xen: jump to iret fixup

Use jmp rather than call for the iret fixup, so its consistent with
the sysexit fixup, and it simplifies the stack (which is already
complex).

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 5d80d53..209c334 100644 (file)
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1042,8 +1042,7 @@ ENTRY(xen_hypervisor_callback)
        cmpl $xen_iret_end_crit,%eax
        jae  1f
 
-       call xen_iret_crit_fixup
-       jmp  2f
+       jmp  xen_iret_crit_fixup
 
 1:     cmpl $xen_sysexit_start_crit,%eax
        jb   2f

diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 1ac0808..53cae92 100644 (file)
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -223,9 +223,7 @@ hyper_iret:
         ds             }  SAVE_ALL state
         eax            }
          :             :
-        ebx            }
-       ----------------
-        return addr     <- esp
+        ebx            }<- esp
        ----------------
 
    In order to deliver the nested exception properly, we need to shift
@@ -240,10 +238,8 @@ hyper_iret:
    it's usermode state which we eventually need to restore.
  */
 ENTRY(xen_iret_crit_fixup)
-       /* offsets +4 for return address */
-
        /*
-          Paranoia: Make sure we're really coming from userspace.
+          Paranoia: Make sure we're really coming from kernel space.
           One could imagine a case where userspace jumps into the
           critical range address, but just before the CPU delivers a GP,
           it decides to deliver an interrupt instead.  Unlikely?
@@ -252,32 +248,32 @@ ENTRY(xen_iret_crit_fixup)
           jump instruction itself, not the destination, but some virtual
           environments get this wrong.
         */
-       movl PT_CS+4(%esp), %ecx
+       movl PT_CS(%esp), %ecx
        andl $SEGMENT_RPL_MASK, %ecx
        cmpl $USER_RPL, %ecx
        je 2f
 
-       lea PT_ORIG_EAX+4(%esp), %esi
-       lea PT_EFLAGS+4(%esp), %edi
+       lea PT_ORIG_EAX(%esp), %esi
+       lea PT_EFLAGS(%esp), %edi
 
        /* If eip is before iret_restore_end then stack
           hasn't been restored yet. */
        cmp $iret_restore_end, %eax
        jae 1f
 
-       movl 0+4(%edi),%eax             /* copy EAX */
-       movl %eax, PT_EAX+4(%esp)
+       movl 0+4(%edi),%eax             /* copy EAX (just above top of frame) */
+       movl %eax, PT_EAX(%esp)
 
        lea ESP_OFFSET(%edi),%edi       /* move dest up over saved regs */
 
        /* set up the copy */
 1:     std
-       mov $(PT_EIP+4) / 4, %ecx       /* copy ret+saved regs up to orig_eax */
+       mov $PT_EIP / 4, %ecx           /* saved regs up to orig_eax */
        rep movsl
        cld
 
        lea 4(%edi),%esp                /* point esp to new frame */
-2:     ret
+2:     jmp xen_do_upcall
 
 
 ENTRY(xen_sysexit)