xref: /linux/arch/s390/kernel/cpcmd.c (revision 827634added7f38b7d724cab1dccdb2b004c13c3)
1 /*
2  *  S390 version
3  *    Copyright IBM Corp. 1999, 2007
4  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
5  *               Christian Borntraeger (cborntra@de.ibm.com),
6  */
7 
8 #define KMSG_COMPONENT "cpcmd"
9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
10 
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/spinlock.h>
15 #include <linux/stddef.h>
16 #include <linux/string.h>
17 #include <asm/ebcdic.h>
18 #include <asm/cpcmd.h>
19 #include <asm/io.h>
20 
21 static DEFINE_SPINLOCK(cpcmd_lock);
22 static char cpcmd_buf[241];
23 
24 static int diag8_noresponse(int cmdlen)
25 {
26 	register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
27 	register unsigned long reg3 asm ("3") = cmdlen;
28 
29 	asm volatile(
30 		"	sam31\n"
31 		"	diag	%1,%0,0x8\n"
32 		"	sam64\n"
33 		: "+d" (reg3) : "d" (reg2) : "cc");
34 	return reg3;
35 }
36 
37 static int diag8_response(int cmdlen, char *response, int *rlen)
38 {
39 	register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
40 	register unsigned long reg3 asm ("3") = (addr_t) response;
41 	register unsigned long reg4 asm ("4") = cmdlen | 0x40000000L;
42 	register unsigned long reg5 asm ("5") = *rlen;
43 
44 	asm volatile(
45 		"	sam31\n"
46 		"	diag	%2,%0,0x8\n"
47 		"	sam64\n"
48 		"	brc	8,1f\n"
49 		"	agr	%1,%4\n"
50 		"1:\n"
51 		: "+d" (reg4), "+d" (reg5)
52 		: "d" (reg2), "d" (reg3), "d" (*rlen) : "cc");
53 	*rlen = reg5;
54 	return reg4;
55 }
56 
57 /*
58  * __cpcmd has some restrictions over cpcmd
59  *  - the response buffer must reside below 2GB (if any)
60  *  - __cpcmd is unlocked and therefore not SMP-safe
61  */
62 int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
63 {
64 	int cmdlen;
65 	int rc;
66 	int response_len;
67 
68 	cmdlen = strlen(cmd);
69 	BUG_ON(cmdlen > 240);
70 	memcpy(cpcmd_buf, cmd, cmdlen);
71 	ASCEBC(cpcmd_buf, cmdlen);
72 
73 	if (response) {
74 		memset(response, 0, rlen);
75 		response_len = rlen;
76 		rc = diag8_response(cmdlen, response, &rlen);
77 		EBCASC(response, response_len);
78         } else {
79 		rc = diag8_noresponse(cmdlen);
80         }
81 	if (response_code)
82 		*response_code = rc;
83 	return rlen;
84 }
85 EXPORT_SYMBOL(__cpcmd);
86 
87 int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
88 {
89 	char *lowbuf;
90 	int len;
91 	unsigned long flags;
92 
93 	if ((virt_to_phys(response) != (unsigned long) response) ||
94 			(((unsigned long)response + rlen) >> 31)) {
95 		lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);
96 		if (!lowbuf) {
97 			pr_warning("The cpcmd kernel function failed to "
98 				   "allocate a response buffer\n");
99 			return -ENOMEM;
100 		}
101 		spin_lock_irqsave(&cpcmd_lock, flags);
102 		len = __cpcmd(cmd, lowbuf, rlen, response_code);
103 		spin_unlock_irqrestore(&cpcmd_lock, flags);
104 		memcpy(response, lowbuf, rlen);
105 		kfree(lowbuf);
106 	} else {
107 		spin_lock_irqsave(&cpcmd_lock, flags);
108 		len = __cpcmd(cmd, response, rlen, response_code);
109 		spin_unlock_irqrestore(&cpcmd_lock, flags);
110 	}
111 	return len;
112 }
113 EXPORT_SYMBOL(cpcmd);
114