s390/string: provide asm lib functions for memcpy and memcmp

Our memcpy and memcmp variants were implemented by calling the corresponding
gcc builtin variants.
However gcc is free to replace a call to __builtin_memcmp with a call to memcmp
which, when called, will result in an endless recursion within memcmp.
So let's provide asm variants and also fix the variants that are used for
uncompressing the kernel image.
In addition remove all other occurences of builtin function calls.

Signed-off-by: Heiko Carstens <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/boot/compressed/misc.c

···
 {
 	char *xs;
 
-	if (c == 0)
-		return __builtin_memset(s, 0, n);
-
-	xs = (char *) s;
-	if (n > 0)
-		do {
-			*xs++ = c;
-		} while (--n > 0);
+	xs = s;
+	while (n--)
+		*xs++ = c;
 	return s;
 }
 
-void *memcpy(void *__dest, __const void *__src, size_t __n)
+void *memcpy(void *dest, const void *src, size_t n)
 {
-	return __builtin_memcpy(__dest, __src, __n);
+	const char *s = src;
+	char *d = dest;
+
+	while (n--)
+		*d++ = *s++;
+	return dest;
 }
 
-void *memmove(void *__dest, __const void *__src, size_t __n)
+void *memmove(void *dest, const void *src, size_t n)
 {
-	char *d;
-	const char *s;
+	const char *s = src;
+	char *d = dest;
 
-	if (__dest <= __src)
-		return __builtin_memcpy(__dest, __src, __n);
-	d = __dest + __n;
-	s = __src + __n;
-	while (__n--)
-		*--d = *--s;
-	return __dest;
+	if (d <= s) {
+		while (n--)
+			*d++ = *s++;
+	} else {
+		d += n;
+		s += n;
+		while (n--)
+			*--d = *--s;
+	}
+	return dest;
 }
 
 static void error(char *x)

arch/s390/include/asm/string.h

···
 
 static inline char *strcpy(char *dst, const char *src)
 {
-#if __GNUC__ < 4
 	register int r0 asm("0") = 0;
 	char *ret = dst;
 
···
 		: "+&a" (dst), "+&a" (src) : "d" (r0)
 		: "cc", "memory");
 	return ret;
-#else
-	return __builtin_strcpy(dst, src);
-#endif
 }
 
 static inline size_t strlen(const char *s)
 {
-#if __GNUC__ < 4
 	register unsigned long r0 asm("0") = 0;
 	const char *tmp = s;
 
···
 		"	jo	0b"
 		: "+d" (r0), "+a" (tmp) :  : "cc");
 	return r0 - (unsigned long) s;
-#else
-	return __builtin_strlen(s);
-#endif
 }
 
 static inline size_t strnlen(const char * s, size_t n)

arch/s390/kernel/s390_ksyms.c

···
 #if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
 EXPORT_SYMBOL(sie64a);
 #endif
+EXPORT_SYMBOL(memcpy);
+EXPORT_SYMBOL(memset);

arch/s390/lib/Makefile

···
 
 lib-y += delay.o string.o uaccess_std.o uaccess_pt.o
 obj-y += usercopy.o
-obj-$(CONFIG_32BIT) += div64.o qrnnd.o ucmpdi2.o
+obj-$(CONFIG_32BIT) += div64.o qrnnd.o ucmpdi2.o mem32.o
+obj-$(CONFIG_64BIT) += mem64.o
 lib-$(CONFIG_64BIT) += uaccess_mvcos.o
 lib-$(CONFIG_SMP) += spinlock.o

arch/s390/lib/mem32.S

···
+/*
+ * String handling functions.
+ *
+ * Copyright IBM Corp. 2012
+ */
+
+#include <linux/linkage.h>
+
+/*
+ * memset implementation
+ *
+ * This code corresponds to the C construct below. We do distinguish
+ * between clearing (c == 0) and setting a memory array (c != 0) simply
+ * because nearly all memset invocations in the kernel clear memory and
+ * the xc instruction is preferred in such cases.
+ *
+ * void *memset(void *s, int c, size_t n)
+ * {
+ *	if (likely(c == 0))
+ *		return __builtin_memset(s, 0, n);
+ *	return __builtin_memset(s, c, n);
+ * }
+ */
+ENTRY(memset)
+	basr	%r5,%r0
+.Lmemset_base:
+	ltr	%r4,%r4
+	bzr	%r14
+	ltr	%r3,%r3
+	jnz	.Lmemset_fill
+	ahi	%r4,-1
+	lr	%r3,%r4
+	srl	%r3,8
+	ltr	%r3,%r3
+	lr	%r1,%r2
+	je	.Lmemset_clear_rest
+.Lmemset_clear_loop:
+	xc	0(256,%r1),0(%r1)
+	la	%r1,256(%r1)
+	brct	%r3,.Lmemset_clear_loop
+.Lmemset_clear_rest:
+	ex	%r4,.Lmemset_xc-.Lmemset_base(%r5)
+	br	%r14
+.Lmemset_fill:
+	stc	%r3,0(%r2)
+	chi	%r4,1
+	lr	%r1,%r2
+	ber	%r14
+	ahi	%r4,-2
+	lr	%r3,%r4
+	srl	%r3,8
+	ltr	%r3,%r3
+	je	.Lmemset_fill_rest
+.Lmemset_fill_loop:
+	mvc	1(256,%r1),0(%r1)
+	la	%r1,256(%r1)
+	brct	%r3,.Lmemset_fill_loop
+.Lmemset_fill_rest:
+	ex	%r4,.Lmemset_mvc-.Lmemset_base(%r5)
+	br	%r14
+.Lmemset_xc:
+	xc	0(1,%r1),0(%r1)
+.Lmemset_mvc:
+	mvc	1(1,%r1),0(%r1)
+
+/*
+ * memcpy implementation
+ *
+ * void *memcpy(void *dest, const void *src, size_t n)
+ */
+ENTRY(memcpy)
+	basr	%r5,%r0
+.Lmemcpy_base:
+	ltr	%r4,%r4
+	bzr	%r14
+	ahi	%r4,-1
+	lr	%r0,%r4
+	srl	%r0,8
+	ltr	%r0,%r0
+	lr	%r1,%r2
+	jnz	.Lmemcpy_loop
+.Lmemcpy_rest:
+	ex	%r4,.Lmemcpy_mvc-.Lmemcpy_base(%r5)
+	br	%r14
+.Lmemcpy_loop:
+	mvc	0(256,%r1),0(%r3)
+	la	%r1,256(%r1)
+	la	%r3,256(%r3)
+	brct	%r0,.Lmemcpy_loop
+	j	.Lmemcpy_rest
+.Lmemcpy_mvc:
+	mvc	0(1,%r1),0(%r3)

arch/s390/lib/mem64.S

···
+/*
+ * String handling functions.
+ *
+ * Copyright IBM Corp. 2012
+ */
+
+#include <linux/linkage.h>
+
+/*
+ * memset implementation
+ *
+ * This code corresponds to the C construct below. We do distinguish
+ * between clearing (c == 0) and setting a memory array (c != 0) simply
+ * because nearly all memset invocations in the kernel clear memory and
+ * the xc instruction is preferred in such cases.
+ *
+ * void *memset(void *s, int c, size_t n)
+ * {
+ *	if (likely(c == 0))
+ *		return __builtin_memset(s, 0, n);
+ *	return __builtin_memset(s, c, n);
+ * }
+ */
+ENTRY(memset)
+	ltgr	%r4,%r4
+	bzr	%r14
+	ltgr	%r3,%r3
+	jnz	.Lmemset_fill
+	aghi	%r4,-1
+	srlg	%r3,%r4,8
+	ltgr	%r3,%r3
+	lgr	%r1,%r2
+	jz	.Lmemset_clear_rest
+.Lmemset_clear_loop:
+	xc	0(256,%r1),0(%r1)
+	la	%r1,256(%r1)
+	brctg	%r3,.Lmemset_clear_loop
+.Lmemset_clear_rest:
+	larl	%r3,.Lmemset_xc
+	ex	%r4,0(%r3)
+	br	%r14
+.Lmemset_fill:
+	stc	%r3,0(%r2)
+	cghi	%r4,1
+	lgr	%r1,%r2
+	ber	%r14
+	aghi	%r4,-2
+	srlg	%r3,%r4,8
+	ltgr	%r3,%r3
+	jz	.Lmemset_fill_rest
+.Lmemset_fill_loop:
+	mvc	1(256,%r1),0(%r1)
+	la	%r1,256(%r1)
+	brctg	%r3,.Lmemset_fill_loop
+.Lmemset_fill_rest:
+	larl	%r3,.Lmemset_mvc
+	ex	%r4,0(%r3)
+	br	%r14
+.Lmemset_xc:
+	xc	0(1,%r1),0(%r1)
+.Lmemset_mvc:
+	mvc	1(1,%r1),0(%r1)
+
+/*
+ * memcpy implementation
+ *
+ * void *memcpy(void *dest, const void *src, size_t n)
+ */
+ENTRY(memcpy)
+	ltgr	%r4,%r4
+	bzr	%r14
+	aghi	%r4,-1
+	srlg	%r5,%r4,8
+	ltgr	%r5,%r5
+	lgr	%r1,%r2
+	jnz	.Lmemcpy_loop
+.Lmemcpy_rest:
+	larl	%r5,.Lmemcpy_mvc
+	ex	%r4,0(%r5)
+	br	%r14
+.Lmemcpy_loop:
+	mvc	0(256,%r1),0(%r3)
+	la	%r1,256(%r1)
+	la	%r3,256(%r3)
+	brctg	%r5,.Lmemcpy_loop
+	j	.Lmemcpy_rest
+.Lmemcpy_mvc:
+	mvc	0(1,%r1),0(%r3)

arch/s390/lib/string.c

···
  */
 size_t strlen(const char *s)
 {
-#if __GNUC__ < 4
 	return __strend(s) - s;
-#else
-	return __builtin_strlen(s);
-#endif
 }
 EXPORT_SYMBOL(strlen);
 
···
  */
 char *strcpy(char *dest, const char *src)
 {
-#if __GNUC__ < 4
 	register int r0 asm("0") = 0;
 	char *ret = dest;
 
···
 		      : "+&a" (dest), "+&a" (src) : "d" (r0)
 		      : "cc", "memory" );
 	return ret;
-#else
-	return __builtin_strcpy(dest, src);
-#endif
 }
 EXPORT_SYMBOL(strcpy);
 
···
 	if (size) {
 		size_t len = (ret >= size) ? size-1 : ret;
 		dest[len] = '\0';
-		__builtin_memcpy(dest, src, len);
+		memcpy(dest, src, len);
 	}
 	return ret;
 }
···
 char *strncpy(char *dest, const char *src, size_t n)
 {
 	size_t len = __strnend(src, n) - src;
-	__builtin_memset(dest + len, 0, n - len);
-	__builtin_memcpy(dest, src, len);
+	memset(dest + len, 0, n - len);
+	memcpy(dest, src, len);
 	return dest;
 }
 EXPORT_SYMBOL(strncpy);
···
 		if (len >= n)
 			len = n - 1;
 		dest[len] = '\0';
-		__builtin_memcpy(dest, src, len);
+		memcpy(dest, src, len);
 	}
 	return res;
 }
···
 	char *p = __strend(dest);
 
 	p[len] = '\0';
-	__builtin_memcpy(p, src, len);
+	memcpy(p, src, len);
 	return dest;
 }
 EXPORT_SYMBOL(strncat);
···
 	return (void *) ret;
 }
 EXPORT_SYMBOL(memscan);
-
-/**
- * memcpy - Copy one area of memory to another
- * @dest: Where to copy to
- * @src: Where to copy from
- * @n: The size of the area.
- *
- * returns a pointer to @dest
- */
-void *memcpy(void *dest, const void *src, size_t n)
-{
-	return __builtin_memcpy(dest, src, n);
-}
-EXPORT_SYMBOL(memcpy);
-
-/**
- * memset - Fill a region of memory with the given value
- * @s: Pointer to the start of the area.
- * @c: The byte to fill the area with
- * @n: The size of the area.
- *
- * returns a pointer to @s
- */
-void *memset(void *s, int c, size_t n)
-{
-	char *xs;
-
-	if (c == 0)
-		return __builtin_memset(s, 0, n);
-
-	xs = (char *) s;
-	if (n > 0)
-		do {
-			*xs++ = c;
-		} while (--n > 0);
-	return s;
-}
-EXPORT_SYMBOL(memset);