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/* SPDX-License-Identifier: MIT */
#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__) */
#ifdef CONFIG_NOLIBC
/**
* Note for syscall registers usage (x86, 32-bit):
* - %eax is the syscall number.
* - %eax is also the return value.
* - %ebx is the 1st argument.
* - %ecx is the 2nd argument.
* - %edx is the 3rd argument.
* - %esi is the 4th argument.
* - %edi is the 5th argument.
* - %ebp is the 6th argument.
*/
#define __do_syscall0(NUM) ({ \
intptr_t eax; \
\
__asm__ volatile( \
"int $0x80" \
: "=a"(eax) /* %eax */ \
: "a"(NUM) /* %eax */ \
: "memory" \
); \
eax; \
})
#define __do_syscall1(NUM, ARG1) ({ \
intptr_t eax; \
\
__asm__ volatile( \
"int $0x80" \
: "=a"(eax) /* %eax */ \
: "a"(NUM), /* %eax */ \
"b"((ARG1)) /* %ebx */ \
: "memory" \
); \
eax; \
})
#define __do_syscall2(NUM, ARG1, ARG2) ({ \
intptr_t eax; \
\
__asm__ volatile( \
"int $0x80" \
: "=a" (eax) /* %eax */ \
: "a"(NUM), /* %eax */ \
"b"((ARG1)), /* %ebx */ \
"c"((ARG2)) /* %ecx */ \
: "memory" \
); \
eax; \
})
#define __do_syscall3(NUM, ARG1, ARG2, ARG3) ({ \
intptr_t eax; \
\
__asm__ volatile( \
"int $0x80" \
: "=a" (eax) /* %eax */ \
: "a"(NUM), /* %eax */ \
"b"((ARG1)), /* %ebx */ \
"c"((ARG2)), /* %ecx */ \
"d"((ARG3)) /* %edx */ \
: "memory" \
); \
eax; \
})
#define __do_syscall4(NUM, ARG1, ARG2, ARG3, ARG4) ({ \
intptr_t eax; \
\
__asm__ volatile( \
"int $0x80" \
: "=a" (eax) /* %eax */ \
: "a"(NUM), /* %eax */ \
"b"((ARG1)), /* %ebx */ \
"c"((ARG2)), /* %ecx */ \
"d"((ARG3)), /* %edx */ \
"S"((ARG4)) /* %esi */ \
: "memory" \
); \
eax; \
})
#define __do_syscall5(NUM, ARG1, ARG2, ARG3, ARG4, ARG5) ({ \
intptr_t eax; \
\
__asm__ volatile( \
"int $0x80" \
: "=a" (eax) /* %eax */ \
: "a"(NUM), /* %eax */ \
"b"((ARG1)), /* %ebx */ \
"c"((ARG2)), /* %ecx */ \
"d"((ARG3)), /* %edx */ \
"S"((ARG4)), /* %esi */ \
"D"((ARG5)) /* %edi */ \
: "memory" \
); \
eax; \
})
/*
* On i386, the 6th argument of syscall goes in %ebp. However, both Clang
* and GCC cannot use %ebp in the clobber list and in the "r" constraint
* without using -fomit-frame-pointer. To make it always available for
* any kind of compilation, the below workaround is implemented:
*
* 1) Push the 6-th argument.
* 2) Push %ebp.
* 3) Load the 6-th argument from 4(%esp) to %ebp.
* 4) Do the syscall (int $0x80).
* 5) Pop %ebp (restore the old value of %ebp).
* 6) Add %esp by 4 (undo the stack pointer).
*
* WARNING:
* Don't use register variables for __do_syscall6(), there is a known
* GCC bug that results in an endless loop.
*
* BugLink: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105032
*
*/
#define __do_syscall6(NUM, ARG1, ARG2, ARG3, ARG4, ARG5, ARG6) ({ \
intptr_t eax = (intptr_t)(NUM); \
intptr_t arg6 = (intptr_t)(ARG6); /* Always in memory */ \
__asm__ volatile ( \
"pushl %[_arg6]\n\t" \
"pushl %%ebp\n\t" \
"movl 4(%%esp),%%ebp\n\t" \
"int $0x80\n\t" \
"popl %%ebp\n\t" \
"addl $4,%%esp" \
: "+a"(eax) /* %eax */ \
: "b"(ARG1), /* %ebx */ \
"c"(ARG2), /* %ecx */ \
"d"(ARG3), /* %edx */ \
"S"(ARG4), /* %esi */ \
"D"(ARG5), /* %edi */ \
[_arg6]"m"(arg6) /* memory */ \
: "memory", "cc" \
); \
eax; \
})
#include "../syscall-defs.h"
#else /* #ifdef CONFIG_NOLIBC */
#error #include "../generic/syscall.h"
#endif /* #ifdef CONFIG_NOLIBC */
#endif /* #if defined(__x86_64__) */
#endif /* #ifndef LIBURING_ARCH_X86_SYSCALL_H */
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