root/lib/check_signature.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/io.h>
#include <linux/export.h>

/**
 *      check_signature         -       find BIOS signatures
 *      @io_addr: mmio address to check
 *      @signature:  signature block
 *      @length: length of signature
 *
 *      Perform a signature comparison with the mmio address io_addr. This
 *      address should have been obtained by ioremap.
 *      Returns 1 on a match.
 */

int check_signature(const volatile void __iomem *io_addr,
                        const unsigned char *signature, int length)
{
        while (length--) {
                if (readb(io_addr) != *signature)
                        return 0;
                io_addr++;
                signature++;
        }
        return 1;
}
EXPORT_SYMBOL(check_signature);