From: Rich Felker <dalias@aerifal.cx>
Date: Sun, 7 Aug 2011 00:45:30 +0000 (-0400)
Subject: ensure the compiler does not move around thread-register-based reads
X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=commitdiff_plain;h=8426a99048261b998a27557cf34f81626ffe9f12

ensure the compiler does not move around thread-register-based reads

if gcc decided to move this across a conditional that checks validity
of the thread register, an invalid thread-register-based read could be
performed and raise sigsegv.
---

diff --git a/arch/i386/pthread_arch.h b/arch/i386/pthread_arch.h
index b17dc87a..0ea0aaca 100644
--- a/arch/i386/pthread_arch.h
+++ b/arch/i386/pthread_arch.h
@@ -1,7 +1,7 @@
 static inline struct pthread *__pthread_self()
 {
 	struct pthread *self;
-	__asm__ ("movl %%gs:0,%0" : "=r" (self) );
+	__asm__ __volatile__ ("movl %%gs:0,%0" : "=r" (self) );
 	return self;
 }
 
diff --git a/arch/x86_64/pthread_arch.h b/arch/x86_64/pthread_arch.h
index c424493a..836187f5 100644
--- a/arch/x86_64/pthread_arch.h
+++ b/arch/x86_64/pthread_arch.h
@@ -1,7 +1,7 @@
 static inline struct pthread *__pthread_self()
 {
 	struct pthread *self;
-	__asm__ ("movq %%fs:0,%0" : "=r" (self) );
+	__asm__ __volatile__ ("movq %%fs:0,%0" : "=r" (self) );
 	return self;
 }