/* SPDX-License-Identifier: MIT */

#ifndef __INTERNAL__LIBURING_SYSCALL_H
	#error "This file should be included from src/syscall.h (liburing)"
#endif

#ifndef LIBURING_ARCH_X86_SYSCALL_H
#define LIBURING_ARCH_X86_SYSCALL_H

#if defined(__x86_64__)
/**
 * Note for syscall registers usage (x86-64):
 *   - %rax is the syscall number.
 *   - %rax is also the return value.
 *   - %rdi is the 1st argument.
 *   - %rsi is the 2nd argument.
 *   - %rdx is the 3rd argument.
 *   - %r10 is the 4th argument (**yes it's %r10, not %rcx!**).
 *   - %r8  is the 5th argument.
 *   - %r9  is the 6th argument.
 *
 * `syscall` instruction will clobber %r11 and %rcx.
 *
 * After the syscall returns to userspace:
 *   - %r11 will contain %rflags.
 *   - %rcx will contain the return address.
 *
 * IOW, after the syscall returns to userspace:
 *   %r11 == %rflags and %rcx == %rip.
 */

#define __do_syscall0(NUM) ({			\
	intptr_t rax;				\
						\
	__asm__ volatile(			\
		"syscall"			\
		: "=a"(rax)	/* %rax */	\
		: "a"(NUM)	/* %rax */	\
		: "rcx", "r11", "memory"	\
	);					\
	rax;					\
})

#define __do_syscall1(NUM, ARG1) ({		\
	intptr_t rax;				\
						\
	__asm__ volatile(			\
		"syscall"			\
		: "=a"(rax)	/* %rax */	\
		: "a"((NUM)),	/* %rax */	\
		  "D"((ARG1))	/* %rdi */	\
		: "rcx", "r11", "memory"	\
	);					\
	rax;					\
})

#define __do_syscall2(NUM, ARG1, ARG2) ({	\
	intptr_t rax;				\
						\
	__asm__ volatile(			\
		"syscall"			\
		: "=a"(rax)	/* %rax */	\
		: "a"((NUM)),	/* %rax */	\
		  "D"((ARG1)),	/* %rdi */	\
		  "S"((ARG2))	/* %rsi */	\
		: "rcx", "r11", "memory"	\
	);					\
	rax;					\
})

#define __do_syscall3(NUM, ARG1, ARG2, ARG3) ({	\
	intptr_t rax;				\
						\
	__asm__ volatile(			\
		"syscall"			\
		: "=a"(rax)	/* %rax */	\
		: "a"((NUM)),	/* %rax */	\
		  "D"((ARG1)),	/* %rdi */	\
		  "S"((ARG2)),	/* %rsi */	\
		  "d"((ARG3))	/* %rdx */	\
		: "rcx", "r11", "memory"	\
	);					\
	rax;					\
})

#define __do_syscall4(NUM, ARG1, ARG2, ARG3, ARG4) ({			\
	intptr_t rax;							\
	register __typeof__(ARG4) __r10 __asm__("r10") = (ARG4);	\
									\
	__asm__ volatile(						\
		"syscall"						\
		: "=a"(rax)	/* %rax */				\
		: "a"((NUM)),	/* %rax */				\
		  "D"((ARG1)),	/* %rdi */				\
		  "S"((ARG2)),	/* %rsi */				\
		  "d"((ARG3)),	/* %rdx */				\
		  "r"(__r10)	/* %r10 */				\
		: "rcx", "r11", "memory"				\
	);								\
	rax;								\
})

#define __do_syscall5(NUM, ARG1, ARG2, ARG3, ARG4, ARG5) ({		\
	intptr_t rax;							\
	register __typeof__(ARG4) __r10 __asm__("r10") = (ARG4);	\
	register __typeof__(ARG5) __r8 __asm__("r8") = (ARG5);		\
									\
	__asm__ volatile(						\
		"syscall"						\
		: "=a"(rax)	/* %rax */				\
		: "a"((NUM)),	/* %rax */				\
		  "D"((ARG1)),	/* %rdi */				\
		  "S"((ARG2)),	/* %rsi */				\
		  "d"((ARG3)),	/* %rdx */				\
		  "r"(__r10),	/* %r10 */				\
		  "r"(__r8)	/* %r8 */				\
		: "rcx", "r11", "memory"				\
	);								\
	rax;								\
})

#define __do_syscall6(NUM, ARG1, ARG2, ARG3, ARG4, ARG5, ARG6) ({	\
	intptr_t rax;							\
	register __typeof__(ARG4) __r10 __asm__("r10") = (ARG4);	\
	register __typeof__(ARG5) __r8 __asm__("r8") = (ARG5);		\
	register __typeof__(ARG6) __r9 __asm__("r9") = (ARG6);		\
									\
	__asm__ volatile(						\
		"syscall"						\
		: "=a"(rax)	/* %rax */				\
		: "a"((NUM)),	/* %rax */				\
		  "D"((ARG1)),	/* %rdi */				\
		  "S"((ARG2)),	/* %rsi */				\
		  "d"((ARG3)),	/* %rdx */				\
		  "r"(__r10),	/* %r10 */				\
		  "r"(__r8),	/* %r8 */				\
		  "r"(__r9)	/* %r9 */				\
		: "rcx", "r11", "memory"				\
	);								\
	rax;								\
})

#include "../syscall-defs.h"

#else /* #if defined(__x86_64__) */

/*
 * For x86 (32-bit), fallback to libc wrapper.
 * We can't use CONFIG_NOLIBC for x86 (32-bit) at the moment.
 *
 * TODO: Add x86 (32-bit) nolibc support.
 */
#ifdef CONFIG_NOLIBC
	#error "x86 (32-bit) is currently not supported for nolibc builds"
#endif
#include "../generic/syscall.h"

#endif /* #if defined(__x86_64__) */

#endif /* #ifndef LIBURING_ARCH_X86_SYSCALL_H */