		ClearPageUncached(&page[i]);

	free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT);
	mutex_unlock(&uc_pool->add_chunk_mutex);
	return -1;
}


/*
 * uncached_alloc_page
 *
 * @starting_nid: node id of node to start with, or -1
 * @n_pages: number of contiguous pages to allocate
 *
 * Allocate the specified number of contiguous uncached pages on the
 * the requested node. If not enough contiguous uncached pages are available
 * on the requested node, roundrobin starting with the next higher node.
 */
unsigned long uncached_alloc_page(int starting_nid, int n_pages)
{
	unsigned long uc_addr;
	struct uncached_pool *uc_pool;
	int nid;

	if (unlikely(starting_nid >= MAX_NUMNODES))
		return 0;

	if (starting_nid < 0)
		starting_nid = numa_node_id();
	nid = starting_nid;

	do {
		if (!node_state(nid, N_HIGH_MEMORY))
			continue;
		uc_pool = &uncached_pools[nid];
		if (uc_pool->pool == NULL)
			continue;
		do {
			uc_addr = gen_pool_alloc(uc_pool->pool,
						 n_pages * PAGE_SIZE);
			if (uc_addr != 0)
				return uc_addr;
		} while (uncached_add_chunk(uc_pool, nid) == 0);

	} while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid);

	return 0;
}
EXPORT_SYMBOL(uncached_alloc_page);


/*
 * uncached_free_page
 *
 * @uc_addr: uncached address of first page to free
 * @n_pages: number of contiguous pages to free
 *
 * Free the specified number of uncached pages.
 */
void uncached_free_page(unsigned long uc_addr, int n_pages)
{
	int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET);
	struct gen_pool *pool = uncached_pools[nid].pool;

	if (unlikely(pool == NULL))
		return;

	if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET)
		panic("uncached_free_page invalid address %lx\n", uc_addr);

	gen_pool_free(pool, uc_addr, n_pages * PAGE_SIZE);
}
EXPORT_SYMBOL(uncached_free_page);


/*
 * uncached_build_memmap,
 *
 * @uc_start: uncached starting address of a chunk of uncached memory
 * @uc_end: uncached ending address of a chunk of uncached memory
 * @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc())
 *
 * Called at boot time to build a map of pages that can be used for
 * memory special operations.
 */
static int __init uncached_build_memmap(u64 uc_start, u64 uc_end, void *arg)
{
	int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET);
	struct gen_pool *pool = uncached_pools[nid].pool;
	size_t size = uc_end - uc_start;

	touch_softlockup_watchdog();

	if (pool != NULL) {
		memset((char *)uc_start, 0, size);
		(void) gen_pool_add(pool, uc_start, size, nid);
	}
	return 0;
}


static int __init uncached_init(void)
{
	int nid;

	for_each_node_state(nid, N_ONLINE) {
		uncached_pools[nid].pool = gen_pool_create(PAGE_SHIFT, nid);
		mutex_init(&uncached_pools[nid].add_chunk_mutex);
	}

	efi_memmap_walk_uc(uncached_build_memmap, NULL);
	return 0;
}

__initcall(uncached_init);