Re: ftrace: sorttable unable to sort ELF64 on 32-bit host

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Mar 24, 2025 at 01:39:12PM -0500, Sahil Gupta wrote:
> > > Hi Steven,
> > >
> > > On 6.12.0, sorttable is unable to sort 64-bit ELFs on 32-bit hosts because
> > > of the parsing of the start_mcount_loc and stop_mcount_loc values in
> > > get_mcount_loc():
> > >
> > >   *_start = strtoul(start_buff, NULL, 16);
> > >
> > > and
> > >
> > >  *_stop = strtoul(stop_buff, NULL, 16);
> > >
> > > This code makes the (often correct) assumption that the host and the target
> > > have the same architecture, however it runs into issues when compiling for
> > > a 64-bit target on a 32-bit host, as unsigned long is shorter than the
> > > pointer width. As a result, I've noticed that both start and stop max out
> > > at 2^32 - 1.
> >
> > So this has been broken for some time?
> 
> Since 2021, it seems like. However, this slipped from my radar since
> we've been using 5.10 for the longest time, which didn't have
> CONFIG_BUILDTIME_MCOUNT_SORT.
> 
> > >
> > > It seems that commit 4acda8ed fixes this issue inadvertently by directly
> > > extracting them from the ELF using the correct width. I'm wondering if it
> > > is possible to backport this as well as the other sorttable refactors to
> > > 6.12.0 since they fix this issue.
> >
> > You should ask Greg KH on this.
> 
> Sounds good, tagging Greg.

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>