sh: Add SH-4A optimized fastpath mutex implementation.
Add fast mutex path implementation for the SH4A architecture Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
parent
5c72f303a2
commit
0c9122323a
|
@ -0,0 +1,107 @@
|
|||
/*
|
||||
* arch/sh/include/asm/mutex-llsc.h
|
||||
*
|
||||
* SH-4A optimized mutex locking primitives
|
||||
*
|
||||
* Please look into asm-generic/mutex-xchg.h for a formal definition.
|
||||
*/
|
||||
#ifndef __ASM_SH_MUTEX_LLSC_H
|
||||
#define __ASM_SH_MUTEX_LLSC_H
|
||||
|
||||
/*
|
||||
* Attempting to lock a mutex on SH4A is done like in ARMv6+ architecure.
|
||||
* with a bastardized atomic decrement (it is not a reliable atomic decrement
|
||||
* but it satisfies the defined semantics for our purpose, while being
|
||||
* smaller and faster than a real atomic decrement or atomic swap.
|
||||
* The idea is to attempt decrementing the lock value only once. If once
|
||||
* decremented it isn't zero, or if its store-back fails due to a dispute
|
||||
* on the exclusive store, we simply bail out immediately through the slow
|
||||
* path where the lock will be reattempted until it succeeds.
|
||||
*/
|
||||
static inline void
|
||||
__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
|
||||
{
|
||||
int __res;
|
||||
|
||||
__asm__ __volatile__ (
|
||||
"movli.l @%1, %0 \n"
|
||||
"dt %0 \n"
|
||||
"movco.l %0, @%1 \n"
|
||||
: "=&z" (__res)
|
||||
: "r" (&(count)->counter)
|
||||
: "t");
|
||||
|
||||
if (unlikely(__res != 0))
|
||||
fail_fn(count);
|
||||
}
|
||||
|
||||
static inline int
|
||||
__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
|
||||
{
|
||||
int __res;
|
||||
|
||||
__asm__ __volatile__ (
|
||||
"movli.l @%1, %0 \n"
|
||||
"dt %0 \n"
|
||||
"movco.l %0, @%1 \n"
|
||||
: "=&z" (__res)
|
||||
: "r" (&(count)->counter)
|
||||
: "t");
|
||||
|
||||
if (unlikely(__res != 0))
|
||||
__res = fail_fn(count);
|
||||
|
||||
return __res;
|
||||
}
|
||||
|
||||
static inline void
|
||||
__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
|
||||
{
|
||||
int __res;
|
||||
|
||||
__asm__ __volatile__ (
|
||||
"1: movli.l @%1, %0 \n\t"
|
||||
"add #1, %0 \n\t"
|
||||
"movco.l %0, @%1 \n\t"
|
||||
"bf 1b\n\t"
|
||||
: "=&z" (__res)
|
||||
: "r" (&(count)->counter)
|
||||
: "t");
|
||||
|
||||
if (unlikely(__res <= 0))
|
||||
fail_fn(count);
|
||||
}
|
||||
|
||||
/*
|
||||
* If the unlock was done on a contended lock, or if the unlock simply fails
|
||||
* then the mutex remains locked.
|
||||
*/
|
||||
#define __mutex_slowpath_needs_to_unlock() 1
|
||||
|
||||
/*
|
||||
* For __mutex_fastpath_trylock we do an atomic decrement and check the
|
||||
* result and put it in the __res variable.
|
||||
*/
|
||||
static inline int
|
||||
__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
|
||||
{
|
||||
int __res, __orig;
|
||||
|
||||
__asm__ __volatile__ (
|
||||
"1: movli.l @%2, %0 \n\t"
|
||||
"dt %0 \n\t"
|
||||
"movco.l %0,@%2 \n\t"
|
||||
"bf 1b \n\t"
|
||||
"cmp/eq #0,%0 \n\t"
|
||||
"bt 2f \n\t"
|
||||
"mov #0, %1 \n\t"
|
||||
"bf 3f \n\t"
|
||||
"2: mov #1, %1 \n\t"
|
||||
"3: "
|
||||
: "=&z" (__orig), "=&r" (__res)
|
||||
: "r" (&count->counter)
|
||||
: "t");
|
||||
|
||||
return __res;
|
||||
}
|
||||
#endif /* __ASM_SH_MUTEX_LLSC_H */
|
|
@ -5,5 +5,8 @@
|
|||
* implementation in place, or pick the atomic_xchg() based generic
|
||||
* implementation. (see asm-generic/mutex-xchg.h for details)
|
||||
*/
|
||||
|
||||
#if defined(CONFIG_CPU_SH4A)
|
||||
#include <asm/mutex-llsc.h>
|
||||
#else
|
||||
#include <asm-generic/mutex-dec.h>
|
||||
#endif
|
||||
|
|
Loading…
Reference in New Issue