Re: [PATCH V12 09/24] LoongArch: Add atomic/locking headers

[Jiaxun Yang]

在2022年6月1日六月 上午10:59，Huacai Chen写道：
> Add common headers (atomic, bitops, barrier and locking) for basic
> LoongArch support.
>
> Reviewed-by: WANG Xuerui <git@xxxxxxxxxx>
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>

Reviewed-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>

Checked against instruction manual and some of my use cases from
LS3A4000’s AMO Ext.

Thanks.


> ---
>  arch/loongarch/include/asm/atomic.h  | 358 +++++++++++++++++++++++++++
>  arch/loongarch/include/asm/barrier.h |  51 ++++
>  arch/loongarch/include/asm/bitops.h  |  33 +++
>  arch/loongarch/include/asm/bitrev.h  |  34 +++
>  arch/loongarch/include/asm/cmpxchg.h | 122 +++++++++
>  arch/loongarch/include/asm/local.h   | 138 +++++++++++
>  arch/loongarch/include/asm/percpu.h  |  20 ++
>  7 files changed, 756 insertions(+)
>  create mode 100644 arch/loongarch/include/asm/atomic.h
>  create mode 100644 arch/loongarch/include/asm/barrier.h
>  create mode 100644 arch/loongarch/include/asm/bitops.h
>  create mode 100644 arch/loongarch/include/asm/bitrev.h
>  create mode 100644 arch/loongarch/include/asm/cmpxchg.h
>  create mode 100644 arch/loongarch/include/asm/local.h
>  create mode 100644 arch/loongarch/include/asm/percpu.h
>
> diff --git a/arch/loongarch/include/asm/atomic.h 
> b/arch/loongarch/include/asm/atomic.h
> new file mode 100644
> index 000000000000..932352342b12
> --- /dev/null
> +++ b/arch/loongarch/include/asm/atomic.h
> @@ -0,0 +1,358 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Atomic operations.
> + *
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef _ASM_ATOMIC_H
> +#define _ASM_ATOMIC_H
> +
> +#include <linux/types.h>
> +#include <asm/barrier.h>
> +#include <asm/cmpxchg.h>
> +#include <asm/compiler.h>
> +
> +#if __SIZEOF_LONG__ == 4
> +#define __LL		"ll.w	"
> +#define __SC		"sc.w	"
> +#define __AMADD		"amadd.w	"
> +#define __AMAND_DB	"amand_db.w	"
> +#define __AMOR_DB	"amor_db.w	"
> +#define __AMXOR_DB	"amxor_db.w	"
> +#elif __SIZEOF_LONG__ == 8
> +#define __LL		"ll.d	"
> +#define __SC		"sc.d	"
> +#define __AMADD		"amadd.d	"
> +#define __AMAND_DB	"amand_db.d	"
> +#define __AMOR_DB	"amor_db.d	"
> +#define __AMXOR_DB	"amxor_db.d	"
> +#endif
> +
> +#define ATOMIC_INIT(i)	  { (i) }
> +
> +/*
> + * arch_atomic_read - read atomic variable
> + * @v: pointer of type atomic_t
> + *
> + * Atomically reads the value of @v.
> + */
> +#define arch_atomic_read(v)	READ_ONCE((v)->counter)
> +
> +/*
> + * arch_atomic_set - set atomic variable
> + * @v: pointer of type atomic_t
> + * @i: required value
> + *
> + * Atomically sets the value of @v to @i.
> + */
> +#define arch_atomic_set(v, i)	WRITE_ONCE((v)->counter, (i))
> +
> +#define ATOMIC_OP(op, I, asm_op)					\
> +static inline void arch_atomic_##op(int i, atomic_t *v)			\
> +{									\
> +	__asm__ __volatile__(						\
> +	"am"#asm_op"_db.w" " $zero, %1, %0	\n"			\
> +	: "+ZB" (v->counter)						\
> +	: "r" (I)							\
> +	: "memory");							\
> +}
> +
> +#define ATOMIC_OP_RETURN(op, I, asm_op, c_op)				\
> +static inline int arch_atomic_##op##_return_relaxed(int i, atomic_t 
> *v)	\
> +{									\
> +	int result;							\
> +									\
> +	__asm__ __volatile__(						\
> +	"am"#asm_op"_db.w" " %1, %2, %0		\n"			\
> +	: "+ZB" (v->counter), "=&r" (result)				\
> +	: "r" (I)							\
> +	: "memory");							\
> +									\
> +	return result c_op I;						\
> +}
> +
> +#define ATOMIC_FETCH_OP(op, I, asm_op)					\
> +static inline int arch_atomic_fetch_##op##_relaxed(int i, atomic_t 
> *v)	\
> +{									\
> +	int result;							\
> +									\
> +	__asm__ __volatile__(						\
> +	"am"#asm_op"_db.w" " %1, %2, %0		\n"			\
> +	: "+ZB" (v->counter), "=&r" (result)				\
> +	: "r" (I)							\
> +	: "memory");							\
> +									\
> +	return result;							\
> +}
> +
> +#define ATOMIC_OPS(op, I, asm_op, c_op)					\
> +	ATOMIC_OP(op, I, asm_op)					\
> +	ATOMIC_OP_RETURN(op, I, asm_op, c_op)				\
> +	ATOMIC_FETCH_OP(op, I, asm_op)
> +
> +ATOMIC_OPS(add, i, add, +)
> +ATOMIC_OPS(sub, -i, add, +)
> +
> +#define arch_atomic_add_return_relaxed	arch_atomic_add_return_relaxed
> +#define arch_atomic_sub_return_relaxed	arch_atomic_sub_return_relaxed
> +#define arch_atomic_fetch_add_relaxed	arch_atomic_fetch_add_relaxed
> +#define arch_atomic_fetch_sub_relaxed	arch_atomic_fetch_sub_relaxed
> +
> +#undef ATOMIC_OPS
> +
> +#define ATOMIC_OPS(op, I, asm_op)					\
> +	ATOMIC_OP(op, I, asm_op)					\
> +	ATOMIC_FETCH_OP(op, I, asm_op)
> +
> +ATOMIC_OPS(and, i, and)
> +ATOMIC_OPS(or, i, or)
> +ATOMIC_OPS(xor, i, xor)
> +
> +#define arch_atomic_fetch_and_relaxed	arch_atomic_fetch_and_relaxed
> +#define arch_atomic_fetch_or_relaxed	arch_atomic_fetch_or_relaxed
> +#define arch_atomic_fetch_xor_relaxed	arch_atomic_fetch_xor_relaxed
> +
> +#undef ATOMIC_OPS
> +#undef ATOMIC_FETCH_OP
> +#undef ATOMIC_OP_RETURN
> +#undef ATOMIC_OP
> +
> +static inline int arch_atomic_fetch_add_unless(atomic_t *v, int a, int 
> u)
> +{
> +       int prev, rc;
> +
> +	__asm__ __volatile__ (
> +		"0:	ll.w	%[p],  %[c]\n"
> +		"	beq	%[p],  %[u], 1f\n"
> +		"	add.w	%[rc], %[p], %[a]\n"
> +		"	sc.w	%[rc], %[c]\n"
> +		"	beqz	%[rc], 0b\n"
> +		"	b	2f\n"
> +		"1:\n"
> +		__WEAK_LLSC_MB
> +		"2:\n"
> +		: [p]"=&r" (prev), [rc]"=&r" (rc),
> +		  [c]"=ZB" (v->counter)
> +		: [a]"r" (a), [u]"r" (u)
> +		: "memory");
> +
> +	return prev;
> +}
> +#define arch_atomic_fetch_add_unless arch_atomic_fetch_add_unless
> +
> +/*
> + * arch_atomic_sub_if_positive - conditionally subtract integer from 
> atomic variable
> + * @i: integer value to subtract
> + * @v: pointer of type atomic_t
> + *
> + * Atomically test @v and subtract @i if @v is greater or equal than 
> @i.
> + * The function returns the old value of @v minus @i.
> + */
> +static inline int arch_atomic_sub_if_positive(int i, atomic_t *v)
> +{
> +	int result;
> +	int temp;
> +
> +	if (__builtin_constant_p(i)) {
> +		__asm__ __volatile__(
> +		"1:	ll.w	%1, %2		# atomic_sub_if_positive\n"
> +		"	addi.w	%0, %1, %3				\n"
> +		"	or	%1, %0, $zero				\n"
> +		"	blt	%0, $zero, 2f				\n"
> +		"	sc.w	%1, %2					\n"
> +		"	beq	$zero, %1, 1b				\n"
> +		"2:							\n"
> +		: "=&r" (result), "=&r" (temp),
> +		  "+" GCC_OFF_SMALL_ASM() (v->counter)
> +		: "I" (-i));
> +	} else {
> +		__asm__ __volatile__(
> +		"1:	ll.w	%1, %2		# atomic_sub_if_positive\n"
> +		"	sub.w	%0, %1, %3				\n"
> +		"	or	%1, %0, $zero				\n"
> +		"	blt	%0, $zero, 2f				\n"
> +		"	sc.w	%1, %2					\n"
> +		"	beq	$zero, %1, 1b				\n"
> +		"2:							\n"
> +		: "=&r" (result), "=&r" (temp),
> +		  "+" GCC_OFF_SMALL_ASM() (v->counter)
> +		: "r" (i));
> +	}
> +
> +	return result;
> +}
> +
> +#define arch_atomic_cmpxchg(v, o, n) (arch_cmpxchg(&((v)->counter), 
> (o), (n)))
> +#define arch_atomic_xchg(v, new) (arch_xchg(&((v)->counter), (new)))
> +
> +/*
> + * arch_atomic_dec_if_positive - decrement by 1 if old value positive
> + * @v: pointer of type atomic_t
> + */
> +#define arch_atomic_dec_if_positive(v)	arch_atomic_sub_if_positive(1, 
> v)
> +
> +#ifdef CONFIG_64BIT
> +
> +#define ATOMIC64_INIT(i)    { (i) }
> +
> +/*
> + * arch_atomic64_read - read atomic variable
> + * @v: pointer of type atomic64_t
> + *
> + */
> +#define arch_atomic64_read(v)	READ_ONCE((v)->counter)
> +
> +/*
> + * arch_atomic64_set - set atomic variable
> + * @v: pointer of type atomic64_t
> + * @i: required value
> + */
> +#define arch_atomic64_set(v, i)	WRITE_ONCE((v)->counter, (i))
> +
> +#define ATOMIC64_OP(op, I, asm_op)					\
> +static inline void arch_atomic64_##op(long i, atomic64_t *v)		\
> +{									\
> +	__asm__ __volatile__(						\
> +	"am"#asm_op"_db.d " " $zero, %1, %0	\n"			\
> +	: "+ZB" (v->counter)						\
> +	: "r" (I)							\
> +	: "memory");							\
> +}
> +
> +#define ATOMIC64_OP_RETURN(op, I, asm_op, c_op)					\
> +static inline long arch_atomic64_##op##_return_relaxed(long i, 
> atomic64_t *v)	\
> +{										\
> +	long result;								\
> +	__asm__ __volatile__(							\
> +	"am"#asm_op"_db.d " " %1, %2, %0		\n"			\
> +	: "+ZB" (v->counter), "=&r" (result)					\
> +	: "r" (I)								\
> +	: "memory");								\
> +										\
> +	return result c_op I;							\
> +}
> +
> +#define ATOMIC64_FETCH_OP(op, I, asm_op)					\
> +static inline long arch_atomic64_fetch_##op##_relaxed(long i, 
> atomic64_t *v)	\
> +{										\
> +	long result;								\
> +										\
> +	__asm__ __volatile__(							\
> +	"am"#asm_op"_db.d " " %1, %2, %0		\n"			\
> +	: "+ZB" (v->counter), "=&r" (result)					\
> +	: "r" (I)								\
> +	: "memory");								\
> +										\
> +	return result;								\
> +}
> +
> +#define ATOMIC64_OPS(op, I, asm_op, c_op)				      \
> +	ATOMIC64_OP(op, I, asm_op)					      \
> +	ATOMIC64_OP_RETURN(op, I, asm_op, c_op)				      \
> +	ATOMIC64_FETCH_OP(op, I, asm_op)
> +
> +ATOMIC64_OPS(add, i, add, +)
> +ATOMIC64_OPS(sub, -i, add, +)
> +
> +#define 
> arch_atomic64_add_return_relaxed	arch_atomic64_add_return_relaxed
> +#define 
> arch_atomic64_sub_return_relaxed	arch_atomic64_sub_return_relaxed
> +#define 
> arch_atomic64_fetch_add_relaxed		arch_atomic64_fetch_add_relaxed
> +#define 
> arch_atomic64_fetch_sub_relaxed		arch_atomic64_fetch_sub_relaxed
> +
> +#undef ATOMIC64_OPS
> +
> +#define ATOMIC64_OPS(op, I, asm_op)					      \
> +	ATOMIC64_OP(op, I, asm_op)					      \
> +	ATOMIC64_FETCH_OP(op, I, asm_op)
> +
> +ATOMIC64_OPS(and, i, and)
> +ATOMIC64_OPS(or, i, or)
> +ATOMIC64_OPS(xor, i, xor)
> +
> +#define arch_atomic64_fetch_and_relaxed	arch_atomic64_fetch_and_relaxed
> +#define arch_atomic64_fetch_or_relaxed	arch_atomic64_fetch_or_relaxed
> +#define arch_atomic64_fetch_xor_relaxed	arch_atomic64_fetch_xor_relaxed
> +
> +#undef ATOMIC64_OPS
> +#undef ATOMIC64_FETCH_OP
> +#undef ATOMIC64_OP_RETURN
> +#undef ATOMIC64_OP
> +
> +static inline long arch_atomic64_fetch_add_unless(atomic64_t *v, long 
> a, long u)
> +{
> +       long prev, rc;
> +
> +	__asm__ __volatile__ (
> +		"0:	ll.d	%[p],  %[c]\n"
> +		"	beq	%[p],  %[u], 1f\n"
> +		"	add.d	%[rc], %[p], %[a]\n"
> +		"	sc.d	%[rc], %[c]\n"
> +		"	beqz	%[rc], 0b\n"
> +		"	b	2f\n"
> +		"1:\n"
> +		__WEAK_LLSC_MB
> +		"2:\n"
> +		: [p]"=&r" (prev), [rc]"=&r" (rc),
> +		  [c] "=ZB" (v->counter)
> +		: [a]"r" (a), [u]"r" (u)
> +		: "memory");
> +
> +	return prev;
> +}
> +#define arch_atomic64_fetch_add_unless arch_atomic64_fetch_add_unless
> +
> +/*
> + * arch_atomic64_sub_if_positive - conditionally subtract integer from 
> atomic variable
> + * @i: integer value to subtract
> + * @v: pointer of type atomic64_t
> + *
> + * Atomically test @v and subtract @i if @v is greater or equal than 
> @i.
> + * The function returns the old value of @v minus @i.
> + */
> +static inline long arch_atomic64_sub_if_positive(long i, atomic64_t *v)
> +{
> +	long result;
> +	long temp;
> +
> +	if (__builtin_constant_p(i)) {
> +		__asm__ __volatile__(
> +		"1:	ll.d	%1, %2	# atomic64_sub_if_positive	\n"
> +		"	addi.d	%0, %1, %3				\n"
> +		"	or	%1, %0, $zero				\n"
> +		"	blt	%0, $zero, 2f				\n"
> +		"	sc.d	%1, %2					\n"
> +		"	beq	%1, $zero, 1b				\n"
> +		"2:							\n"
> +		: "=&r" (result), "=&r" (temp),
> +		  "+" GCC_OFF_SMALL_ASM() (v->counter)
> +		: "I" (-i));
> +	} else {
> +		__asm__ __volatile__(
> +		"1:	ll.d	%1, %2	# atomic64_sub_if_positive	\n"
> +		"	sub.d	%0, %1, %3				\n"
> +		"	or	%1, %0, $zero				\n"
> +		"	blt	%0, $zero, 2f				\n"
> +		"	sc.d	%1, %2					\n"
> +		"	beq	%1, $zero, 1b				\n"
> +		"2:							\n"
> +		: "=&r" (result), "=&r" (temp),
> +		  "+" GCC_OFF_SMALL_ASM() (v->counter)
> +		: "r" (i));
> +	}
> +
> +	return result;
> +}
> +
> +#define arch_atomic64_cmpxchg(v, o, n) \
> +	((__typeof__((v)->counter))arch_cmpxchg(&((v)->counter), (o), (n)))
> +#define arch_atomic64_xchg(v, new) (arch_xchg(&((v)->counter), (new)))
> +
> +/*
> + * arch_atomic64_dec_if_positive - decrement by 1 if old value positive
> + * @v: pointer of type atomic64_t
> + */
> +#define 
> arch_atomic64_dec_if_positive(v)	arch_atomic64_sub_if_positive(1, v)
> +
> +#endif /* CONFIG_64BIT */
> +
> +#endif /* _ASM_ATOMIC_H */
> diff --git a/arch/loongarch/include/asm/barrier.h 
> b/arch/loongarch/include/asm/barrier.h
> new file mode 100644
> index 000000000000..e57571bcaf4f
> --- /dev/null
> +++ b/arch/loongarch/include/asm/barrier.h
> @@ -0,0 +1,51 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef __ASM_BARRIER_H
> +#define __ASM_BARRIER_H
> +
> +#define __sync()	__asm__ __volatile__("dbar 0" : : : "memory")
> +
> +#define fast_wmb()	__sync()
> +#define fast_rmb()	__sync()
> +#define fast_mb()	__sync()
> +#define fast_iob()	__sync()
> +#define wbflush()	__sync()
> +
> +#define wmb()		fast_wmb()
> +#define rmb()		fast_rmb()
> +#define mb()		fast_mb()
> +#define iob()		fast_iob()
> +
> +/**
> + * array_index_mask_nospec() - generate a ~0 mask when index < size, 0 
> otherwise
> + * @index: array element index
> + * @size: number of elements in array
> + *
> + * Returns:
> + *     0 - (@index < @size)
> + */
> +#define array_index_mask_nospec array_index_mask_nospec
> +static inline unsigned long array_index_mask_nospec(unsigned long 
> index,
> +						    unsigned long size)
> +{
> +	unsigned long mask;
> +
> +	__asm__ __volatile__(
> +		"sltu	%0, %1, %2\n\t"
> +#if (__SIZEOF_LONG__ == 4)
> +		"sub.w	%0, $r0, %0\n\t"
> +#elif (__SIZEOF_LONG__ == 8)
> +		"sub.d	%0, $r0, %0\n\t"
> +#endif
> +		: "=r" (mask)
> +		: "r" (index), "r" (size)
> +		:);
> +
> +	return mask;
> +}
> +
> +#include <asm-generic/barrier.h>
> +
> +#endif /* __ASM_BARRIER_H */
> diff --git a/arch/loongarch/include/asm/bitops.h 
> b/arch/loongarch/include/asm/bitops.h
> new file mode 100644
> index 000000000000..69e00f8d8034
> --- /dev/null
> +++ b/arch/loongarch/include/asm/bitops.h
> @@ -0,0 +1,33 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef _ASM_BITOPS_H
> +#define _ASM_BITOPS_H
> +
> +#include <linux/compiler.h>
> +
> +#ifndef _LINUX_BITOPS_H
> +#error only <linux/bitops.h> can be included directly
> +#endif
> +
> +#include <asm/barrier.h>
> +
> +#include <asm-generic/bitops/builtin-ffs.h>
> +#include <asm-generic/bitops/builtin-fls.h>
> +#include <asm-generic/bitops/builtin-__ffs.h>
> +#include <asm-generic/bitops/builtin-__fls.h>
> +
> +#include <asm-generic/bitops/ffz.h>
> +#include <asm-generic/bitops/fls64.h>
> +
> +#include <asm-generic/bitops/sched.h>
> +#include <asm-generic/bitops/hweight.h>
> +
> +#include <asm-generic/bitops/atomic.h>
> +#include <asm-generic/bitops/non-atomic.h>
> +#include <asm-generic/bitops/lock.h>
> +#include <asm-generic/bitops/le.h>
> +#include <asm-generic/bitops/ext2-atomic.h>
> +
> +#endif /* _ASM_BITOPS_H */
> diff --git a/arch/loongarch/include/asm/bitrev.h 
> b/arch/loongarch/include/asm/bitrev.h
> new file mode 100644
> index 000000000000..46f275b9cdf7
> --- /dev/null
> +++ b/arch/loongarch/include/asm/bitrev.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef __LOONGARCH_ASM_BITREV_H__
> +#define __LOONGARCH_ASM_BITREV_H__
> +
> +#include <linux/swab.h>
> +
> +static __always_inline __attribute_const__ u32 __arch_bitrev32(u32 x)
> +{
> +	u32 ret;
> +
> +	asm("bitrev.4b	%0, %1" : "=r"(ret) : "r"(__swab32(x)));
> +	return ret;
> +}
> +
> +static __always_inline __attribute_const__ u16 __arch_bitrev16(u16 x)
> +{
> +	u16 ret;
> +
> +	asm("bitrev.4b	%0, %1" : "=r"(ret) : "r"(__swab16(x)));
> +	return ret;
> +}
> +
> +static __always_inline __attribute_const__ u8 __arch_bitrev8(u8 x)
> +{
> +	u8 ret;
> +
> +	asm("bitrev.4b	%0, %1" : "=r"(ret) : "r"(x));
> +	return ret;
> +}
> +
> +#endif /* __LOONGARCH_ASM_BITREV_H__ */
> diff --git a/arch/loongarch/include/asm/cmpxchg.h 
> b/arch/loongarch/include/asm/cmpxchg.h
> new file mode 100644
> index 000000000000..48613b872bc8
> --- /dev/null
> +++ b/arch/loongarch/include/asm/cmpxchg.h
> @@ -0,0 +1,122 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef __ASM_CMPXCHG_H
> +#define __ASM_CMPXCHG_H
> +
> +#include <asm/barrier.h>
> +#include <linux/build_bug.h>
> +
> +#define __xchg_asm(amswap_db, m, val)		\
> +({						\
> +		__typeof(val) __ret;		\
> +						\
> +		__asm__ __volatile__ (		\
> +		" "amswap_db" %1, %z2, %0 \n"	\
> +		: "+ZB" (*m), "=&r" (__ret)	\
> +		: "Jr" (val)			\
> +		: "memory");			\
> +						\
> +		__ret;				\
> +})
> +
> +static inline unsigned long __xchg(volatile void *ptr, unsigned long x,
> +				   int size)
> +{
> +	switch (size) {
> +	case 4:
> +		return __xchg_asm("amswap_db.w", (volatile u32 *)ptr, (u32)x);
> +
> +	case 8:
> +		return __xchg_asm("amswap_db.d", (volatile u64 *)ptr, (u64)x);
> +
> +	default:
> +		BUILD_BUG();
> +	}
> +
> +	return 0;
> +}
> +
> +#define arch_xchg(ptr, x)						\
> +({									\
> +	__typeof__(*(ptr)) __res;					\
> +									\
> +	__res = (__typeof__(*(ptr)))					\
> +		__xchg((ptr), (unsigned long)(x), sizeof(*(ptr)));	\
> +									\
> +	__res;								\
> +})
> +
> +#define __cmpxchg_asm(ld, st, m, old, new)				\
> +({									\
> +	__typeof(old) __ret;						\
> +									\
> +	__asm__ __volatile__(						\
> +	"1:	" ld "	%0, %2		# __cmpxchg_asm \n"		\
> +	"	bne	%0, %z3, 2f			\n"		\
> +	"	or	$t0, %z4, $zero			\n"		\
> +	"	" st "	$t0, %1				\n"		\
> +	"	beq	$zero, $t0, 1b			\n"		\
> +	"2:						\n"		\
> +	: "=&r" (__ret), "=ZB"(*m)					\
> +	: "ZB"(*m), "Jr" (old), "Jr" (new)				\
> +	: "t0", "memory");						\
> +									\
> +	__ret;								\
> +})
> +
> +static inline unsigned long __cmpxchg(volatile void *ptr, unsigned 
> long old,
> +				      unsigned long new, unsigned int size)
> +{
> +	switch (size) {
> +	case 4:
> +		return __cmpxchg_asm("ll.w", "sc.w", (volatile u32 *)ptr,
> +				     (u32)old, new);
> +
> +	case 8:
> +		return __cmpxchg_asm("ll.d", "sc.d", (volatile u64 *)ptr,
> +				     (u64)old, new);
> +
> +	default:
> +		BUILD_BUG();
> +	}
> +
> +	return 0;
> +}
> +
> +#define arch_cmpxchg_local(ptr, old, new)				\
> +	((__typeof__(*(ptr)))						\
> +		__cmpxchg((ptr),					\
> +			  (unsigned long)(__typeof__(*(ptr)))(old),	\
> +			  (unsigned long)(__typeof__(*(ptr)))(new),	\
> +			  sizeof(*(ptr))))
> +
> +#define arch_cmpxchg(ptr, old, new)					\
> +({									\
> +	__typeof__(*(ptr)) __res;					\
> +									\
> +	__res = arch_cmpxchg_local((ptr), (old), (new));		\
> +									\
> +	__res;								\
> +})
> +
> +#ifdef CONFIG_64BIT
> +#define arch_cmpxchg64_local(ptr, o, n)					\
> +  ({									\
> +	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
> +	arch_cmpxchg_local((ptr), (o), (n));				\
> +  })
> +
> +#define arch_cmpxchg64(ptr, o, n)					\
> +  ({									\
> +	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
> +	arch_cmpxchg((ptr), (o), (n));					\
> +  })
> +#else
> +#include <asm-generic/cmpxchg-local.h>
> +#define arch_cmpxchg64_local(ptr, o, n) 
> __generic_cmpxchg64_local((ptr), (o), (n))
> +#define arch_cmpxchg64(ptr, o, n) arch_cmpxchg64_local((ptr), (o), (n))
> +#endif
> +
> +#endif /* __ASM_CMPXCHG_H */
> diff --git a/arch/loongarch/include/asm/local.h 
> b/arch/loongarch/include/asm/local.h
> new file mode 100644
> index 000000000000..2052a2267337
> --- /dev/null
> +++ b/arch/loongarch/include/asm/local.h
> @@ -0,0 +1,138 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef _ARCH_LOONGARCH_LOCAL_H
> +#define _ARCH_LOONGARCH_LOCAL_H
> +
> +#include <linux/percpu.h>
> +#include <linux/bitops.h>
> +#include <linux/atomic.h>
> +#include <asm/cmpxchg.h>
> +#include <asm/compiler.h>
> +
> +typedef struct {
> +	atomic_long_t a;
> +} local_t;
> +
> +#define LOCAL_INIT(i)	{ ATOMIC_LONG_INIT(i) }
> +
> +#define local_read(l)	atomic_long_read(&(l)->a)
> +#define local_set(l, i) atomic_long_set(&(l)->a, (i))
> +
> +#define local_add(i, l) atomic_long_add((i), (&(l)->a))
> +#define local_sub(i, l) atomic_long_sub((i), (&(l)->a))
> +#define local_inc(l)	atomic_long_inc(&(l)->a)
> +#define local_dec(l)	atomic_long_dec(&(l)->a)
> +
> +/*
> + * Same as above, but return the result value
> + */
> +static inline long local_add_return(long i, local_t *l)
> +{
> +	unsigned long result;
> +
> +	__asm__ __volatile__(
> +	"   " __AMADD " %1, %2, %0      \n"
> +	: "+ZB" (l->a.counter), "=&r" (result)
> +	: "r" (i)
> +	: "memory");
> +	result = result + i;
> +
> +	return result;
> +}
> +
> +static inline long local_sub_return(long i, local_t *l)
> +{
> +	unsigned long result;
> +
> +	__asm__ __volatile__(
> +	"   " __AMADD "%1, %2, %0       \n"
> +	: "+ZB" (l->a.counter), "=&r" (result)
> +	: "r" (-i)
> +	: "memory");
> +
> +	result = result - i;
> +
> +	return result;
> +}
> +
> +#define local_cmpxchg(l, o, n) \
> +	((long)cmpxchg_local(&((l)->a.counter), (o), (n)))
> +#define local_xchg(l, n) (atomic_long_xchg((&(l)->a), (n)))
> +
> +/**
> + * local_add_unless - add unless the number is a given value
> + * @l: pointer of type local_t
> + * @a: the amount to add to l...
> + * @u: ...unless l is equal to u.
> + *
> + * Atomically adds @a to @l, so long as it was not @u.
> + * Returns non-zero if @l was not @u, and zero otherwise.
> + */
> +#define local_add_unless(l, a, u)				\
> +({								\
> +	long c, old;						\
> +	c = local_read(l);					\
> +	while (c != (u) && (old = local_cmpxchg((l), c, c + (a))) != c) \
> +		c = old;					\
> +	c != (u);						\
> +})
> +#define local_inc_not_zero(l) local_add_unless((l), 1, 0)
> +
> +#define local_dec_return(l) local_sub_return(1, (l))
> +#define local_inc_return(l) local_add_return(1, (l))
> +
> +/*
> + * local_sub_and_test - subtract value from variable and test result
> + * @i: integer value to subtract
> + * @l: pointer of type local_t
> + *
> + * Atomically subtracts @i from @l and returns
> + * true if the result is zero, or false for all
> + * other cases.
> + */
> +#define local_sub_and_test(i, l) (local_sub_return((i), (l)) == 0)
> +
> +/*
> + * local_inc_and_test - increment and test
> + * @l: pointer of type local_t
> + *
> + * Atomically increments @l by 1
> + * and returns true if the result is zero, or false for all
> + * other cases.
> + */
> +#define local_inc_and_test(l) (local_inc_return(l) == 0)
> +
> +/*
> + * local_dec_and_test - decrement by 1 and test
> + * @l: pointer of type local_t
> + *
> + * Atomically decrements @l by 1 and
> + * returns true if the result is 0, or false for all other
> + * cases.
> + */
> +#define local_dec_and_test(l) (local_sub_return(1, (l)) == 0)
> +
> +/*
> + * local_add_negative - add and test if negative
> + * @l: pointer of type local_t
> + * @i: integer value to add
> + *
> + * Atomically adds @i to @l and returns true
> + * if the result is negative, or false when
> + * result is greater than or equal to zero.
> + */
> +#define local_add_negative(i, l) (local_add_return(i, (l)) < 0)
> +
> +/* Use these for per-cpu local_t variables: on some archs they are
> + * much more efficient than these naive implementations.  Note they 
> take
> + * a variable, not an address.
> + */
> +
> +#define __local_inc(l)		((l)->a.counter++)
> +#define __local_dec(l)		((l)->a.counter++)
> +#define __local_add(i, l)	((l)->a.counter += (i))
> +#define __local_sub(i, l)	((l)->a.counter -= (i))
> +
> +#endif /* _ARCH_LOONGARCH_LOCAL_H */
> diff --git a/arch/loongarch/include/asm/percpu.h 
> b/arch/loongarch/include/asm/percpu.h
> new file mode 100644
> index 000000000000..b03d8f8b9fd3
> --- /dev/null
> +++ b/arch/loongarch/include/asm/percpu.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +#ifndef __ASM_PERCPU_H
> +#define __ASM_PERCPU_H
> +
> +/* Use r21 for fast access */
> +register unsigned long __my_cpu_offset __asm__("$r21");
> +
> +static inline void set_my_cpu_offset(unsigned long off)
> +{
> +	__my_cpu_offset = off;
> +	csr_write64(off, PERCPU_BASE_KS);
> +}
> +#define __my_cpu_offset __my_cpu_offset
> +
> +#include <asm-generic/percpu.h>
> +
> +#endif /* __ASM_PERCPU_H */
> -- 
> 2.27.0

-- 
- Jiaxun