perf/core: Implement the 'perf_kprobe' PMU (e12f03d7) · Commits · e / devices / android_kernel_fairphone_FP5

include/linux/trace_events.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -533,6 +533,10 @@ extern int perf_trace_init(struct perf_event *event);
		extern void perf_trace_destroy(struct perf_event *event);
		extern int perf_trace_add(struct perf_event *event, int flags);
		extern void perf_trace_del(struct perf_event *event, int flags);
		#ifdef CONFIG_KPROBE_EVENTS
		extern int perf_kprobe_init(struct perf_event *event, bool is_retprobe);
		extern void perf_kprobe_destroy(struct perf_event *event);
		#endif
		extern int ftrace_profile_set_filter(struct perf_event *event, int event_id,
		char *filter_str);
		extern void ftrace_profile_free_filter(struct perf_event *event);

kernel/events/core.c

+107 −35

Original line number	Diff line number	Diff line
		@@ -7992,9 +7992,77 @@ static struct pmu perf_tracepoint = {
		.read = perf_swevent_read,
		};

		#ifdef CONFIG_KPROBE_EVENTS
		/*
		* Flags in config, used by dynamic PMU kprobe and uprobe
		* The flags should match following PMU_FORMAT_ATTR().
		*
		* PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe
		* if not set, create kprobe/uprobe
		*/
		enum perf_probe_config {
		PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0, /* [k,u]retprobe */
		};

		PMU_FORMAT_ATTR(retprobe, "config:0");

		static struct attribute *probe_attrs[] = {
		&format_attr_retprobe.attr,
		NULL,
		};

		static struct attribute_group probe_format_group = {
		.name = "format",
		.attrs = probe_attrs,
		};

		static const struct attribute_group *probe_attr_groups[] = {
		&probe_format_group,
		NULL,
		};

		static int perf_kprobe_event_init(struct perf_event *event);
		static struct pmu perf_kprobe = {
		.task_ctx_nr = perf_sw_context,
		.event_init = perf_kprobe_event_init,
		.add = perf_trace_add,
		.del = perf_trace_del,
		.start = perf_swevent_start,
		.stop = perf_swevent_stop,
		.read = perf_swevent_read,
		.attr_groups = probe_attr_groups,
		};

		static int perf_kprobe_event_init(struct perf_event *event)
		{
		int err;
		bool is_retprobe;

		if (event->attr.type != perf_kprobe.type)
		return -ENOENT;
		/*
		* no branch sampling for probe events
		*/
		if (has_branch_stack(event))
		return -EOPNOTSUPP;

		is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
		err = perf_kprobe_init(event, is_retprobe);
		if (err)
		return err;

		event->destroy = perf_kprobe_destroy;

		return 0;
		}
		#endif /* CONFIG_KPROBE_EVENTS */

		static inline void perf_tp_register(void)
		{
		perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
		#ifdef CONFIG_KPROBE_EVENTS
		perf_pmu_register(&perf_kprobe, "kprobe", -1);
		#endif
		}

		static void perf_event_free_filter(struct perf_event *event)
		@@ -8071,13 +8139,28 @@ 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()
		*/
		static inline bool perf_event_is_tracing(struct perf_event *event)
		{
		if (event->pmu == &perf_tracepoint)
		return true;
		#ifdef CONFIG_KPROBE_EVENTS
		if (event->pmu == &perf_kprobe)
		return true;
		#endif
		return false;
		}

		static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
		{
		bool is_kprobe, is_tracepoint, is_syscall_tp;
		struct bpf_prog *prog;
		int ret;

		if (event->attr.type != PERF_TYPE_TRACEPOINT)
		if (!perf_event_is_tracing(event))
		return perf_event_set_bpf_handler(event, prog_fd);

		is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_UKPROBE;
		@@ -8116,7 +8199,7 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)

		static void perf_event_free_bpf_prog(struct perf_event *event)
		{
		if (event->attr.type != PERF_TYPE_TRACEPOINT) {
		if (!perf_event_is_tracing(event)) {
		perf_event_free_bpf_handler(event);
		return;
		}
		@@ -8535,47 +8618,36 @@ perf_event_set_addr_filter(struct perf_event event, char filter_str)
		return ret;
		}

		static int
		perf_tracepoint_set_filter(struct perf_event event, char filter_str)
		static int perf_event_set_filter(struct perf_event event, void __user arg)
		{
		int ret = -EINVAL;
		char *filter_str;

		filter_str = strndup_user(arg, PAGE_SIZE);
		if (IS_ERR(filter_str))
		return PTR_ERR(filter_str);

		#ifdef CONFIG_EVENT_TRACING
		if (perf_event_is_tracing(event)) {
		struct perf_event_context *ctx = event->ctx;
		int ret;

		/*
		* Beware, here be dragons!!
		*
		* the tracepoint muck will deadlock against ctx->mutex, but the tracepoint
		* stuff does not actually need it. So temporarily drop ctx->mutex. As per
		* perf_event_ctx_lock() we already have a reference on ctx.
		* the tracepoint muck will deadlock against ctx->mutex, but
		* the tracepoint stuff does not actually need it. So
		* temporarily drop ctx->mutex. As per perf_event_ctx_lock() we
		* already have a reference on ctx.
		*
		* This can result in event getting moved to a different ctx, but that
		* does not affect the tracepoint state.
		* This can result in event getting moved to a different ctx,
		* but that does not affect the tracepoint state.
		*/
		mutex_unlock(&ctx->mutex);
		ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
		mutex_lock(&ctx->mutex);

		return ret;
		}

		static int perf_event_set_filter(struct perf_event event, void __user arg)
		{
		char *filter_str;
		int ret = -EINVAL;

		if ((event->attr.type != PERF_TYPE_TRACEPOINT \|\|
		!IS_ENABLED(CONFIG_EVENT_TRACING)) &&
		!has_addr_filter(event))
		return -EINVAL;

		filter_str = strndup_user(arg, PAGE_SIZE);
		if (IS_ERR(filter_str))
		return PTR_ERR(filter_str);

		if (IS_ENABLED(CONFIG_EVENT_TRACING) &&
		event->attr.type == PERF_TYPE_TRACEPOINT)
		ret = perf_tracepoint_set_filter(event, filter_str);
		else if (has_addr_filter(event))
		} else
		#endif
		if (has_addr_filter(event))
		ret = perf_event_set_addr_filter(event, filter_str);

		kfree(filter_str);

kernel/trace/trace_event_perf.c

+49 −0

Original line number	Diff line number	Diff line
		@@ -8,6 +8,7 @@
		#include <linux/module.h>
		#include <linux/kprobes.h>
		#include "trace.h"
		#include "trace_probe.h"

		static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];

		@@ -237,6 +238,54 @@ void perf_trace_destroy(struct perf_event *p_event)
		mutex_unlock(&event_mutex);
		}

		#ifdef CONFIG_KPROBE_EVENTS
		int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe)
		{
		int ret;
		char *func = NULL;
		struct trace_event_call *tp_event;

		if (p_event->attr.kprobe_func) {
		func = kzalloc(KSYM_NAME_LEN, GFP_KERNEL);
		if (!func)
		return -ENOMEM;
		ret = strncpy_from_user(
		func, u64_to_user_ptr(p_event->attr.kprobe_func),
		KSYM_NAME_LEN);
		if (ret < 0)
		goto out;

		if (func[0] == '\0') {
		kfree(func);
		func = NULL;
		}
		}

		tp_event = create_local_trace_kprobe(
		func, (void *)(unsigned long)(p_event->attr.kprobe_addr),
		p_event->attr.probe_offset, is_retprobe);
		if (IS_ERR(tp_event)) {
		ret = PTR_ERR(tp_event);
		goto out;
		}

		ret = perf_trace_event_init(tp_event, p_event);
		if (ret)
		destroy_local_trace_kprobe(tp_event);
		out:
		kfree(func);
		return ret;
		}

		void perf_kprobe_destroy(struct perf_event *p_event)
		{
		perf_trace_event_close(p_event);
		perf_trace_event_unreg(p_event);

		destroy_local_trace_kprobe(p_event->tp_event);
		}
		#endif /* CONFIG_KPROBE_EVENTS */

		int perf_trace_add(struct perf_event *p_event, int flags)
		{
		struct trace_event_call *tp_event = p_event->tp_event;

kernel/trace/trace_kprobe.c

+83 −8

Original line number	Diff line number	Diff line
		@@ -438,6 +438,14 @@ disable_trace_kprobe(struct trace_kprobe tk, struct trace_event_file file)
		disable_kprobe(&tk->rp.kp);
		wait = 1;
		}

		/*
		* if tk is not added to any list, it must be a local trace_kprobe
		* created with perf_event_open. We don't need to wait for these
		* trace_kprobes
		*/
		if (list_empty(&tk->list))
		wait = 0;
		out:
		if (wait) {
		/*
		@@ -1313,12 +1321,9 @@ static struct trace_event_functions kprobe_funcs = {
		.trace = print_kprobe_event
		};

		static int register_kprobe_event(struct trace_kprobe *tk)
		static inline void init_trace_event_call(struct trace_kprobe *tk,
		struct trace_event_call *call)
		{
		struct trace_event_call *call = &tk->tp.call;
		int ret;

		/* Initialize trace_event_call */
		INIT_LIST_HEAD(&call->class->fields);
		if (trace_kprobe_is_return(tk)) {
		call->event.funcs = &kretprobe_funcs;
		@@ -1327,6 +1332,19 @@ static int register_kprobe_event(struct trace_kprobe *tk)
		call->event.funcs = &kprobe_funcs;
		call->class->define_fields = kprobe_event_define_fields;
		}

		call->flags = TRACE_EVENT_FL_KPROBE;
		call->class->reg = kprobe_register;
		call->data = tk;
		}

		static int register_kprobe_event(struct trace_kprobe *tk)
		{
		struct trace_event_call *call = &tk->tp.call;
		int ret = 0;

		init_trace_event_call(tk, call);

		if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
		return -ENOMEM;
		ret = register_trace_event(&call->event);
		@@ -1334,9 +1352,6 @@ static int register_kprobe_event(struct trace_kprobe *tk)
		kfree(call->print_fmt);
		return -ENODEV;
		}
		call->flags = TRACE_EVENT_FL_KPROBE;
		call->class->reg = kprobe_register;
		call->data = tk;
		ret = trace_add_event_call(call);
		if (ret) {
		pr_info("Failed to register kprobe event: %s\n",
		@@ -1358,6 +1373,66 @@ static int unregister_kprobe_event(struct trace_kprobe *tk)
		return ret;
		}

		#ifdef CONFIG_PERF_EVENTS
		/* create a trace_kprobe, but don't add it to global lists */
		struct trace_event_call *
		create_local_trace_kprobe(char func, void addr, unsigned long offs,
		bool is_return)
		{
		struct trace_kprobe *tk;
		int ret;
		char *event;

		/*
		* local trace_kprobes are not added to probe_list, so they are never
		* searched in find_trace_kprobe(). Therefore, there is no concern of
		* duplicated name here.
		*/
		event = func ? func : "DUMMY_EVENT";

		tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func,
		offs, 0 /* maxactive /, 0 / nargs */,
		is_return);

		if (IS_ERR(tk)) {
		pr_info("Failed to allocate trace_probe.(%d)\n",
		(int)PTR_ERR(tk));
		return ERR_CAST(tk);
		}

		init_trace_event_call(tk, &tk->tp.call);

		if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
		ret = -ENOMEM;
		goto error;
		}

		ret = __register_trace_kprobe(tk);
		if (ret < 0)
		goto error;

		return &tk->tp.call;
		error:
		free_trace_kprobe(tk);
		return ERR_PTR(ret);
		}

		void destroy_local_trace_kprobe(struct trace_event_call *event_call)
		{
		struct trace_kprobe *tk;

		tk = container_of(event_call, struct trace_kprobe, tp.call);

		if (trace_probe_is_enabled(&tk->tp)) {
		WARN_ON(1);
		return;
		}

		__unregister_trace_kprobe(tk);
		free_trace_kprobe(tk);
		}
		#endif /* CONFIG_PERF_EVENTS */

		/* Make a tracefs interface for controlling probe points */
		static __init int init_kprobe_trace(void)
		{

kernel/trace/trace_probe.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -404,3 +404,10 @@ store_trace_args(int ent_size, struct trace_probe tp, struct pt_regs regs,
		}

		extern int set_print_fmt(struct trace_probe *tp, bool is_return);

		#ifdef CONFIG_PERF_EVENTS
		extern struct trace_event_call *
		create_local_trace_kprobe(char func, void addr, unsigned long offs,
		bool is_return);
		extern void destroy_local_trace_kprobe(struct trace_event_call *event_call);
		#endif