arch/x86/include/asm/syscall.h

Source file repositories/reference/linux-study-clean/arch/x86/include/asm/syscall.h

File Facts

System
Linux kernel
Corpus path
arch/x86/include/asm/syscall.h
Extension
.h
Size
4455 bytes
Lines
185
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: syscall or user/kernel boundary
Status
core 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_X86_SYSCALL_H
#define _ASM_X86_SYSCALL_H

#include <uapi/linux/audit.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <asm/thread_info.h>	/* for TS_COMPAT */
#include <asm/unistd.h>

/* This is used purely for kernel/trace/trace_syscalls.c */
typedef long (*sys_call_ptr_t)(const struct pt_regs *);
extern const sys_call_ptr_t sys_call_table[];

/*
 * These may not exist, but still put the prototypes in so we
 * can use IS_ENABLED().
 */
extern long ia32_sys_call(const struct pt_regs *, unsigned int nr);
extern long x32_sys_call(const struct pt_regs *, unsigned int nr);
extern long x64_sys_call(const struct pt_regs *, unsigned int nr);

/*
 * Only the low 32 bits of orig_ax are meaningful, so we return int.
 * This importantly ignores the high bits on 64-bit, so comparisons
 * sign-extend the low 32 bits.
 */
static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
{
	return regs->orig_ax;
}

static inline void syscall_set_nr(struct task_struct *task,
				  struct pt_regs *regs,
				  int nr)
{
	regs->orig_ax = nr;
}

static inline void syscall_rollback(struct task_struct *task,
				    struct pt_regs *regs)
{
	regs->ax = regs->orig_ax;
}

static inline long syscall_get_error(struct task_struct *task,
				     struct pt_regs *regs)
{
	unsigned long error = regs->ax;
#ifdef CONFIG_IA32_EMULATION
	/*
	 * TS_COMPAT is set for 32-bit syscall entries and then
	 * remains set until we return to user mode.
	 */
	if (task->thread_info.status & (TS_COMPAT|TS_I386_REGS_POKED))
		/*
		 * Sign-extend the value so (int)-EFOO becomes (long)-EFOO
		 * and will match correctly in comparisons.
		 */
		error = (long) (int) error;
#endif
	return IS_ERR_VALUE(error) ? error : 0;
}

static inline long syscall_get_return_value(struct task_struct *task,
					    struct pt_regs *regs)
{
	return regs->ax;
}

static inline void syscall_set_return_value(struct task_struct *task,
					    struct pt_regs *regs,
					    int error, long val)
{
	regs->ax = (long) error ?: val;
}

#ifdef CONFIG_X86_32

static inline void syscall_get_arguments(struct task_struct *task,
					 struct pt_regs *regs,
					 unsigned long *args)
{
	args[0] = regs->bx;
	args[1] = regs->cx;
	args[2] = regs->dx;
	args[3] = regs->si;
	args[4] = regs->di;
	args[5] = regs->bp;
}

Annotation

Implementation Notes