arch/x86/kernel/cpu/microcode/intel_lib.c

   1 /*
   2  *      Intel CPU Microcode Update Driver for Linux
   3  *
   4  *      Copyright (C) 2012 Fenghua Yu <fenghua.yu@intel.com>
   5  *                         H Peter Anvin" <hpa@zytor.com>
   6  *
   7  *      This driver allows to upgrade microcode on Intel processors
   8  *      belonging to IA-32 family - PentiumPro, Pentium II,
   9  *      Pentium III, Xeon, Pentium 4, etc.
  10  *
  11  *      Reference: Section 8.11 of Volume 3a, IA-32 Intel? Architecture
  12  *      Software Developer's Manual
  13  *      Order Number 253668 or free download from:
  14  *
  15  *      http://developer.intel.com/Assets/PDF/manual/253668.pdf
  16  *
  17  *      For more information, go to http://www.urbanmyth.org/microcode
  18  *
  19  *      This program is free software; you can redistribute it and/or
  20  *      modify it under the terms of the GNU General Public License
  21  *      as published by the Free Software Foundation; either version
  22  *      2 of the License, or (at your option) any later version.
  23  *
  24  */
  25 #include <linux/firmware.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/kernel.h>
  28
  29 #include <asm/microcode_intel.h>
  30 #include <asm/processor.h>
  31 #include <asm/msr.h>
  32
  33 static inline bool cpu_signatures_match(unsigned int s1, unsigned int p1,
  34                                         unsigned int s2, unsigned int p2)
  35 {
  36         if (s1 != s2)
  37                 return false;
  38
  39         /* Processor flags are either both 0 ... */
  40         if (!p1 && !p2)
  41                 return true;
  42
  43         /* ... or they intersect. */
  44         return p1 & p2;
  45 }
  46
  47 int microcode_sanity_check(void *mc, int print_err)
  48 {
  49         unsigned long total_size, data_size, ext_table_size;
  50         struct microcode_header_intel *mc_header = mc;
  51         struct extended_sigtable *ext_header = NULL;
  52         u32 sum, orig_sum, ext_sigcount = 0, i;
  53         struct extended_signature *ext_sig;
  54
  55         total_size = get_totalsize(mc_header);
  56         data_size = get_datasize(mc_header);
  57
  58         if (data_size + MC_HEADER_SIZE > total_size) {
  59                 if (print_err)
  60                         pr_err("Error: bad microcode data file size.\n");
  61                 return -EINVAL;
  62         }
  63
  64         if (mc_header->ldrver != 1 || mc_header->hdrver != 1) {
  65                 if (print_err)
  66                         pr_err("Error: invalid/unknown microcode update format.\n");
  67                 return -EINVAL;
  68         }
  69
  70         ext_table_size = total_size - (MC_HEADER_SIZE + data_size);
  71         if (ext_table_size) {
  72                 u32 ext_table_sum = 0;
  73                 u32 *ext_tablep;
  74
  75                 if ((ext_table_size < EXT_HEADER_SIZE)
  76                  || ((ext_table_size - EXT_HEADER_SIZE) % EXT_SIGNATURE_SIZE)) {
  77                         if (print_err)
  78                                 pr_err("Error: truncated extended signature table.\n");
  79                         return -EINVAL;
  80                 }
  81
  82                 ext_header = mc + MC_HEADER_SIZE + data_size;
  83                 if (ext_table_size != exttable_size(ext_header)) {
  84                         if (print_err)
  85                                 pr_err("Error: extended signature table size mismatch.\n");
  86                         return -EFAULT;
  87                 }
  88
  89                 ext_sigcount = ext_header->count;
  90
  91                 /*
  92                  * Check extended table checksum: the sum of all dwords that
  93                  * comprise a valid table must be 0.
  94                  */
  95                 ext_tablep = (u32 *)ext_header;
  96
  97                 i = ext_table_size / sizeof(u32);
  98                 while (i--)
  99                         ext_table_sum += ext_tablep[i];
 100
 101                 if (ext_table_sum) {
 102                         if (print_err)
 103                                 pr_warn("Bad extended signature table checksum, aborting.\n");
 104                         return -EINVAL;
 105                 }
 106         }
 107
 108         /*
 109          * Calculate the checksum of update data and header. The checksum of
 110          * valid update data and header including the extended signature table
 111          * must be 0.
 112          */
 113         orig_sum = 0;
 114         i = (MC_HEADER_SIZE + data_size) / sizeof(u32);
 115         while (i--)
 116                 orig_sum += ((u32 *)mc)[i];
 117
 118         if (orig_sum) {
 119                 if (print_err)
 120                         pr_err("Bad microcode data checksum, aborting.\n");
 121                 return -EINVAL;
 122         }
 123
 124         if (!ext_table_size)
 125                 return 0;
 126
 127         /*
 128          * Check extended signature checksum: 0 => valid.
 129          */
 130         for (i = 0; i < ext_sigcount; i++) {
 131                 ext_sig = (void *)ext_header + EXT_HEADER_SIZE +
 132                           EXT_SIGNATURE_SIZE * i;
 133
 134                 sum = (mc_header->sig + mc_header->pf + mc_header->cksum) -
 135                       (ext_sig->sig + ext_sig->pf + ext_sig->cksum);
 136                 if (sum) {
 137                         if (print_err)
 138                                 pr_err("Bad extended signature checksum, aborting.\n");
 139                         return -EINVAL;
 140                 }
 141         }
 142         return 0;
 143 }
 144 EXPORT_SYMBOL_GPL(microcode_sanity_check);
 145
 146 /*
 147  * Returns 1 if update has been found, 0 otherwise.
 148  */
 149 int find_matching_signature(void *mc, unsigned int csig, int cpf)
 150 {
 151         struct microcode_header_intel *mc_hdr = mc;
 152         struct extended_sigtable *ext_hdr;
 153         struct extended_signature *ext_sig;
 154         int i;
 155
 156         if (cpu_signatures_match(csig, cpf, mc_hdr->sig, mc_hdr->pf))
 157                 return 1;
 158
 159         /* Look for ext. headers: */
 160         if (get_totalsize(mc_hdr) <= get_datasize(mc_hdr) + MC_HEADER_SIZE)
 161                 return 0;
 162
 163         ext_hdr = mc + get_datasize(mc_hdr) + MC_HEADER_SIZE;
 164         ext_sig = (void *)ext_hdr + EXT_HEADER_SIZE;
 165
 166         for (i = 0; i < ext_hdr->count; i++) {
 167                 if (cpu_signatures_match(csig, cpf, ext_sig->sig, ext_sig->pf))
 168                         return 1;
 169                 ext_sig++;
 170         }
 171         return 0;
 172 }
 173
 174 /*
 175  * Returns 1 if update has been found, 0 otherwise.
 176  */
 177 int has_newer_microcode(void *mc, unsigned int csig, int cpf, int new_rev)
 178 {
 179         struct microcode_header_intel *mc_hdr = mc;
 180
 181         if (mc_hdr->rev <= new_rev)
 182                 return 0;
 183
 184         return find_matching_signature(mc, csig, cpf);
 185 }
 186 EXPORT_SYMBOL_GPL(has_newer_microcode);