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>

9 files changed, 39 insertions, 16 deletions

diff --git a/src/internal/syscall/unix/pidfd_linux.go b/src/internal/syscall/unix/pidfd_linux.go
new file mode 100644
index 0000000000..02cfaa062c
--- /dev/null
+++ b/src/internal/syscall/unix/pidfd_linux.go
@@ -0,0 +1,15 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package unix
+
+import "syscall"
+
+func PidFDSendSignal(pidfd uintptr, s syscall.Signal) error {
+	_, _, errno := syscall.Syscall(pidfdSendSignalTrap, pidfd, uintptr(s), 0)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
diff --git a/src/internal/syscall/unix/sysnum_linux_386.go b/src/internal/syscall/unix/sysnum_linux_386.go
index 2bda08ccf1..9f750a1c03 100644
--- a/src/internal/syscall/unix/sysnum_linux_386.go
+++ b/src/internal/syscall/unix/sysnum_linux_386.go
@@ -5,6 +5,7 @@
 package unix
 
 const (
-	getrandomTrap     uintptr = 355
-	copyFileRangeTrap uintptr = 377
+	getrandomTrap       uintptr = 355
+	copyFileRangeTrap   uintptr = 377
+	pidfdSendSignalTrap uintptr = 424
 )
diff --git a/src/internal/syscall/unix/sysnum_linux_amd64.go b/src/internal/syscall/unix/sysnum_linux_amd64.go
index ae5239ebfb..706898d41e 100644
--- a/src/internal/syscall/unix/sysnum_linux_amd64.go
+++ b/src/internal/syscall/unix/sysnum_linux_amd64.go
@@ -5,6 +5,7 @@
 package unix
 
 const (
-	getrandomTrap     uintptr = 318
-	copyFileRangeTrap uintptr = 326
+	getrandomTrap       uintptr = 318
+	copyFileRangeTrap   uintptr = 326
+	pidfdSendSignalTrap uintptr = 424
 )
diff --git a/src/internal/syscall/unix/sysnum_linux_arm.go b/src/internal/syscall/unix/sysnum_linux_arm.go
index acaec05879..c00644b552 100644
--- a/src/internal/syscall/unix/sysnum_linux_arm.go
+++ b/src/internal/syscall/unix/sysnum_linux_arm.go
@@ -5,6 +5,7 @@
 package unix
 
 const (
-	getrandomTrap     uintptr = 384
-	copyFileRangeTrap uintptr = 391
+	getrandomTrap       uintptr = 384
+	copyFileRangeTrap   uintptr = 391
+	pidfdSendSignalTrap uintptr = 424
 )
diff --git a/src/internal/syscall/unix/sysnum_linux_generic.go b/src/internal/syscall/unix/sysnum_linux_generic.go
index 8c132c6bf5..bf25428e7e 100644
--- a/src/internal/syscall/unix/sysnum_linux_generic.go
+++ b/src/internal/syscall/unix/sysnum_linux_generic.go
@@ -11,6 +11,7 @@ package unix
 // means only arm64 loong64 and riscv64 use the standard numbers.
 
 const (
-	getrandomTrap     uintptr = 278
-	copyFileRangeTrap uintptr = 285
+	getrandomTrap       uintptr = 278
+	copyFileRangeTrap   uintptr = 285
+	pidfdSendSignalTrap uintptr = 424
 )
diff --git a/src/internal/syscall/unix/sysnum_linux_mips64x.go b/src/internal/syscall/unix/sysnum_linux_mips64x.go
index bca526d2b9..6a9e238ce3 100644
--- a/src/internal/syscall/unix/sysnum_linux_mips64x.go
+++ b/src/internal/syscall/unix/sysnum_linux_mips64x.go
@@ -7,6 +7,7 @@
 package unix
 
 const (
-	getrandomTrap     uintptr = 5313
-	copyFileRangeTrap uintptr = 5320
+	getrandomTrap       uintptr = 5313
+	copyFileRangeTrap   uintptr = 5320
+	pidfdSendSignalTrap uintptr = 5424
 )
diff --git a/src/internal/syscall/unix/sysnum_linux_mipsx.go b/src/internal/syscall/unix/sysnum_linux_mipsx.go
index c86195e496..22d38f148e 100644
--- a/src/internal/syscall/unix/sysnum_linux_mipsx.go
+++ b/src/internal/syscall/unix/sysnum_linux_mipsx.go
@@ -7,6 +7,7 @@
 package unix
 
 const (
-	getrandomTrap     uintptr = 4353
-	copyFileRangeTrap uintptr = 4360
+	getrandomTrap       uintptr = 4353
+	copyFileRangeTrap   uintptr = 4360
+	pidfdSendSignalTrap uintptr = 4424
 )
diff --git a/src/internal/syscall/unix/sysnum_linux_ppc64x.go b/src/internal/syscall/unix/sysnum_linux_ppc64x.go
index a4dcf2bc9d..945ec28c2a 100644
--- a/src/internal/syscall/unix/sysnum_linux_ppc64x.go
+++ b/src/internal/syscall/unix/sysnum_linux_ppc64x.go
@@ -7,6 +7,7 @@
 package unix
 
 const (
-	getrandomTrap     uintptr = 359
-	copyFileRangeTrap uintptr = 379
+	getrandomTrap       uintptr = 359
+	copyFileRangeTrap   uintptr = 379
+	pidfdSendSignalTrap uintptr = 424
 )
diff --git a/src/internal/syscall/unix/sysnum_linux_s390x.go b/src/internal/syscall/unix/sysnum_linux_s390x.go
index bf2c01e4e1..2c74343820 100644
--- a/src/internal/syscall/unix/sysnum_linux_s390x.go
+++ b/src/internal/syscall/unix/sysnum_linux_s390x.go
@@ -5,6 +5,7 @@
 package unix
 
 const (
-	getrandomTrap     uintptr = 349
-	copyFileRangeTrap uintptr = 375
+	getrandomTrap       uintptr = 349
+	copyFileRangeTrap   uintptr = 375
+	pidfdSendSignalTrap uintptr = 424
 )