runtime: Add vdso on freebsd/riscv64

Use rdtime to retrieve the timecounter, same as the FreeBSD libc. Updates #53466 Change-Id: I48816e9100036f1ef483e4d3afcf10db0d3b85f8 Reviewed-on: https://go-review.googlesource.com/c/go/+/443036 Reviewed-by: Meng Zhuo <[email protected]> Reviewed-by: Dmitri Goutnik <[email protected]> TryBot-Result: Gopher Robot <[email protected]> Reviewed-by: David Chase <[email protected]> Reviewed-by: Than McIntosh <[email protected]> Reviewed-by: Yuval Pavel Zholkover <[email protected]> Run-TryBot: Meng Zhuo <[email protected]>
golang · Oct 20, 2022 · 0e56c31 · 0e56c31
1 parent 4b5558e
commit 0e56c31
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Showing 2 changed files with 18 additions and 1 deletion.
diff --git a/src/runtime/sys_freebsd_riscv64.s b/src/runtime/sys_freebsd_riscv64.s
@@ -428,3 +428,9 @@ TEXT runtime·closeonexec(SB),NOSPLIT|NOFRAME,$0
 	MOV	$SYS_fcntl, T0
 	ECALL
 	RET
+
+// func getCntxct() uint32
+TEXT runtime·getCntxct(SB),NOSPLIT|NOFRAME,$0
+	RDTIME	A0
+	MOVW	A0, ret+0(FP)
+	RET
diff --git a/src/runtime/vdso_freebsd_riscv64.go b/src/runtime/vdso_freebsd_riscv64.go
@@ -4,7 +4,18 @@
 
 package runtime
 
+const (
+	_VDSO_TH_ALGO_RISCV_RDTIME = 1
+)
+
+func getCntxct() uint32
+
 //go:nosplit
 func (th *vdsoTimehands) getTimecounter() (uint32, bool) {
-	return 0, false
+	switch th.algo {
+	case _VDSO_TH_ALGO_RISCV_RDTIME:
+		return getCntxct(), true
+	default:
+		return 0, false
+	}
 }