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authorDavid S. Miller <davem@davemloft.net>2009-06-15 06:02:23 -0400
committerDavid S. Miller <davem@davemloft.net>2009-06-15 06:02:23 -0400
commit9cbc1cb8cd46ce1f7645b9de249b2ce8460129bb (patch)
tree8d104ec2a459346b99413b0b77421ca7b9936c1a /arch/s390/mm/maccess.c
parentca44d6e60f9de26281fda203f58b570e1748c015 (diff)
parent45e3e1935e2857c54783291107d33323b3ef33c8 (diff)
Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts: Documentation/feature-removal-schedule.txt drivers/scsi/fcoe/fcoe.c net/core/drop_monitor.c net/core/net-traces.c
Diffstat (limited to 'arch/s390/mm/maccess.c')
-rw-r--r--arch/s390/mm/maccess.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c
new file mode 100644
index 000000000000..81756271dc44
--- /dev/null
+++ b/arch/s390/mm/maccess.c
@@ -0,0 +1,61 @@
1/*
2 * Access kernel memory without faulting -- s390 specific implementation.
3 *
4 * Copyright IBM Corp. 2009
5 *
6 * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
7 *
8 */
9
10#include <linux/uaccess.h>
11#include <linux/kernel.h>
12#include <linux/types.h>
13#include <linux/errno.h>
14#include <asm/system.h>
15
16/*
17 * This function writes to kernel memory bypassing DAT and possible
18 * write protection. It copies one to four bytes from src to dst
19 * using the stura instruction.
20 * Returns the number of bytes copied or -EFAULT.
21 */
22static long probe_kernel_write_odd(void *dst, void *src, size_t size)
23{
24 unsigned long count, aligned;
25 int offset, mask;
26 int rc = -EFAULT;
27
28 aligned = (unsigned long) dst & ~3UL;
29 offset = (unsigned long) dst & 3;
30 count = min_t(unsigned long, 4 - offset, size);
31 mask = (0xf << (4 - count)) & 0xf;
32 mask >>= offset;
33 asm volatile(
34 " bras 1,0f\n"
35 " icm 0,0,0(%3)\n"
36 "0: l 0,0(%1)\n"
37 " lra %1,0(%1)\n"
38 "1: ex %2,0(1)\n"
39 "2: stura 0,%1\n"
40 " la %0,0\n"
41 "3:\n"
42 EX_TABLE(0b,3b) EX_TABLE(1b,3b) EX_TABLE(2b,3b)
43 : "+d" (rc), "+a" (aligned)
44 : "a" (mask), "a" (src) : "cc", "memory", "0", "1");
45 return rc ? rc : count;
46}
47
48long probe_kernel_write(void *dst, void *src, size_t size)
49{
50 long copied = 0;
51
52 while (size) {
53 copied = probe_kernel_write_odd(dst, src, size);
54 if (copied < 0)
55 break;
56 dst += copied;
57 src += copied;
58 size -= copied;
59 }
60 return copied < 0 ? -EFAULT : 0;
61}