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Linux kernel mirror (for testing)
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linux
1#ifndef __PARISC_LDCW_H
2#define __PARISC_LDCW_H
3
4#ifndef CONFIG_PA20
5/* Because kmalloc only guarantees 8-byte alignment for kmalloc'd data,
6 and GCC only guarantees 8-byte alignment for stack locals, we can't
7 be assured of 16-byte alignment for atomic lock data even if we
8 specify "__attribute ((aligned(16)))" in the type declaration. So,
9 we use a struct containing an array of four ints for the atomic lock
10 type and dynamically select the 16-byte aligned int from the array
11 for the semaphore. */
12
13#define __PA_LDCW_ALIGNMENT 16
14#define __ldcw_align(a) ({ \
15 unsigned long __ret = (unsigned long) &(a)->lock[0]; \
16 __ret = (__ret + __PA_LDCW_ALIGNMENT - 1) \
17 & ~(__PA_LDCW_ALIGNMENT - 1); \
18 (volatile unsigned int *) __ret; \
19})
20#define __LDCW "ldcw"
21
22#else /*CONFIG_PA20*/
23/* From: "Jim Hull" <jim.hull of hp.com>
24 I've attached a summary of the change, but basically, for PA 2.0, as
25 long as the ",CO" (coherent operation) completer is specified, then the
26 16-byte alignment requirement for ldcw and ldcd is relaxed, and instead
27 they only require "natural" alignment (4-byte for ldcw, 8-byte for
28 ldcd). */
29
30#define __PA_LDCW_ALIGNMENT 4
31#define __ldcw_align(a) (&(a)->slock)
32#define __LDCW "ldcw,co"
33
34#endif /*!CONFIG_PA20*/
35
36/* LDCW, the only atomic read-write operation PA-RISC has. *sigh*. */
37#define __ldcw(a) ({ \
38 unsigned __ret; \
39 __asm__ __volatile__(__LDCW " 0(%2),%0" \
40 : "=r" (__ret), "+m" (*(a)) : "r" (a)); \
41 __ret; \
42})
43
44#ifdef CONFIG_SMP
45# define __lock_aligned __attribute__((__section__(".data..lock_aligned")))
46#endif
47
48#endif /* __PARISC_LDCW_H */