X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Fx86-linux-os.c;h=373ffc53e51f4a937f19accd871e5ef9c29b10b6;hb=eac461c1f1ca91cfe282c779291d582ed6b336cb;hp=5b55fdc3792c1e779d1aace0adf5878716635bac;hpb=13adeede88d026548e4d2da497f93d8024706a2b;p=sbcl.git

diff --git a/src/runtime/x86-linux-os.c b/src/runtime/x86-linux-os.c
index 5b55fdc..373ffc5 100644
--- a/src/runtime/x86-linux-os.c
+++ b/src/runtime/x86-linux-os.c
@@ -69,20 +69,19 @@ void debug_get_ldt()
     printf("%d bytes in ldt: print/x local_ldt_copy\n", n);
 }
 
-volatile lispobj modify_ldt_lock;       /* protect all calls to modify_ldt */
+#ifdef LISP_FEATURE_SB_THREAD
+pthread_mutex_t modify_ldt_lock = PTHREAD_MUTEX_INITIALIZER;
+#endif
 
 int arch_os_thread_init(struct thread *thread) {
     stack_t sigstack;
 #ifdef LISP_FEATURE_SB_THREAD
-    /* FIXME Lock ordering rules: all_threads_lock must usually be
-     * held when getting modify_ldt_lock
-     */
     struct user_desc ldt_entry = {
         1, 0, 0, /* index, address, length filled in later */
         1, MODIFY_LDT_CONTENTS_DATA, 0, 0, 0, 1
     };
     int n;
-    get_spinlock(&modify_ldt_lock,(long)thread);
+    thread_mutex_lock(&modify_ldt_lock);
     n=modify_ldt(0,local_ldt_copy,sizeof local_ldt_copy);
     /* get next free ldt entry */
 
@@ -96,7 +95,7 @@ int arch_os_thread_init(struct thread *thread) {
     ldt_entry.limit=dynamic_values_bytes;
     ldt_entry.limit_in_pages=0;
     if (modify_ldt (1, &ldt_entry, sizeof (ldt_entry)) != 0) {
-        modify_ldt_lock=0;
+        thread_mutex_unlock(&modify_ldt_lock);
         /* modify_ldt call failed: something magical is not happening */
         return 0;
     }
@@ -105,11 +104,28 @@ int arch_os_thread_init(struct thread *thread) {
                            + (1 << 2) /* TI set = LDT */
                            + 3)); /* privilege level */
     thread->tls_cookie=n;
-    modify_ldt_lock=0;
+    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;
+#else
     pthread_setspecific(specials,thread);
 #endif
+#endif
 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
     /* Signal handlers are run on the control stack, so if it is exhausted
      * we had better use an alternate stack for whatever signal tells us
@@ -138,16 +154,13 @@ int arch_os_thread_cleanup(struct thread *thread) {
         0, 0, 0,
         0, MODIFY_LDT_CONTENTS_DATA, 0, 0, 0, 0
     };
+    int result;
 
     ldt_entry.entry_number=thread->tls_cookie;
-    get_spinlock(&modify_ldt_lock,(long)thread);
-    if (modify_ldt (1, &ldt_entry, sizeof (ldt_entry)) != 0) {
-        modify_ldt_lock=0;
-        /* modify_ldt call failed: something magical is not happening */
-        return 0;
-    }
-    modify_ldt_lock=0;
-    return 1;
+    thread_mutex_lock(&modify_ldt_lock);
+    result = modify_ldt(1, &ldt_entry, sizeof (ldt_entry));
+    thread_mutex_unlock(&modify_ldt_lock);
+    return result;
 }
 
 
@@ -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