From 99158f10e91768d34c5004c40c42f802b719bcae Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 24 May 2016 15:48:38 -0700 Subject: [PATCH] x86/xen: Simplify set_aliased_prot() A year ago, via the following commit: aa1acff356bb ("x86/xen: Probe target addresses in set_aliased_prot() before the hypercall") I added an explicit probe to work around a hypercall issue. The code can be simplified by using probe_kernel_read(). No change in functionality. Signed-off-by: Andy Lutomirski Reviewed-by: Andrew Cooper Acked-by: David Vrabel Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: David Vrabel Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jan Beulich Cc: Kees Cook Cc: Konrad Rzeszutek Wilk Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: xen-devel Link: http://lkml.kernel.org/r/0706f1a2538e481194514197298cca6b5e3f2638.1464129798.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/xen/enlighten.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 760789ae8562..0f87db2cc6a8 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -521,9 +521,7 @@ static void set_aliased_prot(void *v, pgprot_t prot) preempt_disable(); - pagefault_disable(); /* Avoid warnings due to being atomic. */ - __get_user(dummy, (unsigned char __user __force *)v); - pagefault_enable(); + probe_kernel_read(&dummy, v, 1); if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0)) BUG(); -- 2.20.1