Merge branch 'generic-string-functions'

This makes <asm/word-at-a-time.h> actually live up to its promise of
allowing architectures to help tune the string functions that do their
work a word at a time.

David had already taken the x86 strncpy_from_user() function, modified
it to work on sparc, and then done the extra work to make it generically
useful.  This then expands on that work by making x86 use that generic
version, completing the circle.

But more importantly, it fixes up the word-at-a-time interfaces so that
it's now easy to also support things like strnlen_user(), and pretty
much most random string functions.

David reports that it all works fine on sparc, and Jonas Bonn reported
that an earlier version of this worked on OpenRISC too.  It's pretty
easy for architectures to add support for this and just replace their
private versions with the generic code.

* generic-string-functions:
  sparc: use the new generic strnlen_user() function
  x86: use the new generic strnlen_user() function
  lib: add generic strnlen_user() function
  word-at-a-time: make the interfaces truly generic
  x86: use generic strncpy_from_user routine

8 files changed, 35 insertions, 209 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 81c3e8b..d700811 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -93,6 +93,8 @@ config X86
 	select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
 	select GENERIC_TIME_VSYSCALL if X86_64
 	select KTIME_SCALAR if X86_32
+	select GENERIC_STRNCPY_FROM_USER
+	select GENERIC_STRNLEN_USER
 
 config INSTRUCTION_DECODER
 	def_bool (KPROBES || PERF_EVENTS || UPROBES)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 851fe0d..04cd688 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -32,6 +32,7 @@
 
 #define segment_eq(a, b)	((a).seg == (b).seg)
 
+#define user_addr_max() (current_thread_info()->addr_limit.seg)
 #define __addr_ok(addr)					\
 	((unsigned long __force)(addr) <		\
 	 (current_thread_info()->addr_limit.seg))
@@ -565,6 +566,9 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 extern __must_check long
 strncpy_from_user(char *dst, const char __user *src, long count);
 
+extern __must_check long strlen_user(const char __user *str);
+extern __must_check long strnlen_user(const char __user *str, long n);
+
 /*
  * movsl can be slow when source and dest are not both 8-byte aligned
  */
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 8084bc73..576e39b 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -213,23 +213,6 @@ static inline unsigned long __must_check copy_from_user(void *to,
 	return n;
 }
 
-/**
- * strlen_user: - Get the size of a string in user space.
- * @str: The string to measure.
- *
- * Context: User context only.  This function may sleep.
- *
- * Get the size of a NUL-terminated string in user space.
- *
- * Returns the size of the string INCLUDING the terminating NUL.
- * On exception, returns 0.
- *
- * If there is a limit on the length of a valid string, you may wish to
- * consider using strnlen_user() instead.
- */
-#define strlen_user(str) strnlen_user(str, LONG_MAX)
-
-long strnlen_user(const char __user *str, long 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);
 
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index fcd4b6f..8e796fb 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -208,9 +208,6 @@ int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
 	}
 }
 
-__must_check long strnlen_user(const char __user *str, long n);
-__must_check long __strnlen_user(const char __user *str, long n);
-__must_check long strlen_user(const char __user *str);
 __must_check unsigned long clear_user(void __user *mem, unsigned long len);
 __must_check unsigned long __clear_user(void __user *mem, unsigned long len);
 
diff --git a/arch/x86/include/asm/word-at-a-time.h b/arch/x86/include/asm/word-at-a-time.h
index ae03fac..5b238981 100644
--- a/arch/x86/include/asm/word-at-a-time.h
+++ b/arch/x86/include/asm/word-at-a-time.h
@@ -10,6 +10,11 @@
  * bit count instruction, that might be better than the multiply
  * and shift, for example.
  */
+struct word_at_a_time {
+	const unsigned long one_bits, high_bits;
+};
+
+#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
 
 #ifdef CONFIG_64BIT
 
@@ -37,10 +42,31 @@ static inline long count_masked_bytes(long mask)
 
 #endif
 
-/* Return the high bit set in the first byte that is a zero */
-static inline unsigned long has_zero(unsigned long a)
+/* Return nonzero if it has a zero */
+static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
+{
+	unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
+	*bits = mask;
+	return mask;
+}
+
+static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
+{
+	return bits;
+}
+
+static inline unsigned long create_zero_mask(unsigned long bits)
+{
+	bits = (bits - 1) & ~bits;
+	return bits >> 7;
+}
+
+/* The mask we created is directly usable as a bytemask */
+#define zero_bytemask(mask) (mask)
+
+static inline unsigned long find_zero(unsigned long mask)
 {
-	return ((a - REPEAT_BYTE(0x01)) & ~a) & REPEAT_BYTE(0x80);
+	return count_masked_bytes(mask);
 }
 
 /*
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index 2e4e4b0..f61ee67 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -43,100 +43,3 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
 	return len;
 }
 EXPORT_SYMBOL_GPL(copy_from_user_nmi);
-
-/*
- * Do a strncpy, return length of string without final '\0'.
- * 'count' is the user-supplied count (return 'count' if we
- * hit it), 'max' is the address space maximum (and we return
- * -EFAULT if we hit it).
- */
-static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max)
-{
-	long res = 0;
-
-	/*
-	 * Truncate 'max' to the user-specified limit, so that
-	 * we only have one limit we need to check in the loop
-	 */
-	if (max > count)
-		max = count;
-
-	while (max >= sizeof(unsigned long)) {
-		unsigned long c, mask;
-
-		/* Fall back to byte-at-a-time if we get a page fault */
-		if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
-			break;
-		mask = has_zero(c);
-		if (mask) {
-			mask = (mask - 1) & ~mask;
-			mask >>= 7;
-			*(unsigned long *)(dst+res) = c & mask;
-			return res + count_masked_bytes(mask);
-		}
-		*(unsigned long *)(dst+res) = c;
-		res += sizeof(unsigned long);
-		max -= sizeof(unsigned long);
-	}
-
-	while (max) {
-		char c;
-
-		if (unlikely(__get_user(c,src+res)))
-			return -EFAULT;
-		dst[res] = c;
-		if (!c)
-			return res;
-		res++;
-		max--;
-	}
-
-	/*
-	 * Uhhuh. We hit 'max'. But was that the user-specified maximum
-	 * too? If so, that's ok - we got as much as the user asked for.
-	 */
-	if (res >= count)
-		return res;
-
-	/*
-	 * Nope: we hit the address space limit, and we still had more
-	 * characters the caller would have wanted. That's an EFAULT.
-	 */
-	return -EFAULT;
-}
-
-/**
- * strncpy_from_user: - Copy a NUL terminated string from userspace.
- * @dst:   Destination address, in kernel space.  This buffer must be at
- *         least @count bytes long.
- * @src:   Source address, in user space.
- * @count: Maximum number of bytes to copy, including the trailing NUL.
- *
- * Copies a NUL-terminated string from userspace to kernel space.
- *
- * On success, returns the length of the string (not including the trailing
- * NUL).
- *
- * If access to userspace fails, returns -EFAULT (some data may have been
- * copied).
- *
- * If @count is smaller than the length of the string, copies @count bytes
- * and returns @count.
- */
-long
-strncpy_from_user(char *dst, const char __user *src, long count)
-{
-	unsigned long max_addr, src_addr;
-
-	if (unlikely(count <= 0))
-		return 0;
-
-	max_addr = current_thread_info()->addr_limit.seg;
-	src_addr = (unsigned long)src;
-	if (likely(src_addr < max_addr)) {
-		unsigned long max = max_addr - src_addr;
-		return do_strncpy_from_user(dst, src, count, max);
-	}
-	return -EFAULT;
-}
-EXPORT_SYMBOL(strncpy_from_user);
diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 883b216..1781b2f 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -95,47 +95,6 @@ __clear_user(void __user *to, unsigned long n)
 }
 EXPORT_SYMBOL(__clear_user);
 
-/**
- * strnlen_user: - Get the size of a string in user space.
- * @s: The string to measure.
- * @n: The maximum valid length
- *
- * Get the size of a NUL-terminated string in user space.
- *
- * Returns the size of the string INCLUDING the terminating NUL.
- * On exception, returns 0.
- * If the string is too long, returns a value greater than @n.
- */
-long strnlen_user(const char __user *s, long n)
-{
-	unsigned long mask = -__addr_ok(s);
-	unsigned long res, tmp;
-
-	might_fault();
-
-	__asm__ __volatile__(
-		"	testl %0, %0\n"
-		"	jz 3f\n"
-		"	andl %0,%%ecx\n"
-		"0:	repne; scasb\n"
-		"	setne %%al\n"
-		"	subl %%ecx,%0\n"
-		"	addl %0,%%eax\n"
-		"1:\n"
-		".section .fixup,\"ax\"\n"
-		"2:	xorl %%eax,%%eax\n"
-		"	jmp 1b\n"
-		"3:	movb $1,%%al\n"
-		"	jmp 1b\n"
-		".previous\n"
-		_ASM_EXTABLE(0b,2b)
-		:"=&r" (n), "=&D" (s), "=&a" (res), "=&c" (tmp)
-		:"0" (n), "1" (s), "2" (0), "3" (mask)
-		:"cc");
-	return res & mask;
-}
-EXPORT_SYMBOL(strnlen_user);
-
 #ifdef CONFIG_X86_INTEL_USERCOPY
 static unsigned long
 __copy_user_intel(void __user *to, const void *from, unsigned long size)
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index 0d0326f..e5b130b 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -52,54 +52,6 @@ unsigned long clear_user(void __user *to, unsigned long n)
 }
 EXPORT_SYMBOL(clear_user);
 
-/*
- * Return the size of a string (including the ending 0)
- *
- * Return 0 on exception, a value greater than N if too long
- */
-
-long __strnlen_user(const char __user *s, long n)
-{
-	long res = 0;
-	char c;
-
-	while (1) {
-		if (res>n)
-			return n+1;
-		if (__get_user(c, s))
-			return 0;
-		if (!c)
-			return res+1;
-		res++;
-		s++;
-	}
-}
-EXPORT_SYMBOL(__strnlen_user);
-
-long strnlen_user(const char __user *s, long n)
-{
-	if (!access_ok(VERIFY_READ, s, 1))
-		return 0;
-	return __strnlen_user(s, n);
-}
-EXPORT_SYMBOL(strnlen_user);
-
-long strlen_user(const char __user *s)
-{
-	long res = 0;
-	char c;
-
-	for (;;) {
-		if (get_user(c, s))
-			return 0;
-		if (!c)
-			return res+1;
-		res++;
-		s++;
-	}
-}
-EXPORT_SYMBOL(strlen_user);
-
 unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len)
 {
 	if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) {