commit cae10b5b5bdc53480bd2e985f1e43eb8910e40f8
author Claudio Imbrenda <imbrenda@linux.ibm.com> Mon Jun 22 18:21:34 2020 +0200
committer Paolo Bonzini <pbonzini@redhat.com> Mon Jun 22 13:45:58 2020 -0400
tree 9a2ee91254e2daebc1e358f7d0011d272ff325ee
parent a434c431d8eb20f9363a8d74e91f21a8faf13e0f

x86/cstart.S: initialize stack before using it

It seems the 32-bit initialization code uses the stack before actually
initializing it.

Probably the boot loader leaves a reasonable value in the stack pointer so
this issue has not been noticed before.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-Id: <20200622162141.279716-2-imbrenda@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

x86/cstart.S

diff --git a/x86/cstart.S b/x86/cstart.S
index 38ac19b..fa62e09 100644
--- a/x86/cstart.S
+++ b/x86/cstart.S
@@ -96,13 +96,13 @@
 
 .globl start
 start:
+        mov $stacktop, %esp
         push %ebx
         call setup_multiboot
         call setup_libcflat
         mov mb_cmdline(%ebx), %eax
         mov %eax, __args
         call __setup_args
-        mov $stacktop, %esp
         setup_percpu_area
         call prepare_32
         jmpl $8, $start32