xnu-1456.1.26.tar.gz

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

diff --git a/osfmk/i386/cswitch.s b/osfmk/i386/cswitch.s
index 0668c465ef5c1c0c2e34628cffd819f202cb15df..3110cc2c64a367bea5cbdd98caba8ad1c68d0361 100644 (file)
--- a/osfmk/i386/cswitch.s
+++ b/osfmk/i386/cswitch.s
@@ -80,14 +80,15 @@
 Entry(Load_context)
        movl    S_ARG0,%ecx                     /* get thread */
        movl    TH_KERNEL_STACK(%ecx),%ecx      /* get kernel stack */
-       lea     KERNEL_STACK_SIZE-IKS_SIZE-IEL_SIZE(%ecx),%edx
-                                               /* point to stack top */
+       lea     -IKS_SIZE-IEL_SIZE(%ecx),%edx
+       add     EXT(kernel_stack_size),%edx             /* point to stack top */
        movl    %ecx,%gs:CPU_ACTIVE_STACK       /* store stack address */
        movl    %edx,%gs:CPU_KERNEL_STACK       /* store stack top */
 
        movl    %edx,%esp
        movl    %edx,%ebp
 
+       subl    $12, %esp                       /* align stack */
        xorl    %eax,%eax                       /* return zero (no old thread) */
        pushl   %eax
        call    EXT(thread_continue)
@@ -103,7 +104,7 @@ Entry(Switch_context)
        /* 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    %gs:CPU_KERNEL_STACK,%ecx       /* get old kernel stack top */
        movl    %ebx,KSS_EBX(%ecx)              /* save registers */
        movl    %ebp,KSS_EBP(%ecx)
        movl    %edi,KSS_EDI(%ecx)
@@ -112,14 +113,15 @@ Entry(Switch_context)
        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    TH_KERNEL_STACK(%ebx),%ecx      /* get its kernel stack */
-       lea     KERNEL_STACK_SIZE-IKS_SIZE-IEL_SIZE(%ecx),%ebx
+       movl    8(%esp),%ecx                    /* get new thread */
+       movl    %ecx,%gs:CPU_ACTIVE_THREAD      /* new thread is active */
+       movl    TH_KERNEL_STACK(%ecx),%ebx      /* get its kernel stack */
+       lea     -IKS_SIZE-IEL_SIZE(%ebx),%ecx
+       add     EXT(kernel_stack_size),%ecx
                                                /* point to stack top */
 
-       movl    %ecx,%gs:CPU_ACTIVE_STACK       /* set current stack */
-       movl    %ebx,%gs:CPU_KERNEL_STACK       /* set stack top */
+       movl    %ebx,%gs:CPU_ACTIVE_STACK       /* set current stack */
+       movl    %ecx,%gs:CPU_KERNEL_STACK       /* set stack top */
 
        
        movl    KSS_ESP(%ecx),%esp              /* switch stacks */
@@ -130,6 +132,7 @@ Entry(Switch_context)
        jmp     *KSS_EIP(%ecx)                  /* return old thread */
 
 Entry(Thread_continue)
+       subl    $12, %esp                       /* align stack */
        pushl   %eax                            /* push the thread argument */
        xorl    %ebp,%ebp                       /* zero frame pointer */
        call    *%ebx                           /* call real continuation */
@@ -146,7 +149,7 @@ Entry(Thread_continue)
  *
  */
 Entry(Shutdown_context)
-       movl    %gs:CPU_ACTIVE_STACK,%ecx /* get old kernel stack */
+       movl    %gs:CPU_KERNEL_STACK,%ecx /* get old kernel stack */
        movl    %ebx,KSS_EBX(%ecx)              /* save registers */
        movl    %ebp,KSS_EBP(%ecx)
        movl    %edi,KSS_EDI(%ecx)
@@ -154,6 +157,7 @@ Entry(Shutdown_context)
        popl    KSS_EIP(%ecx)                   /* save return PC */
        movl    %esp,KSS_ESP(%ecx)              /* save SP */
 
+       movl    %gs:CPU_ACTIVE_STACK,%ecx       /* get old stack */
        movl    0(%esp),%eax                    /* get old thread */
        movl    %ecx,TH_KERNEL_STACK(%eax)      /* save old stack */
        movl    4(%esp),%ebx                    /* get routine to run next */
@@ -161,6 +165,7 @@ Entry(Shutdown_context)
 
        movl    %gs:CPU_INT_STACK_TOP,%esp      /* switch to interrupt stack */
 
+       subl    $12, %esp                       /* align stack */
        pushl   %esi                            /* push argument */
        call    *%ebx                           /* call routine to run */
        hlt                                     /* (should never return) */