Distributions build drivers as modules, including network and filesystem
drivers which export numerous tracepoints. This enables
bpf(BPF_RAW_TRACEPOINT_OPEN) to attach to those tracepoints.
Signed-off-by: Matt Mullins <[email protected]>
---
v1->v2:
* avoid taking the mutex in bpf_event_notify when op is neither COMING nor
GOING.
* check that kzalloc actually succeeded
I didn't try to check list_empty before taking the mutex since I want to avoid
races between bpf_event_notify and bpf_get_raw_tracepoint. Additionally,
list_for_each_entry_safe is not strictly necessary upon MODULE_STATE_GOING, but
Alexei suggested I use it to protect against fragility if the subsequent break;
eventually disappears.
include/linux/module.h | 4 ++
include/linux/trace_events.h | 8 ++-
kernel/bpf/syscall.c | 11 ++--
kernel/module.c | 5 ++
kernel/trace/bpf_trace.c | 99 +++++++++++++++++++++++++++++++++++-
5 files changed, 120 insertions(+), 7 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h
index fce6b4335e36..5f147dd5e709 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -432,6 +432,10 @@ struct module {
unsigned int num_tracepoints;
tracepoint_ptr_t *tracepoints_ptrs;
#endif
+#ifdef CONFIG_BPF_EVENTS
+ unsigned int num_bpf_raw_events;
+ struct bpf_raw_event_map *bpf_raw_events;
+#endif
#ifdef HAVE_JUMP_LABEL
struct jump_entry *jump_entries;
unsigned int num_jump_entries;
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 4130a5497d40..8a62731673f7 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -471,7 +471,8 @@ void perf_event_detach_bpf_prog(struct perf_event *event);
int perf_event_query_prog_array(struct perf_event *event, void __user *info);
int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog);
int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf_prog *prog);
-struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name);
+struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name);
+void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp);
int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
u32 *fd_type, const char **buf,
u64 *probe_offset, u64 *probe_addr);
@@ -502,10 +503,13 @@ static inline int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf
{
return -EOPNOTSUPP;
}
-static inline struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
+static inline struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)
{
return NULL;
}
+static inline void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
+{
+}
static inline int bpf_get_perf_event_info(const struct perf_event *event,
u32 *prog_id, u32 *fd_type,
const char **buf, u64 *probe_offset,
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 70fb11106fc2..754370e3155e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1609,6 +1609,7 @@ static int bpf_raw_tracepoint_release(struct inode *inode, struct file *filp)
bpf_probe_unregister(raw_tp->btp, raw_tp->prog);
bpf_prog_put(raw_tp->prog);
}
+ bpf_put_raw_tracepoint(raw_tp->btp);
kfree(raw_tp);
return 0;
}
@@ -1634,13 +1635,15 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
return -EFAULT;
tp_name[sizeof(tp_name) - 1] = 0;
- btp = bpf_find_raw_tracepoint(tp_name);
+ btp = bpf_get_raw_tracepoint(tp_name);
if (!btp)
return -ENOENT;
raw_tp = kzalloc(sizeof(*raw_tp), GFP_USER);
- if (!raw_tp)
- return -ENOMEM;
+ if (!raw_tp) {
+ err = -ENOMEM;
+ goto out_put_btp;
+ }
raw_tp->btp = btp;
prog = bpf_prog_get_type(attr->raw_tracepoint.prog_fd,
@@ -1668,6 +1671,8 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
bpf_prog_put(prog);
out_free_tp:
kfree(raw_tp);
+out_put_btp:
+ bpf_put_raw_tracepoint(btp);
return err;
}
diff --git a/kernel/module.c b/kernel/module.c
index 49a405891587..06ec68f08387 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3093,6 +3093,11 @@ static int find_module_sections(struct module *mod, struct load_info *info)
sizeof(*mod->tracepoints_ptrs),
&mod->num_tracepoints);
#endif
+#ifdef CONFIG_BPF_EVENTS
+ mod->bpf_raw_events = section_objs(info, "__bpf_raw_tp_map",
+ sizeof(*mod->bpf_raw_events),
+ &mod->num_bpf_raw_events);
+#endif
#ifdef HAVE_JUMP_LABEL
mod->jump_entries = section_objs(info, "__jump_table",
sizeof(*mod->jump_entries),
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 9864a35c8bb5..9ddb6fddb4e0 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -17,6 +17,43 @@
#include "trace_probe.h"
#include "trace.h"
+#ifdef CONFIG_MODULES
+struct bpf_trace_module {
+ struct module *module;
+ struct list_head list;
+};
+
+static LIST_HEAD(bpf_trace_modules);
+static DEFINE_MUTEX(bpf_module_mutex);
+
+static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
+{
+ struct bpf_raw_event_map *btp, *ret = NULL;
+ struct bpf_trace_module *btm;
+ unsigned int i;
+
+ mutex_lock(&bpf_module_mutex);
+ list_for_each_entry(btm, &bpf_trace_modules, list) {
+ for (i = 0; i < btm->module->num_bpf_raw_events; ++i) {
+ btp = &btm->module->bpf_raw_events[i];
+ if (!strcmp(btp->tp->name, name)) {
+ if (try_module_get(btm->module))
+ ret = btp;
+ goto out;
+ }
+ }
+ }
+out:
+ mutex_unlock(&bpf_module_mutex);
+ return ret;
+}
+#else
+static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
+{
+ return NULL;
+}
+#endif /* CONFIG_MODULES */
+
u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
u64 bpf_get_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
@@ -1076,7 +1113,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
extern struct bpf_raw_event_map __start__bpf_raw_tp[];
extern struct bpf_raw_event_map __stop__bpf_raw_tp[];
-struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
+struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)
{
struct bpf_raw_event_map *btp = __start__bpf_raw_tp;
@@ -1084,7 +1121,16 @@ struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
if (!strcmp(btp->tp->name, name))
return btp;
}
- return NULL;
+
+ return bpf_get_raw_tracepoint_module(name);
+}
+
+void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
+{
+ struct module *mod = __module_address((unsigned long)btp);
+
+ if (mod)
+ module_put(mod);
}
static __always_inline
@@ -1222,3 +1268,52 @@ int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
return err;
}
+
+#ifdef CONFIG_MODULES
+int bpf_event_notify(struct notifier_block *nb, unsigned long op, void *module)
+{
+ struct bpf_trace_module *btm, *tmp;
+ struct module *mod = module;
+
+ if (mod->num_bpf_raw_events == 0 ||
+ (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING))
+ return 0;
+
+ mutex_lock(&bpf_module_mutex);
+
+ switch (op) {
+ case MODULE_STATE_COMING:
+ btm = kzalloc(sizeof(*btm), GFP_KERNEL);
+ if (btm) {
+ btm->module = module;
+ list_add(&btm->list, &bpf_trace_modules);
+ }
+ break;
+ case MODULE_STATE_GOING:
+ list_for_each_entry_safe(btm, tmp, &bpf_trace_modules, list) {
+ if (btm->module == module) {
+ list_del(&btm->list);
+ kfree(btm);
+ break;
+ }
+ }
+ break;
+ }
+
+ mutex_unlock(&bpf_module_mutex);
+
+ return 0;
+}
+
+static struct notifier_block bpf_module_nb = {
+ .notifier_call = bpf_event_notify,
+};
+
+int __init bpf_event_init(void)
+{
+ register_module_notifier(&bpf_module_nb);
+ return 0;
+}
+
+fs_initcall(bpf_event_init);
+#endif /* CONFIG_MODULES */
--
2.17.1
On Wed, Dec 12, 2018 at 04:42:37PM -0800, Matt Mullins wrote:
> Distributions build drivers as modules, including network and filesystem
> drivers which export numerous tracepoints. This enables
> bpf(BPF_RAW_TRACEPOINT_OPEN) to attach to those tracepoints.
>
> Signed-off-by: Matt Mullins <[email protected]>
> ---
> v1->v2:
> * avoid taking the mutex in bpf_event_notify when op is neither COMING nor
> GOING.
> * check that kzalloc actually succeeded
>
> I didn't try to check list_empty before taking the mutex since I want to avoid
> races between bpf_event_notify and bpf_get_raw_tracepoint. Additionally,
> list_for_each_entry_safe is not strictly necessary upon MODULE_STATE_GOING, but
> Alexei suggested I use it to protect against fragility if the subsequent break;
> eventually disappears.
>
> include/linux/module.h | 4 ++
> include/linux/trace_events.h | 8 ++-
> kernel/bpf/syscall.c | 11 ++--
> kernel/module.c | 5 ++
> kernel/trace/bpf_trace.c | 99 +++++++++++++++++++++++++++++++++++-
> 5 files changed, 120 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/module.h b/include/linux/module.h
> index fce6b4335e36..5f147dd5e709 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -432,6 +432,10 @@ struct module {
> unsigned int num_tracepoints;
> tracepoint_ptr_t *tracepoints_ptrs;
> #endif
> +#ifdef CONFIG_BPF_EVENTS
> + unsigned int num_bpf_raw_events;
> + struct bpf_raw_event_map *bpf_raw_events;
> +#endif
> #ifdef HAVE_JUMP_LABEL
> struct jump_entry *jump_entries;
> unsigned int num_jump_entries;
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index 4130a5497d40..8a62731673f7 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -471,7 +471,8 @@ void perf_event_detach_bpf_prog(struct perf_event *event);
> int perf_event_query_prog_array(struct perf_event *event, void __user *info);
> int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog);
> int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf_prog *prog);
> -struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name);
> +struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name);
> +void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp);
> int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
> u32 *fd_type, const char **buf,
> u64 *probe_offset, u64 *probe_addr);
> @@ -502,10 +503,13 @@ static inline int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf
> {
> return -EOPNOTSUPP;
> }
> -static inline struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
> +static inline struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)
> {
> return NULL;
> }
> +static inline void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
> +{
> +}
> static inline int bpf_get_perf_event_info(const struct perf_event *event,
> u32 *prog_id, u32 *fd_type,
> const char **buf, u64 *probe_offset,
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 70fb11106fc2..754370e3155e 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -1609,6 +1609,7 @@ static int bpf_raw_tracepoint_release(struct inode *inode, struct file *filp)
> bpf_probe_unregister(raw_tp->btp, raw_tp->prog);
> bpf_prog_put(raw_tp->prog);
> }
> + bpf_put_raw_tracepoint(raw_tp->btp);
> kfree(raw_tp);
> return 0;
> }
> @@ -1634,13 +1635,15 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> return -EFAULT;
> tp_name[sizeof(tp_name) - 1] = 0;
>
> - btp = bpf_find_raw_tracepoint(tp_name);
> + btp = bpf_get_raw_tracepoint(tp_name);
> if (!btp)
> return -ENOENT;
>
> raw_tp = kzalloc(sizeof(*raw_tp), GFP_USER);
> - if (!raw_tp)
> - return -ENOMEM;
> + if (!raw_tp) {
> + err = -ENOMEM;
> + goto out_put_btp;
> + }
> raw_tp->btp = btp;
>
> prog = bpf_prog_get_type(attr->raw_tracepoint.prog_fd,
> @@ -1668,6 +1671,8 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> bpf_prog_put(prog);
> out_free_tp:
> kfree(raw_tp);
> +out_put_btp:
> + bpf_put_raw_tracepoint(btp);
> return err;
> }
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 49a405891587..06ec68f08387 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3093,6 +3093,11 @@ static int find_module_sections(struct module *mod, struct load_info *info)
> sizeof(*mod->tracepoints_ptrs),
> &mod->num_tracepoints);
> #endif
> +#ifdef CONFIG_BPF_EVENTS
> + mod->bpf_raw_events = section_objs(info, "__bpf_raw_tp_map",
> + sizeof(*mod->bpf_raw_events),
> + &mod->num_bpf_raw_events);
> +#endif
> #ifdef HAVE_JUMP_LABEL
> mod->jump_entries = section_objs(info, "__jump_table",
> sizeof(*mod->jump_entries),
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 9864a35c8bb5..9ddb6fddb4e0 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -17,6 +17,43 @@
> #include "trace_probe.h"
> #include "trace.h"
>
> +#ifdef CONFIG_MODULES
> +struct bpf_trace_module {
> + struct module *module;
> + struct list_head list;
> +};
> +
> +static LIST_HEAD(bpf_trace_modules);
> +static DEFINE_MUTEX(bpf_module_mutex);
> +
> +static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
> +{
> + struct bpf_raw_event_map *btp, *ret = NULL;
> + struct bpf_trace_module *btm;
> + unsigned int i;
> +
> + mutex_lock(&bpf_module_mutex);
> + list_for_each_entry(btm, &bpf_trace_modules, list) {
> + for (i = 0; i < btm->module->num_bpf_raw_events; ++i) {
> + btp = &btm->module->bpf_raw_events[i];
> + if (!strcmp(btp->tp->name, name)) {
> + if (try_module_get(btm->module))
> + ret = btp;
> + goto out;
> + }
> + }
> + }
> +out:
> + mutex_unlock(&bpf_module_mutex);
> + return ret;
> +}
> +#else
> +static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
> +{
> + return NULL;
> +}
> +#endif /* CONFIG_MODULES */
> +
> u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
> u64 bpf_get_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
>
> @@ -1076,7 +1113,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
> extern struct bpf_raw_event_map __start__bpf_raw_tp[];
> extern struct bpf_raw_event_map __stop__bpf_raw_tp[];
>
> -struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
> +struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)
> {
> struct bpf_raw_event_map *btp = __start__bpf_raw_tp;
>
> @@ -1084,7 +1121,16 @@ struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
> if (!strcmp(btp->tp->name, name))
> return btp;
> }
> - return NULL;
> +
> + return bpf_get_raw_tracepoint_module(name);
> +}
> +
> +void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
> +{
> + struct module *mod = __module_address((unsigned long)btp);
> +
> + if (mod)
> + module_put(mod);
> }
>
> static __always_inline
> @@ -1222,3 +1268,52 @@ int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
>
> return err;
> }
> +
> +#ifdef CONFIG_MODULES
> +int bpf_event_notify(struct notifier_block *nb, unsigned long op, void *module)
> +{
> + struct bpf_trace_module *btm, *tmp;
> + struct module *mod = module;
> +
> + if (mod->num_bpf_raw_events == 0 ||
> + (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING))
> + return 0;
> +
> + mutex_lock(&bpf_module_mutex);
> +
> + switch (op) {
> + case MODULE_STATE_COMING:
> + btm = kzalloc(sizeof(*btm), GFP_KERNEL);
> + if (btm) {
> + btm->module = module;
> + list_add(&btm->list, &bpf_trace_modules);
> + }
Is it fine to return 0 on !btm case?
Other looks good.
> + break;
> + case MODULE_STATE_GOING:
> + list_for_each_entry_safe(btm, tmp, &bpf_trace_modules, list) {
> + if (btm->module == module) {
> + list_del(&btm->list);
> + kfree(btm);
> + break;
> + }
> + }
> + break;
> + }
> +
> + mutex_unlock(&bpf_module_mutex);
> +
> + return 0;
> +}
> +
> +static struct notifier_block bpf_module_nb = {
> + .notifier_call = bpf_event_notify,
> +};
> +
> +int __init bpf_event_init(void)
> +{
> + register_module_notifier(&bpf_module_nb);
> + return 0;
> +}
> +
> +fs_initcall(bpf_event_init);
> +#endif /* CONFIG_MODULES */
> --
> 2.17.1
>
On Thu, 2018-12-13 at 19:22 +0000, Martin Lau wrote:
> On Wed, Dec 12, 2018 at 04:42:37PM -0800, Matt Mullins wrote:
> > Distributions build drivers as modules, including network and filesystem
> > drivers which export numerous tracepoints. This enables
> > bpf(BPF_RAW_TRACEPOINT_OPEN) to attach to those tracepoints.
> >
> > Signed-off-by: Matt Mullins <[email protected]>
> > ---
> > v1->v2:
> > * avoid taking the mutex in bpf_event_notify when op is neither COMING nor
> > GOING.
> > * check that kzalloc actually succeeded
> >
> > I didn't try to check list_empty before taking the mutex since I want to avoid
> > races between bpf_event_notify and bpf_get_raw_tracepoint. Additionally,
> > list_for_each_entry_safe is not strictly necessary upon MODULE_STATE_GOING, but
> > Alexei suggested I use it to protect against fragility if the subsequent break;
> > eventually disappears.
> >
> > include/linux/module.h | 4 ++
> > include/linux/trace_events.h | 8 ++-
> > kernel/bpf/syscall.c | 11 ++--
> > kernel/module.c | 5 ++
> > kernel/trace/bpf_trace.c | 99 +++++++++++++++++++++++++++++++++++-
> > 5 files changed, 120 insertions(+), 7 deletions(-)
> >
> > diff --git a/include/linux/module.h b/include/linux/module.h
> > index fce6b4335e36..5f147dd5e709 100644
> > --- a/include/linux/module.h
> > +++ b/include/linux/module.h
> > @@ -432,6 +432,10 @@ struct module {
> > unsigned int num_tracepoints;
> > tracepoint_ptr_t *tracepoints_ptrs;
> > #endif
> > +#ifdef CONFIG_BPF_EVENTS
> > + unsigned int num_bpf_raw_events;
> > + struct bpf_raw_event_map *bpf_raw_events;
> > +#endif
> > #ifdef HAVE_JUMP_LABEL
> > struct jump_entry *jump_entries;
> > unsigned int num_jump_entries;
> > diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> > index 4130a5497d40..8a62731673f7 100644
> > --- a/include/linux/trace_events.h
> > +++ b/include/linux/trace_events.h
> > @@ -471,7 +471,8 @@ void perf_event_detach_bpf_prog(struct perf_event *event);
> > int perf_event_query_prog_array(struct perf_event *event, void __user *info);
> > int bpf_probe_register(struct bpf_raw_event_map *btp, struct bpf_prog *prog);
> > int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf_prog *prog);
> > -struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name);
> > +struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name);
> > +void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp);
> > int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
> > u32 *fd_type, const char **buf,
> > u64 *probe_offset, u64 *probe_addr);
> > @@ -502,10 +503,13 @@ static inline int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf
> > {
> > return -EOPNOTSUPP;
> > }
> > -static inline struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
> > +static inline struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)
> > {
> > return NULL;
> > }
> > +static inline void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
> > +{
> > +}
> > static inline int bpf_get_perf_event_info(const struct perf_event *event,
> > u32 *prog_id, u32 *fd_type,
> > const char **buf, u64 *probe_offset,
> > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > index 70fb11106fc2..754370e3155e 100644
> > --- a/kernel/bpf/syscall.c
> > +++ b/kernel/bpf/syscall.c
> > @@ -1609,6 +1609,7 @@ static int bpf_raw_tracepoint_release(struct inode *inode, struct file *filp)
> > bpf_probe_unregister(raw_tp->btp, raw_tp->prog);
> > bpf_prog_put(raw_tp->prog);
> > }
> > + bpf_put_raw_tracepoint(raw_tp->btp);
> > kfree(raw_tp);
> > return 0;
> > }
> > @@ -1634,13 +1635,15 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> > return -EFAULT;
> > tp_name[sizeof(tp_name) - 1] = 0;
> >
> > - btp = bpf_find_raw_tracepoint(tp_name);
> > + btp = bpf_get_raw_tracepoint(tp_name);
> > if (!btp)
> > return -ENOENT;
> >
> > raw_tp = kzalloc(sizeof(*raw_tp), GFP_USER);
> > - if (!raw_tp)
> > - return -ENOMEM;
> > + if (!raw_tp) {
> > + err = -ENOMEM;
> > + goto out_put_btp;
> > + }
> > raw_tp->btp = btp;
> >
> > prog = bpf_prog_get_type(attr->raw_tracepoint.prog_fd,
> > @@ -1668,6 +1671,8 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> > bpf_prog_put(prog);
> > out_free_tp:
> > kfree(raw_tp);
> > +out_put_btp:
> > + bpf_put_raw_tracepoint(btp);
> > return err;
> > }
> >
> > diff --git a/kernel/module.c b/kernel/module.c
> > index 49a405891587..06ec68f08387 100644
> > --- a/kernel/module.c
> > +++ b/kernel/module.c
> > @@ -3093,6 +3093,11 @@ static int find_module_sections(struct module *mod, struct load_info *info)
> > sizeof(*mod->tracepoints_ptrs),
> > &mod->num_tracepoints);
> > #endif
> > +#ifdef CONFIG_BPF_EVENTS
> > + mod->bpf_raw_events = section_objs(info, "__bpf_raw_tp_map",
> > + sizeof(*mod->bpf_raw_events),
> > + &mod->num_bpf_raw_events);
> > +#endif
> > #ifdef HAVE_JUMP_LABEL
> > mod->jump_entries = section_objs(info, "__jump_table",
> > sizeof(*mod->jump_entries),
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index 9864a35c8bb5..9ddb6fddb4e0 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -17,6 +17,43 @@
> > #include "trace_probe.h"
> > #include "trace.h"
> >
> > +#ifdef CONFIG_MODULES
> > +struct bpf_trace_module {
> > + struct module *module;
> > + struct list_head list;
> > +};
> > +
> > +static LIST_HEAD(bpf_trace_modules);
> > +static DEFINE_MUTEX(bpf_module_mutex);
> > +
> > +static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
> > +{
> > + struct bpf_raw_event_map *btp, *ret = NULL;
> > + struct bpf_trace_module *btm;
> > + unsigned int i;
> > +
> > + mutex_lock(&bpf_module_mutex);
> > + list_for_each_entry(btm, &bpf_trace_modules, list) {
> > + for (i = 0; i < btm->module->num_bpf_raw_events; ++i) {
> > + btp = &btm->module->bpf_raw_events[i];
> > + if (!strcmp(btp->tp->name, name)) {
> > + if (try_module_get(btm->module))
> > + ret = btp;
> > + goto out;
> > + }
> > + }
> > + }
> > +out:
> > + mutex_unlock(&bpf_module_mutex);
> > + return ret;
> > +}
> > +#else
> > +static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
> > +{
> > + return NULL;
> > +}
> > +#endif /* CONFIG_MODULES */
> > +
> > u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
> > u64 bpf_get_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
> >
> > @@ -1076,7 +1113,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
> > extern struct bpf_raw_event_map __start__bpf_raw_tp[];
> > extern struct bpf_raw_event_map __stop__bpf_raw_tp[];
> >
> > -struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
> > +struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)
> > {
> > struct bpf_raw_event_map *btp = __start__bpf_raw_tp;
> >
> > @@ -1084,7 +1121,16 @@ struct bpf_raw_event_map *bpf_find_raw_tracepoint(const char *name)
> > if (!strcmp(btp->tp->name, name))
> > return btp;
> > }
> > - return NULL;
> > +
> > + return bpf_get_raw_tracepoint_module(name);
> > +}
> > +
> > +void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
> > +{
> > + struct module *mod = __module_address((unsigned long)btp);
> > +
> > + if (mod)
> > + module_put(mod);
> > }
> >
> > static __always_inline
> > @@ -1222,3 +1268,52 @@ int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
> >
> > return err;
> > }
> > +
> > +#ifdef CONFIG_MODULES
> > +int bpf_event_notify(struct notifier_block *nb, unsigned long op, void *module)
> > +{
> > + struct bpf_trace_module *btm, *tmp;
> > + struct module *mod = module;
> > +
> > + if (mod->num_bpf_raw_events == 0 ||
> > + (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING))
> > + return 0;
> > +
> > + mutex_lock(&bpf_module_mutex);
> > +
> > + switch (op) {
> > + case MODULE_STATE_COMING:
> > + btm = kzalloc(sizeof(*btm), GFP_KERNEL);
> > + if (btm) {
> > + btm->module = module;
> > + list_add(&btm->list, &bpf_trace_modules);
> > + }
>
> Is it fine to return 0 on !btm case?
That effectively just means we'll be ignoring tracepoints for a module
that is loaded while we can't allocate a bpf_trace_module (24 bytes) to
track it. That feels like reasonable behavior to me.
>
> Other looks good.
>
> > + break;
> > + case MODULE_STATE_GOING:
> > + list_for_each_entry_safe(btm, tmp, &bpf_trace_modules, list) {
> > + if (btm->module == module) {
> > + list_del(&btm->list);
> > + kfree(btm);
> > + break;
> > + }
> > + }
> > + break;
> > + }
> > +
> > + mutex_unlock(&bpf_module_mutex);
> > +
> > + return 0;
> > +}
> > +
> > +static struct notifier_block bpf_module_nb = {
> > + .notifier_call = bpf_event_notify,
> > +};
> > +
> > +int __init bpf_event_init(void)
> > +{
> > + register_module_notifier(&bpf_module_nb);
> > + return 0;
> > +}
> > +
> > +fs_initcall(bpf_event_init);
> > +#endif /* CONFIG_MODULES */
> > --
> > 2.17.1
> >
On Thu, Dec 13, 2018 at 11:38:51AM -0800, Matt Mullins wrote:
> On Thu, 2018-12-13 at 19:22 +0000, Martin Lau wrote:
> > On Wed, Dec 12, 2018 at 04:42:37PM -0800, Matt Mullins wrote:
> > > Distributions build drivers as modules, including network and filesystem
> > > drivers which export numerous tracepoints. This enables
> > > bpf(BPF_RAW_TRACEPOINT_OPEN) to attach to those tracepoints.
> > >
Acked-by: Martin KaFai Lau <[email protected]>
[ ... ]
> > > +#ifdef CONFIG_MODULES
> > > +int bpf_event_notify(struct notifier_block *nb, unsigned long op, void *module)
> > > +{
> > > + struct bpf_trace_module *btm, *tmp;
> > > + struct module *mod = module;
> > > +
> > > + if (mod->num_bpf_raw_events == 0 ||
> > > + (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING))
> > > + return 0;
> > > +
> > > + mutex_lock(&bpf_module_mutex);
> > > +
> > > + switch (op) {
> > > + case MODULE_STATE_COMING:
> > > + btm = kzalloc(sizeof(*btm), GFP_KERNEL);
> > > + if (btm) {
> > > + btm->module = module;
> > > + list_add(&btm->list, &bpf_trace_modules);
> > > + }
> >
> > Is it fine to return 0 on !btm case?
>
> That effectively just means we'll be ignoring tracepoints for a module
> that is loaded while we can't allocate a bpf_trace_module (24 bytes) to
> track it. That feels like reasonable behavior to me.
ok.
On Wed, Dec 12, 2018 at 04:42:37PM -0800, Matt Mullins wrote:
> Distributions build drivers as modules, including network and filesystem
> drivers which export numerous tracepoints. This enables
> bpf(BPF_RAW_TRACEPOINT_OPEN) to attach to those tracepoints.
>
> Signed-off-by: Matt Mullins <[email protected]>
> ---
> v1->v2:
> * avoid taking the mutex in bpf_event_notify when op is neither COMING nor
> GOING.
> * check that kzalloc actually succeeded
Applied, Thanks