com32/sysdump/dmi.c

   1 /*
   2  * Dump DMI information in a way hopefully compatible with dmidecode
   3  */
   4
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <stdlib.h>
   8 #include "sysdump.h"
   9 #include "backend.h"
  10
  11 struct dmi_header {
  12     char signature[5];
  13     uint8_t csum;
  14     uint16_t tbllen;
  15     uint32_t tbladdr;
  16     uint16_t nstruc;
  17     uint8_t revision;
  18     uint8_t reserved;
  19 };
  20
  21 struct smbios_header {
  22     char signature[4];
  23     uint8_t csum;
  24     uint8_t len;
  25     uint8_t major;
  26     uint8_t minor;
  27     uint16_t maxsize;
  28     uint8_t revision;
  29     uint8_t fmt[5];
  30
  31     struct dmi_header dmi;
  32 };
  33
  34 static uint8_t checksum(const void *buf, size_t len)
  35 {
  36     const uint8_t *p = buf;
  37     uint8_t csum = 0;
  38
  39     while (len--)
  40         csum += *p++;
  41
  42     return csum;
  43 }
  44
  45 static bool is_old_dmi(size_t dptr)
  46 {
  47     const struct dmi_header *dmi = (void *)dptr;
  48
  49     return !memcmp(dmi->signature, "_DMI_", 5) &&
  50         !checksum(dmi, 0x0f);
  51     return false;
  52 }
  53
  54 static bool is_smbios(size_t dptr)
  55 {
  56     const struct smbios_header *smb = (void *)dptr;
  57
  58     return !memcmp(smb->signature, "_SM_", 4) &&
  59         !checksum(smb, smb->len) &&
  60         is_old_dmi(dptr+16);
  61 }
  62
  63 static void dump_smbios(struct backend *be, size_t dptr)
  64 {
  65     const struct smbios_header *smb = (void *)dptr;
  66     struct smbios_header smx = *smb;
  67     char filename[32];
  68
  69     snprintf(filename, sizeof filename, "dmi/%05x.%08x",
  70              dptr, smb->dmi.tbladdr);
  71     cpio_hdr(be, MODE_FILE, smb->dmi.tbllen + 32, filename);
  72
  73     /*
  74      * Adjust the address of the smbios table to be 32, to
  75      * make dmidecode happy.  The checksum on the smbios table is unchanged,
  76      * since it includes the checksum on the dmi table.
  77      */
  78     smx.dmi.tbladdr = sizeof smx;
  79     smx.dmi.csum -= checksum(&smx.dmi, 0x0f);
  80
  81     write_data(be, &smx, sizeof smx);
  82     write_data(be, (const void *)smb->dmi.tbladdr, smb->dmi.tbllen);
  83 }
  84
  85 static void dump_old_dmi(struct backend *be, size_t dptr)
  86 {
  87     const struct dmi_header *dmi = (void *)dptr;
  88     struct fake {
  89         struct dmi_header dmi;
  90         char pad[16];
  91     } fake;
  92     char filename[32];
  93
  94     snprintf(filename, sizeof filename, "dmi/%05x.%08x",
  95              dptr, dmi->tbladdr);
  96     cpio_hdr(be, MODE_FILE, dmi->tbllen + 32, filename);
  97
  98     /*
  99      * Adjust the address of the smbios table to be 32, to
 100      * make dmidecode happy.
 101      */
 102     fake.dmi = *dmi;
 103     memset(&fake.pad, 0, sizeof fake.pad);
 104     fake.dmi.tbladdr = sizeof fake;
 105     fake.dmi.csum -= checksum(&fake.dmi, 0x0f);
 106
 107     write_data(be, &fake, sizeof fake);
 108     write_data(be, (const void *)dmi->tbladdr, dmi->tbllen);
 109 }
 110
 111 void dump_dmi(struct backend *be)
 112 {
 113     size_t dptr;
 114
 115     cpio_mkdir(be, "dmi");
 116
 117     /* Search for _SM_ or _DMI_ structure */
 118     for (dptr = 0xf0000 ; dptr < 0x100000 ; dptr += 16) {
 119         if (is_smbios(dptr)) {
 120             dump_smbios(be, dptr);
 121             dptr += 16;         /* Skip the subsequent DMI header */
 122         } else if (is_old_dmi(dptr)) {
 123             dump_old_dmi(be, dptr);
 124         }
 125     }
 126 }