runtime: correct error handling in several FreeBSD syscall wrappers

The FreeBSD syscall convention uses the carry flag to indicate whether
an error has occured. The sys_umtx_op, thr_new, and pipe2 syscall
wrappers were failing to account for this convention and silently
suppressing errors as a result. This commit corrects these wrappers
by copying the pattern used by the other fallible syscall wrappers.

Note that futexsleep1 must now explicitly ignore the ETIMEDOUT error
from sys_umtx_op. Previously ETIMEDOUT was implicitly ignored because
sys_umtx_op never returned an error.

Fixes #43106.

Change-Id: I9c422b87cf4c6d308003bf42c3b419f785578b5d
Reviewed-on: https://go-review.googlesource.com/c/go/+/276892
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Trust: Than McIntosh <thanm@google.com>

src/runtime/defs_freebsd_386.go

@@ -13,10 +13,11 @@ const (
 )
 
 const (
-	_EINTR  = 0x4
+	_EINTR     = 0x4
-	_EFAULT = 0xe
+	_EFAULT    = 0xe
-	_EAGAIN = 0x23
+	_EAGAIN    = 0x23
-	_ENOSYS = 0x4e
+	_ENOSYS    = 0x4e
+	_ETIMEDOUT = 0x3c
 
 	_O_NONBLOCK = 0x4
 	_O_CLOEXEC  = 0x100000

src/runtime/defs_freebsd_amd64.go

@@ -13,10 +13,11 @@ const (
 )
 
 const (
-	_EINTR  = 0x4
+	_EINTR     = 0x4
-	_EFAULT = 0xe
+	_EFAULT    = 0xe
-	_EAGAIN = 0x23
+	_EAGAIN    = 0x23
-	_ENOSYS = 0x4e
+	_ENOSYS    = 0x4e
+	_ETIMEDOUT = 0x3c
 
 	_O_NONBLOCK = 0x4
 	_O_CLOEXEC  = 0x100000

src/runtime/defs_freebsd_arm.go

@@ -13,10 +13,11 @@ const (
 )
 
 const (
-	_EINTR  = 0x4
+	_EINTR     = 0x4
-	_EFAULT = 0xe
+	_EFAULT    = 0xe
-	_EAGAIN = 0x23
+	_EAGAIN    = 0x23
-	_ENOSYS = 0x4e
+	_ENOSYS    = 0x4e
+	_ETIMEDOUT = 0x3c
 
 	_O_NONBLOCK = 0x4
 	_O_CLOEXEC  = 0x100000

src/runtime/defs_freebsd_arm64.go

@@ -13,10 +13,11 @@ const (
 )
 
 const (
-	_EINTR  = 0x4
+	_EINTR     = 0x4
-	_EFAULT = 0xe
+	_EFAULT    = 0xe
-	_EAGAIN = 0x23
+	_EAGAIN    = 0x23
-	_ENOSYS = 0x4e
+	_ENOSYS    = 0x4e
+	_ETIMEDOUT = 0x3c
 
 	_O_NONBLOCK = 0x4
 	_O_CLOEXEC  = 0x100000

src/runtime/os_freebsd.go

@@ -166,7 +166,7 @@ func futexsleep1(addr *uint32, val uint32, ns int64) {
 		utp = &ut
 	}
 	ret := sys_umtx_op(addr, _UMTX_OP_WAIT_UINT_PRIVATE, val, unsafe.Sizeof(*utp), utp)
-	if ret >= 0 || ret == -_EINTR {
+	if ret >= 0 || ret == -_EINTR || ret == -_ETIMEDOUT {
 		return
 	}
 	print("umtx_wait addr=", addr, " val=", val, " ret=", ret, "\n")
@@ -208,7 +208,6 @@ func newosproc(mp *m) {
 
 	var oset sigset
 	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
-	// TODO: Check for error.
 	ret := thr_new(&param, int32(unsafe.Sizeof(param)))
 	sigprocmask(_SIG_SETMASK, &oset, nil)
 	if ret < 0 {

src/runtime/sys_freebsd_386.s

@@ -13,12 +13,16 @@
 TEXT runtime·sys_umtx_op(SB),NOSPLIT,$-4
 	MOVL	$454, AX
 	INT	$0x80
+	JAE	2(PC)
+	NEGL	AX
 	MOVL	AX, ret+20(FP)
 	RET
 
 TEXT runtime·thr_new(SB),NOSPLIT,$-4
 	MOVL	$455, AX
 	INT	$0x80
+	JAE	2(PC)
+	NEGL	AX
 	MOVL	AX, ret+8(FP)
 	RET
 
@@ -120,6 +124,8 @@ TEXT runtime·pipe2(SB),NOSPLIT,$12-16
 	MOVL	flags+0(FP), BX
 	MOVL	BX, 8(SP)
 	INT	$0x80
+	JAE	2(PC)
+	NEGL	AX
 	MOVL	AX, errno+12(FP)
 	RET
 

src/runtime/sys_freebsd_amd64.s

@@ -18,6 +18,8 @@ TEXT runtime·sys_umtx_op(SB),NOSPLIT,$0
 	MOVQ ut+24(FP), R8
 	MOVL $454, AX
 	SYSCALL
+	JCC	2(PC)
+	NEGQ	AX
 	MOVL	AX, ret+32(FP)
 	RET
 
@@ -26,6 +28,8 @@ TEXT runtime·thr_new(SB),NOSPLIT,$0
 	MOVL size+8(FP), SI
 	MOVL $455, AX
 	SYSCALL
+	JCC	2(PC)
+	NEGQ	AX
 	MOVL	AX, ret+16(FP)
 	RET
 
@@ -118,6 +122,8 @@ TEXT runtime·pipe2(SB),NOSPLIT,$0-20
 	MOVL	flags+0(FP), SI
 	MOVL	$542, AX
 	SYSCALL
+	JCC	2(PC)
+	NEGQ	AX
 	MOVL	AX, errno+16(FP)
 	RET
 

src/runtime/sys_freebsd_arm.s

@@ -51,6 +51,7 @@ TEXT runtime·sys_umtx_op(SB),NOSPLIT,$0
 	ADD $20, R13 // arg 5 is passed on stack
 	MOVW $SYS__umtx_op, R7
 	SWI $0
+	RSB.CS $0, R0
 	SUB $20, R13
 	// BCS error
 	MOVW	R0, ret+20(FP)
@@ -61,6 +62,7 @@ TEXT runtime·thr_new(SB),NOSPLIT,$0
 	MOVW size+4(FP), R1
 	MOVW $SYS_thr_new, R7
 	SWI $0
+	RSB.CS $0, R0
 	MOVW	R0, ret+8(FP)
 	RET
 
@@ -144,6 +146,7 @@ TEXT runtime·pipe2(SB),NOSPLIT,$0-16
 	MOVW	flags+0(FP), R1
 	MOVW	$SYS_pipe2, R7
 	SWI	$0
+	RSB.CS $0, R0
 	MOVW	R0, errno+12(FP)
 	RET
 

src/runtime/sys_freebsd_arm64.s

@@ -60,6 +60,9 @@ TEXT runtime·sys_umtx_op(SB),NOSPLIT,$0
 	MOVD	ut+24(FP), R4
 	MOVD	$SYS__umtx_op, R8
 	SVC
+	BCC	ok
+	NEG	R0, R0
+ok:
 	MOVW	R0, ret+32(FP)
 	RET
 
@@ -69,6 +72,9 @@ TEXT runtime·thr_new(SB),NOSPLIT,$0
 	MOVW	size+8(FP), R1
 	MOVD	$SYS_thr_new, R8
 	SVC
+	BCC	ok
+	NEG	R0, R0
+ok:
 	MOVW	R0, ret+16(FP)
 	RET