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/* 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;								\
})

static inline void *__sys_mmap(void *addr, size_t length, int prot, int flags,
			       int fd, off_t offset)
{
	return (void *) __do_syscall6(__NR_mmap, addr, length, prot, flags, fd,
				      offset);
}

static inline int __sys_munmap(void *addr, size_t length)
{
	return (int) __do_syscall2(__NR_munmap, addr, length);
}

static inline int __sys_madvise(void *addr, size_t length, int advice)
{
	return (int) __do_syscall3(__NR_madvise, addr, length, advice);
}

static inline int __sys_getrlimit(int resource, struct rlimit *rlim)
{
	return (int) __do_syscall2(__NR_getrlimit, resource, rlim);
}

static inline int __sys_setrlimit(int resource, const struct rlimit *rlim)
{
	return (int) __do_syscall2(__NR_setrlimit, resource, rlim);
}

static inline int __sys_close(int fd)
{
	return (int) __do_syscall1(__NR_close, fd);
}

static inline int ____sys_io_uring_register(int fd, unsigned opcode,
					    const void *arg, unsigned nr_args)
{
	return (int) __do_syscall4(__NR_io_uring_register, fd, opcode, arg,
				   nr_args);
}

static inline int ____sys_io_uring_setup(unsigned entries,
					 struct io_uring_params *p)
{
	return (int) __do_syscall2(__NR_io_uring_setup, entries, p);
}

static inline int ____sys_io_uring_enter2(int fd, unsigned to_submit,
					  unsigned min_complete, unsigned flags,
					  sigset_t *sig, int sz)
{
	return (int) __do_syscall6(__NR_io_uring_enter, fd, to_submit,
				   min_complete, flags, sig, sz);
}

static inline int ____sys_io_uring_enter(int fd, unsigned to_submit,
					 unsigned min_complete, unsigned flags,
					 sigset_t *sig)
{
	return ____sys_io_uring_enter2(fd, to_submit, min_complete, flags, sig,
				       _NSIG / 8);
}

#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 */