s390: get rid of zeroing, switch to RAW_COPY_USER

[folded a fix from Martin]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/s390/Kconfig

@@ -178,6 +178,7 @@ config S390
 	select ARCH_HAS_SCALED_CPUTIME
 	select VIRT_TO_BUS
 	select HAVE_NMI
+	select ARCH_HAS_RAW_COPY_USER
 
 
 config SCHED_OMIT_FRAME_POINTER

arch/s390/include/asm/uaccess.h

@@ -60,47 +60,14 @@ static inline int __range_ok(unsigned long addr, unsigned long size)
 
 #define access_ok(type, addr, size) __access_ok(addr, size)
 
-/**
- * __copy_from_user: - Copy a block of data from user space, with less checking.
- * @to:   Destination address, in kernel space.
- * @from: Source address, in user space.
- * @n:	  Number of bytes to copy.
- *
- * Context: User context only. This function may sleep if pagefaults are
- *          enabled.
- *
- * Copy data from user space to kernel space.  Caller must check
- * the specified block with access_ok() before calling this function.
- *
- * Returns number of bytes that could not be copied.
- * On success, this will be zero.
- *
- * If some data could not be copied, this function will pad the copied
- * data to the requested size using zero bytes.
- */
-unsigned long __must_check __copy_from_user(void *to, const void __user *from,
-					    unsigned long n);
+unsigned long __must_check
+raw_copy_from_user(void *to, const void __user *from, unsigned long n);
 
-/**
- * __copy_to_user: - Copy a block of data into user space, with less checking.
- * @to:   Destination address, in user space.
- * @from: Source address, in kernel space.
- * @n:	  Number of bytes to copy.
- *
- * Context: User context only. This function may sleep if pagefaults are
- *          enabled.
- *
- * Copy data from kernel space to user space.  Caller must check
- * the specified block with access_ok() before calling this function.
- *
- * Returns number of bytes that could not be copied.
- * On success, this will be zero.
- */
-unsigned long __must_check __copy_to_user(void __user *to, const void *from,
-					  unsigned long n);
+unsigned long __must_check
+raw_copy_to_user(void __user *to, const void *from, unsigned long n);
 
-#define __copy_to_user_inatomic __copy_to_user
-#define __copy_from_user_inatomic __copy_from_user
+#define INLINE_COPY_FROM_USER
+#define INLINE_COPY_TO_USER
 
 #ifdef CONFIG_HAVE_MARCH_Z10_FEATURES
 
@@ -189,13 +156,13 @@ static inline int __get_user_fn(void *x, const void __user *ptr, unsigned long s
 
 static inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
 {
-	size = __copy_to_user(ptr, x, size);
+	size = raw_copy_to_user(ptr, x, size);
 	return size ? -EFAULT : 0;
 }
 
 static inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size)
 {
-	size = __copy_from_user(x, ptr, size);
+	size = raw_copy_from_user(x, ptr, size);
 	return size ? -EFAULT : 0;
 }
 
@@ -285,77 +252,8 @@ int __get_user_bad(void) __attribute__((noreturn));
 #define __put_user_unaligned __put_user
 #define __get_user_unaligned __get_user
 
-extern void __compiletime_error("usercopy buffer size is too small")
-__bad_copy_user(void);
-
-static inline void copy_user_overflow(int size, unsigned long count)
-{
-	WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
-}
-
-/**
- * copy_to_user: - Copy a block of data into user space.
- * @to:   Destination address, in user space.
- * @from: Source address, in kernel space.
- * @n:    Number of bytes to copy.
- *
- * Context: User context only. This function may sleep if pagefaults are
- *          enabled.
- *
- * Copy data from kernel space to user space.
- *
- * Returns number of bytes that could not be copied.
- * On success, this will be zero.
- */
-static inline unsigned long __must_check
-copy_to_user(void __user *to, const void *from, unsigned long n)
-{
-	might_fault();
-	return __copy_to_user(to, from, n);
-}
-
-/**
- * copy_from_user: - Copy a block of data from user space.
- * @to:   Destination address, in kernel space.
- * @from: Source address, in user space.
- * @n:    Number of bytes to copy.
- *
- * Context: User context only. This function may sleep if pagefaults are
- *          enabled.
- *
- * Copy data from user space to kernel space.
- *
- * Returns number of bytes that could not be copied.
- * On success, this will be zero.
- *
- * If some data could not be copied, this function will pad the copied
- * data to the requested size using zero bytes.
- */
-static inline unsigned long __must_check
-copy_from_user(void *to, const void __user *from, unsigned long n)
-{
-	unsigned int sz = __compiletime_object_size(to);
-
-	might_fault();
-	if (unlikely(sz != -1 && sz < n)) {
-		if (!__builtin_constant_p(n))
-			copy_user_overflow(sz, n);
-		else
-			__bad_copy_user();
-		return n;
-	}
-	return __copy_from_user(to, from, n);
-}
-
 unsigned long __must_check
-__copy_in_user(void __user *to, const void __user *from, unsigned long n);
-
-static inline unsigned long __must_check
-copy_in_user(void __user *to, const void __user *from, unsigned long n)
-{
-	might_fault();
-	return __copy_in_user(to, from, n);
-}
+raw_copy_in_user(void __user *to, const void __user *from, unsigned long n);
 
 /*
  * Copy a null terminated string from userspace.

arch/s390/lib/uaccess.c

@@ -26,7 +26,7 @@ static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr
 	tmp1 = -4096UL;
 	asm volatile(
 		"0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n"
-		"9: jz    7f\n"
+		"6: jz    4f\n"
 		"1: algr  %0,%3\n"
 		"   slgr  %1,%3\n"
 		"   slgr  %2,%3\n"
@@ -35,23 +35,13 @@ static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr
 		"   nr    %4,%3\n"	/* %4 = (ptr + 4095) & -4096 */
 		"   slgr  %4,%1\n"
 		"   clgr  %0,%4\n"	/* copy crosses next page boundary? */
-		"   jnh   4f\n"
+		"   jnh   5f\n"
 		"3: .insn ss,0xc80000000000,0(%4,%2),0(%1),0\n"
-		"10:slgr  %0,%4\n"
-		"   algr  %2,%4\n"
-		"4: lghi  %4,-1\n"
-		"   algr  %4,%0\n"	/* copy remaining size, subtract 1 */
-		"   bras  %3,6f\n"	/* memset loop */
-		"   xc    0(1,%2),0(%2)\n"
-		"5: xc    0(256,%2),0(%2)\n"
-		"   la    %2,256(%2)\n"
-		"6: aghi  %4,-256\n"
-		"   jnm   5b\n"
-		"   ex    %4,0(%3)\n"
-		"   j     8f\n"
-		"7: slgr  %0,%0\n"
-		"8:\n"
-		EX_TABLE(0b,2b) EX_TABLE(3b,4b) EX_TABLE(9b,2b) EX_TABLE(10b,4b)
+		"7: slgr  %0,%4\n"
+		"   j     5f\n"
+		"4: slgr  %0,%0\n"
+		"5:\n"
+		EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
 		: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 		: "d" (reg0) : "cc", "memory");
 	return size;
@@ -67,49 +57,38 @@ static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
 	asm volatile(
 		"   sacf  0\n"
 		"0: mvcp  0(%0,%2),0(%1),%3\n"
-		"10:jz    8f\n"
+		"7: jz    5f\n"
 		"1: algr  %0,%3\n"
 		"   la    %1,256(%1)\n"
 		"   la    %2,256(%2)\n"
 		"2: mvcp  0(%0,%2),0(%1),%3\n"
-		"11:jnz   1b\n"
-		"   j     8f\n"
+		"8: jnz   1b\n"
+		"   j     5f\n"
 		"3: la    %4,255(%1)\n"	/* %4 = ptr + 255 */
 		"   lghi  %3,-4096\n"
 		"   nr    %4,%3\n"	/* %4 = (ptr + 255) & -4096 */
 		"   slgr  %4,%1\n"
 		"   clgr  %0,%4\n"	/* copy crosses next page boundary? */
-		"   jnh   5f\n"
+		"   jnh   6f\n"
 		"4: mvcp  0(%4,%2),0(%1),%3\n"
-		"12:slgr  %0,%4\n"
-		"   algr  %2,%4\n"
-		"5: lghi  %4,-1\n"
-		"   algr  %4,%0\n"	/* copy remaining size, subtract 1 */
-		"   bras  %3,7f\n"	/* memset loop */
-		"   xc    0(1,%2),0(%2)\n"
-		"6: xc    0(256,%2),0(%2)\n"
-		"   la    %2,256(%2)\n"
-		"7: aghi  %4,-256\n"
-		"   jnm   6b\n"
-		"   ex    %4,0(%3)\n"
-		"   j     9f\n"
-		"8: slgr  %0,%0\n"
-		"9: sacf  768\n"
-		EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,5b)
-		EX_TABLE(10b,3b) EX_TABLE(11b,3b) EX_TABLE(12b,5b)
+		"9: slgr  %0,%4\n"
+		"   j     6f\n"
+		"5: slgr  %0,%0\n"
+		"6: sacf  768\n"
+		EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
+		EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
 		: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 		: : "cc", "memory");
 	return size;
 }
 
-unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n)
+unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-	check_object_size(to, n, false);
 	if (static_branch_likely(&have_mvcos))
 		return copy_from_user_mvcos(to, from, n);
 	return copy_from_user_mvcp(to, from, n);
 }
-EXPORT_SYMBOL(__copy_from_user);
+EXPORT_SYMBOL(raw_copy_from_user);
 
 static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x,
 					       unsigned long size)
@@ -176,14 +155,13 @@ static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x,
 	return size;
 }
 
-unsigned long __copy_to_user(void __user *to, const void *from, unsigned long n)
+unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-	check_object_size(from, n, true);
 	if (static_branch_likely(&have_mvcos))
 		return copy_to_user_mvcos(to, from, n);
 	return copy_to_user_mvcs(to, from, n);
 }
-EXPORT_SYMBOL(__copy_to_user);
+EXPORT_SYMBOL(raw_copy_to_user);
 
 static inline unsigned long copy_in_user_mvcos(void __user *to, const void __user *from,
 					       unsigned long size)
@@ -240,13 +218,13 @@ static inline unsigned long copy_in_user_mvc(void __user *to, const void __user
 	return size;
 }
 
-unsigned long __copy_in_user(void __user *to, const void __user *from, unsigned long n)
+unsigned long raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
 {
 	if (static_branch_likely(&have_mvcos))
 		return copy_in_user_mvcos(to, from, n);
 	return copy_in_user_mvc(to, from, n);
 }
-EXPORT_SYMBOL(__copy_in_user);
+EXPORT_SYMBOL(raw_copy_in_user);
 
 static inline unsigned long clear_user_mvcos(void __user *to, unsigned long size)
 {