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 b17dc87..0ea0aac 100644 (file)
--- 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 c424493..836187f 100644 (file)
--- 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;
 }