1 // Copyright 2022 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Package syscall provides the syscall primitives required for the runtime. 6 package syscall 7 8 import ( 9 "unsafe" 10 ) 11 12 // TODO(https://go.dev/issue/51087): This package is incomplete and currently 13 // only contains very minimal support for Linux. 14 15 // Syscall6 calls system call number 'num' with arguments a1-6. 16 func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr) 17 18 // syscall_RawSyscall6 is a push linkname to export Syscall6 as 19 // syscall.RawSyscall6. 20 // 21 // //go:uintptrkeepalive because the uintptr argument may be converted pointers 22 // that need to be kept alive in the caller (this is implied for Syscall6 since 23 // it has no body). 24 // 25 // //go:nosplit because stack copying does not account for uintptrkeepalive, so 26 // the stack must not grow. Stack copying cannot blindly assume that all 27 // uintptr arguments are pointers, because some values may look like pointers, 28 // but not really be pointers, and adjusting their value would break the call. 29 // 30 // This is a separate wrapper because we can't export one function as two 31 // names. The assembly implementations name themselves Syscall6 would not be 32 // affected by a linkname. 33 // 34 //go:uintptrkeepalive 35 //go:nosplit 36 //go:linkname syscall_RawSyscall6 syscall.RawSyscall6 37 func syscall_RawSyscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr) { 38 return Syscall6(num, a1, a2, a3, a4, a5, a6) 39 } 40 41 func EpollCreate1(flags int32) (fd int32, errno uintptr) { 42 r1, _, e := Syscall6(SYS_EPOLL_CREATE1, uintptr(flags), 0, 0, 0, 0, 0) 43 return int32(r1), e 44 } 45 46 var _zero uintptr 47 48 func EpollWait(epfd int32, events []EpollEvent, maxev, waitms int32) (n int32, errno uintptr) { 49 var ev unsafe.Pointer 50 if len(events) > 0 { 51 ev = unsafe.Pointer(&events[0]) 52 } else { 53 ev = unsafe.Pointer(&_zero) 54 } 55 r1, _, e := Syscall6(SYS_EPOLL_PWAIT, uintptr(epfd), uintptr(ev), uintptr(maxev), uintptr(waitms), 0, 0) 56 return int32(r1), e 57 } 58 59 func EpollCtl(epfd, op, fd int32, event *EpollEvent) (errno uintptr) { 60 _, _, e := Syscall6(SYS_EPOLL_CTL, uintptr(epfd), uintptr(op), uintptr(fd), uintptr(unsafe.Pointer(event)), 0, 0) 61 return e 62 } 63