linux-kernel - [PATCH v6 06/13] x86, usercopy: replace open coded stac/clac with __uaccess

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Message-ID: <151727416438.33451.17309465232057176966.stgit@dwillia2-desk3.amr.corp.intel.com>
Date:   Mon, 29 Jan 2018 17:02:44 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     tglx@...utronix.de, mingo@...nel.org
Cc:     linux-arch@...r.kernel.org, Tom Lendacky <thomas.lendacky@....com>,
        Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com, gregkh@...uxfoundation.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        "H. Peter Anvin" <hpa@...or.com>, torvalds@...ux-foundation.org,
        alan@...ux.intel.com
Subject: [PATCH v6 06/13] x86,
 usercopy: replace open coded stac/clac with __uaccess_{begin, end}

In preparation for converting some __uaccess_begin() instances to
__uacess_begin_nospec(), make sure all 'from user' uaccess paths are
using the _begin(), _end() helpers rather than open-coded stac() and
clac().

There are no functional changes in this patch.

Suggested-by: Ingo Molnar <mingo@...hat.com>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Kees Cook <keescook@...omium.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 arch/x86/lib/usercopy_32.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 1b377f734e64..de3436719e26 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -331,12 +331,12 @@ do {									\
 
 unsigned long __copy_user_ll(void *to, const void *from, unsigned long n)
 {
-	stac();
+	__uaccess_begin();
 	if (movsl_is_ok(to, from, n))
 		__copy_user(to, from, n);
 	else
 		n = __copy_user_intel(to, from, n);
-	clac();
+	__uaccess_end();
 	return n;
 }
 EXPORT_SYMBOL(__copy_user_ll);
@@ -344,7 +344,7 @@ EXPORT_SYMBOL(__copy_user_ll);
 unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *from,
 					unsigned long n)
 {
-	stac();
+	__uaccess_begin();
 #ifdef CONFIG_X86_INTEL_USERCOPY
 	if (n > 64 && static_cpu_has(X86_FEATURE_XMM2))
 		n = __copy_user_intel_nocache(to, from, n);
@@ -353,7 +353,7 @@ unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *fr
 #else
 	__copy_user(to, from, n);
 #endif
-	clac();
+	__uaccess_end();
 	return n;
 }
 EXPORT_SYMBOL(__copy_from_user_ll_nocache_nozero);