From: Cherry Mui <cherryyz@google.com>
Date: Wed, 4 Aug 2021 23:41:19 +0000 (-0400)
Subject: runtime: accept restartable sequence pcdata values in isAsyncSafePoint
X-Git-Tag: go1.18beta1~1743
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=8ff16c19909e5aecf51c6b993cba36ea51791f34;p=gostls13.git

runtime: accept restartable sequence pcdata values in isAsyncSafePoint

If the pcdata value indicates a restartable sequence, it is okay
to asynchronously preempt (and resume at the restart PC). Accept
it in isAsyncSafePoint.

Fixes #47530.

Change-Id: I419225717c8eee5812f3235338262da5895aad0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/340011
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Austin Clements <austin@google.com>
---

diff --git a/src/runtime/preempt.go b/src/runtime/preempt.go
index a38ab79398..334bac779e 100644
--- a/src/runtime/preempt.go
+++ b/src/runtime/preempt.go
@@ -399,7 +399,7 @@ func isAsyncSafePoint(gp *g, pc, sp, lr uintptr) (bool, uintptr) {
 		return false, 0
 	}
 	up, startpc := pcdatavalue2(f, _PCDATA_UnsafePoint, pc)
-	if up != _PCDATA_UnsafePointSafe {
+	if up == _PCDATA_UnsafePointUnsafe {
 		// Unsafe-point marked by compiler. This includes
 		// atomic sequences (e.g., write barrier) and nosplit
 		// functions (except at calls).