lib/check_signature.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/io.h>
   3 #include <linux/export.h>
   4
   5 /**
   6  *      check_signature         -       find BIOS signatures
   7  *      @io_addr: mmio address to check
   8  *      @signature:  signature block
   9  *      @length: length of signature
  10  *
  11  *      Perform a signature comparison with the mmio address io_addr. This
  12  *      address should have been obtained by ioremap.
  13  *      Returns 1 on a match.
  14  */
  15
  16 int check_signature(const volatile void __iomem *io_addr,
  17                         const unsigned char *signature, int length)
  18 {
  19         while (length--) {
  20                 if (readb(io_addr) != *signature)
  21                         return 0;
  22                 io_addr++;
  23                 signature++;
  24         }
  25         return 1;
  26 }
  27 EXPORT_SYMBOL(check_signature);