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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/cache.h>
16#include <linux/delay.h>
17#include <linux/uaccess.h>
18#include <linux/module.h>
19#include <linux/mm.h>
20#include <linux/atomic.h>
21#include <asm/futex.h>
22#include <arch/chip.h>
23
24/* See <asm/atomic_32.h> */
25#if ATOMIC_LOCKS_FOUND_VIA_TABLE()
26
27/*
28 * A block of memory containing locks for atomic ops. Each instance of this
29 * struct will be homed on a different CPU.
30 */
31struct atomic_locks_on_cpu {
32 int lock[ATOMIC_HASH_L2_SIZE];
33} __attribute__((aligned(ATOMIC_HASH_L2_SIZE * 4)));
34
35static DEFINE_PER_CPU(struct atomic_locks_on_cpu, atomic_lock_pool);
36
37/* The locks we'll use until __init_atomic_per_cpu is called. */
38static struct atomic_locks_on_cpu __initdata initial_atomic_locks;
39
40/* Hash into this vector to get a pointer to lock for the given atomic. */
41struct atomic_locks_on_cpu *atomic_lock_ptr[ATOMIC_HASH_L1_SIZE]
42 __write_once = {
43 [0 ... ATOMIC_HASH_L1_SIZE-1] (&initial_atomic_locks)
44};
45
46#else /* ATOMIC_LOCKS_FOUND_VIA_TABLE() */
47
48/* This page is remapped on startup to be hash-for-home. */
49int atomic_locks[PAGE_SIZE / sizeof(int)] __page_aligned_bss;
50
51#endif /* ATOMIC_LOCKS_FOUND_VIA_TABLE() */
52
53static inline int *__atomic_hashed_lock(volatile void *v)
54{
55 /* NOTE: this code must match "sys_cmpxchg" in kernel/intvec_32.S */
56#if ATOMIC_LOCKS_FOUND_VIA_TABLE()
57 unsigned long i =
58 (unsigned long) v & ((PAGE_SIZE-1) & -sizeof(long long));
59 unsigned long n = __insn_crc32_32(0, i);
60
61 /* Grab high bits for L1 index. */
62 unsigned long l1_index = n >> ((sizeof(n) * 8) - ATOMIC_HASH_L1_SHIFT);
63 /* Grab low bits for L2 index. */
64 unsigned long l2_index = n & (ATOMIC_HASH_L2_SIZE - 1);
65
66 return &atomic_lock_ptr[l1_index]->lock[l2_index];
67#else
68 /*
69 * Use bits [3, 3 + ATOMIC_HASH_SHIFT) as the lock index.
70 * Using mm works here because atomic_locks is page aligned.
71 */
72 unsigned long ptr = __insn_mm((unsigned long)v >> 1,
73 (unsigned long)atomic_locks,
74 2, (ATOMIC_HASH_SHIFT + 2) - 1);
75 return (int *)ptr;
76#endif
77}
78
79#ifdef CONFIG_SMP
80/* Return whether the passed pointer is a valid atomic lock pointer. */
81static int is_atomic_lock(int *p)
82{
83#if ATOMIC_LOCKS_FOUND_VIA_TABLE()
84 int i;
85 for (i = 0; i < ATOMIC_HASH_L1_SIZE; ++i) {
86
87 if (p >= &atomic_lock_ptr[i]->lock[0] &&
88 p < &atomic_lock_ptr[i]->lock[ATOMIC_HASH_L2_SIZE]) {
89 return 1;
90 }
91 }
92 return 0;
93#else
94 return p >= &atomic_locks[0] && p < &atomic_locks[ATOMIC_HASH_SIZE];
95#endif
96}
97
98void __atomic_fault_unlock(int *irqlock_word)
99{
100 BUG_ON(!is_atomic_lock(irqlock_word));
101 BUG_ON(*irqlock_word != 1);
102 *irqlock_word = 0;
103}
104
105#endif /* CONFIG_SMP */
106
107static inline int *__atomic_setup(volatile void *v)
108{
109 /* Issue a load to the target to bring it into cache. */
110 *(volatile int *)v;
111 return __atomic_hashed_lock(v);
112}
113
114int _atomic_xchg(atomic_t *v, int n)
115{
116 return __atomic_xchg(&v->counter, __atomic_setup(v), n).val;
117}
118EXPORT_SYMBOL(_atomic_xchg);
119
120int _atomic_xchg_add(atomic_t *v, int i)
121{
122 return __atomic_xchg_add(&v->counter, __atomic_setup(v), i).val;
123}
124EXPORT_SYMBOL(_atomic_xchg_add);
125
126int _atomic_xchg_add_unless(atomic_t *v, int a, int u)
127{
128 /*
129 * Note: argument order is switched here since it is easier
130 * to use the first argument consistently as the "old value"
131 * in the assembly, as is done for _atomic_cmpxchg().
132 */
133 return __atomic_xchg_add_unless(&v->counter, __atomic_setup(v), u, a)
134 .val;
135}
136EXPORT_SYMBOL(_atomic_xchg_add_unless);
137
138int _atomic_cmpxchg(atomic_t *v, int o, int n)
139{
140 return __atomic_cmpxchg(&v->counter, __atomic_setup(v), o, n).val;
141}
142EXPORT_SYMBOL(_atomic_cmpxchg);
143
144unsigned long _atomic_or(volatile unsigned long *p, unsigned long mask)
145{
146 return __atomic_or((int *)p, __atomic_setup(p), mask).val;
147}
148EXPORT_SYMBOL(_atomic_or);
149
150unsigned long _atomic_andn(volatile unsigned long *p, unsigned long mask)
151{
152 return __atomic_andn((int *)p, __atomic_setup(p), mask).val;
153}
154EXPORT_SYMBOL(_atomic_andn);
155
156unsigned long _atomic_xor(volatile unsigned long *p, unsigned long mask)
157{
158 return __atomic_xor((int *)p, __atomic_setup(p), mask).val;
159}
160EXPORT_SYMBOL(_atomic_xor);
161
162
163u64 _atomic64_xchg(atomic64_t *v, u64 n)
164{
165 return __atomic64_xchg(&v->counter, __atomic_setup(v), n);
166}
167EXPORT_SYMBOL(_atomic64_xchg);
168
169u64 _atomic64_xchg_add(atomic64_t *v, u64 i)
170{
171 return __atomic64_xchg_add(&v->counter, __atomic_setup(v), i);
172}
173EXPORT_SYMBOL(_atomic64_xchg_add);
174
175u64 _atomic64_xchg_add_unless(atomic64_t *v, u64 a, u64 u)
176{
177 /*
178 * Note: argument order is switched here since it is easier
179 * to use the first argument consistently as the "old value"
180 * in the assembly, as is done for _atomic_cmpxchg().
181 */
182 return __atomic64_xchg_add_unless(&v->counter, __atomic_setup(v),
183 u, a);
184}
185EXPORT_SYMBOL(_atomic64_xchg_add_unless);
186
187u64 _atomic64_cmpxchg(atomic64_t *v, u64 o, u64 n)
188{
189 return __atomic64_cmpxchg(&v->counter, __atomic_setup(v), o, n);
190}
191EXPORT_SYMBOL(_atomic64_cmpxchg);
192
193
194static inline int *__futex_setup(int __user *v)
195{
196 /*
197 * Issue a prefetch to the counter to bring it into cache.
198 * As for __atomic_setup, but we can't do a read into the L1
199 * since it might fault; instead we do a prefetch into the L2.
200 */
201 __insn_prefetch(v);
202 return __atomic_hashed_lock((int __force *)v);
203}
204
205struct __get_user futex_set(u32 __user *v, int i)
206{
207 return __atomic_xchg((int __force *)v, __futex_setup(v), i);
208}
209
210struct __get_user futex_add(u32 __user *v, int n)
211{
212 return __atomic_xchg_add((int __force *)v, __futex_setup(v), n);
213}
214
215struct __get_user futex_or(u32 __user *v, int n)
216{
217 return __atomic_or((int __force *)v, __futex_setup(v), n);
218}
219
220struct __get_user futex_andn(u32 __user *v, int n)
221{
222 return __atomic_andn((int __force *)v, __futex_setup(v), n);
223}
224
225struct __get_user futex_xor(u32 __user *v, int n)
226{
227 return __atomic_xor((int __force *)v, __futex_setup(v), n);
228}
229
230struct __get_user futex_cmpxchg(u32 __user *v, int o, int n)
231{
232 return __atomic_cmpxchg((int __force *)v, __futex_setup(v), o, n);
233}
234
235/*
236 * If any of the atomic or futex routines hit a bad address (not in
237 * the page tables at kernel PL) this routine is called. The futex
238 * routines are never used on kernel space, and the normal atomics and
239 * bitops are never used on user space. So a fault on kernel space
240 * must be fatal, but a fault on userspace is a futex fault and we
241 * need to return -EFAULT. Note that the context this routine is
242 * invoked in is the context of the "_atomic_xxx()" routines called
243 * by the functions in this file.
244 */
245struct __get_user __atomic_bad_address(int __user *addr)
246{
247 if (unlikely(!access_ok(VERIFY_WRITE, addr, sizeof(int))))
248 panic("Bad address used for kernel atomic op: %p\n", addr);
249 return (struct __get_user) { .err = -EFAULT };
250}
251
252
253#if CHIP_HAS_CBOX_HOME_MAP()
254static int __init noatomichash(char *str)
255{
256 pr_warning("noatomichash is deprecated.\n");
257 return 1;
258}
259__setup("noatomichash", noatomichash);
260#endif
261
262void __init __init_atomic_per_cpu(void)
263{
264#if ATOMIC_LOCKS_FOUND_VIA_TABLE()
265
266 unsigned int i;
267 int actual_cpu;
268
269 /*
270 * Before this is called from setup, we just have one lock for
271 * all atomic objects/operations. Here we replace the
272 * elements of atomic_lock_ptr so that they point at per_cpu
273 * integers. This seemingly over-complex approach stems from
274 * the fact that DEFINE_PER_CPU defines an entry for each cpu
275 * in the grid, not each cpu from 0..ATOMIC_HASH_SIZE-1. But
276 * for efficient hashing of atomics to their locks we want a
277 * compile time constant power of 2 for the size of this
278 * table, so we use ATOMIC_HASH_SIZE.
279 *
280 * Here we populate atomic_lock_ptr from the per cpu
281 * atomic_lock_pool, interspersing by actual cpu so that
282 * subsequent elements are homed on consecutive cpus.
283 */
284
285 actual_cpu = cpumask_first(cpu_possible_mask);
286
287 for (i = 0; i < ATOMIC_HASH_L1_SIZE; ++i) {
288 /*
289 * Preincrement to slightly bias against using cpu 0,
290 * which has plenty of stuff homed on it already.
291 */
292 actual_cpu = cpumask_next(actual_cpu, cpu_possible_mask);
293 if (actual_cpu >= nr_cpu_ids)
294 actual_cpu = cpumask_first(cpu_possible_mask);
295
296 atomic_lock_ptr[i] = &per_cpu(atomic_lock_pool, actual_cpu);
297 }
298
299#else /* ATOMIC_LOCKS_FOUND_VIA_TABLE() */
300
301 /* Validate power-of-two and "bigger than cpus" assumption */
302 BUILD_BUG_ON(ATOMIC_HASH_SIZE & (ATOMIC_HASH_SIZE-1));
303 BUG_ON(ATOMIC_HASH_SIZE < nr_cpu_ids);
304
305 /*
306 * On TILEPro we prefer to use a single hash-for-home
307 * page, since this means atomic operations are less
308 * likely to encounter a TLB fault and thus should
309 * in general perform faster. You may wish to disable
310 * this in situations where few hash-for-home tiles
311 * are configured.
312 */
313 BUG_ON((unsigned long)atomic_locks % PAGE_SIZE != 0);
314
315 /* The locks must all fit on one page. */
316 BUILD_BUG_ON(ATOMIC_HASH_SIZE * sizeof(int) > PAGE_SIZE);
317
318 /*
319 * We use the page offset of the atomic value's address as
320 * an index into atomic_locks, excluding the low 3 bits.
321 * That should not produce more indices than ATOMIC_HASH_SIZE.
322 */
323 BUILD_BUG_ON((PAGE_SIZE >> 3) > ATOMIC_HASH_SIZE);
324
325#endif /* ATOMIC_LOCKS_FOUND_VIA_TABLE() */
326
327 /* The futex code makes this assumption, so we validate it here. */
328 BUILD_BUG_ON(sizeof(atomic_t) != sizeof(int));
329}