Re: [PATCH v2] kheaders: Move from proc to sysfs
From: Masahiro Yamada
Date: Sat May 04 2019 - 21:51:56 EST
On Sat, May 4, 2019 at 9:26 PM Joel Fernandes (Google)
<joel@xxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxx>
> Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
> ---
> This patch applies on top of the previous patch that was applied to the
> driver tree:
> https://lore.kernel.org/patchwork/patch/1067310/
>
> v1->v2: Fixed some kconfig nits (Masami).
My name is Masahiro, just in case.
>
> init/Kconfig | 16 ++++-----
> kernel/Makefile | 4 +--
> kernel/{gen_ikh_data.sh => gen_kheaders.sh} | 2 +-
> kernel/kheaders.c | 40 +++++++++------------
> 4 files changed, 26 insertions(+), 36 deletions(-)
> rename kernel/{gen_ikh_data.sh => gen_kheaders.sh} (98%)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 26a364a95b57..c3661991b089 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -579,15 +579,13 @@ config IKCONFIG_PROC
> This option enables access to the kernel configuration file
> through /proc/config.gz.
>
> -config IKHEADERS_PROC
> - tristate "Enable kernel header artifacts through /proc/kheaders.tar.xz"
> - depends on PROC_FS
> - help
> - This option enables access to the kernel header and other artifacts that
> - are generated during the build process. These can be used to build eBPF
> - tracing programs, or similar programs. If you build the headers as a
> - module, a module called kheaders.ko is built which can be loaded on-demand
> - to get access to the headers.
> +config IKHEADERS
> + tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
In v1, I suggested to change "depends on PROC_FS"
to "depends on SYSFS".
fs/sysfs/ must be compiled to make this feature work.
> + help
> + This option enables access to the in-kernel headers that are generated during
> + the build process. These can be used to build eBPF tracing programs,
> + or similar programs. If you build the headers as a module, a module called
While you are touching the help,
could you make the number of spaces
between sentences consistent?
Thanks.
> + kheaders.ko is built which can be loaded on-demand to get access to headers.
>
> config LOG_BUF_SHIFT
> int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 12399614c350..b32a558fae2f 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -70,7 +70,7 @@ obj-$(CONFIG_UTS_NS) += utsname.o
> obj-$(CONFIG_USER_NS) += user_namespace.o
> obj-$(CONFIG_PID_NS) += pid_namespace.o
> obj-$(CONFIG_IKCONFIG) += configs.o
> -obj-$(CONFIG_IKHEADERS_PROC) += kheaders.o
> +obj-$(CONFIG_IKHEADERS) += kheaders.o
> obj-$(CONFIG_SMP) += stop_machine.o
> obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
> obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
> @@ -126,7 +126,7 @@ $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE
> $(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz
>
> quiet_cmd_genikh = CHK $(obj)/kheaders_data.tar.xz
> -cmd_genikh = $(srctree)/kernel/gen_ikh_data.sh $@
> +cmd_genikh = $(srctree)/kernel/gen_kheaders.sh $@
> $(obj)/kheaders_data.tar.xz: FORCE
> $(call cmd,genikh)
>
> diff --git a/kernel/gen_ikh_data.sh b/kernel/gen_kheaders.sh
> similarity index 98%
> rename from kernel/gen_ikh_data.sh
> rename to kernel/gen_kheaders.sh
> index 591a94f7b387..581b83534587 100755
> --- a/kernel/gen_ikh_data.sh
> +++ b/kernel/gen_kheaders.sh
> @@ -2,7 +2,7 @@
> # SPDX-License-Identifier: GPL-2.0
>
> # This script generates an archive consisting of kernel headers
> -# for CONFIG_IKHEADERS_PROC.
> +# for CONFIG_IKHEADERS.
> set -e
> spath="$(dirname "$(readlink -f "$0")")"
> kroot="$spath/.."
> 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