From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Mon, 26 Oct 2020 19:35:23 +0000 (+0000)
Subject: runtime: make sysMemStats' methods nosplit
X-Git-Tag: go1.16beta1~509
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=22d2b984a680900ebbec6268f93a839286b6f130;p=gostls13.git

runtime: make sysMemStats' methods nosplit

sysMemStats are updated early on in runtime initialization, so
triggering a stack growth would be bad. Mark them nosplit.

Thank you so much to cherryyz@google.com for finding this fix!

Fixes #42218.

Change-Id: Ic62db76e6a4f829355d7eaabed1727c51adfbd0f
Reviewed-on: https://go-review.googlesource.com/c/go/+/265157
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
---

diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go
index 512a06cffa..07f466ec49 100644
--- a/src/runtime/mstats.go
+++ b/src/runtime/mstats.go
@@ -720,11 +720,17 @@ func flushallmcaches() {
 type sysMemStat uint64
 
 // load atomically reads the value of the stat.
+//
+// Must be nosplit as it is called in runtime initialization, e.g. newosproc0.
+//go:nosplit
 func (s *sysMemStat) load() uint64 {
 	return atomic.Load64((*uint64)(s))
 }
 
 // add atomically adds the sysMemStat by n.
+//
+// Must be nosplit as it is called in runtime initialization, e.g. newosproc0.
+//go:nosplit
 func (s *sysMemStat) add(n int64) {
 	if s == nil {
 		return