x86/usercopy: Replace open coded stac/clac with __uaccess_{begin, end}

BugLink: http://bugs.launchpad.net/bugs/1748072
commit b5c4ae4f35325d520b230bab6eb3310613b72ac1

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().

No functional changes.

Suggested-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: kernel-hardening@lists.openwall.com
Cc: gregkh@linuxfoundation.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: torvalds@linux-foundation.org
Cc: alan@linux.intel.com
Link: https://lkml.kernel.org/r/151727416438.33451.17309465232057176966.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 1b377f734e64a8e7629c0f9503aa5c0f4ef0ce4b..de3436719e26dffc63c4ca76d33cbe30e84ba9e9 100644 (file)
--- 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);