x86, smap: Add STAC and CLAC instructions to control user space access

[cascardo/linux.git] / arch / x86 / lib / usercopy_64.c

diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index e5b130b..05928aa 100644 (file)
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -18,6 +18,7 @@ unsigned long __clear_user(void __user *addr, unsigned long size)
        might_fault();
        /* no memory constraint because it doesn't change any memory gcc knows
           about */
+       stac();
        asm volatile(
                "       testq  %[size8],%[size8]\n"
                "       jz     4f\n"
@@ -40,6 +41,7 @@ unsigned long __clear_user(void __user *addr, unsigned long size)
                : [size8] "=&c"(size), [dst] "=&D" (__d0)
                : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
                  [zero] "r" (0UL), [eight] "r" (8UL));
+       clac();
        return size;
 }
 EXPORT_SYMBOL(__clear_user);
@@ -82,5 +84,6 @@ copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest)
        for (c = 0, zero_len = len; zerorest && zero_len; --zero_len)
                if (__put_user_nocheck(c, to++, sizeof(char)))
                        break;
+       clac();
        return len;
 }