runtime: keep //go:cgo_unsafe_args arguments alive to prevent GC

When syscall's DLL.FindProc calls into syscall_getprocaddress with a
byte slice pointer, we need to keep those bytes alive. Otherwise the GC
will collect the allocation, and we wind up calling `GetProcAddress` on
garbage, which showed up as various flakes in the builders. It turns out
that this problem extends to many uses of //go:cgo_unsafe_args
throughout, on all platforms. So this patch fixes the issue by keeping
non-integer pointer arguments alive through their invocation in
//go:cgo_unsafe_args functions.

Fixes #49731.

Change-Id: I93e4fbc2e8e210cb3fc53149708758bb33f2f9c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/367654
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Patrik Nyblom <pnyb@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/runtime/sys_openbsd1.go b/src/runtime/sys_openbsd1.go
index 4b80f60226..d852e3c58a 100644
--- a/src/runtime/sys_openbsd1.go
+++ b/src/runtime/sys_openbsd1.go
@@ -14,7 +14,10 @@ import (
 //go:nosplit
 //go:cgo_unsafe_args
 func thrsleep(ident uintptr, clock_id int32, tsp *timespec, lock uintptr, abort *uint32) int32 {
-	return libcCall(unsafe.Pointer(abi.FuncPCABI0(thrsleep_trampoline)), unsafe.Pointer(&ident))
+	ret := libcCall(unsafe.Pointer(abi.FuncPCABI0(thrsleep_trampoline)), unsafe.Pointer(&ident))
+	KeepAlive(tsp)
+	KeepAlive(abort)
+	return ret
 }
 func thrsleep_trampoline()