#! perl
use strict;
use warnings;

my ($process) = <DATA>;     # slurp in all the data at once

# Use a look-ahead assertion
while ($process =~ /(0x[0-9a-f]{1,2})(.*?)(?=0x[0-9a-f]{1,2}|\Z)/gi)
{
    my ($hex, $text) = ($1, $2);
    print "Match found: $hex$text\n" if $text =~ /in mmgsdi_evt_cb/;
}

print "Finished\n";

__DATA__
0x0 in mmgsdi_evt_cb mmgsdi X mmgsdi Y 0xd in mmgsdi_evt_cb 0x1a in mmgsdi_evt_cb 0xe in mmgsdi_evt_cb 0xf in mmgsdi_evt_cb mmgsdi Z 0x13 in mmgsdi_evt_cb mmgsdi Z mmgsdi Z