1 files changed, 168 insertions, 0 deletions
diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c
new file mode 100644
index 00000000..e1335dc2
--- /dev/null
+++ b/arch/s390/mm/maccess.c
@@ -0,0 +1,168 @@
+/*
+ * Access kernel memory without faulting -- s390 specific implementation.
+ *
+ * Copyright IBM Corp. 2009
+ *
+ *   Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
+ *
+ */
+
+#include <linux/uaccess.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/gfp.h>
+#include <asm/ctl_reg.h>
+
+/*
+ * This function writes to kernel memory bypassing DAT and possible
+ * write protection. It copies one to four bytes from src to dst
+ * using the stura instruction.
+ * Returns the number of bytes copied or -EFAULT.
+ */
+static long probe_kernel_write_odd(void *dst, const void *src, size_t size)
+{
+	unsigned long count, aligned;
+	int offset, mask;
+	int rc = -EFAULT;
+
+	aligned = (unsigned long) dst & ~3UL;
+	offset = (unsigned long) dst & 3;
+	count = min_t(unsigned long, 4 - offset, size);
+	mask = (0xf << (4 - count)) & 0xf;
+	mask >>= offset;
+	asm volatile(
+		"	bras	1,0f\n"
+		"	icm	0,0,0(%3)\n"
+		"0:	l	0,0(%1)\n"
+		"	lra	%1,0(%1)\n"
+		"1:	ex	%2,0(1)\n"
+		"2:	stura	0,%1\n"
+		"	la	%0,0\n"
+		"3:\n"
+		EX_TABLE(0b,3b) EX_TABLE(1b,3b) EX_TABLE(2b,3b)
+		: "+d" (rc), "+a" (aligned)
+		: "a" (mask), "a" (src) : "cc", "memory", "0", "1");
+	return rc ? rc : count;
+}
+
+long probe_kernel_write(void *dst, const void *src, size_t size)
+{
+	long copied = 0;
+
+	while (size) {
+		copied = probe_kernel_write_odd(dst, src, size);
+		if (copied < 0)
+			break;
+		dst += copied;
+		src += copied;
+		size -= copied;
+	}
+	return copied < 0 ? -EFAULT : 0;
+}
+
+static int __memcpy_real(void *dest, void *src, size_t count)
+{
+	register unsigned long _dest asm("2") = (unsigned long) dest;
+	register unsigned long _len1 asm("3") = (unsigned long) count;
+	register unsigned long _src  asm("4") = (unsigned long) src;
+	register unsigned long _len2 asm("5") = (unsigned long) count;
+	int rc = -EFAULT;
+
+	asm volatile (
+		"0:	mvcle	%1,%2,0x0\n"
+		"1:	jo	0b\n"
+		"	lhi	%0,0x0\n"
+		"2:\n"
+		EX_TABLE(1b,2b)
+		: "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1),
+		  "+d" (_len2), "=m" (*((long *) dest))
+		: "m" (*((long *) src))
+		: "cc", "memory");
+	return rc;
+}
+
+/*
+ * Copy memory in real mode (kernel to kernel)
+ */
+int memcpy_real(void *dest, void *src, size_t count)
+{
+	unsigned long flags;
+	int rc;
+
+	if (!count)
+		return 0;
+	local_irq_save(flags);
+	__arch_local_irq_stnsm(0xfbUL);
+	rc = __memcpy_real(dest, src, count);
+	local_irq_restore(flags);
+	return rc;
+}
+
+/*
+ * Copy memory to absolute zero
+ */
+void copy_to_absolute_zero(void *dest, void *src, size_t count)
+{
+	unsigned long cr0;
+
+	BUG_ON((unsigned long) dest + count >= sizeof(struct _lowcore));
+	preempt_disable();
+	__ctl_store(cr0, 0, 0);
+	__ctl_clear_bit(0, 28); /* disable lowcore protection */
+	memcpy_real(dest + store_prefix(), src, count);
+	__ctl_load(cr0, 0, 0);
+	preempt_enable();
+}
+
+/*
+ * Copy memory from kernel (real) to user (virtual)
+ */
+int copy_to_user_real(void __user *dest, void *src, size_t count)
+{
+	int offs = 0, size, rc;
+	char *buf;
+
+	buf = (char *) __get_free_page(GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	rc = -EFAULT;
+	while (offs < count) {
+		size = min(PAGE_SIZE, count - offs);
+		if (memcpy_real(buf, src + offs, size))
+			goto out;
+		if (copy_to_user(dest + offs, buf, size))
+			goto out;
+		offs += size;
+	}
+	rc = 0;
+out:
+	free_page((unsigned long) buf);
+	return rc;
+}
+
+/*
+ * Copy memory from user (virtual) to kernel (real)
+ */
+int copy_from_user_real(void *dest, void __user *src, size_t count)
+{
+	int offs = 0, size, rc;
+	char *buf;
+
+	buf = (char *) __get_free_page(GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	rc = -EFAULT;
+	while (offs < count) {
+		size = min(PAGE_SIZE, count - offs);
+		if (copy_from_user(buf, src + offs, size))
+			goto out;
+		if (memcpy_real(dest + offs, buf, size))
+			goto out;
+		offs += size;
+	}
+	rc = 0;
+out:
+	free_page((unsigned long) buf);
+	return rc;
+}