From: Dmitriy Vyukov <dvyukov@google.com>
Date: Wed, 3 Apr 2013 22:11:34 +0000 (+1100)
Subject: runtime: fix data/bss shadow memory mapping for race detector
X-Git-Tag: go1.1rc2~192
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=12b7db3d578f9764416ae987a4fa2e90125f379c;p=gostls13.git

runtime: fix data/bss shadow memory mapping for race detector
Fixes #5175.
Race detector runtime expects values passed to MapShadow() to be page-aligned,
because they are used in mmap() call. If they are not aligned mmap() trims
either beginning or end of the mapping.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8325043
---

diff --git a/src/pkg/runtime/race.c b/src/pkg/runtime/race.c
index cfd97041a8..ce250b5b63 100644
--- a/src/pkg/runtime/race.c
+++ b/src/pkg/runtime/race.c
@@ -36,11 +36,14 @@ static bool onstack(uintptr argp);
 uintptr
 runtime·raceinit(void)
 {
-	uintptr racectx;
+	uintptr racectx, start, size;
 
 	m->racecall = true;
 	runtime∕race·Initialize(&racectx);
-	runtime∕race·MapShadow(noptrdata, enoptrbss - noptrdata);
+	// Round data segment to page boundaries, because it's used in mmap().
+	start = (uintptr)noptrdata & ~(PageSize-1);
+	size = ROUND((uintptr)enoptrbss - start, PageSize);
+	runtime∕race·MapShadow((void*)start, size);
 	m->racecall = false;
 	return racectx;
 }