xref: /openbmc/linux/arch/s390/kernel/cpcmd.c (revision 09c434b8)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  S390 version
4  *    Copyright IBM Corp. 1999, 2007
5  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
6  *               Christian Borntraeger (cborntra@de.ibm.com),
7  */
8 
9 #define KMSG_COMPONENT "cpcmd"
10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
11 
12 #include <linux/kernel.h>
13 #include <linux/export.h>
14 #include <linux/slab.h>
15 #include <linux/spinlock.h>
16 #include <linux/stddef.h>
17 #include <linux/string.h>
18 #include <linux/mm.h>
19 #include <asm/diag.h>
20 #include <asm/ebcdic.h>
21 #include <asm/cpcmd.h>
22 #include <asm/io.h>
23 
24 static DEFINE_SPINLOCK(cpcmd_lock);
25 static char cpcmd_buf[241];
26 
27 static 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 		"	diag	%1,%0,0x8\n"
34 		: "+d" (reg3) : "d" (reg2) : "cc");
35 	return reg3;
36 }
37 
38 static int diag8_response(int cmdlen, char *response, int *rlen)
39 {
40 	register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
41 	register unsigned long reg3 asm ("3") = (addr_t) response;
42 	register unsigned long reg4 asm ("4") = cmdlen | 0x40000000L;
43 	register unsigned long reg5 asm ("5") = *rlen;
44 
45 	asm volatile(
46 		"	diag	%2,%0,0x8\n"
47 		"	brc	8,1f\n"
48 		"	agr	%1,%4\n"
49 		"1:\n"
50 		: "+d" (reg4), "+d" (reg5)
51 		: "d" (reg2), "d" (reg3), "d" (*rlen) : "cc");
52 	*rlen = reg5;
53 	return reg4;
54 }
55 
56 /*
57  * __cpcmd has some restrictions over cpcmd
58  *  - __cpcmd is unlocked and therefore not SMP-safe
59  */
60 int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
61 {
62 	int cmdlen;
63 	int rc;
64 	int response_len;
65 
66 	cmdlen = strlen(cmd);
67 	BUG_ON(cmdlen > 240);
68 	memcpy(cpcmd_buf, cmd, cmdlen);
69 	ASCEBC(cpcmd_buf, cmdlen);
70 
71 	diag_stat_inc(DIAG_STAT_X008);
72 	if (response) {
73 		memset(response, 0, rlen);
74 		response_len = rlen;
75 		rc = diag8_response(cmdlen, response, &rlen);
76 		EBCASC(response, response_len);
77         } else {
78 		rc = diag8_noresponse(cmdlen);
79         }
80 	if (response_code)
81 		*response_code = rc;
82 	return rlen;
83 }
84 EXPORT_SYMBOL(__cpcmd);
85 
86 int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
87 {
88 	unsigned long flags;
89 	char *lowbuf;
90 	int len;
91 
92 	if (is_vmalloc_or_module_addr(response)) {
93 		lowbuf = kmalloc(rlen, GFP_KERNEL);
94 		if (!lowbuf) {
95 			pr_warn("The cpcmd kernel function failed to allocate a response buffer\n");
96 			return -ENOMEM;
97 		}
98 		spin_lock_irqsave(&cpcmd_lock, flags);
99 		len = __cpcmd(cmd, lowbuf, rlen, response_code);
100 		spin_unlock_irqrestore(&cpcmd_lock, flags);
101 		memcpy(response, lowbuf, rlen);
102 		kfree(lowbuf);
103 	} else {
104 		spin_lock_irqsave(&cpcmd_lock, flags);
105 		len = __cpcmd(cmd, response, rlen, response_code);
106 		spin_unlock_irqrestore(&cpcmd_lock, flags);
107 	}
108 	return len;
109 }
110 EXPORT_SYMBOL(cpcmd);
111