From: Haoran Luo <haoran.luo@chaitin.com>
Date: Tue, 8 Dec 2020 14:29:04 +0000 (+0000)
Subject: runtime: prevent stack growth after fork in runtime.sigfillset
X-Git-Tag: go1.16beta1~63
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=6fa06d960b5ec38867a35dc278ae318ecff1b6c6;p=gostls13.git

runtime: prevent stack growth after fork in runtime.sigfillset

This fixes the unexpected growth of stack in child process, which
is caused by stack checking code in runtime.sigfillset called from
runtime.sigset while clearing the signal handlers in child process.

The redundant stack checking code is generated due to missing
'//go:nosplit' directive that should be annotated for
runtime.sigfillset.

Fixes #43066
Updates #21314

Change-Id: I9483a962a4b0747074313991841e2440ee32198c
Reviewed-on: https://go-review.googlesource.com/c/go/+/276173
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Austin Clements <austin@google.com>
---

diff --git a/src/runtime/os_linux_be64.go b/src/runtime/os_linux_be64.go
index 14fbad5d5f..9860002ee4 100644
--- a/src/runtime/os_linux_be64.go
+++ b/src/runtime/os_linux_be64.go
@@ -38,6 +38,7 @@ func sigdelset(mask *sigset, i int) {
 	*mask &^= 1 << (uint(i) - 1)
 }
 
+//go:nosplit
 func sigfillset(mask *uint64) {
 	*mask = ^uint64(0)
 }
diff --git a/src/runtime/os_linux_generic.go b/src/runtime/os_linux_generic.go
index 14810e3cc3..e1d0952ddf 100644
--- a/src/runtime/os_linux_generic.go
+++ b/src/runtime/os_linux_generic.go
@@ -38,6 +38,7 @@ func sigdelset(mask *sigset, i int) {
 	(*mask)[(i-1)/32] &^= 1 << ((uint32(i) - 1) & 31)
 }
 
+//go:nosplit
 func sigfillset(mask *uint64) {
 	*mask = ^uint64(0)
 }
diff --git a/src/runtime/os_linux_mips64x.go b/src/runtime/os_linux_mips64x.go
index 4ff66f9538..815a83a04b 100644
--- a/src/runtime/os_linux_mips64x.go
+++ b/src/runtime/os_linux_mips64x.go
@@ -48,6 +48,7 @@ func sigdelset(mask *sigset, i int) {
 	(*mask)[(i-1)/64] &^= 1 << ((uint32(i) - 1) & 63)
 }
 
+//go:nosplit
 func sigfillset(mask *[2]uint64) {
 	(*mask)[0], (*mask)[1] = ^uint64(0), ^uint64(0)
 }
diff --git a/src/runtime/os_linux_mipsx.go b/src/runtime/os_linux_mipsx.go
index 87962ed982..00fb02e4bf 100644
--- a/src/runtime/os_linux_mipsx.go
+++ b/src/runtime/os_linux_mipsx.go
@@ -42,6 +42,7 @@ func sigdelset(mask *sigset, i int) {
 	(*mask)[(i-1)/32] &^= 1 << ((uint32(i) - 1) & 31)
 }
 
+//go:nosplit
 func sigfillset(mask *[4]uint32) {
 	(*mask)[0], (*mask)[1], (*mask)[2], (*mask)[3] = ^uint32(0), ^uint32(0), ^uint32(0), ^uint32(0)
 }