syscall: call internal/runtime/syscall.Syscall6 in RawSyscall6

For #65355

Change-Id: I9168d9a767e3b2ece65ac6dcab6827ab6f6b11bb
Reviewed-on: https://go-review.googlesource.com/c/go/+/560136
Reviewed-by: Michael Knyszek <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Michael Pratt <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>

Author: panjf2000

src/internal/runtime/syscall/syscall_linux.go

@@ -15,29 +15,6 @@ import (
 // Syscall6 calls system call number 'num' with arguments a1-6.
 func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)
 
-// syscall_RawSyscall6 is a push linkname to export Syscall6 as
-// syscall.RawSyscall6.
-//
-// //go:uintptrkeepalive because the uintptr argument may be converted pointers
-// that need to be kept alive in the caller (this is implied for Syscall6 since
-// it has no body).
-//
-// //go:nosplit because stack copying does not account for uintptrkeepalive, so
-// the stack must not grow. Stack copying cannot blindly assume that all
-// uintptr arguments are pointers, because some values may look like pointers,
-// but not really be pointers, and adjusting their value would break the call.
-//
-// This is a separate wrapper because we can't export one function as two
-// names. The assembly implementations name themselves Syscall6 would not be
-// affected by a linkname.
-//
-//go:uintptrkeepalive
-//go:nosplit
-//go:linkname syscall_RawSyscall6 syscall.RawSyscall6
-func syscall_RawSyscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr) {
-	return Syscall6(num, a1, a2, a3, a4, a5, a6)
-}
-
 func EpollCreate1(flags int32) (fd int32, errno uintptr) {
 	r1, _, e := Syscall6(SYS_EPOLL_CREATE1, uintptr(flags), 0, 0, 0, 0, 0)
 	return int32(r1), e

src/syscall/syscall_linux.go

@@ -13,17 +13,11 @@ package syscall
 
 import (
 	"internal/itoa"
+	runtimesyscall "internal/runtime/syscall"
 	"runtime"
 	"unsafe"
 )
 
-// N.B. RawSyscall6 is provided via linkname by internal/runtime/syscall.
-//
-// Errno is uintptr and thus compatible with the internal/runtime/syscall
-// definition.
-
-func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
-
 // Pull in entersyscall/exitsyscall for Syscall/Syscall6.
 //
 // Note that this can't be a push linkname because the runtime already has a
@@ -40,8 +34,7 @@ func runtime_exitsyscall()
 // N.B. For the Syscall functions below:
 //
 // //go:uintptrkeepalive because the uintptr argument may be converted pointers
-// that need to be kept alive in the caller (this is implied for RawSyscall6
-// since it has no body).
+// that need to be kept alive in the caller.
 //
 // //go:nosplit because stack copying does not account for uintptrkeepalive, so
 // the stack must not grow. Stack copying cannot blindly assume that all
@@ -62,6 +55,17 @@ func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
 	return RawSyscall6(trap, a1, a2, a3, 0, 0, 0)
 }
 
+//go:uintptrkeepalive
+//go:nosplit
+//go:norace
+//go:linkname RawSyscall6
+func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
+	var errno uintptr
+	r1, r2, errno = runtimesyscall.Syscall6(trap, a1, a2, a3, a4, a5, a6)
+	err = Errno(errno)
+	return
+}
+
 //go:uintptrkeepalive
 //go:nosplit
 //go:linkname Syscall