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xen: jump to iret fixup

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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>
This commit is contained in:
Jeremy Fitzhardinge 2008-03-17 16:37:22 -07:00 committed by Ingo Molnar
parent dbe9e994c9
commit 0f2c876952
2 changed files with 10 additions and 15 deletions
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3
arch/x86/kernel/entry_32.S
View File

@ -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

22
arch/x86/xen/xen-asm.S
View File

@ -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)