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Commit a38d1107 authored by Matt Mullins's avatar Matt Mullins Committed by Alexei Starovoitov
Browse files

bpf: support raw tracepoints in modules 



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: default avatarMatt Mullins <mmullins@fb.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent a137401d

include/linux/module.h

+4 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/trace_events.h

+6 −2
Original line number Diff line number Diff line
@@ -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,

kernel/bpf/syscall.c

+8 −3
Original line number Diff line number Diff line
@@ -1604,6 +1604,7 @@ 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;

}
@@ -1629,13 +1630,15 @@ 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,
@@ -1663,6 +1666,8 @@ 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;

}

kernel/module.c

+5 −0
Original line number Diff line number Diff line
@@ -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),

kernel/trace/bpf_trace.c

+97 −2
Original line number Diff line number Diff line
@@ -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 */