x86: uaccess: move 32-bit and 64-bit parts into proper <asm/uaccess_N.h> header

The x86 <asm/uaccess.h> file has grown features that are specific to
x86-64 like LAM support and the related access_ok() changes.  They
really should be in the <asm/uaccess_64.h> file and not pollute the
generic x86 header.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/include/asm/uaccess.h

@@ -16,83 +16,10 @@
 #include <asm/extable.h>
 #include <asm/tlbflush.h>
 
-#ifdef CONFIG_ADDRESS_MASKING
-/*
- * Mask out tag bits from the address.
- *
- * Magic with the 'sign' allows to untag userspace pointer without any branches
- * while leaving kernel addresses intact.
- */
-static inline unsigned long __untagged_addr(unsigned long addr)
-{
-	long sign;
-
-	/*
-	 * Refer tlbstate_untag_mask directly to avoid RIP-relative relocation
-	 * in alternative instructions. The relocation gets wrong when gets
-	 * copied to the target place.
-	 */
-	asm (ALTERNATIVE("",
-			 "sar $63, %[sign]\n\t" /* user_ptr ? 0 : -1UL */
-			 "or %%gs:tlbstate_untag_mask, %[sign]\n\t"
-			 "and %[sign], %[addr]\n\t", X86_FEATURE_LAM)
-	     : [addr] "+r" (addr), [sign] "=r" (sign)
-	     : "m" (tlbstate_untag_mask), "[sign]" (addr));
-
-	return addr;
-}
-
-#define untagged_addr(addr)	({					\
-	unsigned long __addr = (__force unsigned long)(addr);		\
-	(__force __typeof__(addr))__untagged_addr(__addr);		\
-})
-
-static inline unsigned long __untagged_addr_remote(struct mm_struct *mm,
-						   unsigned long addr)
-{
-	long sign = addr >> 63;
-
-	mmap_assert_locked(mm);
-	addr &= (mm)->context.untag_mask | sign;
-
-	return addr;
-}
-
-#define untagged_addr_remote(mm, addr)	({				\
-	unsigned long __addr = (__force unsigned long)(addr);		\
-	(__force __typeof__(addr))__untagged_addr_remote(mm, __addr);	\
-})
-
+#ifdef CONFIG_X86_32
+# include <asm/uaccess_32.h>
 #else
-#define untagged_addr(addr)	(addr)
-#endif
-
-#ifdef CONFIG_X86_64
-/*
- * On x86-64, we may have tag bits in the user pointer. Rather than
- * mask them off, just change the rules for __access_ok().
- *
- * Make the rule be that 'ptr+size' must not overflow, and must not
- * have the high bit set. Compilers generally understand about
- * unsigned overflow and the CF bit and generate reasonable code for
- * this. Although it looks like the combination confuses at least
- * clang (and instead of just doing an "add" followed by a test of
- * SF and CF, you'll see that unnecessary comparison).
- *
- * For the common case of small sizes that can be checked at compile
- * time, don't even bother with the addition, and just check that the
- * base pointer is ok.
- */
-static inline bool __access_ok(const void __user *ptr, unsigned long size)
-{
-	if (__builtin_constant_p(size <= PAGE_SIZE) && size <= PAGE_SIZE) {
-		return (long)ptr >= 0;
-	} else {
-		unsigned long sum = size + (unsigned long)ptr;
-		return (long) sum >= 0 && sum >= (unsigned long)ptr;
-	}
-}
-#define __access_ok __access_ok
+# include <asm/uaccess_64.h>
 #endif
 
 #include <asm-generic/access_ok.h>
@@ -583,14 +510,6 @@ extern struct movsl_mask {
 
 #define ARCH_HAS_NOCACHE_UACCESS 1
 
-#ifdef CONFIG_X86_32
-unsigned long __must_check clear_user(void __user *mem, unsigned long len);
-unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
-# include <asm/uaccess_32.h>
-#else
-# include <asm/uaccess_64.h>
-#endif
-
 /*
  * The "unsafe" user accesses aren't really "unsafe", but the naming
  * is a big fat warning: you have to not only do the access_ok()

arch/x86/include/asm/uaccess_32.h

@@ -33,4 +33,7 @@ __copy_from_user_inatomic_nocache(void *to, const void __user *from,
        return __copy_from_user_ll_nocache_nozero(to, from, n);
 }
 
+unsigned long __must_check clear_user(void __user *mem, unsigned long len);
+unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
+
 #endif /* _ASM_X86_UACCESS_32_H */

arch/x86/include/asm/uaccess_64.h

@@ -12,6 +12,81 @@
 #include <asm/cpufeatures.h>
 #include <asm/page.h>
 
+#ifdef CONFIG_ADDRESS_MASKING
+/*
+ * Mask out tag bits from the address.
+ *
+ * Magic with the 'sign' allows to untag userspace pointer without any branches
+ * while leaving kernel addresses intact.
+ */
+static inline unsigned long __untagged_addr(unsigned long addr)
+{
+	long sign;
+
+	/*
+	 * Refer tlbstate_untag_mask directly to avoid RIP-relative relocation
+	 * in alternative instructions. The relocation gets wrong when gets
+	 * copied to the target place.
+	 */
+	asm (ALTERNATIVE("",
+			 "sar $63, %[sign]\n\t" /* user_ptr ? 0 : -1UL */
+			 "or %%gs:tlbstate_untag_mask, %[sign]\n\t"
+			 "and %[sign], %[addr]\n\t", X86_FEATURE_LAM)
+	     : [addr] "+r" (addr), [sign] "=r" (sign)
+	     : "m" (tlbstate_untag_mask), "[sign]" (addr));
+
+	return addr;
+}
+
+#define untagged_addr(addr)	({					\
+	unsigned long __addr = (__force unsigned long)(addr);		\
+	(__force __typeof__(addr))__untagged_addr(__addr);		\
+})
+
+static inline unsigned long __untagged_addr_remote(struct mm_struct *mm,
+						   unsigned long addr)
+{
+	long sign = addr >> 63;
+
+	mmap_assert_locked(mm);
+	addr &= (mm)->context.untag_mask | sign;
+
+	return addr;
+}
+
+#define untagged_addr_remote(mm, addr)	({				\
+	unsigned long __addr = (__force unsigned long)(addr);		\
+	(__force __typeof__(addr))__untagged_addr_remote(mm, __addr);	\
+})
+
+#endif
+
+/*
+ * On x86-64, we may have tag bits in the user pointer. Rather than
+ * mask them off, just change the rules for __access_ok().
+ *
+ * Make the rule be that 'ptr+size' must not overflow, and must not
+ * have the high bit set. Compilers generally understand about
+ * unsigned overflow and the CF bit and generate reasonable code for
+ * this. Although it looks like the combination confuses at least
+ * clang (and instead of just doing an "add" followed by a test of
+ * SF and CF, you'll see that unnecessary comparison).
+ *
+ * For the common case of small sizes that can be checked at compile
+ * time, don't even bother with the addition, and just check that the
+ * base pointer is ok.
+ */
+static inline bool __access_ok(const void __user *ptr, unsigned long size)
+{
+	if (__builtin_constant_p(size <= PAGE_SIZE) && size <= PAGE_SIZE) {
+		return (long)ptr >= 0;
+	} else {
+		unsigned long sum = size + (unsigned long)ptr;
+		return (long) sum >= 0 && sum >= (unsigned long)ptr;
+	}
+}
+#define __access_ok __access_ok
+
 /*
  * Copy To/From Userspace
  */
@@ -106,7 +181,7 @@ static __always_inline __must_check unsigned long __clear_user(void __user *addr
 
 static __always_inline unsigned long clear_user(void __user *to, unsigned long n)
 {
-	if (access_ok(to, n))
+	if (__access_ok(to, n))
 		return __clear_user(to, n);
 	return n;
 }