From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Lucas De Marchi <lucas.de.marchi@gmail.com>
Cc: Matthias Maennich <maennich@google.com>,
lkml <linux-kernel@vger.kernel.org>,
"Cc: Android Kernel" <kernel-team@android.com>,
Stefan Wahren <stefan.wahren@i2se.com>,
Jessica Yu <jeyu@kernel.org>, Martijn Coenen <maco@android.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-modules <linux-modules@vger.kernel.org>
Subject: Re: [PATCH] depmod: create and use System.map.no_namespaces
Date: Sat, 5 Oct 2019 16:53:56 +0900 [thread overview]
Message-ID: <CAK7LNAQ10xCm52PrgUvE=Z+d4BabuATSRpw+kL9Xm=O-ik_Duw@mail.gmail.com> (raw)
In-Reply-To: <CAKi4VALPF7r25SJ+9jazeRz612pv_4MmhjOsJ8aumW_JO29VvA@mail.gmail.com>
On Sat, Oct 5, 2019 at 3:25 AM Lucas De Marchi
<lucas.de.marchi@gmail.com> wrote:
>
> On Fri, Oct 4, 2019 at 2:57 AM Matthias Maennich <maennich@google.com> wrote:
> >
> > depmod in its current version is not aware of symbol namespace in
> > ksymtab entries introduced with 8651ec01daed ("module: add support for
> > symbol namespaces."). They have the form
> >
> > __ksymtab_NAMESPACE.symbol_name
> >
> > A fix for kmod's depmod has been proposed [1]. In order to support older
> > versions of depmod as well, create a System.map.no_namespaces during
> > scripts/depmod.sh that has the pre-namespaces format. That way users do
> > not immediately upgrade the userspace tool.
> >
> > [1] https://lore.kernel.org/linux-modules/20191004094136.166621-1-maennich@google.com/
> >
> > Reported-by: Stefan Wahren <stefan.wahren@i2se.com>
> > Fixes: 8651ec01daed ("module: add support for symbol namespaces.")
> > Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> > Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
> > Cc: Jessica Yu <jeyu@kernel.org>
> > Cc: Martijn Coenen <maco@android.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: linux-modules@vger.kernel.org
> > Signed-off-by: Matthias Maennich <maennich@google.com>
> > ---
> >
> > Please note this depends on the new ksymtab entry format proposed in
> > https://lore.kernel.org/lkml/20191003075826.7478-2-yamada.masahiro@socionext.com/
>
> I don't really agree with that thought, more below.
>
> >
> > That is likely to be merged soon as well as it fixes problems in 5.4-rc*, hence
> > this patch depends on it.
> >
> > Cheers,
> > Matthias
> >
> > .gitignore | 1 +
> > scripts/depmod.sh | 8 +++++++-
> > 2 files changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/.gitignore b/.gitignore
> > index 70580bdd352c..5ed58a7cb433 100644
> > --- a/.gitignore
> > +++ b/.gitignore
> > @@ -59,6 +59,7 @@ modules.order
> > /vmlinux-gdb.py
> > /vmlinuz
> > /System.map
> > +/System.map.no_namespaces
> > /Module.markers
> > /modules.builtin.modinfo
> >
> > diff --git a/scripts/depmod.sh b/scripts/depmod.sh
> > index e083bcae343f..602e1af072c7 100755
> > --- a/scripts/depmod.sh
> > +++ b/scripts/depmod.sh
> > @@ -39,7 +39,13 @@ if $depmod_hack_needed; then
> > KERNELRELEASE=99.98.$KERNELRELEASE
> > fi
> >
> > -set -- -ae -F System.map
> > +# Older versions of depmod do not support symbol namespaces in ksymtab entries,
> > +# hence create an alternative System.map with namespace patched out to use for
> > +# depmod. I.e. transform entries as follows:
> > +# __ksymtab_NAMESPACE.symbol_name -> __ksymtab_symbol_name
> > +sed 's/__ksymtab_.*\./__ksymtab_/' System.map > System.map.no_namespaces
>
> So people with old kmod will have to know they need to pass
> System.map.no_namespaces rather than the usual
> System.map. Also, distros will need to be update to also copy the new
> file to the kernel package (or upgrade/patch kmod).
>
> I'd rather maintain the current format and fix the bug that patch is
> fixing. The namespace
> in the end IMO is just a small annoyance with a reason to exist.
I agree, this fix is bad.
We should not bother kmod or any tools.
And System.map.no_namespaces is a cheesy workaround.
BTW, I expressed my negative opinion in the review process
for the patch set. I am still not convinced with the
namespace feature, but anyway it was merged
(with poor review and test).
Get back on track, probably the right fix would be to
stop using __ksymtab_<namespace>.<symbol>.
It is not used for any purposes but passing
<namespace> / <symbol> pairs to modpost.
For example, __kstrtabns_##sym points to
the namespace string, so it would be possible
to parse it from modpost?
Then, asm("__ksymtab_" #ns NS_SEPARATOR #sym)
will go away.
Masahiro
> Lucas De Marchi
>
> > +
> > +set -- -ae -F System.map.no_namespaces
> > if test -n "$INSTALL_MOD_PATH"; then
> > set -- "$@" -b "$INSTALL_MOD_PATH"
> > fi
> > --
> > 2.23.0.581.g78d2f28ef7-goog
> >
>
>
> --
> Lucas De Marchi
--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2019-10-05 7:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190917231031.81341-1-maennich@google.com>
2019-10-04 9:57 ` [PATCH] depmod: create and use System.map.no_namespaces Matthias Maennich
2019-10-04 18:25 ` Lucas De Marchi
2019-10-05 7:53 ` Masahiro Yamada [this message]
2019-10-07 6:46 ` Matthias Maennich
2019-10-07 11:25 ` Jessica Yu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAK7LNAQ10xCm52PrgUvE=Z+d4BabuATSRpw+kL9Xm=O-ik_Duw@mail.gmail.com' \
--to=yamada.masahiro@socionext.com \
--cc=gregkh@linuxfoundation.org \
--cc=jeyu@kernel.org \
--cc=kernel-team@android.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-modules@vger.kernel.org \
--cc=lucas.de.marchi@gmail.com \
--cc=maco@android.com \
--cc=maennich@google.com \
--cc=stefan.wahren@i2se.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).