arch/s390/kernel/cpcmd.c

   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/diag.h>
  18 #include <asm/ebcdic.h>
  19 #include <asm/cpcmd.h>
  20 #include <asm/io.h>
  21
  22 static DEFINE_SPINLOCK(cpcmd_lock);
  23 static char cpcmd_buf[241];
  24
  25 static int diag8_noresponse(int cmdlen)
  26 {
  27         register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
  28         register unsigned long reg3 asm ("3") = cmdlen;
  29
  30         asm volatile(
  31                 "       sam31\n"
  32                 "       diag    %1,%0,0x8\n"
  33                 "       sam64\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                 "       sam31\n"
  47                 "       diag    %2,%0,0x8\n"
  48                 "       sam64\n"
  49                 "       brc     8,1f\n"
  50                 "       agr     %1,%4\n"
  51                 "1:\n"
  52                 : "+d" (reg4), "+d" (reg5)
  53                 : "d" (reg2), "d" (reg3), "d" (*rlen) : "cc");
  54         *rlen = reg5;
  55         return reg4;
  56 }
  57
  58 /*
  59  * __cpcmd has some restrictions over cpcmd
  60  *  - the response buffer must reside below 2GB (if any)
  61  *  - __cpcmd is unlocked and therefore not SMP-safe
  62  */
  63 int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
  64 {
  65         int cmdlen;
  66         int rc;
  67         int response_len;
  68
  69         cmdlen = strlen(cmd);
  70         BUG_ON(cmdlen > 240);
  71         memcpy(cpcmd_buf, cmd, cmdlen);
  72         ASCEBC(cpcmd_buf, cmdlen);
  73
  74         diag_stat_inc(DIAG_STAT_X008);
  75         if (response) {
  76                 memset(response, 0, rlen);
  77                 response_len = rlen;
  78                 rc = diag8_response(cmdlen, response, &rlen);
  79                 EBCASC(response, response_len);
  80         } else {
  81                 rc = diag8_noresponse(cmdlen);
  82         }
  83         if (response_code)
  84                 *response_code = rc;
  85         return rlen;
  86 }
  87 EXPORT_SYMBOL(__cpcmd);
  88
  89 int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
  90 {
  91         char *lowbuf;
  92         int len;
  93         unsigned long flags;
  94
  95         if ((virt_to_phys(response) != (unsigned long) response) ||
  96                         (((unsigned long)response + rlen) >> 31)) {
  97                 lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);
  98                 if (!lowbuf) {
  99                         pr_warn("The cpcmd kernel function failed to allocate a response buffer\n");
 100                         return -ENOMEM;
 101                 }
 102                 spin_lock_irqsave(&cpcmd_lock, flags);
 103                 len = __cpcmd(cmd, lowbuf, rlen, response_code);
 104                 spin_unlock_irqrestore(&cpcmd_lock, flags);
 105                 memcpy(response, lowbuf, rlen);
 106                 kfree(lowbuf);
 107         } else {
 108                 spin_lock_irqsave(&cpcmd_lock, flags);
 109                 len = __cpcmd(cmd, response, rlen, response_code);
 110                 spin_unlock_irqrestore(&cpcmd_lock, flags);
 111         }
 112         return len;
 113 }
 114 EXPORT_SYMBOL(cpcmd);