diff options
author | David S. Miller <davem@davemloft.net> | 2009-06-15 06:02:23 -0400 |
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committer | David S. Miller <davem@davemloft.net> | 2009-06-15 06:02:23 -0400 |
commit | 9cbc1cb8cd46ce1f7645b9de249b2ce8460129bb (patch) | |
tree | 8d104ec2a459346b99413b0b77421ca7b9936c1a /arch/s390/mm/maccess.c | |
parent | ca44d6e60f9de26281fda203f58b570e1748c015 (diff) | |
parent | 45e3e1935e2857c54783291107d33323b3ef33c8 (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.c | 61 |
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 | */ | ||
22 | static 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 | |||
48 | long 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 | } | ||