runtime: move epoll syscalls to runtime/internal/syscall

This change moves Linux epoll's syscalls implementation to the
"runtime/internal/syscall" package. The intention in this CL was to
minimise behavioural changes but make the code more generalised. This
also will allow adding new syscalls (like epoll_pwait2) without the
need to implement assembly stubs for each arch.

It also drops epoll_create as not all architectures provide this call.
epoll_create1 was added to the kernel in version 2.6.27 and Go requires
Linux kernel version 2.6.32 or later since Go 1.18. So it is safe to
always use epoll_create1.

This is a resubmit as the previous CL 421994 was reverted due to test
failures after the merge with the master. The issue was fixed in
CL 438615

For #53824
For #51087

Change-Id: I1bd0f23a85b4f9b80178c5dd36fd3e95ff4f9648
Reviewed-on: https://go-review.googlesource.com/c/go/+/440115
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>

1 files changed, 0 insertions, 9 deletions

diff --git a/src/runtime/runtime_linux_test.go b/src/runtime/runtime_linux_test.go
index a753aeea58..6af5561e91 100644
--- a/src/runtime/runtime_linux_test.go
+++ b/src/runtime/runtime_linux_test.go
@@ -53,15 +53,6 @@ func TestMincoreErrorSign(t *testing.T) {
 	}
 }
 
-func TestEpollctlErrorSign(t *testing.T) {
-	v := Epollctl(-1, 1, -1, unsafe.Pointer(&EpollEvent{}))
-
-	const EBADF = 0x09
-	if v != -EBADF {
-		t.Errorf("epollctl = %v, want %v", v, -EBADF)
-	}
-}
-
 func TestKernelStructSize(t *testing.T) {
 	// Check that the Go definitions of structures exchanged with the kernel are
 	// the same size as what the kernel defines.