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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Sat, 4 May 2019 09:21:41 +0900
Message-ID: <CAK7LNASkR7cauvcLprgrTKNv-iY4yjS278FPGJ-UEYTBrANKYw@mail.gmail.com>
Subject: Re: [PATCH] kheaders: Move from proc to sysfs
To:     "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Adrian Ratiu <adrian.ratiu@collabora.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        atish patra <atishp04@gmail.com>, bpf@vger.kernel.org,
        Brendan Gregg <bgregg@netflix.com>,
        Brendan Gregg <brendan.d.gregg@gmail.com>,
        Daniel Colascione <dancol@google.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Dan Williams <dan.j.williams@intel.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        duyuchao <yuchao.du@unisoc.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Guenter Roeck <groeck@chromium.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Karim Yaghmour <karim.yaghmour@opersys.com>,
        Kees Cook <keescook@chromium.org>,
        "Cc: Android Kernel" <kernel-team@android.com>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        linux-trace-devel@vger.kernel.org,
        Manjo Raja Rao <linux@manojrajarao.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        =?UTF-8?Q?Micha=C5=82_Gregorczyk?= <michalgr@fb.com>,
        Michal Gregorczyk <michalgr@live.com>,
        Mohammad Husain <russoue@gmail.com>,
        Olof Johansson <olof@lixom.net>,
        Qais Yousef <qais.yousef@arm.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Shuah Khan <shuah@kernel.org>,
        Srinivas Ramana <sramana@codeaurora.org>,
        Tamir Carmeli <carmeli.tamir@gmail.com>,
        Yonghong Song <yhs@fb.com>
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On Sat, May 4, 2019 at 9:18 AM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> On Sat, May 4, 2019 at 3:27 AM Joel Fernandes (Google)
> <joel@joelfernandes.org> wrote:
> >
> > The kheaders archive consisting of the kernel headers used for compiling
> > bpf programs is in /proc. However there is concern that moving it here
> > will make it permanent. Let us move it to /sys/kernel as discussed [1].
> >
> > [1] https://lore.kernel.org/patchwork/patch/1067310/#1265969
> >
> > Suggested-by: Steven Rostedt <rostedt@goodmis.org>
> > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> > ---
> > This patch applies on top of the previous patch that was applied to the
> > driver tree:
> > https://lore.kernel.org/patchwork/patch/1067310/
> >
> >  kernel/kheaders.c | 40 ++++++++++++++++------------------------
>
>
> Please rename CONFIG_IKHEADERS_PROC.
>
> Thanks.


Please adjust Kconfig prompt.
  tristate "Enable kernel header artifacts through /proc/kheaders.tar.xz"


"depends on PROC_FS"  ->  "depends on SYSFS"


>
>
>
> >  1 file changed, 16 insertions(+), 24 deletions(-)
> >
> > diff --git a/kernel/kheaders.c b/kernel/kheaders.c
> > index 70ae6052920d..6a16f8f6898d 100644
> > --- a/kernel/kheaders.c
> > +++ b/kernel/kheaders.c
> > @@ -8,9 +8,8 @@
> >
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> > -#include <linux/proc_fs.h>
> > +#include <linux/kobject.h>
> >  #include <linux/init.h>
> > -#include <linux/uaccess.h>
> >
> >  /*
> >   * Define kernel_headers_data and kernel_headers_data_end, within which the
> > @@ -31,39 +30,32 @@ extern char kernel_headers_data;
> >  extern char kernel_headers_data_end;
> >
> >  static ssize_t
> > -ikheaders_read_current(struct file *file, char __user *buf,
> > -                     size_t len, loff_t *offset)
> > +ikheaders_read(struct file *file,  struct kobject *kobj,
> > +              struct bin_attribute *bin_attr,
> > +              char *buf, loff_t off, size_t len)
> >  {
> > -       return simple_read_from_buffer(buf, len, offset,
> > -                                      &kernel_headers_data,
> > -                                      &kernel_headers_data_end -
> > -                                      &kernel_headers_data);
> > +       memcpy(buf, &kernel_headers_data + off, len);
> > +       return len;
> >  }
> >
> > -static const struct file_operations ikheaders_file_ops = {
> > -       .read = ikheaders_read_current,
> > -       .llseek = default_llseek,
> > +static struct bin_attribute kheaders_attr __ro_after_init = {
> > +       .attr = {
> > +               .name = "kheaders.tar.xz",
> > +               .mode = S_IRUGO,
> > +       },
> > +       .read = &ikheaders_read,
> >  };
> >
> >  static int __init ikheaders_init(void)
> >  {
> > -       struct proc_dir_entry *entry;
> > -
> > -       /* create the current headers file */
> > -       entry = proc_create("kheaders.tar.xz", S_IRUGO, NULL,
> > -                           &ikheaders_file_ops);
> > -       if (!entry)
> > -               return -ENOMEM;
> > -
> > -       proc_set_size(entry,
> > -                     &kernel_headers_data_end -
> > -                     &kernel_headers_data);
> > -       return 0;
> > +       kheaders_attr.size = (&kernel_headers_data_end -
> > +                             &kernel_headers_data);
> > +       return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);
> >  }
> >
> >  static void __exit ikheaders_cleanup(void)
> >  {
> > -       remove_proc_entry("kheaders.tar.xz", NULL);
> > +       sysfs_remove_bin_file(kernel_kobj, &kheaders_attr);
> >  }
> >
> >  module_init(ikheaders_init);
> > --
> > 2.21.0.1020.gf2820cf01a-goog
>
>
>
> --
> Best Regards
> Masahiro Yamada


-- 
Best Regards
Masahiro Yamada