[v3] kheaders: Move from proc to sysfs
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Message ID 20190506013456.86061-1-joel@joelfernandes.org
State New
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  • [v3] kheaders: Move from proc to sysfs
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Commit Message

Joel Fernandes May 6, 2019, 1:34 a.m. UTC
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/

v2->v3: Fixed sysfs file mode nit (Greg).
v1->v2: Fixed some kconfig nits.

 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%)

Comments

Masahiro Yamada May 8, 2019, 3:43 a.m. UTC | #1
On Mon, May 6, 2019 at 10:37 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/
>
> v2->v3: Fixed sysfs file mode nit (Greg).
> v1->v2: Fixed some kconfig nits.
>
>  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"


I suggested "depends on SYSFS" twice, both in v1 and v2.

https://lore.kernel.org/patchwork/patch/1069806/#1266147
https://lore.kernel.org/patchwork/patch/1070005/#1266279



> +       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
> +         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)"
Joel Fernandes May 9, 2019, 10:47 p.m. UTC | #2
On Wed, May 08, 2019 at 12:43:34PM +0900, Masahiro Yamada wrote:
> On Mon, May 6, 2019 at 10:37 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/
> >
> > v2->v3: Fixed sysfs file mode nit (Greg).
> > v1->v2: Fixed some kconfig nits.
> >
> >  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"
> 
> 
> I suggested "depends on SYSFS" twice, both in v1 and v2.
> 
> https://lore.kernel.org/patchwork/patch/1069806/#1266147
> https://lore.kernel.org/patchwork/patch/1070005/#1266279

Sorry about missing that. I have made a note of this, and can address it in a
later patch. There is a more pressing issue with allmodconfig regression
times so I will look into that first. Also a vacation is taking up some of my
time.

Needless to say I will get to it soon and the point has been duly noted!

thanks,

 - Joel

Patch
diff mbox series

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"
+	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
+	  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..8f69772af77b 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 = 0444,
+	},
+	.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);