[PATCH] Restore memory used for IP computation

[Frediano Ziglio <frediano.ziglio@xxxxxxxxx>]

We need to write in some location but no reasons to not
trying to restore what we potentially overwrote.

Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
---
 xen/arch/x86/boot/head.S | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index d8ac0f0494..3e1e9e05b6 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -418,13 +418,17 @@ __pvh_start:
          * absolute stack address as the native path, for lack of a better
          * alternative.
          */
-        mov     $0x1000, %esp
+        mov     $0xffc, %esp
+        pop     %edx
 
         /* Calculate the load base address. */
         call    1f
 1:      pop     %esi
         sub     $sym_offs(1b), %esi
 
+        /* Restore clobbered stack */
+        push    %edx
+
         /* Set up stack. */
         lea     STACK_SIZE - CPUINFO_sizeof + sym_esi(cpu0_stack), %esp
 
@@ -468,13 +472,17 @@ __start:
          * this page for a temporary stack, being one of the safest locations
          * to clobber.
          */
-        mov     $0x1000, %esp
+        mov     $0xffc, %esp
+        pop     %edx
 
         /* Calculate the load base address. */
         call    1f
 1:      pop     %esi
         sub     $sym_offs(1b), %esi
 
+        /* Restore clobbered stack */
+        push    %edx
+
         /* Set up stack. */
         lea     STACK_SIZE - CPUINFO_sizeof + sym_esi(cpu0_stack), %esp
 
-- 
2.46.0