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Commit 0f2c8769 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

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: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent dbe9e994

arch/x86/kernel/entry_32.S

+1 −2
Original line number Diff line number Diff line
@@ -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

arch/x86/xen/xen-asm.S

+9 −13
Original line number Diff line number Diff line
@@ -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)