internal/syscall/unix: add PidFDSendSignal for Linux

CL 520266 added pidfd_send_signal linux syscall numbers to the
syscall package for the sake of a unit test.

As pidfd_send_signal will be used from the os package, let's revert the
changes to syscall package, add the pidfd_send_signal syscall numbers
and the implementation to internal/syscall/unix, and change the above
test to use it.

Updates #51246.
For #62654.

Change-Id: I862174c3c1a64baf1080792bdb3a1c1d1b417bb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/528436
Run-TryBot: Kirill Kolyshkin <kolyshkin@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>

12 files changed, 46 insertions, 56 deletions

diff --git a/src/syscall/exec_linux_test.go b/src/syscall/exec_linux_test.go
index 976275e1dc..68ec6fe3f8 100644
--- a/src/syscall/exec_linux_test.go
+++ b/src/syscall/exec_linux_test.go
@@ -12,6 +12,7 @@ import (
 	"flag"
 	"fmt"
 	"internal/platform"
+	"internal/syscall/unix"
 	"internal/testenv"
 	"io"
 	"os"
@@ -560,11 +561,11 @@ func testPidFD(t *testing.T, userns bool) error {
 
 	// Use pidfd to send a signal to the child.
 	sig := syscall.SIGINT
-	if _, _, e := syscall.Syscall(syscall.Sys_pidfd_send_signal, uintptr(pidfd), uintptr(sig), 0); e != 0 {
-		if e != syscall.EINVAL && testenv.SyscallIsNotSupported(e) {
-			t.Skip("pidfd_send_signal syscall not supported:", e)
+	if err := unix.PidFDSendSignal(uintptr(pidfd), sig); err != nil {
+		if err != syscall.EINVAL && testenv.SyscallIsNotSupported(err) {
+			t.Skip("pidfd_send_signal syscall not supported:", err)
 		}
-		t.Fatal("pidfd_send_signal syscall failed:", e)
+		t.Fatal("pidfd_send_signal syscall failed:", err)
 	}
 	// Check if the child received our signal.
 	err = cmd.Wait()
diff --git a/src/syscall/export_linux_test.go b/src/syscall/export_linux_test.go
index a09db60753..3aa877cfe3 100644
--- a/src/syscall/export_linux_test.go
+++ b/src/syscall/export_linux_test.go
@@ -10,6 +10,5 @@ var (
 )
 
 const (
-	Sys_GETEUID           = sys_GETEUID
-	Sys_pidfd_send_signal = _SYS_pidfd_send_signal
+	Sys_GETEUID = sys_GETEUID
 )
diff --git a/src/syscall/syscall_linux_386.go b/src/syscall/syscall_linux_386.go
index 1ab6c5e148..a559f7e288 100644
--- a/src/syscall/syscall_linux_386.go
+++ b/src/syscall/syscall_linux_386.go
@@ -7,11 +7,10 @@ package syscall
 import "unsafe"
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS32
-	_SYS_clone3            = 435
-	_SYS_faccessat2        = 439
-	_SYS_pidfd_send_signal = 424
-	_SYS_fchmodat2         = 452
+	_SYS_setgroups  = SYS_SETGROUPS32
+	_SYS_clone3     = 435
+	_SYS_faccessat2 = 439
+	_SYS_fchmodat2  = 452
 )
 
 func setTimespec(sec, nsec int64) Timespec {
diff --git a/src/syscall/syscall_linux_amd64.go b/src/syscall/syscall_linux_amd64.go
index 1083a507c7..ec52f8a4bd 100644
--- a/src/syscall/syscall_linux_amd64.go
+++ b/src/syscall/syscall_linux_amd64.go
@@ -9,11 +9,10 @@ import (
 )
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS
-	_SYS_clone3            = 435
-	_SYS_faccessat2        = 439
-	_SYS_pidfd_send_signal = 424
-	_SYS_fchmodat2         = 452
+	_SYS_setgroups  = SYS_SETGROUPS
+	_SYS_clone3     = 435
+	_SYS_faccessat2 = 439
+	_SYS_fchmodat2  = 452
 )
 
 //sys	Dup2(oldfd int, newfd int) (err error)
diff --git a/src/syscall/syscall_linux_arm.go b/src/syscall/syscall_linux_arm.go
index 2641cd2868..a6d92cea13 100644
--- a/src/syscall/syscall_linux_arm.go
+++ b/src/syscall/syscall_linux_arm.go
@@ -7,11 +7,10 @@ package syscall
 import "unsafe"
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS32
-	_SYS_clone3            = 435
-	_SYS_faccessat2        = 439
-	_SYS_pidfd_send_signal = 424
-	_SYS_fchmodat2         = 452
+	_SYS_setgroups  = SYS_SETGROUPS32
+	_SYS_clone3     = 435
+	_SYS_faccessat2 = 439
+	_SYS_fchmodat2  = 452
 )
 
 func setTimespec(sec, nsec int64) Timespec {
diff --git a/src/syscall/syscall_linux_arm64.go b/src/syscall/syscall_linux_arm64.go
index 74d6e3a958..b87b51c0c0 100644
--- a/src/syscall/syscall_linux_arm64.go
+++ b/src/syscall/syscall_linux_arm64.go
@@ -7,11 +7,10 @@ package syscall
 import "unsafe"
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS
-	_SYS_clone3            = 435
-	_SYS_faccessat2        = 439
-	_SYS_pidfd_send_signal = 424
-	_SYS_fchmodat2         = 452
+	_SYS_setgroups  = SYS_SETGROUPS
+	_SYS_clone3     = 435
+	_SYS_faccessat2 = 439
+	_SYS_fchmodat2  = 452
 )
 
 //sys	EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error) = SYS_EPOLL_PWAIT
diff --git a/src/syscall/syscall_linux_loong64.go b/src/syscall/syscall_linux_loong64.go
index eb275bc717..634cf30cf2 100644
--- a/src/syscall/syscall_linux_loong64.go
+++ b/src/syscall/syscall_linux_loong64.go
@@ -7,11 +7,10 @@ package syscall
 import "unsafe"
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS
-	_SYS_clone3            = 435
-	_SYS_faccessat2        = 439
-	_SYS_pidfd_send_signal = 424
-	_SYS_fchmodat2         = 452
+	_SYS_setgroups  = SYS_SETGROUPS
+	_SYS_clone3     = 435
+	_SYS_faccessat2 = 439
+	_SYS_fchmodat2  = 452
 )
 
 //sys	EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error) = SYS_EPOLL_PWAIT
diff --git a/src/syscall/syscall_linux_mips64x.go b/src/syscall/syscall_linux_mips64x.go
index 3bdee928ed..41106ed81f 100644
--- a/src/syscall/syscall_linux_mips64x.go
+++ b/src/syscall/syscall_linux_mips64x.go
@@ -11,11 +11,10 @@ import (
 )
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS
-	_SYS_clone3            = 5435
-	_SYS_faccessat2        = 5439
-	_SYS_pidfd_send_signal = 5424
-	_SYS_fchmodat2         = 5452
+	_SYS_setgroups  = SYS_SETGROUPS
+	_SYS_clone3     = 5435
+	_SYS_faccessat2 = 5439
+	_SYS_fchmodat2  = 5452
 )
 
 //sys	Dup2(oldfd int, newfd int) (err error)
diff --git a/src/syscall/syscall_linux_mipsx.go b/src/syscall/syscall_linux_mipsx.go
index 7253c648e7..7d4f8f2264 100644
--- a/src/syscall/syscall_linux_mipsx.go
+++ b/src/syscall/syscall_linux_mipsx.go
@@ -9,11 +9,10 @@ package syscall
 import "unsafe"
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS
-	_SYS_clone3            = 4435
-	_SYS_faccessat2        = 4439
-	_SYS_pidfd_send_signal = 4424
-	_SYS_fchmodat2         = 4452
+	_SYS_setgroups  = SYS_SETGROUPS
+	_SYS_clone3     = 4435
+	_SYS_faccessat2 = 4439
+	_SYS_fchmodat2  = 4452
 )
 
 func Syscall9(trap, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err Errno)
diff --git a/src/syscall/syscall_linux_ppc64x.go b/src/syscall/syscall_linux_ppc64x.go
index 9cfe2dc695..13c184c44f 100644
--- a/src/syscall/syscall_linux_ppc64x.go
+++ b/src/syscall/syscall_linux_ppc64x.go
@@ -11,11 +11,10 @@ import (
 )
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS
-	_SYS_clone3            = 435
-	_SYS_faccessat2        = 439
-	_SYS_pidfd_send_signal = 424
-	_SYS_fchmodat2         = 452
+	_SYS_setgroups  = SYS_SETGROUPS
+	_SYS_clone3     = 435
+	_SYS_faccessat2 = 439
+	_SYS_fchmodat2  = 452
 )
 
 //sys	Dup2(oldfd int, newfd int) (err error)
diff --git a/src/syscall/syscall_linux_riscv64.go b/src/syscall/syscall_linux_riscv64.go
index 61fb4c1668..00872a74fb 100644
--- a/src/syscall/syscall_linux_riscv64.go
+++ b/src/syscall/syscall_linux_riscv64.go
@@ -7,11 +7,10 @@ package syscall
 import "unsafe"
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS
-	_SYS_clone3            = 435
-	_SYS_faccessat2        = 439
-	_SYS_pidfd_send_signal = 424
-	_SYS_fchmodat2         = 452
+	_SYS_setgroups  = SYS_SETGROUPS
+	_SYS_clone3     = 435
+	_SYS_faccessat2 = 439
+	_SYS_fchmodat2  = 452
 )
 
 //sys	EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error) = SYS_EPOLL_PWAIT
diff --git a/src/syscall/syscall_linux_s390x.go b/src/syscall/syscall_linux_s390x.go
index 3a0afc404a..ea667ec1da 100644
--- a/src/syscall/syscall_linux_s390x.go
+++ b/src/syscall/syscall_linux_s390x.go
@@ -7,11 +7,10 @@ package syscall
 import "unsafe"
 
 const (
-	_SYS_setgroups         = SYS_SETGROUPS
-	_SYS_clone3            = 435
-	_SYS_faccessat2        = 439
-	_SYS_pidfd_send_signal = 424
-	_SYS_fchmodat2         = 452
+	_SYS_setgroups  = SYS_SETGROUPS
+	_SYS_clone3     = 435
+	_SYS_faccessat2 = 439
+	_SYS_fchmodat2  = 452
 )
 
 //sys	Dup2(oldfd int, newfd int) (err error)