Root/arch/s390/kernel/cpcmd.c

1/*
2 * arch/s390/kernel/cpcmd.c
3 *
4 * S390 version
5 * Copyright IBM Corp. 1999,2007
6 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
7 * Christian Borntraeger (cborntra@de.ibm.com),
8 */
9
10#define KMSG_COMPONENT "cpcmd"
11#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
12
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16#include <linux/spinlock.h>
17#include <linux/stddef.h>
18#include <linux/string.h>
19#include <asm/ebcdic.h>
20#include <asm/cpcmd.h>
21#include <asm/system.h>
22#include <asm/io.h>
23
24static DEFINE_SPINLOCK(cpcmd_lock);
25static char cpcmd_buf[241];
26
27static int diag8_noresponse(int cmdlen)
28{
29    register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
30    register unsigned long reg3 asm ("3") = cmdlen;
31
32    asm volatile(
33#ifndef CONFIG_64BIT
34        " diag %1,%0,0x8\n"
35#else /* CONFIG_64BIT */
36        " sam31\n"
37        " diag %1,%0,0x8\n"
38        " sam64\n"
39#endif /* CONFIG_64BIT */
40        : "+d" (reg3) : "d" (reg2) : "cc");
41    return reg3;
42}
43
44static int diag8_response(int cmdlen, char *response, int *rlen)
45{
46    register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
47    register unsigned long reg3 asm ("3") = (addr_t) response;
48    register unsigned long reg4 asm ("4") = cmdlen | 0x40000000L;
49    register unsigned long reg5 asm ("5") = *rlen;
50
51    asm volatile(
52#ifndef CONFIG_64BIT
53        " diag %2,%0,0x8\n"
54        " brc 8,1f\n"
55        " ar %1,%4\n"
56#else /* CONFIG_64BIT */
57        " sam31\n"
58        " diag %2,%0,0x8\n"
59        " sam64\n"
60        " brc 8,1f\n"
61        " agr %1,%4\n"
62#endif /* CONFIG_64BIT */
63        "1:\n"
64        : "+d" (reg4), "+d" (reg5)
65        : "d" (reg2), "d" (reg3), "d" (*rlen) : "cc");
66    *rlen = reg5;
67    return reg4;
68}
69
70/*
71 * __cpcmd has some restrictions over cpcmd
72 * - the response buffer must reside below 2GB (if any)
73 * - __cpcmd is unlocked and therefore not SMP-safe
74 */
75int __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
76{
77    int cmdlen;
78    int rc;
79    int response_len;
80
81    cmdlen = strlen(cmd);
82    BUG_ON(cmdlen > 240);
83    memcpy(cpcmd_buf, cmd, cmdlen);
84    ASCEBC(cpcmd_buf, cmdlen);
85
86    if (response) {
87        memset(response, 0, rlen);
88        response_len = rlen;
89        rc = diag8_response(cmdlen, response, &rlen);
90        EBCASC(response, response_len);
91        } else {
92        rc = diag8_noresponse(cmdlen);
93        }
94    if (response_code)
95        *response_code = rc;
96    return rlen;
97}
98EXPORT_SYMBOL(__cpcmd);
99
100int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
101{
102    char *lowbuf;
103    int len;
104    unsigned long flags;
105
106    if ((virt_to_phys(response) != (unsigned long) response) ||
107            (((unsigned long)response + rlen) >> 31)) {
108        lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);
109        if (!lowbuf) {
110            pr_warning("The cpcmd kernel function failed to "
111                   "allocate a response buffer\n");
112            return -ENOMEM;
113        }
114        spin_lock_irqsave(&cpcmd_lock, flags);
115        len = __cpcmd(cmd, lowbuf, rlen, response_code);
116        spin_unlock_irqrestore(&cpcmd_lock, flags);
117        memcpy(response, lowbuf, rlen);
118        kfree(lowbuf);
119    } else {
120        spin_lock_irqsave(&cpcmd_lock, flags);
121        len = __cpcmd(cmd, response, rlen, response_code);
122        spin_unlock_irqrestore(&cpcmd_lock, flags);
123    }
124    return len;
125}
126EXPORT_SYMBOL(cpcmd);
127

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