Baremetal kernels clear .bss early in the boot but Xen PV guests don't execute that code. They have been able to run without problems because Xen domain builder happens to give out zeroed pages. However, since this is not really guaranteed, .bss should be explicitly cleared. Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx --- arch/x86/xen/xen-head.S | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index b65f59a..11dbe49 100644 --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -38,6 +38,20 @@ __INIT ENTRY(startup_xen) cld + +#ifdef CONFIG_X86_32 +#define WSIZE_SHIFT 2 +#else +#define WSIZE_SHIFT 3 +#endif + /* Clear .bss */ + xor %eax,%eax + mov $__bss_start, %__ASM_REG(di) + mov $__bss_stop, %__ASM_REG(cx) + sub %__ASM_REG(di), %__ASM_REG(cx) + shr $WSIZE_SHIFT, %__ASM_REG(cx) + rep __ASM_SIZE(stos) + #ifdef CONFIG_X86_32 mov %esi,xen_start_info mov $init_thread_union+THREAD_SIZE,%esp -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html