xnu-1228.7.58.tar.gz

[apple/xnu.git] / osfmk / i386 / cswitch.s

diff --git a/osfmk/i386/cswitch.s b/osfmk/i386/cswitch.s
index c61d9ad366b84e4a38e1534f0ea9a2e1a015a2a8..0668c465ef5c1c0c2e34628cffd819f202cb15df 100644 (file)
--- a/osfmk/i386/cswitch.s
+++ b/osfmk/i386/cswitch.s
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -72,6 +72,7 @@
 
 #define        CX(addr, reg)   addr(,reg,4)
 
+       .text
 /*
  * Context switch routines for i386.
  */
@@ -92,23 +93,27 @@ Entry(Load_context)
        call    EXT(thread_continue)
 
 /*
- *     This really only has to save registers
+ *     This has to save registers only
  *     when there is no explicit continuation.
  */
 
 Entry(Switch_context)
-       movl    %gs:CPU_ACTIVE_STACK,%ecx /* get old kernel stack */
+       popl    %eax                            /* pop return PC */
 
+       /* Test for a continuation and skip all state saving if so... */
+       cmpl    $0,4(%esp)
+       jne     5f
+       movl    %gs:CPU_ACTIVE_STACK,%ecx       /* get old kernel stack */
        movl    %ebx,KSS_EBX(%ecx)              /* save registers */
        movl    %ebp,KSS_EBP(%ecx)
        movl    %edi,KSS_EDI(%ecx)
        movl    %esi,KSS_ESI(%ecx)
-       popl    KSS_EIP(%ecx)                   /* save return PC */
+       movl    %eax,KSS_EIP(%ecx)              /* save return PC */
        movl    %esp,KSS_ESP(%ecx)              /* save SP */
-
+5:
        movl    0(%esp),%eax                    /* return old thread */
        movl    8(%esp),%ebx                    /* get new thread */
-       movl    %ebx,%gs:CPU_ACTIVE_THREAD                /* new thread is active */
+       movl    %ebx,%gs:CPU_ACTIVE_THREAD      /* new thread is active */
        movl    TH_KERNEL_STACK(%ebx),%ecx      /* get its kernel stack */
        lea     KERNEL_STACK_SIZE-IKS_SIZE-IEL_SIZE(%ecx),%ebx
                                                /* point to stack top */
@@ -116,9 +121,7 @@ Entry(Switch_context)
        movl    %ecx,%gs:CPU_ACTIVE_STACK       /* set current stack */
        movl    %ebx,%gs:CPU_KERNEL_STACK       /* set stack top */
 
-
-       movl    $0,%gs:CPU_ACTIVE_KLOADED
-
+       
        movl    KSS_ESP(%ecx),%esp              /* switch stacks */
        movl    KSS_ESI(%ecx),%esi              /* restore registers */
        movl    KSS_EDI(%ecx),%edi
@@ -132,19 +135,17 @@ Entry(Thread_continue)
        call    *%ebx                           /* call real continuation */
 
 /*
- * void machine_processor_shutdown(thread_t thread,
- *                                void (*routine)(processor_t),
- *                                processor_t processor)
+ * thread_t Shutdown_context(thread_t thread,
+ *                      void (*routine)(processor_t),
+ *                      processor_t processor)
  *
  * saves the kernel context of the thread,
  * switches to the interrupt stack,
  * continues the thread (with thread_continue),
  * then runs routine on the interrupt stack.
  *
- * Assumes that the thread is a kernel thread (thus
- * has no FPU state)
  */
-Entry(machine_processor_shutdown)
+Entry(Shutdown_context)
        movl    %gs:CPU_ACTIVE_STACK,%ecx /* get old kernel stack */
        movl    %ebx,KSS_EBX(%ecx)              /* save registers */
        movl    %ebp,KSS_EBP(%ecx)
@@ -163,10 +164,3 @@ Entry(machine_processor_shutdown)
        pushl   %esi                            /* push argument */
        call    *%ebx                           /* call routine to run */
        hlt                                     /* (should never return) */
-
-
-        .text
-
-       .globl  EXT(locore_end)
-LEXT(locore_end)
-