From 6d76013381ed28979cd122eb4b249a88b5e384fa Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Tue, 16 Oct 2007 23:26:40 -0700 Subject: [PATCH] Add /sys/module/name/notes This patch adds the /sys/module//notes/ magic directory, which has a file for each allocated SHT_NOTE section that appears in .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: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/module.h | 3 ++ kernel/module.c | 106 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 109 insertions(+) diff --git a/include/linux/module.h b/include/linux/module.h index 5523e10fb2f0..642f325e4917 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -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. */ diff --git a/kernel/module.c b/kernel/module.c index 35246a61a7e9..c24c3c35405a 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -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, + ¬es_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 = ¬es_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, + ¬es_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, -- 2.30.2