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bpf: support raw tracepoints in modules

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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 <mmullins@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Matt Mullins
2018-12-12 16:42:37 -08:00
committed by Alexei Starovoitov
parent a137401d85
commit a38d1107f9
5 changed files with 120 additions and 7 deletions
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99
kernel/trace/bpf_trace.c
View File

@@ -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 */