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locking/atomic: hexagon: remove redundant arch_atomic_cmpxchg

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Hexagon's implementation of arch_atomic_cmpxchg() is identical to its
implementation of arch_cmpxchg(). Have it define arch_atomic_cmpxchg()
in terms of arch_cmpxchg(), matching what it does for arch_atomic_xchg()
and arch_xchg().

At the same time, remove the kerneldoc comments for hexagon's
arch_atomic_xchg() and arch_atomic_cmpxchg(). The arch_atomic_*()
namespace is shared by all architectures and the API should be
documented centrally, and the comments aren't all that helpful as-is.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-4-mark.rutland@arm.com
This commit is contained in:
Mark Rutland 2023-06-05 08:01:00 +01:00 committed by Peter Zijlstra
parent 14d72d4b6f
commit a7bafa7969
1 changed files with 4 additions and 42 deletions
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46
arch/hexagon/include/asm/atomic.h
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@ -36,49 +36,11 @@ static inline void arch_atomic_set(atomic_t *v, int new)
*/
#define arch_atomic_read(v) READ_ONCE((v)->counter)
/**
* arch_atomic_xchg - atomic
* @v: pointer to memory to change
* @new: new value (technically passed in a register -- see xchg)
*/
#define arch_atomic_xchg(v, new) (arch_xchg(&((v)->counter), (new)))
#define arch_atomic_xchg(v, new) \
(arch_xchg(&((v)->counter), (new)))
/**
* arch_atomic_cmpxchg - atomic compare-and-exchange values
* @v: pointer to value to change
* @old: desired old value to match
* @new: new value to put in
*
* Parameters are then pointer, value-in-register, value-in-register,
* and the output is the old value.
*
* Apparently this is complicated for archs that don't support
* the memw_locked like we do (or it's broken or whatever).
*
* Kind of the lynchpin of the rest of the generically defined routines.
* Remember V2 had that bug with dotnew predicate set by memw_locked.
*
* "old" is "expected" old val, __oldval is actual old value
*/
static inline int arch_atomic_cmpxchg(atomic_t *v, int old, int new)
{
int __oldval;
asm volatile(
"1: %0 = memw_locked(%1);\n"
" { P0 = cmp.eq(%0,%2);\n"
" if (!P0.new) jump:nt 2f; }\n"
" memw_locked(%1,P0) = %3;\n"
" if (!P0) jump 1b;\n"
"2:\n"
: "=&r" (__oldval)
: "r" (&v->counter), "r" (old), "r" (new)
: "memory", "p0"
);
return __oldval;
}
#define arch_atomic_cmpxchg(v, old, new) \
(arch_cmpxchg(&((v)->counter), (old), (new)))
#define ATOMIC_OP(op) \
static inline void arch_atomic_##op(int i, atomic_t *v) \