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Subject[PATCH 31 of 31] 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>

---
arch/x86/kernel/entry_32.S | 3 +--
arch/x86/xen/xen-asm.S | 22 +++++++++-------------
2 files changed, 10 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1049,8 +1049,7 @@
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
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -223,9 +223,7 @@
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 @@
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 @@
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)



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