Commit 6d760133 authored by Roland McGrath's avatar Roland McGrath Committed by Linus Torvalds
Browse files

Add /sys/module/name/notes 



This patch adds the /sys/module/<name>/notes/ magic directory, which has a
file for each allocated SHT_NOTE section that appears in <name>.ko.  This
is the counterpart for each module of /sys/kernel/notes for vmlinux.
Reading this delivers the contents of the module's SHT_NOTE sections.  This
lets userland easily glean any detailed information about that module's
build that was stored there at compile time (e.g.  by ld --build-id).

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ae0b78d0

include/linux/module.h

+3 −0
Original line number Diff line number Diff line
@@ -343,6 +343,9 @@ struct module 


	/* Section attributes */

	struct module_sect_attrs *sect_attrs;



	/* Notes attributes */

	struct module_notes_attrs *notes_attrs;

#endif



	/* Per-cpu data. */

kernel/module.c

+106 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/moduleloader.h>

#include <linux/init.h>

#include <linux/kallsyms.h>

#include <linux/sysfs.h>

#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>
@@ -1047,6 +1048,100 @@ static void remove_sect_attrs(struct module *mod) 
	}

}



/*

 * /sys/module/foo/notes/.section.name gives contents of SHT_NOTE sections.

 */



struct module_notes_attrs {

	struct kobject *dir;

	unsigned int notes;

	struct bin_attribute attrs[0];

};



static ssize_t module_notes_read(struct kobject *kobj,

				 struct bin_attribute *bin_attr,

				 char *buf, loff_t pos, size_t count)

{

	/*

	 * The caller checked the pos and count against our size.

	 */

	memcpy(buf, bin_attr->private + pos, count);

	return count;

}



static void free_notes_attrs(struct module_notes_attrs *notes_attrs,

			     unsigned int i)

{

	if (notes_attrs->dir) {

		while (i-- > 0)

			sysfs_remove_bin_file(notes_attrs->dir,

					      &notes_attrs->attrs[i]);

		kobject_del(notes_attrs->dir);

	}

	kfree(notes_attrs);

}



static void add_notes_attrs(struct module *mod, unsigned int nsect,

			    char *secstrings, Elf_Shdr *sechdrs)

{

	unsigned int notes, loaded, i;

	struct module_notes_attrs *notes_attrs;

	struct bin_attribute *nattr;



	/* Count notes sections and allocate structures.  */

	notes = 0;

	for (i = 0; i < nsect; i++)

		if ((sechdrs[i].sh_flags & SHF_ALLOC) &&

		    (sechdrs[i].sh_type == SHT_NOTE))

			++notes;



	if (notes == 0)

		return;



	notes_attrs = kzalloc(sizeof(*notes_attrs)

			      + notes * sizeof(notes_attrs->attrs[0]),

			      GFP_KERNEL);

	if (notes_attrs == NULL)

		return;



	notes_attrs->notes = notes;

	nattr = &notes_attrs->attrs[0];

	for (loaded = i = 0; i < nsect; ++i) {

		if (!(sechdrs[i].sh_flags & SHF_ALLOC))

			continue;

		if (sechdrs[i].sh_type == SHT_NOTE) {

			nattr->attr.name = mod->sect_attrs->attrs[loaded].name;

			nattr->attr.mode = S_IRUGO;

			nattr->size = sechdrs[i].sh_size;

			nattr->private = (void *) sechdrs[i].sh_addr;

			nattr->read = module_notes_read;

			++nattr;

		}

		++loaded;

	}



	notes_attrs->dir = kobject_add_dir(&mod->mkobj.kobj, "notes");

	if (!notes_attrs->dir)

		goto out;



	for (i = 0; i < notes; ++i)

		if (sysfs_create_bin_file(notes_attrs->dir,

					  &notes_attrs->attrs[i]))

			goto out;



	mod->notes_attrs = notes_attrs;

	return;



  out:

	free_notes_attrs(notes_attrs, i);

}



static void remove_notes_attrs(struct module *mod)

{

	if (mod->notes_attrs)

		free_notes_attrs(mod->notes_attrs, mod->notes_attrs->notes);

}



#else



static inline void add_sect_attrs(struct module *mod, unsigned int nsect,
@@ -1057,6 +1152,15 @@ static inline void add_sect_attrs(struct module *mod, unsigned int nsect, 
static inline void remove_sect_attrs(struct module *mod)

{

}



static inline void add_notes_attrs(struct module *mod, unsigned int nsect,

				   char *sectstrings, Elf_Shdr *sechdrs)

{

}



static inline void remove_notes_attrs(struct module *mod)

{

}

#endif /* CONFIG_KALLSYMS */



#ifdef CONFIG_SYSFS
@@ -1191,6 +1295,7 @@ static void free_module(struct module *mod) 
{

	/* Delete from various lists */

	stop_machine_run(__unlink_module, mod, NR_CPUS);

	remove_notes_attrs(mod);

	remove_sect_attrs(mod);

	mod_kobject_remove(mod);
@@ -1918,6 +2023,7 @@ static struct module *load_module(void __user *umod, 
	if (err < 0)

		goto arch_cleanup;

	add_sect_attrs(mod, hdr->e_shnum, secstrings, sechdrs);

	add_notes_attrs(mod, hdr->e_shnum, secstrings, sechdrs);



	/* Size of section 0 is 0, so this works well if no unwind info. */

	mod->unwind_info = unwind_add_table(mod,

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