x86, smap: Do not abuse the [f][x]rstor_checking() functions for user space

With SMAP, the [f][x]rstor_checking() functions are no longer usable
for user-space pointers by applying a simple __force cast.  Instead,
create new [f][x]rstor_user() functions which do the proper SMAP
magic.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1343171129-2747-3-git-send-email-suresh.b.siddha@intel.com

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
index 409b9ccf5518..831dbb9c6c02 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -181,11 +181,28 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
                           "m" (*fx));
 }
 
+static inline int fxrstor_user(struct i387_fxsave_struct __user *fx)
+{
+        if (config_enabled(CONFIG_X86_32))
+                return user_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+        else if (config_enabled(CONFIG_AS_FXSAVEQ))
+                return user_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
+
+        /* See comment in fpu_fxsave() below. */
+        return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
+                          "m" (*fx));
+}
+
 static inline int frstor_checking(struct i387_fsave_struct *fx)
 {
         return check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
 }
 
+static inline int frstor_user(struct i387_fsave_struct __user *fx)
+{
+        return user_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
 static inline void fpu_fxsave(struct fpu *fpu)
 {
         if (config_enabled(CONFIG_X86_32))