Unverified Commit 4420658a authored by Guo Ren's avatar Guo Ren Committed by Palmer Dabbelt
Browse files

riscv: atomic: Add custom conditional atomic operation implementation 



Add conditional atomic operations' custom implementation (similar
to dec_if_positive), here is the list:
 - arch_atomic_inc_unless_negative
 - arch_atomic_dec_unless_positive
 - arch_atomic64_inc_unless_negative
 - arch_atomic64_dec_unless_positive

Signed-off-by: default avatarGuo Ren <guoren@linux.alibaba.com>
Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20220505035526.2974382-4-guoren@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 1d7f6932

arch/riscv/include/asm/atomic.h

+82 −0
Original line number Diff line number Diff line
@@ -310,6 +310,46 @@ ATOMIC_OPS() 
#undef ATOMIC_OPS

#undef ATOMIC_OP



static __always_inline bool arch_atomic_inc_unless_negative(atomic_t *v)

{

	int prev, rc;



	__asm__ __volatile__ (

		"0:	lr.w      %[p],  %[c]\n"

		"	bltz      %[p],  1f\n"

		"	addi      %[rc], %[p], 1\n"

		"	sc.w.rl   %[rc], %[rc], %[c]\n"

		"	bnez      %[rc], 0b\n"

		"	fence     rw, rw\n"

		"1:\n"

		: [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)

		:

		: "memory");

	return !(prev < 0);

}



#define arch_atomic_inc_unless_negative arch_atomic_inc_unless_negative



static __always_inline bool arch_atomic_dec_unless_positive(atomic_t *v)

{

	int prev, rc;



	__asm__ __volatile__ (

		"0:	lr.w      %[p],  %[c]\n"

		"	bgtz      %[p],  1f\n"

		"	addi      %[rc], %[p], -1\n"

		"	sc.w.rl   %[rc], %[rc], %[c]\n"

		"	bnez      %[rc], 0b\n"

		"	fence     rw, rw\n"

		"1:\n"

		: [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)

		:

		: "memory");

	return !(prev > 0);

}



#define arch_atomic_dec_unless_positive arch_atomic_dec_unless_positive



static __always_inline int arch_atomic_dec_if_positive(atomic_t *v)

{

       int prev, rc;
@@ -331,6 +371,48 @@ static __always_inline int arch_atomic_dec_if_positive(atomic_t *v) 
#define arch_atomic_dec_if_positive arch_atomic_dec_if_positive



#ifndef CONFIG_GENERIC_ATOMIC64

static __always_inline bool arch_atomic64_inc_unless_negative(atomic64_t *v)

{

	s64 prev;

	long rc;



	__asm__ __volatile__ (

		"0:	lr.d      %[p],  %[c]\n"

		"	bltz      %[p],  1f\n"

		"	addi      %[rc], %[p], 1\n"

		"	sc.d.rl   %[rc], %[rc], %[c]\n"

		"	bnez      %[rc], 0b\n"

		"	fence     rw, rw\n"

		"1:\n"

		: [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)

		:

		: "memory");

	return !(prev < 0);

}



#define arch_atomic64_inc_unless_negative arch_atomic64_inc_unless_negative



static __always_inline bool arch_atomic64_dec_unless_positive(atomic64_t *v)

{

	s64 prev;

	long rc;



	__asm__ __volatile__ (

		"0:	lr.d      %[p],  %[c]\n"

		"	bgtz      %[p],  1f\n"

		"	addi      %[rc], %[p], -1\n"

		"	sc.d.rl   %[rc], %[rc], %[c]\n"

		"	bnez      %[rc], 0b\n"

		"	fence     rw, rw\n"

		"1:\n"

		: [p]"=&r" (prev), [rc]"=&r" (rc), [c]"+A" (v->counter)

		:

		: "memory");

	return !(prev > 0);

}



#define arch_atomic64_dec_unless_positive arch_atomic64_dec_unless_positive



static __always_inline s64 arch_atomic64_dec_if_positive(atomic64_t *v)

{

       s64 prev;