From: Sami Tolvanen <samitolvanen@google.com>
Date: Wed, 14 Dec 2016 20:32:07 +0000 (-0800)
Subject: Revert "FROMLIST: arm64: xen: Enable user access before a privcmd hvc call"
X-Git-Tag: firefly_0821_release~176^2~28
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=91b3735c3d1823b1993efab03b97e8bbe7fa8d1f;p=firefly-linux-kernel-4.4.55.git

Revert "FROMLIST: arm64: xen: Enable user access before a privcmd hvc call"

This reverts commit 4dbc88bd2b6a74fd33483ee2593dcf2bd858eabe.

Bug: 31432001
Change-Id: I2c3d591a2c631e7ff02c0bcb91624735e8c12f0a
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---

diff --git a/arch/arm64/xen/hypercall.S b/arch/arm64/xen/hypercall.S
index 6d6e4af1a4bf..8bbe9401f4f0 100644
--- a/arch/arm64/xen/hypercall.S
+++ b/arch/arm64/xen/hypercall.S
@@ -49,7 +49,6 @@
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
-#include <asm/uaccess.h>
 #include <xen/interface/xen.h>
 
 
@@ -90,24 +89,6 @@ ENTRY(privcmd_call)
 	mov x2, x3
 	mov x3, x4
 	mov x4, x5
-#ifdef CONFIG_ARM64_SW_TTBR0_PAN
-	/*
-	 * Privcmd calls are issued by the userspace. The kernel needs to
-	 * enable access to TTBR0_EL1 as the hypervisor would issue stage 1
-	 * translations to user memory via AT instructions. Since AT
-	 * instructions are not affected by the PAN bit (ARMv8.1), we only
-	 * need the explicit uaccess_enable/disable if the TTBR0 PAN emulation
-	 * is enabled (it implies that hardware UAO and PAN disabled).
-	 */
-	uaccess_enable_not_uao x6, x7
-#endif
 	hvc XEN_IMM
-
-#ifdef CONFIG_ARM64_SW_TTBR0_PAN
-	/*
-	 * Disable userspace access from kernel once the hyp call completed.
-	 */
-	uaccess_disable_not_uao x6
-#endif
 	ret
 ENDPROC(privcmd_call);