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perf/bpf: Reorder bpf_overflow_handler() ahead of __perf_event_overflow()

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This will allow __perf_event_overflow() to call bpf_overflow_handler().

Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240412015019.7060-2-khuey@kylehuey.com
This commit is contained in:
Kyle Huey 2024-04-11 18:50:13 -07:00 committed by Ingo Molnar
parent acf68d98ca
commit 4c03fe11b9
1 changed files with 92 additions and 91 deletions
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183
kernel/events/core.c
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@ -9563,6 +9563,98 @@ static inline bool sample_is_allowed(struct perf_event *event, struct pt_regs *r
return true;
}
#ifdef CONFIG_BPF_SYSCALL
static void bpf_overflow_handler(struct perf_event *event,
struct perf_sample_data *data,
struct pt_regs *regs)
{
struct bpf_perf_event_data_kern ctx = {
.data = data,
.event = event,
};
struct bpf_prog *prog;
int ret = 0;
ctx.regs = perf_arch_bpf_user_pt_regs(regs);
if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
goto out;
rcu_read_lock();
prog = READ_ONCE(event->prog);
if (prog) {
perf_prepare_sample(data, event, regs);
ret = bpf_prog_run(prog, &ctx);
}
rcu_read_unlock();
out:
__this_cpu_dec(bpf_prog_active);
if (!ret)
return;
event->orig_overflow_handler(event, data, regs);
}
static int perf_event_set_bpf_handler(struct perf_event *event,
struct bpf_prog *prog,
u64 bpf_cookie)
{
if (event->overflow_handler_context)
/* hw breakpoint or kernel counter */
return -EINVAL;
if (event->prog)
return -EEXIST;
if (prog->type != BPF_PROG_TYPE_PERF_EVENT)
return -EINVAL;
if (event->attr.precise_ip &&
prog->call_get_stack &&
(!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) ||
event->attr.exclude_callchain_kernel ||
event->attr.exclude_callchain_user)) {
/*
* On perf_event with precise_ip, calling bpf_get_stack()
* may trigger unwinder warnings and occasional crashes.
* bpf_get_[stack|stackid] works around this issue by using
* callchain attached to perf_sample_data. If the
* perf_event does not full (kernel and user) callchain
* attached to perf_sample_data, do not allow attaching BPF
* program that calls bpf_get_[stack|stackid].
*/
return -EPROTO;
}
event->prog = prog;
event->bpf_cookie = bpf_cookie;
event->orig_overflow_handler = READ_ONCE(event->overflow_handler);
WRITE_ONCE(event->overflow_handler, bpf_overflow_handler);
return 0;
}
static void perf_event_free_bpf_handler(struct perf_event *event)
{
struct bpf_prog *prog = event->prog;
if (!prog)
return;
WRITE_ONCE(event->overflow_handler, event->orig_overflow_handler);
event->prog = NULL;
bpf_prog_put(prog);
}
#else
static int perf_event_set_bpf_handler(struct perf_event *event,
struct bpf_prog *prog,
u64 bpf_cookie)
{
return -EOPNOTSUPP;
}
static void perf_event_free_bpf_handler(struct perf_event *event)
{
}
#endif
/*
* Generic event overflow handling, sampling.
*/
@ -10441,97 +10533,6 @@ static void perf_event_free_filter(struct perf_event *event)
ftrace_profile_free_filter(event);
}
#ifdef CONFIG_BPF_SYSCALL
static void bpf_overflow_handler(struct perf_event *event,
struct perf_sample_data *data,
struct pt_regs *regs)
{
struct bpf_perf_event_data_kern ctx = {
.data = data,
.event = event,
};
struct bpf_prog *prog;
int ret = 0;
ctx.regs = perf_arch_bpf_user_pt_regs(regs);
if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
goto out;
rcu_read_lock();
prog = READ_ONCE(event->prog);
if (prog) {
perf_prepare_sample(data, event, regs);
ret = bpf_prog_run(prog, &ctx);
}
rcu_read_unlock();
out:
__this_cpu_dec(bpf_prog_active);
if (!ret)
return;
event->orig_overflow_handler(event, data, regs);
}
static int perf_event_set_bpf_handler(struct perf_event *event,
struct bpf_prog *prog,
u64 bpf_cookie)
{
if (event->overflow_handler_context)
/* hw breakpoint or kernel counter */
return -EINVAL;
if (event->prog)
return -EEXIST;
if (prog->type != BPF_PROG_TYPE_PERF_EVENT)
return -EINVAL;
if (event->attr.precise_ip &&
prog->call_get_stack &&
(!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) ||
event->attr.exclude_callchain_kernel ||
event->attr.exclude_callchain_user)) {
/*
* On perf_event with precise_ip, calling bpf_get_stack()
* may trigger unwinder warnings and occasional crashes.
* bpf_get_[stack|stackid] works around this issue by using
* callchain attached to perf_sample_data. If the
* perf_event does not full (kernel and user) callchain
* attached to perf_sample_data, do not allow attaching BPF
* program that calls bpf_get_[stack|stackid].
*/
return -EPROTO;
}
event->prog = prog;
event->bpf_cookie = bpf_cookie;
event->orig_overflow_handler = READ_ONCE(event->overflow_handler);
WRITE_ONCE(event->overflow_handler, bpf_overflow_handler);
return 0;
}
static void perf_event_free_bpf_handler(struct perf_event *event)
{
struct bpf_prog *prog = event->prog;
if (!prog)
return;
WRITE_ONCE(event->overflow_handler, event->orig_overflow_handler);
event->prog = NULL;
bpf_prog_put(prog);
}
#else
static int perf_event_set_bpf_handler(struct perf_event *event,
struct bpf_prog *prog,
u64 bpf_cookie)
{
return -EOPNOTSUPP;
}
static void perf_event_free_bpf_handler(struct perf_event *event)
{
}
#endif
/*
* returns true if the event is a tracepoint, or a kprobe/upprobe created
* with perf_event_open()