X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Fx86-linux-os.c;h=373ffc53e51f4a937f19accd871e5ef9c29b10b6;hb=35ab27e7aab71c94aa6be12da15603c7fd87fca8;hp=c15665d1c41df58143ce8dd42509eea16d7c8024;hpb=9a19ce460a70a6c1de36095b3e2621116b91cc80;p=sbcl.git

diff --git a/src/runtime/x86-linux-os.c b/src/runtime/x86-linux-os.c
index c15665d..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;
@@ -208,7 +221,8 @@ os_context_sigmask_addr(os_context_t *context)
 void
 os_restore_fp_control(os_context_t *context)
 {
-    asm ("fldcw %0" : : "m" (context->uc_mcontext.fpregs->cw));
+    if (context->uc_mcontext.fpregs)
+        asm ("fldcw %0" : : "m" (context->uc_mcontext.fpregs->cw));
 }
 
 void