Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/*
2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
12 * more details.
13 */
14
15#include <linux/string.h>
16#include <linux/smp.h>
17#include <linux/module.h>
18#include <linux/uaccess.h>
19#include <asm/fixmap.h>
20#include <asm/kmap_types.h>
21#include <asm/tlbflush.h>
22#include <hv/hypervisor.h>
23#include <arch/chip.h>
24
25
26#if !CHIP_HAS_COHERENT_LOCAL_CACHE()
27
28/* Defined in memcpy.S */
29extern unsigned long __memcpy_asm(void *to, const void *from, unsigned long n);
30extern unsigned long __copy_to_user_inatomic_asm(
31 void __user *to, const void *from, unsigned long n);
32extern unsigned long __copy_from_user_inatomic_asm(
33 void *to, const void __user *from, unsigned long n);
34extern unsigned long __copy_from_user_zeroing_asm(
35 void *to, const void __user *from, unsigned long n);
36
37typedef unsigned long (*memcpy_t)(void *, const void *, unsigned long);
38
39/* Size above which to consider TLB games for performance */
40#define LARGE_COPY_CUTOFF 2048
41
42/* Communicate to the simulator what we are trying to do. */
43#define sim_allow_multiple_caching(b) \
44 __insn_mtspr(SPR_SIM_CONTROL, \
45 SIM_CONTROL_ALLOW_MULTIPLE_CACHING | ((b) << _SIM_CONTROL_OPERATOR_BITS))
46
47/*
48 * Copy memory by briefly enabling incoherent cacheline-at-a-time mode.
49 *
50 * We set up our own source and destination PTEs that we fully control.
51 * This is the only way to guarantee that we don't race with another
52 * thread that is modifying the PTE; we can't afford to try the
53 * copy_{to,from}_user() technique of catching the interrupt, since
54 * we must run with interrupts disabled to avoid the risk of some
55 * other code seeing the incoherent data in our cache. (Recall that
56 * our cache is indexed by PA, so even if the other code doesn't use
57 * our kmap_atomic virtual addresses, they'll still hit in cache using
58 * the normal VAs that aren't supposed to hit in cache.)
59 */
60static void memcpy_multicache(void *dest, const void *source,
61 pte_t dst_pte, pte_t src_pte, int len)
62{
63 int idx;
64 unsigned long flags, newsrc, newdst;
65 pmd_t *pmdp;
66 pte_t *ptep;
67 int type0, type1;
68 int cpu = get_cpu();
69
70 /*
71 * Disable interrupts so that we don't recurse into memcpy()
72 * in an interrupt handler, nor accidentally reference
73 * the PA of the source from an interrupt routine. Also
74 * notify the simulator that we're playing games so we don't
75 * generate spurious coherency warnings.
76 */
77 local_irq_save(flags);
78 sim_allow_multiple_caching(1);
79
80 /* Set up the new dest mapping */
81 type0 = kmap_atomic_idx_push();
82 idx = FIX_KMAP_BEGIN + (KM_TYPE_NR * cpu) + type0;
83 newdst = __fix_to_virt(idx) + ((unsigned long)dest & (PAGE_SIZE-1));
84 pmdp = pmd_offset(pud_offset(pgd_offset_k(newdst), newdst), newdst);
85 ptep = pte_offset_kernel(pmdp, newdst);
86 if (pte_val(*ptep) != pte_val(dst_pte)) {
87 set_pte(ptep, dst_pte);
88 local_flush_tlb_page(NULL, newdst, PAGE_SIZE);
89 }
90
91 /* Set up the new source mapping */
92 type1 = kmap_atomic_idx_push();
93 idx += (type0 - type1);
94 src_pte = hv_pte_set_nc(src_pte);
95 src_pte = hv_pte_clear_writable(src_pte); /* be paranoid */
96 newsrc = __fix_to_virt(idx) + ((unsigned long)source & (PAGE_SIZE-1));
97 pmdp = pmd_offset(pud_offset(pgd_offset_k(newsrc), newsrc), newsrc);
98 ptep = pte_offset_kernel(pmdp, newsrc);
99 __set_pte(ptep, src_pte); /* set_pte() would be confused by this */
100 local_flush_tlb_page(NULL, newsrc, PAGE_SIZE);
101
102 /* Actually move the data. */
103 __memcpy_asm((void *)newdst, (const void *)newsrc, len);
104
105 /*
106 * Remap the source as locally-cached and not OLOC'ed so that
107 * we can inval without also invaling the remote cpu's cache.
108 * This also avoids known errata with inv'ing cacheable oloc data.
109 */
110 src_pte = hv_pte_set_mode(src_pte, HV_PTE_MODE_CACHE_NO_L3);
111 src_pte = hv_pte_set_writable(src_pte); /* need write access for inv */
112 __set_pte(ptep, src_pte); /* set_pte() would be confused by this */
113 local_flush_tlb_page(NULL, newsrc, PAGE_SIZE);
114
115 /*
116 * Do the actual invalidation, covering the full L2 cache line
117 * at the end since __memcpy_asm() is somewhat aggressive.
118 */
119 __inv_buffer((void *)newsrc, len);
120
121 /*
122 * We're done: notify the simulator that all is back to normal,
123 * and re-enable interrupts and pre-emption.
124 */
125 kmap_atomic_idx_pop();
126 kmap_atomic_idx_pop();
127 sim_allow_multiple_caching(0);
128 local_irq_restore(flags);
129 put_cpu();
130}
131
132/*
133 * Identify large copies from remotely-cached memory, and copy them
134 * via memcpy_multicache() if they look good, otherwise fall back
135 * to the particular kind of copying passed as the memcpy_t function.
136 */
137static unsigned long fast_copy(void *dest, const void *source, int len,
138 memcpy_t func)
139{
140 /*
141 * Check if it's big enough to bother with. We may end up doing a
142 * small copy via TLB manipulation if we're near a page boundary,
143 * but presumably we'll make it up when we hit the second page.
144 */
145 while (len >= LARGE_COPY_CUTOFF) {
146 int copy_size, bytes_left_on_page;
147 pte_t *src_ptep, *dst_ptep;
148 pte_t src_pte, dst_pte;
149 struct page *src_page, *dst_page;
150
151 /* Is the source page oloc'ed to a remote cpu? */
152retry_source:
153 src_ptep = virt_to_pte(current->mm, (unsigned long)source);
154 if (src_ptep == NULL)
155 break;
156 src_pte = *src_ptep;
157 if (!hv_pte_get_present(src_pte) ||
158 !hv_pte_get_readable(src_pte) ||
159 hv_pte_get_mode(src_pte) != HV_PTE_MODE_CACHE_TILE_L3)
160 break;
161 if (get_remote_cache_cpu(src_pte) == smp_processor_id())
162 break;
163 src_page = pfn_to_page(hv_pte_get_pfn(src_pte));
164 get_page(src_page);
165 if (pte_val(src_pte) != pte_val(*src_ptep)) {
166 put_page(src_page);
167 goto retry_source;
168 }
169 if (pte_huge(src_pte)) {
170 /* Adjust the PTE to correspond to a small page */
171 int pfn = hv_pte_get_pfn(src_pte);
172 pfn += (((unsigned long)source & (HPAGE_SIZE-1))
173 >> PAGE_SHIFT);
174 src_pte = pfn_pte(pfn, src_pte);
175 src_pte = pte_mksmall(src_pte);
176 }
177
178 /* Is the destination page writable? */
179retry_dest:
180 dst_ptep = virt_to_pte(current->mm, (unsigned long)dest);
181 if (dst_ptep == NULL) {
182 put_page(src_page);
183 break;
184 }
185 dst_pte = *dst_ptep;
186 if (!hv_pte_get_present(dst_pte) ||
187 !hv_pte_get_writable(dst_pte)) {
188 put_page(src_page);
189 break;
190 }
191 dst_page = pfn_to_page(hv_pte_get_pfn(dst_pte));
192 if (dst_page == src_page) {
193 /*
194 * Source and dest are on the same page; this
195 * potentially exposes us to incoherence if any
196 * part of src and dest overlap on a cache line.
197 * Just give up rather than trying to be precise.
198 */
199 put_page(src_page);
200 break;
201 }
202 get_page(dst_page);
203 if (pte_val(dst_pte) != pte_val(*dst_ptep)) {
204 put_page(dst_page);
205 goto retry_dest;
206 }
207 if (pte_huge(dst_pte)) {
208 /* Adjust the PTE to correspond to a small page */
209 int pfn = hv_pte_get_pfn(dst_pte);
210 pfn += (((unsigned long)dest & (HPAGE_SIZE-1))
211 >> PAGE_SHIFT);
212 dst_pte = pfn_pte(pfn, dst_pte);
213 dst_pte = pte_mksmall(dst_pte);
214 }
215
216 /* All looks good: create a cachable PTE and copy from it */
217 copy_size = len;
218 bytes_left_on_page =
219 PAGE_SIZE - (((int)source) & (PAGE_SIZE-1));
220 if (copy_size > bytes_left_on_page)
221 copy_size = bytes_left_on_page;
222 bytes_left_on_page =
223 PAGE_SIZE - (((int)dest) & (PAGE_SIZE-1));
224 if (copy_size > bytes_left_on_page)
225 copy_size = bytes_left_on_page;
226 memcpy_multicache(dest, source, dst_pte, src_pte, copy_size);
227
228 /* Release the pages */
229 put_page(dst_page);
230 put_page(src_page);
231
232 /* Continue on the next page */
233 dest += copy_size;
234 source += copy_size;
235 len -= copy_size;
236 }
237
238 return func(dest, source, len);
239}
240
241void *memcpy(void *to, const void *from, __kernel_size_t n)
242{
243 if (n < LARGE_COPY_CUTOFF)
244 return (void *)__memcpy_asm(to, from, n);
245 else
246 return (void *)fast_copy(to, from, n, __memcpy_asm);
247}
248
249unsigned long __copy_to_user_inatomic(void __user *to, const void *from,
250 unsigned long n)
251{
252 if (n < LARGE_COPY_CUTOFF)
253 return __copy_to_user_inatomic_asm(to, from, n);
254 else
255 return fast_copy(to, from, n, __copy_to_user_inatomic_asm);
256}
257
258unsigned long __copy_from_user_inatomic(void *to, const void __user *from,
259 unsigned long n)
260{
261 if (n < LARGE_COPY_CUTOFF)
262 return __copy_from_user_inatomic_asm(to, from, n);
263 else
264 return fast_copy(to, from, n, __copy_from_user_inatomic_asm);
265}
266
267unsigned long __copy_from_user_zeroing(void *to, const void __user *from,
268 unsigned long n)
269{
270 if (n < LARGE_COPY_CUTOFF)
271 return __copy_from_user_zeroing_asm(to, from, n);
272 else
273 return fast_copy(to, from, n, __copy_from_user_zeroing_asm);
274}
275
276#endif /* !CHIP_HAS_COHERENT_LOCAL_CACHE() */