runtime: print errno on clock_gettime failure on OpenBSD

For #49532.

Change-Id: I5afc64c987f0519903128550a7dac3a0f5e592cf
Reviewed-on: https://go-review.googlesource.com/c/go/+/368334
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>

5 files changed, 34 insertions, 12 deletions

diff --git a/src/runtime/sys_openbsd2.go b/src/runtime/sys_openbsd2.go
index a7786fe65a..4d50b4f6b1 100644
--- a/src/runtime/sys_openbsd2.go
+++ b/src/runtime/sys_openbsd2.go
@@ -174,7 +174,13 @@ func nanotime1() int64 {
 		clock_id int32
 		tp       unsafe.Pointer
 	}{_CLOCK_MONOTONIC, unsafe.Pointer(&ts)}
-	libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args))
+	if errno := libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args)); errno < 0 {
+		// Avoid growing the nosplit stack.
+		systemstack(func() {
+			println("runtime: errno", -errno)
+			throw("clock_gettime failed")
+		})
+	}
 	return ts.tv_sec*1e9 + int64(ts.tv_nsec)
 }
 func clock_gettime_trampoline()
@@ -186,7 +192,13 @@ func walltime() (int64, int32) {
 		clock_id int32
 		tp       unsafe.Pointer
 	}{_CLOCK_REALTIME, unsafe.Pointer(&ts)}
-	libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args))
+	if errno := libcCall(unsafe.Pointer(abi.FuncPCABI0(clock_gettime_trampoline)), unsafe.Pointer(&args)); errno < 0 {
+		// Avoid growing the nosplit stack.
+		systemstack(func() {
+			println("runtime: errno", -errno)
+			throw("clock_gettime failed")
+		})
+	}
 	return ts.tv_sec, int32(ts.tv_nsec)
 }
 
diff --git a/src/runtime/sys_openbsd_386.s b/src/runtime/sys_openbsd_386.s
index 7830b61b7d..890b96b673 100644
--- a/src/runtime/sys_openbsd_386.s
+++ b/src/runtime/sys_openbsd_386.s
@@ -520,8 +520,11 @@ TEXT runtime·clock_gettime_trampoline(SB),NOSPLIT,$0
 	MOVL	BX, 4(SP)		// arg 2 - clock_id
 	CALL	libc_clock_gettime(SB)
 	CMPL	AX, $-1
-	JNE	2(PC)
-	MOVL	$0xf1, 0xf1		// crash on failure
+	JNE	noerr
+	CALL	libc_errno(SB)
+	MOVL	(AX), AX
+	NEGL	AX			// caller expects negative errno
+noerr:
 	MOVL	BP, SP
 	POPL	BP
 	RET
diff --git a/src/runtime/sys_openbsd_amd64.s b/src/runtime/sys_openbsd_amd64.s
index fc89ee6cbb..fc6d5dc387 100644
--- a/src/runtime/sys_openbsd_amd64.s
+++ b/src/runtime/sys_openbsd_amd64.s
@@ -369,8 +369,11 @@ TEXT runtime·clock_gettime_trampoline(SB),NOSPLIT,$0
 	MOVL	0(DI), DI		// arg 1 clock_id
 	CALL	libc_clock_gettime(SB)
 	TESTL	AX, AX
-	JEQ	2(PC)
-	MOVL	$0xf1, 0xf1  // crash
+	JEQ	noerr
+	CALL	libc_errno(SB)
+	MOVL	(AX), AX		// errno
+	NEGL	AX			// caller expects negative errno value
+noerr:
 	POPQ	BP
 	RET
 
diff --git a/src/runtime/sys_openbsd_arm.s b/src/runtime/sys_openbsd_arm.s
index 143fcf0518..a9cb1fbafe 100644
--- a/src/runtime/sys_openbsd_arm.s
+++ b/src/runtime/sys_openbsd_arm.s
@@ -407,9 +407,11 @@ TEXT runtime·clock_gettime_trampoline(SB),NOSPLIT,$0
 	MOVW	0(R0), R0		// arg 1 clock_id
 	BL	libc_clock_gettime(SB)
 	CMP	$-1, R0
-	BNE	3(PC)
-	MOVW	$0, R8			// crash on failure
-	MOVW	R8, (R8)
+	BNE	noerr
+	BL	libc_errno(SB)
+	MOVW	(R0), R0		// errno
+	RSB.CS	$0, R0			// caller expects negative errno
+noerr:
 	MOVW	R9, R13
 	RET
 
diff --git a/src/runtime/sys_openbsd_arm64.s b/src/runtime/sys_openbsd_arm64.s
index 9b4acc90a5..3fa7e1ede2 100644
--- a/src/runtime/sys_openbsd_arm64.s
+++ b/src/runtime/sys_openbsd_arm64.s
@@ -359,9 +359,11 @@ TEXT runtime·clock_gettime_trampoline(SB),NOSPLIT,$0
 	MOVD	0(R0), R0		// arg 1 - clock_id
 	CALL	libc_clock_gettime(SB)
 	CMP	$-1, R0
-	BNE	3(PC)
-	MOVD	$0, R0			// crash on failure
-	MOVD	R0, (R0)
+	BNE	noerr
+	CALL	libc_errno(SB)
+	MOVW	(R0), R0		// errno
+	NEG	R0, R0			// caller expects negative errno value
+noerr:
 	RET
 
 TEXT runtime·fcntl_trampoline(SB),NOSPLIT,$0