X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Fx86-linux-os.c;h=373ffc53e51f4a937f19accd871e5ef9c29b10b6;hb=d8422b9967f465801891907396bcc5bfde0f3297;hp=ddbe154236cccc0d4302c61caed03302873071ba;hpb=842d3c24e4a1a6b5ebadb9ee754814174a951029;p=sbcl.git

diff --git a/src/runtime/x86-linux-os.c b/src/runtime/x86-linux-os.c
index ddbe154..373ffc5 100644
--- a/src/runtime/x86-linux-os.c
+++ b/src/runtime/x86-linux-os.c
@@ -106,6 +106,19 @@ int arch_os_thread_init(struct thread *thread) {
     thread->tls_cookie=n;
     pthread_mutex_unlock(&modify_ldt_lock);
 
+    /* now %fs:0 refers to the current thread.  Useful!  Less usefully,
+     * Linux/x86 isn't capable of reporting a faulting si_addr on a
+     * segment as defined above (whereas faults on the segment that %gs
+     * usually points are reported just fine...).  As a special
+     * workaround, we store each thread structure's absolute address as
+     * as slot in itself, so that within the thread,
+     *   movl %fs:SELFPTR_OFFSET,x
+     * stores the absolute address of %fs:0 into x.
+     */
+#ifdef LISP_FEATURE_SB_SAFEPOINT
+    thread->selfptr = thread;
+#endif
+
     if(n<0) return 0;
 #ifdef LISP_FEATURE_GCC_TLS
     current_thread = thread;