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authorRalf Baechle <ralf@linux-mips.org>2006-10-30 22:45:07 -0500
committerRalf Baechle <ralf@linux-mips.org>2006-12-04 17:43:14 -0500
commit0004a9dfeaa709a7f853487aba19932c9b1a87c8 (patch)
treee9f1f4b1ca897e57f46778cef283617ba83fc855 /include/asm-mips/system.h
parent08f57f7ffe5819e537301b1f1109fa4fc670bfff (diff)
[MIPS] Cleanup memory barriers for weakly ordered systems.
Also the R4000 / R4600 LL/SC instructions imply a sync so no explicit sync needed. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'include/asm-mips/system.h')
-rw-r--r--include/asm-mips/system.h156
1 files changed, 10 insertions, 146 deletions
diff --git a/include/asm-mips/system.h b/include/asm-mips/system.h
index 3056feed5a36..9428057a50cf 100644
--- a/include/asm-mips/system.h
+++ b/include/asm-mips/system.h
@@ -3,7 +3,7 @@
3 * License. See the file "COPYING" in the main directory of this archive 3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details. 4 * for more details.
5 * 5 *
6 * Copyright (C) 1994, 95, 96, 97, 98, 99, 2003 by Ralf Baechle 6 * Copyright (C) 1994, 95, 96, 97, 98, 99, 2003, 06 by Ralf Baechle
7 * Copyright (C) 1996 by Paul M. Antoine 7 * Copyright (C) 1996 by Paul M. Antoine
8 * Copyright (C) 1999 Silicon Graphics 8 * Copyright (C) 1999 Silicon Graphics
9 * Kevin D. Kissell, kevink@mips.org and Carsten Langgaard, carstenl@mips.com 9 * Kevin D. Kissell, kevink@mips.org and Carsten Langgaard, carstenl@mips.com
@@ -16,132 +16,12 @@
16#include <linux/irqflags.h> 16#include <linux/irqflags.h>
17 17
18#include <asm/addrspace.h> 18#include <asm/addrspace.h>
19#include <asm/barrier.h>
19#include <asm/cpu-features.h> 20#include <asm/cpu-features.h>
20#include <asm/dsp.h> 21#include <asm/dsp.h>
21#include <asm/ptrace.h> 22#include <asm/ptrace.h>
22#include <asm/war.h> 23#include <asm/war.h>
23 24
24/*
25 * read_barrier_depends - Flush all pending reads that subsequents reads
26 * depend on.
27 *
28 * No data-dependent reads from memory-like regions are ever reordered
29 * over this barrier. All reads preceding this primitive are guaranteed
30 * to access memory (but not necessarily other CPUs' caches) before any
31 * reads following this primitive that depend on the data return by
32 * any of the preceding reads. This primitive is much lighter weight than
33 * rmb() on most CPUs, and is never heavier weight than is
34 * rmb().
35 *
36 * These ordering constraints are respected by both the local CPU
37 * and the compiler.
38 *
39 * Ordering is not guaranteed by anything other than these primitives,
40 * not even by data dependencies. See the documentation for
41 * memory_barrier() for examples and URLs to more information.
42 *
43 * For example, the following code would force ordering (the initial
44 * value of "a" is zero, "b" is one, and "p" is "&a"):
45 *
46 * <programlisting>
47 * CPU 0 CPU 1
48 *
49 * b = 2;
50 * memory_barrier();
51 * p = &b; q = p;
52 * read_barrier_depends();
53 * d = *q;
54 * </programlisting>
55 *
56 * because the read of "*q" depends on the read of "p" and these
57 * two reads are separated by a read_barrier_depends(). However,
58 * the following code, with the same initial values for "a" and "b":
59 *
60 * <programlisting>
61 * CPU 0 CPU 1
62 *
63 * a = 2;
64 * memory_barrier();
65 * b = 3; y = b;
66 * read_barrier_depends();
67 * x = a;
68 * </programlisting>
69 *
70 * does not enforce ordering, since there is no data dependency between
71 * the read of "a" and the read of "b". Therefore, on some CPUs, such
72 * as Alpha, "y" could be set to 3 and "x" to 0. Use rmb()
73 * in cases like this where there are no data dependencies.
74 */
75
76#define read_barrier_depends() do { } while(0)
77
78#ifdef CONFIG_CPU_HAS_SYNC
79#define __sync() \
80 __asm__ __volatile__( \
81 ".set push\n\t" \
82 ".set noreorder\n\t" \
83 ".set mips2\n\t" \
84 "sync\n\t" \
85 ".set pop" \
86 : /* no output */ \
87 : /* no input */ \
88 : "memory")
89#else
90#define __sync() do { } while(0)
91#endif
92
93#define __fast_iob() \
94 __asm__ __volatile__( \
95 ".set push\n\t" \
96 ".set noreorder\n\t" \
97 "lw $0,%0\n\t" \
98 "nop\n\t" \
99 ".set pop" \
100 : /* no output */ \
101 : "m" (*(int *)CKSEG1) \
102 : "memory")
103
104#define fast_wmb() __sync()
105#define fast_rmb() __sync()
106#define fast_mb() __sync()
107#define fast_iob() \
108 do { \
109 __sync(); \
110 __fast_iob(); \
111 } while (0)
112
113#ifdef CONFIG_CPU_HAS_WB
114
115#include <asm/wbflush.h>
116
117#define wmb() fast_wmb()
118#define rmb() fast_rmb()
119#define mb() wbflush()
120#define iob() wbflush()
121
122#else /* !CONFIG_CPU_HAS_WB */
123
124#define wmb() fast_wmb()
125#define rmb() fast_rmb()
126#define mb() fast_mb()
127#define iob() fast_iob()
128
129#endif /* !CONFIG_CPU_HAS_WB */
130
131#ifdef CONFIG_SMP
132#define smp_mb() mb()
133#define smp_rmb() rmb()
134#define smp_wmb() wmb()
135#define smp_read_barrier_depends() read_barrier_depends()
136#else
137#define smp_mb() barrier()
138#define smp_rmb() barrier()
139#define smp_wmb() barrier()
140#define smp_read_barrier_depends() do { } while(0)
141#endif
142
143#define set_mb(var, value) \
144do { var = value; mb(); } while (0)
145 25
146/* 26/*
147 * switch_to(n) should switch tasks to task nr n, first 27 * switch_to(n) should switch tasks to task nr n, first
@@ -217,9 +97,6 @@ static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
217 " .set mips3 \n" 97 " .set mips3 \n"
218 " sc %2, %1 \n" 98 " sc %2, %1 \n"
219 " beqzl %2, 1b \n" 99 " beqzl %2, 1b \n"
220#ifdef CONFIG_SMP
221 " sync \n"
222#endif
223 " .set mips0 \n" 100 " .set mips0 \n"
224 : "=&r" (retval), "=m" (*m), "=&r" (dummy) 101 : "=&r" (retval), "=m" (*m), "=&r" (dummy)
225 : "R" (*m), "Jr" (val) 102 : "R" (*m), "Jr" (val)
@@ -235,9 +112,6 @@ static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
235 " .set mips3 \n" 112 " .set mips3 \n"
236 " sc %2, %1 \n" 113 " sc %2, %1 \n"
237 " beqz %2, 1b \n" 114 " beqz %2, 1b \n"
238#ifdef CONFIG_SMP
239 " sync \n"
240#endif
241 " .set mips0 \n" 115 " .set mips0 \n"
242 : "=&r" (retval), "=m" (*m), "=&r" (dummy) 116 : "=&r" (retval), "=m" (*m), "=&r" (dummy)
243 : "R" (*m), "Jr" (val) 117 : "R" (*m), "Jr" (val)
@@ -251,6 +125,8 @@ static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
251 local_irq_restore(flags); /* implies memory barrier */ 125 local_irq_restore(flags); /* implies memory barrier */
252 } 126 }
253 127
128 smp_mb();
129
254 return retval; 130 return retval;
255} 131}
256 132
@@ -268,9 +144,6 @@ static inline __u64 __xchg_u64(volatile __u64 * m, __u64 val)
268 " move %2, %z4 \n" 144 " move %2, %z4 \n"
269 " scd %2, %1 \n" 145 " scd %2, %1 \n"
270 " beqzl %2, 1b \n" 146 " beqzl %2, 1b \n"
271#ifdef CONFIG_SMP
272 " sync \n"
273#endif
274 " .set mips0 \n" 147 " .set mips0 \n"
275 : "=&r" (retval), "=m" (*m), "=&r" (dummy) 148 : "=&r" (retval), "=m" (*m), "=&r" (dummy)
276 : "R" (*m), "Jr" (val) 149 : "R" (*m), "Jr" (val)
@@ -284,9 +157,6 @@ static inline __u64 __xchg_u64(volatile __u64 * m, __u64 val)
284 " move %2, %z4 \n" 157 " move %2, %z4 \n"
285 " scd %2, %1 \n" 158 " scd %2, %1 \n"
286 " beqz %2, 1b \n" 159 " beqz %2, 1b \n"
287#ifdef CONFIG_SMP
288 " sync \n"
289#endif
290 " .set mips0 \n" 160 " .set mips0 \n"
291 : "=&r" (retval), "=m" (*m), "=&r" (dummy) 161 : "=&r" (retval), "=m" (*m), "=&r" (dummy)
292 : "R" (*m), "Jr" (val) 162 : "R" (*m), "Jr" (val)
@@ -300,6 +170,8 @@ static inline __u64 __xchg_u64(volatile __u64 * m, __u64 val)
300 local_irq_restore(flags); /* implies memory barrier */ 170 local_irq_restore(flags); /* implies memory barrier */
301 } 171 }
302 172
173 smp_mb();
174
303 return retval; 175 return retval;
304} 176}
305#else 177#else
@@ -345,9 +217,6 @@ static inline unsigned long __cmpxchg_u32(volatile int * m, unsigned long old,
345 " .set mips3 \n" 217 " .set mips3 \n"
346 " sc $1, %1 \n" 218 " sc $1, %1 \n"
347 " beqzl $1, 1b \n" 219 " beqzl $1, 1b \n"
348#ifdef CONFIG_SMP
349 " sync \n"
350#endif
351 "2: \n" 220 "2: \n"
352 " .set pop \n" 221 " .set pop \n"
353 : "=&r" (retval), "=R" (*m) 222 : "=&r" (retval), "=R" (*m)
@@ -365,9 +234,6 @@ static inline unsigned long __cmpxchg_u32(volatile int * m, unsigned long old,
365 " .set mips3 \n" 234 " .set mips3 \n"
366 " sc $1, %1 \n" 235 " sc $1, %1 \n"
367 " beqz $1, 1b \n" 236 " beqz $1, 1b \n"
368#ifdef CONFIG_SMP
369 " sync \n"
370#endif
371 "2: \n" 237 "2: \n"
372 " .set pop \n" 238 " .set pop \n"
373 : "=&r" (retval), "=R" (*m) 239 : "=&r" (retval), "=R" (*m)
@@ -383,6 +249,8 @@ static inline unsigned long __cmpxchg_u32(volatile int * m, unsigned long old,
383 local_irq_restore(flags); /* implies memory barrier */ 249 local_irq_restore(flags); /* implies memory barrier */
384 } 250 }
385 251
252 smp_mb();
253
386 return retval; 254 return retval;
387} 255}
388 256
@@ -402,9 +270,6 @@ static inline unsigned long __cmpxchg_u64(volatile int * m, unsigned long old,
402 " move $1, %z4 \n" 270 " move $1, %z4 \n"
403 " scd $1, %1 \n" 271 " scd $1, %1 \n"
404 " beqzl $1, 1b \n" 272 " beqzl $1, 1b \n"
405#ifdef CONFIG_SMP
406 " sync \n"
407#endif
408 "2: \n" 273 "2: \n"
409 " .set pop \n" 274 " .set pop \n"
410 : "=&r" (retval), "=R" (*m) 275 : "=&r" (retval), "=R" (*m)
@@ -420,9 +285,6 @@ static inline unsigned long __cmpxchg_u64(volatile int * m, unsigned long old,
420 " move $1, %z4 \n" 285 " move $1, %z4 \n"
421 " scd $1, %1 \n" 286 " scd $1, %1 \n"
422 " beqz $1, 1b \n" 287 " beqz $1, 1b \n"
423#ifdef CONFIG_SMP
424 " sync \n"
425#endif
426 "2: \n" 288 "2: \n"
427 " .set pop \n" 289 " .set pop \n"
428 : "=&r" (retval), "=R" (*m) 290 : "=&r" (retval), "=R" (*m)
@@ -438,6 +300,8 @@ static inline unsigned long __cmpxchg_u64(volatile int * m, unsigned long old,
438 local_irq_restore(flags); /* implies memory barrier */ 300 local_irq_restore(flags); /* implies memory barrier */
439 } 301 }
440 302
303 smp_mb();
304
441 return retval; 305 return retval;
442} 306}
443#else 307#else
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