arch/loongarch/include/asm/percpu.h

Source file repositories/reference/linux-study-clean/arch/loongarch/include/asm/percpu.h

File Facts

System
Linux kernel
Corpus path
arch/loongarch/include/asm/percpu.h
Extension
.h
Size
5097 bytes
Lines
185
Domain
Architecture Layer
Bucket
arch/loongarch
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __ASM_PERCPU_H
#define __ASM_PERCPU_H

#include <asm/cmpxchg.h>
#include <asm/loongarch.h>

/*
 * The "address" (in fact, offset from $r21) of a per-CPU variable is close to
 * the loading address of main kernel image, but far from where the modules are
 * loaded. Tell the compiler this fact when using explicit relocs.
 */
#if defined(MODULE) && defined(CONFIG_AS_HAS_EXPLICIT_RELOCS) && defined(CONFIG_64BIT)
# if __has_attribute(model)
#  define PER_CPU_ATTRIBUTES __attribute__((model("extreme")))
# else
#  error compiler support for the model attribute is necessary when a recent assembler is used
# endif
#endif

/* 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_write(off, PERCPU_BASE_KS);
}

#define __my_cpu_offset					\
({							\
	__asm__ __volatile__("":"+r"(__my_cpu_offset));	\
	__my_cpu_offset;				\
})

#ifdef CONFIG_CPU_HAS_AMO

#define PERCPU_OP(op, asm_op, c_op)					\
static __always_inline unsigned long __percpu_##op(void *ptr,		\
			unsigned long val, int size)			\
{									\
	unsigned long ret;						\
									\
	switch (size) {							\
	case 4:								\
		__asm__ __volatile__(					\
		"am"#asm_op".w"	" %[ret], %[val], %[ptr]	\n"	\
		: [ret] "=&r" (ret), [ptr] "+ZB"(*(u32 *)ptr)		\
		: [val] "r" (val));					\
		break;							\
	case 8:								\
		__asm__ __volatile__(					\
		"am"#asm_op".d" " %[ret], %[val], %[ptr]	\n"	\
		: [ret] "=&r" (ret), [ptr] "+ZB"(*(u64 *)ptr)		\
		: [val] "r" (val));					\
		break;							\
	default:							\
		ret = 0;						\
		BUILD_BUG();						\
	}								\
									\
	return ret c_op val;						\
}

PERCPU_OP(add, add, +)
PERCPU_OP(and, and, &)
PERCPU_OP(or, or, |)
#undef PERCPU_OP

#endif

#ifdef CONFIG_64BIT

#define __pcpu_op_1(op)		op ".b "
#define __pcpu_op_2(op)		op ".h "
#define __pcpu_op_4(op)		op ".w "
#define __pcpu_op_8(op)		op ".d "

#define _percpu_read(size, _pcp)					\
({									\
	typeof(_pcp) __pcp_ret;						\
									\
	__asm__ __volatile__(						\
		__pcpu_op_##size("ldx") "%[ret], $r21, %[ptr]	\n"	\
		: [ret] "=&r"(__pcp_ret)				\
		: [ptr] "r"(&(_pcp))					\
		: "memory");						\
									\
	__pcp_ret;							\
})

Annotation

Implementation Notes