1 files changed, 77 insertions, 28 deletions

diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c
index 304e070..dff631d 100644
--- a/arch/s390/lib/uaccess_pt.c
+++ b/arch/s390/lib/uaccess_pt.c
@@ -14,6 +14,63 @@
 #include <asm/futex.h>
 #include "uaccess.h"
 
+#ifndef CONFIG_64BIT
+#define AHI	"ahi"
+#define SLR	"slr"
+#else
+#define AHI	"aghi"
+#define SLR	"slgr"
+#endif
+
+static size_t strnlen_kernel(size_t count, const char __user *src)
+{
+	register unsigned long reg0 asm("0") = 0UL;
+	unsigned long tmp1, tmp2;
+
+	asm volatile(
+		"   la	  %2,0(%1)\n"
+		"   la	  %3,0(%0,%1)\n"
+		"  "SLR"  %0,%0\n"
+		"0: srst  %3,%2\n"
+		"   jo	  0b\n"
+		"   la	  %0,1(%3)\n"	/* strnlen_kernel results includes \0 */
+		"  "SLR"  %0,%1\n"
+		"1:\n"
+		EX_TABLE(0b,1b)
+		: "+a" (count), "+a" (src), "=a" (tmp1), "=a" (tmp2)
+		: "d" (reg0) : "cc", "memory");
+	return count;
+}
+
+static size_t copy_in_kernel(size_t count, void __user *to,
+			     const void __user *from)
+{
+	unsigned long tmp1;
+
+	asm volatile(
+		"  "AHI"  %0,-1\n"
+		"   jo	  5f\n"
+		"   bras  %3,3f\n"
+		"0:"AHI"  %0,257\n"
+		"1: mvc	  0(1,%1),0(%2)\n"
+		"   la	  %1,1(%1)\n"
+		"   la	  %2,1(%2)\n"
+		"  "AHI"  %0,-1\n"
+		"   jnz	  1b\n"
+		"   j	  5f\n"
+		"2: mvc	  0(256,%1),0(%2)\n"
+		"   la	  %1,256(%1)\n"
+		"   la	  %2,256(%2)\n"
+		"3:"AHI"  %0,-256\n"
+		"   jnm	  2b\n"
+		"4: ex	  %0,1b-0b(%3)\n"
+		"5:"SLR"  %0,%0\n"
+		"6:\n"
+		EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
+		: "+a" (count), "+a" (to), "+a" (from), "=a" (tmp1)
+		: : "cc", "memory");
+	return count;
+}
 
 /*
  * Returns kernel address for user virtual address. If the returned address is
@@ -123,10 +180,8 @@ size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
 {
 	size_t rc;
 
-	if (segment_eq(get_fs(), KERNEL_DS)) {
-		memcpy(to, (void __kernel __force *) from, n);
-		return 0;
-	}
+	if (segment_eq(get_fs(), KERNEL_DS))
+		return copy_in_kernel(n, (void __user *) to, from);
 	rc = __user_copy_pt((unsigned long) from, to, n, 0);
 	if (unlikely(rc))
 		memset(to + n - rc, 0, rc);
@@ -135,30 +190,28 @@ size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
 
 size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
 {
-	if (segment_eq(get_fs(), KERNEL_DS)) {
-		memcpy((void __kernel __force *) to, from, n);
-		return 0;
-	}
+	if (segment_eq(get_fs(), KERNEL_DS))
+		return copy_in_kernel(n, to, (void __user *) from);
 	return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
 }
 
 static size_t clear_user_pt(size_t n, void __user *to)
 {
+	void *zpage = &empty_zero_page;
 	long done, size, ret;
 
-	if (segment_eq(get_fs(), KERNEL_DS)) {
-		memset((void __kernel __force *) to, 0, n);
-		return 0;
-	}
 	done = 0;
 	do {
 		if (n - done > PAGE_SIZE)
 			size = PAGE_SIZE;
 		else
 			size = n - done;
-		ret = __user_copy_pt((unsigned long) to + done,
-				      &empty_zero_page, size, 1);
+		if (segment_eq(get_fs(), KERNEL_DS))
+			ret = copy_in_kernel(n, to, (void __user *) zpage);
+		else
+			ret = __user_copy_pt((unsigned long) to, zpage, size, 1);
 		done += size;
+		to += size;
 		if (ret)
 			return ret + n - done;
 	} while (done < n);
@@ -175,7 +228,7 @@ static size_t strnlen_user_pt(size_t count, const char __user *src)
 	if (unlikely(!count))
 		return 0;
 	if (segment_eq(get_fs(), KERNEL_DS))
-		return strnlen((const char __kernel __force *) src, count) + 1;
+		return strnlen_kernel(count, src);
 	done = 0;
 retry:
 	spin_lock(&mm->page_table_lock);
@@ -206,19 +259,17 @@ static size_t strncpy_from_user_pt(size_t count, const char __user *src,
 
 	if (unlikely(!count))
 		return 0;
-	if (segment_eq(get_fs(), KERNEL_DS)) {
-		len = strnlen((const char __kernel __force *) src, count) + 1;
-		if (len > count)
-			len = count;
-		memcpy(dst, (const char __kernel __force *) src, len);
-		return (dst[len - 1] == '\0') ? len - 1 : len;
-	}
 	done = 0;
 	do {
 		offset = (size_t)src & ~PAGE_MASK;
 		len = min(count - done, PAGE_SIZE - offset);
-		if (__user_copy_pt((unsigned long) src, dst, len, 0))
-			return -EFAULT;
+		if (segment_eq(get_fs(), KERNEL_DS)) {
+			if (copy_in_kernel(len, (void __user *) dst, src))
+				return -EFAULT;
+		} else {
+			if (__user_copy_pt((unsigned long) src, dst, len, 0))
+				return -EFAULT;
+		}
 		len_str = strnlen(dst, len);
 		done += len_str;
 		src += len_str;
@@ -237,10 +288,8 @@ static size_t copy_in_user_pt(size_t n, void __user *to,
 	unsigned long kaddr_to, kaddr_from;
 	int write_user;
 
-	if (segment_eq(get_fs(), KERNEL_DS)) {
-		memcpy((void __force *) to, (void __force *) from, n);
-		return 0;
-	}
+	if (segment_eq(get_fs(), KERNEL_DS))
+		return copy_in_kernel(n, to, from);
 	done = 0;
 retry:
 	spin_lock(&mm->page_table_lock);