| Message ID | 20201105045140.2589346-5-andrii@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | Integrate kernel module BTF support | expand |
On Wed, 4 Nov 2020 20:51:39 -0800 Andrii Nakryiko wrote: > Add kernel module listener that will load/validate and unload module BTF. > Module BTFs gets ID generated for them, which makes it possible to iterate > them with existing BTF iteration API. They are given their respective module's > names, which will get reported through GET_OBJ_INFO API. They are also marked > as in-kernel BTFs for tooling to distinguish them from user-provided BTFs. > > Also, similarly to vmlinux BTF, kernel module BTFs are exposed through > sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space > tools to inspect module BTF contents and dump their types with existing tools: Is there any precedent for creating per-module files under a new sysfs directory structure? My intuition would be that these files belong under /sys/module/ Also the CC list on these patches is quite narrow. You should have at least CCed the module maintainer. Adding some folks now. > [vmuser@archvm bpf]$ ls -la /sys/kernel/btf > total 0 > drwxr-xr-x 2 root root 0 Nov 4 19:46 . > drwxr-xr-x 13 root root 0 Nov 4 19:46 .. > > ... > > -r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass > -r--r--r-- 1 root root 100225 Nov 4 19:46 kvm > -r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel > -r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr > -r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw > -r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux > > Signed-off-by: Andrii Nakryiko <andrii@kernel.org> > --- > include/linux/bpf.h | 2 + > include/linux/module.h | 4 + > kernel/bpf/btf.c | 193 +++++++++++++++++++++++++++++++++++++++++ > kernel/bpf/sysfs_btf.c | 2 +- > kernel/module.c | 32 +++++++ > 5 files changed, 232 insertions(+), 1 deletion(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 2fffd30e13ac..3cb89cd7177b 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -36,9 +36,11 @@ struct seq_operations; > struct bpf_iter_aux_info; > struct bpf_local_storage; > struct bpf_local_storage_map; > +struct kobject; > > extern struct idr btf_idr; > extern spinlock_t btf_idr_lock; > +extern struct kobject *btf_kobj; > > typedef int (*bpf_iter_init_seq_priv_t)(void *private_data, > struct bpf_iter_aux_info *aux); > diff --git a/include/linux/module.h b/include/linux/module.h > index a29187f7c360..20fce258ffba 100644 > --- a/include/linux/module.h > +++ b/include/linux/module.h > @@ -475,6 +475,10 @@ struct module { > unsigned int num_bpf_raw_events; > struct bpf_raw_event_map *bpf_raw_events; > #endif > +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES > + unsigned int btf_data_size; > + void *btf_data; > +#endif > #ifdef CONFIG_JUMP_LABEL > struct jump_entry *jump_entries; > unsigned int num_jump_entries; > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index 6a99677e57c0..475d1b95b3d8 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -23,6 +23,8 @@ > #include <linux/perf_event.h> > #include <linux/bsearch.h> > #include <linux/btf_ids.h> > +#include <linux/kobject.h> > +#include <linux/sysfs.h> > #include <net/sock.h> > > /* BTF (BPF Type Format) is the meta data format which describes > @@ -4487,6 +4489,75 @@ struct btf *btf_parse_vmlinux(void) > return ERR_PTR(err); > } > > +static struct btf *btf_parse_module(const char *module_name, const void *data, unsigned int data_size) > +{ > + struct btf_verifier_env *env = NULL; > + struct bpf_verifier_log *log; > + struct btf *btf = NULL, *base_btf; > + int err; > + > + base_btf = bpf_get_btf_vmlinux(); > + if (IS_ERR(base_btf)) > + return base_btf; > + if (!base_btf) > + return ERR_PTR(-EINVAL); > + > + env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN); > + if (!env) > + return ERR_PTR(-ENOMEM); > + > + log = &env->log; > + log->level = BPF_LOG_KERNEL; > + > + btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN); > + if (!btf) { > + err = -ENOMEM; > + goto errout; > + } > + env->btf = btf; > + > + btf->base_btf = base_btf; > + btf->start_id = base_btf->nr_types; > + btf->start_str_off = base_btf->hdr.str_len; > + btf->kernel_btf = true; > + snprintf(btf->name, sizeof(btf->name), "%s", module_name); > + > + btf->data = kvmalloc(data_size, GFP_KERNEL | __GFP_NOWARN); > + if (!btf->data) { > + err = -ENOMEM; > + goto errout; > + } > + memcpy(btf->data, data, data_size); > + btf->data_size = data_size; > + > + err = btf_parse_hdr(env); > + if (err) > + goto errout; > + > + btf->nohdr_data = btf->data + btf->hdr.hdr_len; > + > + err = btf_parse_str_sec(env); > + if (err) > + goto errout; > + > + err = btf_check_all_metas(env); > + if (err) > + goto errout; > + > + btf_verifier_env_free(env); > + refcount_set(&btf->refcnt, 1); > + return btf; > + > +errout: > + btf_verifier_env_free(env); > + if (btf) { > + kvfree(btf->data); > + kvfree(btf->types); > + kfree(btf); > + } > + return ERR_PTR(err); > +} > + > struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog) > { > struct bpf_prog *tgt_prog = prog->aux->dst_prog; > @@ -5660,3 +5731,125 @@ bool btf_id_set_contains(const struct btf_id_set *set, u32 id) > { > return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL; > } > + > +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES > +struct btf_module { > + struct list_head list; > + struct module *module; > + struct btf *btf; > + struct bin_attribute *sysfs_attr; > +}; > + > +static LIST_HEAD(btf_modules); > +static DEFINE_MUTEX(btf_module_mutex); > + > +static ssize_t > +btf_module_read(struct file *file, struct kobject *kobj, > + struct bin_attribute *bin_attr, > + char *buf, loff_t off, size_t len) > +{ > + const struct btf *btf = bin_attr->private; > + > + memcpy(buf, btf->data + off, len); > + return len; > +} > + > +static int btf_module_notify(struct notifier_block *nb, unsigned long op, > + void *module) > +{ > + struct btf_module *btf_mod, *tmp; > + struct module *mod = module; > + struct btf *btf; > + int err = 0; > + > + if (mod->btf_data_size == 0 || > + (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING)) > + goto out; > + > + switch (op) { > + case MODULE_STATE_COMING: > + btf_mod = kzalloc(sizeof(*btf_mod), GFP_KERNEL); > + if (!btf_mod) { > + err = -ENOMEM; > + goto out; > + } > + btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size); > + if (IS_ERR(btf)) { > + kfree(btf_mod); > + err = PTR_ERR(btf); > + goto out; > + } > + err = btf_alloc_id(btf); > + if (err) { > + btf_free(btf); > + kfree(btf_mod); > + goto out; > + } > + > + mutex_lock(&btf_module_mutex); > + btf_mod->module = module; > + btf_mod->btf = btf; > + list_add(&btf_mod->list, &btf_modules); > + mutex_unlock(&btf_module_mutex); > + > + if (IS_ENABLED(CONFIG_SYSFS)) { > + struct bin_attribute *attr; > + > + attr = kzalloc(sizeof(*attr), GFP_KERNEL); > + if (!attr) { > + WARN(1, "failed to register module [%s] BTF in sysfs\n", mod->name); > + goto out; > + } > + > + attr->attr.name = btf->name; > + attr->attr.mode = 0444; > + attr->size = btf->data_size; > + attr->private = btf; > + attr->read = btf_module_read; > + > + err = sysfs_create_bin_file(btf_kobj, attr); > + if (err) { > + kfree(attr); > + WARN(1, "failed to register module [%s] BTF in sysfs: %d\n", > + mod->name, err); > + err = 0; > + goto out; > + } > + > + btf_mod->sysfs_attr = attr; > + } > + > + break; > + case MODULE_STATE_GOING: > + mutex_lock(&btf_module_mutex); > + list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) { > + if (btf_mod->module != module) > + continue; > + > + list_del(&btf_mod->list); > + if (btf_mod->sysfs_attr) > + sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr); > + btf_put(btf_mod->btf); > + kfree(btf_mod->sysfs_attr); > + kfree(btf_mod); > + break; > + } > + mutex_unlock(&btf_module_mutex); > + break; > + } > +out: > + return notifier_from_errno(err); > +} > + > +static struct notifier_block btf_module_nb = { > + .notifier_call = btf_module_notify, > +}; > + > +static int __init btf_module_init(void) > +{ > + register_module_notifier(&btf_module_nb); > + return 0; > +} > + > +fs_initcall(btf_module_init); > +#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */ > diff --git a/kernel/bpf/sysfs_btf.c b/kernel/bpf/sysfs_btf.c > index 11b3380887fa..ef6911aee3bb 100644 > --- a/kernel/bpf/sysfs_btf.c > +++ b/kernel/bpf/sysfs_btf.c > @@ -26,7 +26,7 @@ static struct bin_attribute bin_attr_btf_vmlinux __ro_after_init = { > .read = btf_vmlinux_read, > }; > > -static struct kobject *btf_kobj; > +struct kobject *btf_kobj; > > static int __init btf_vmlinux_init(void) > { > diff --git a/kernel/module.c b/kernel/module.c > index a4fa44a652a7..af71fc53eb25 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -380,6 +380,35 @@ static void *section_objs(const struct load_info *info, > return (void *)info->sechdrs[sec].sh_addr; > } > > +/* Find a module section: 0 means not found. Ignores SHF_ALLOC flag. */ > +static unsigned int find_any_sec(const struct load_info *info, const char *name) > +{ > + unsigned int i; > + > + for (i = 1; i < info->hdr->e_shnum; i++) { > + Elf_Shdr *shdr = &info->sechdrs[i]; > + if (strcmp(info->secstrings + shdr->sh_name, name) == 0) > + return i; > + } > + return 0; > +} > + > +/* > + * Find a module section, or NULL. Fill in number of "objects" in section. > + * Ignores SHF_ALLOC flag. > + */ > +static void *any_section_objs(const struct load_info *info, > + const char *name, > + size_t object_size, > + unsigned int *num) > +{ > + unsigned int sec = find_any_sec(info, name); > + > + /* Section 0 has sh_addr 0 and sh_size 0. */ > + *num = info->sechdrs[sec].sh_size / object_size; > + return (void *)info->sechdrs[sec].sh_addr; > +} > + > /* Provided by the linker */ > extern const struct kernel_symbol __start___ksymtab[]; > extern const struct kernel_symbol __stop___ksymtab[]; > @@ -3250,6 +3279,9 @@ static int find_module_sections(struct module *mod, struct load_info *info) > sizeof(*mod->bpf_raw_events), > &mod->num_bpf_raw_events); > #endif > +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES > + mod->btf_data = any_section_objs(info, ".BTF", 1, &mod->btf_data_size); > +#endif > #ifdef CONFIG_JUMP_LABEL > mod->jump_entries = section_objs(info, "__jump_table", > sizeof(*mod->jump_entries),
On Thu, Nov 05, 2020 at 08:39:25AM -0800, Jakub Kicinski wrote: > On Wed, 4 Nov 2020 20:51:39 -0800 Andrii Nakryiko wrote: > > Add kernel module listener that will load/validate and unload module BTF. > > Module BTFs gets ID generated for them, which makes it possible to iterate > > them with existing BTF iteration API. They are given their respective module's > > names, which will get reported through GET_OBJ_INFO API. They are also marked > > as in-kernel BTFs for tooling to distinguish them from user-provided BTFs. > > > > Also, similarly to vmlinux BTF, kernel module BTFs are exposed through > > sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space > > tools to inspect module BTF contents and dump their types with existing tools: > > Is there any precedent for creating per-module files under a new > sysfs directory structure? My intuition would be that these files > belong under /sys/module/ Ick, why? What's wrong with them under btf? The module core code "owns" the /sys/modules/ tree. If you want others to mess with that, it will get tricky. > Also the CC list on these patches is quite narrow. You should have > at least CCed the module maintainer. Adding some folks now. > > > [vmuser@archvm bpf]$ ls -la /sys/kernel/btf > > total 0 > > drwxr-xr-x 2 root root 0 Nov 4 19:46 . > > drwxr-xr-x 13 root root 0 Nov 4 19:46 .. > > > > ... > > > > -r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass > > -r--r--r-- 1 root root 100225 Nov 4 19:46 kvm > > -r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel > > -r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr > > -r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw > > -r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux > > > > Signed-off-by: Andrii Nakryiko <andrii@kernel.org> > > --- > > include/linux/bpf.h | 2 + > > include/linux/module.h | 4 + > > kernel/bpf/btf.c | 193 +++++++++++++++++++++++++++++++++++++++++ > > kernel/bpf/sysfs_btf.c | 2 +- > > kernel/module.c | 32 +++++++ > > 5 files changed, 232 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > index 2fffd30e13ac..3cb89cd7177b 100644 > > --- a/include/linux/bpf.h > > +++ b/include/linux/bpf.h > > @@ -36,9 +36,11 @@ struct seq_operations; > > struct bpf_iter_aux_info; > > struct bpf_local_storage; > > struct bpf_local_storage_map; > > +struct kobject; > > > > extern struct idr btf_idr; > > extern spinlock_t btf_idr_lock; > > +extern struct kobject *btf_kobj; I don't see any Documentation/ABI/ updates for the sysfs changes here, did I miss it? thanks, greg k-h
On Thu, 5 Nov 2020 17:46:16 +0100 Greg Kroah-Hartman wrote: > On Thu, Nov 05, 2020 at 08:39:25AM -0800, Jakub Kicinski wrote: > > On Wed, 4 Nov 2020 20:51:39 -0800 Andrii Nakryiko wrote: > > > Add kernel module listener that will load/validate and unload module BTF. > > > Module BTFs gets ID generated for them, which makes it possible to iterate > > > them with existing BTF iteration API. They are given their respective module's > > > names, which will get reported through GET_OBJ_INFO API. They are also marked > > > as in-kernel BTFs for tooling to distinguish them from user-provided BTFs. > > > > > > Also, similarly to vmlinux BTF, kernel module BTFs are exposed through > > > sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space > > > tools to inspect module BTF contents and dump their types with existing tools: > > > > Is there any precedent for creating per-module files under a new > > sysfs directory structure? My intuition would be that these files > > belong under /sys/module/ > > Ick, why? What's wrong with them under btf? The module core code > "owns" the /sys/modules/ tree. If you want others to mess with that, > it will get tricky. It's debug info, that's where I would look for it. Clearly I'd be wrong to do so :)
On Thu, Nov 5, 2020 at 8:45 AM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > On Thu, Nov 05, 2020 at 08:39:25AM -0800, Jakub Kicinski wrote: > > On Wed, 4 Nov 2020 20:51:39 -0800 Andrii Nakryiko wrote: > > > Add kernel module listener that will load/validate and unload module BTF. > > > Module BTFs gets ID generated for them, which makes it possible to iterate > > > them with existing BTF iteration API. They are given their respective module's > > > names, which will get reported through GET_OBJ_INFO API. They are also marked > > > as in-kernel BTFs for tooling to distinguish them from user-provided BTFs. > > > > > > Also, similarly to vmlinux BTF, kernel module BTFs are exposed through > > > sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space > > > tools to inspect module BTF contents and dump their types with existing tools: > > > > Is there any precedent for creating per-module files under a new > > sysfs directory structure? My intuition would be that these files > > belong under /sys/module/ > > Ick, why? What's wrong with them under btf? The module core code > "owns" the /sys/modules/ tree. If you want others to mess with that, it > will get tricky. > > > > Also the CC list on these patches is quite narrow. You should have > > at least CCed the module maintainer. Adding some folks now. > > > > > [vmuser@archvm bpf]$ ls -la /sys/kernel/btf > > > total 0 > > > drwxr-xr-x 2 root root 0 Nov 4 19:46 . > > > drwxr-xr-x 13 root root 0 Nov 4 19:46 .. > > > > > > ... > > > > > > -r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass > > > -r--r--r-- 1 root root 100225 Nov 4 19:46 kvm > > > -r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel > > > -r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr > > > -r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw > > > -r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux > > > > > > Signed-off-by: Andrii Nakryiko <andrii@kernel.org> > > > --- > > > include/linux/bpf.h | 2 + > > > include/linux/module.h | 4 + > > > kernel/bpf/btf.c | 193 +++++++++++++++++++++++++++++++++++++++++ > > > kernel/bpf/sysfs_btf.c | 2 +- > > > kernel/module.c | 32 +++++++ > > > 5 files changed, 232 insertions(+), 1 deletion(-) > > > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > > index 2fffd30e13ac..3cb89cd7177b 100644 > > > --- a/include/linux/bpf.h > > > +++ b/include/linux/bpf.h > > > @@ -36,9 +36,11 @@ struct seq_operations; > > > struct bpf_iter_aux_info; > > > struct bpf_local_storage; > > > struct bpf_local_storage_map; > > > +struct kobject; > > > > > > extern struct idr btf_idr; > > > extern spinlock_t btf_idr_lock; > > > +extern struct kobject *btf_kobj; > > I don't see any Documentation/ABI/ updates for the sysfs changes here, > did I miss it? > Nope, my bad, completely forgot to add it. Last time I touched sysfs was quite a while ago, I forgot about adding ABI description. Will add in the next version. > thanks, > > greg k-h
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2fffd30e13ac..3cb89cd7177b 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -36,9 +36,11 @@ struct seq_operations; struct bpf_iter_aux_info; struct bpf_local_storage; struct bpf_local_storage_map; +struct kobject; extern struct idr btf_idr; extern spinlock_t btf_idr_lock; +extern struct kobject *btf_kobj; typedef int (*bpf_iter_init_seq_priv_t)(void *private_data, struct bpf_iter_aux_info *aux); diff --git a/include/linux/module.h b/include/linux/module.h index a29187f7c360..20fce258ffba 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -475,6 +475,10 @@ struct module { unsigned int num_bpf_raw_events; struct bpf_raw_event_map *bpf_raw_events; #endif +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES + unsigned int btf_data_size; + void *btf_data; +#endif #ifdef CONFIG_JUMP_LABEL struct jump_entry *jump_entries; unsigned int num_jump_entries; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6a99677e57c0..475d1b95b3d8 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -23,6 +23,8 @@ #include <linux/perf_event.h> #include <linux/bsearch.h> #include <linux/btf_ids.h> +#include <linux/kobject.h> +#include <linux/sysfs.h> #include <net/sock.h> /* BTF (BPF Type Format) is the meta data format which describes @@ -4487,6 +4489,75 @@ struct btf *btf_parse_vmlinux(void) return ERR_PTR(err); } +static struct btf *btf_parse_module(const char *module_name, const void *data, unsigned int data_size) +{ + struct btf_verifier_env *env = NULL; + struct bpf_verifier_log *log; + struct btf *btf = NULL, *base_btf; + int err; + + base_btf = bpf_get_btf_vmlinux(); + if (IS_ERR(base_btf)) + return base_btf; + if (!base_btf) + return ERR_PTR(-EINVAL); + + env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN); + if (!env) + return ERR_PTR(-ENOMEM); + + log = &env->log; + log->level = BPF_LOG_KERNEL; + + btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN); + if (!btf) { + err = -ENOMEM; + goto errout; + } + env->btf = btf; + + btf->base_btf = base_btf; + btf->start_id = base_btf->nr_types; + btf->start_str_off = base_btf->hdr.str_len; + btf->kernel_btf = true; + snprintf(btf->name, sizeof(btf->name), "%s", module_name); + + btf->data = kvmalloc(data_size, GFP_KERNEL | __GFP_NOWARN); + if (!btf->data) { + err = -ENOMEM; + goto errout; + } + memcpy(btf->data, data, data_size); + btf->data_size = data_size; + + err = btf_parse_hdr(env); + if (err) + goto errout; + + btf->nohdr_data = btf->data + btf->hdr.hdr_len; + + err = btf_parse_str_sec(env); + if (err) + goto errout; + + err = btf_check_all_metas(env); + if (err) + goto errout; + + btf_verifier_env_free(env); + refcount_set(&btf->refcnt, 1); + return btf; + +errout: + btf_verifier_env_free(env); + if (btf) { + kvfree(btf->data); + kvfree(btf->types); + kfree(btf); + } + return ERR_PTR(err); +} + struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog) { struct bpf_prog *tgt_prog = prog->aux->dst_prog; @@ -5660,3 +5731,125 @@ bool btf_id_set_contains(const struct btf_id_set *set, u32 id) { return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL; } + +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES +struct btf_module { + struct list_head list; + struct module *module; + struct btf *btf; + struct bin_attribute *sysfs_attr; +}; + +static LIST_HEAD(btf_modules); +static DEFINE_MUTEX(btf_module_mutex); + +static ssize_t +btf_module_read(struct file *file, struct kobject *kobj, + struct bin_attribute *bin_attr, + char *buf, loff_t off, size_t len) +{ + const struct btf *btf = bin_attr->private; + + memcpy(buf, btf->data + off, len); + return len; +} + +static int btf_module_notify(struct notifier_block *nb, unsigned long op, + void *module) +{ + struct btf_module *btf_mod, *tmp; + struct module *mod = module; + struct btf *btf; + int err = 0; + + if (mod->btf_data_size == 0 || + (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING)) + goto out; + + switch (op) { + case MODULE_STATE_COMING: + btf_mod = kzalloc(sizeof(*btf_mod), GFP_KERNEL); + if (!btf_mod) { + err = -ENOMEM; + goto out; + } + btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size); + if (IS_ERR(btf)) { + kfree(btf_mod); + err = PTR_ERR(btf); + goto out; + } + err = btf_alloc_id(btf); + if (err) { + btf_free(btf); + kfree(btf_mod); + goto out; + } + + mutex_lock(&btf_module_mutex); + btf_mod->module = module; + btf_mod->btf = btf; + list_add(&btf_mod->list, &btf_modules); + mutex_unlock(&btf_module_mutex); + + if (IS_ENABLED(CONFIG_SYSFS)) { + struct bin_attribute *attr; + + attr = kzalloc(sizeof(*attr), GFP_KERNEL); + if (!attr) { + WARN(1, "failed to register module [%s] BTF in sysfs\n", mod->name); + goto out; + } + + attr->attr.name = btf->name; + attr->attr.mode = 0444; + attr->size = btf->data_size; + attr->private = btf; + attr->read = btf_module_read; + + err = sysfs_create_bin_file(btf_kobj, attr); + if (err) { + kfree(attr); + WARN(1, "failed to register module [%s] BTF in sysfs: %d\n", + mod->name, err); + err = 0; + goto out; + } + + btf_mod->sysfs_attr = attr; + } + + break; + case MODULE_STATE_GOING: + mutex_lock(&btf_module_mutex); + list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) { + if (btf_mod->module != module) + continue; + + list_del(&btf_mod->list); + if (btf_mod->sysfs_attr) + sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr); + btf_put(btf_mod->btf); + kfree(btf_mod->sysfs_attr); + kfree(btf_mod); + break; + } + mutex_unlock(&btf_module_mutex); + break; + } +out: + return notifier_from_errno(err); +} + +static struct notifier_block btf_module_nb = { + .notifier_call = btf_module_notify, +}; + +static int __init btf_module_init(void) +{ + register_module_notifier(&btf_module_nb); + return 0; +} + +fs_initcall(btf_module_init); +#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */ diff --git a/kernel/bpf/sysfs_btf.c b/kernel/bpf/sysfs_btf.c index 11b3380887fa..ef6911aee3bb 100644 --- a/kernel/bpf/sysfs_btf.c +++ b/kernel/bpf/sysfs_btf.c @@ -26,7 +26,7 @@ static struct bin_attribute bin_attr_btf_vmlinux __ro_after_init = { .read = btf_vmlinux_read, }; -static struct kobject *btf_kobj; +struct kobject *btf_kobj; static int __init btf_vmlinux_init(void) { diff --git a/kernel/module.c b/kernel/module.c index a4fa44a652a7..af71fc53eb25 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -380,6 +380,35 @@ static void *section_objs(const struct load_info *info, return (void *)info->sechdrs[sec].sh_addr; } +/* Find a module section: 0 means not found. Ignores SHF_ALLOC flag. */ +static unsigned int find_any_sec(const struct load_info *info, const char *name) +{ + unsigned int i; + + for (i = 1; i < info->hdr->e_shnum; i++) { + Elf_Shdr *shdr = &info->sechdrs[i]; + if (strcmp(info->secstrings + shdr->sh_name, name) == 0) + return i; + } + return 0; +} + +/* + * Find a module section, or NULL. Fill in number of "objects" in section. + * Ignores SHF_ALLOC flag. + */ +static void *any_section_objs(const struct load_info *info, + const char *name, + size_t object_size, + unsigned int *num) +{ + unsigned int sec = find_any_sec(info, name); + + /* Section 0 has sh_addr 0 and sh_size 0. */ + *num = info->sechdrs[sec].sh_size / object_size; + return (void *)info->sechdrs[sec].sh_addr; +} + /* Provided by the linker */ extern const struct kernel_symbol __start___ksymtab[]; extern const struct kernel_symbol __stop___ksymtab[]; @@ -3250,6 +3279,9 @@ static int find_module_sections(struct module *mod, struct load_info *info) sizeof(*mod->bpf_raw_events), &mod->num_bpf_raw_events); #endif +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES + mod->btf_data = any_section_objs(info, ".BTF", 1, &mod->btf_data_size); +#endif #ifdef CONFIG_JUMP_LABEL mod->jump_entries = section_objs(info, "__jump_table", sizeof(*mod->jump_entries),
Add kernel module listener that will load/validate and unload module BTF. Module BTFs gets ID generated for them, which makes it possible to iterate them with existing BTF iteration API. They are given their respective module's names, which will get reported through GET_OBJ_INFO API. They are also marked as in-kernel BTFs for tooling to distinguish them from user-provided BTFs. Also, similarly to vmlinux BTF, kernel module BTFs are exposed through sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space tools to inspect module BTF contents and dump their types with existing tools: [vmuser@archvm bpf]$ ls -la /sys/kernel/btf total 0 drwxr-xr-x 2 root root 0 Nov 4 19:46 . drwxr-xr-x 13 root root 0 Nov 4 19:46 .. ... -r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass -r--r--r-- 1 root root 100225 Nov 4 19:46 kvm -r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel -r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr -r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw -r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- include/linux/bpf.h | 2 + include/linux/module.h | 4 + kernel/bpf/btf.c | 193 +++++++++++++++++++++++++++++++++++++++++ kernel/bpf/sysfs_btf.c | 2 +- kernel/module.c | 32 +++++++ 5 files changed, 232 insertions(+), 1 deletion(-)