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Postings from July 2012
Father,
I do not know if it is OK to reply to perlbug-followup@perl.org,
so I CC'ed you explicitly.
On 07/04, Father Chrysostomos via RT wrote:
>
> I don’t supposed it’s possible to
> write an automated test for this, is it?
Well, please see below. Not sure it is the best...
So. The test-case assumes 64-bit linux, otherwise it won't work.
It exploits the fact that vdso is mmapped at "high" address which
can't fit in I32.
It does mremap(vdso_addr, 1, 1, 0) which is "nop" but should return
the original address.
Btw, "-w" complains:
Hexadecimal number > 0xffffffff non-portable at ...
a bit annoying on 64-bit systems... Not sure why Perl_grok_hex()
thinks this is not portable.
Oleg.
-------------------------------------------------------------------
#!/usr/bin/perl -w
use strict;
sub find_vdso()
{
open my $maps, '<', '/proc/self/maps' or die;
/^(.*?)-.*\[vdso\]$/ and return hex $1 for <$maps>;
}
my $vdso_addr = find_vdso || die 'not 64-bit linux?';
my $ret = syscall 25, # __NR_mremap
$vdso_addr, # old_addr
1, # old_len
1, # new_len
0, # flags
0; # new_addr (unused)
$ret == $vdso_addr or die "FAILED\n";
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