LoongArch: Add atomic/locking headers

mainline inclusion
from mainline-v5.19-rc1
commit 5b0b14e5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5OHOB
CVE: NA

--------------------------------

Add common headers (atomic, bitops, barrier and locking) for basic
LoongArch support.
Reviewed-by: NWANG Xuerui <git@xen0n.name>
Reviewed-by: NJiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: NHuacai Chen <chenhuacai@loongson.cn>

arch/loongarch/include/asm/atomic.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Atomic operations.
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef _ASM_ATOMIC_H
+#define _ASM_ATOMIC_H
+
+#define ARCH_ATOMIC
+
+#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 */

arch/loongarch/include/asm/barrier.h

+/* 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 */

arch/loongarch/include/asm/bitops.h

+/* 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/find.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 */

arch/loongarch/include/asm/bitrev.h

+/* 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__ */

arch/loongarch/include/asm/cmpxchg.h

+/* 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 */

arch/loongarch/include/asm/local.h

+/* 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 */

arch/loongarch/include/asm/percpu.h

+/* 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 */