Commit 39d95420 authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google) Committed by Steven Rostedt (Google)
Browse files

fprobe: Skip exit_handler if entry_handler returns !0 

Skip hooking function return and calling exit_handler if the
entry_handler() returns !0.

Link: https://lkml.kernel.org/r/167526699798.433354.10998365726830117303.stgit@mhiramat.roam.corp.google.com



Cc: Florent Revest <revest@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 7e7ef1bf

include/linux/fprobe.h

+2 −2
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ struct fprobe { 
	size_t			entry_data_size;

	int			nr_maxactive;



	void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,

	int (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,

			     struct pt_regs *regs, void *entry_data);

	void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip,

			     struct pt_regs *regs, void *entry_data);

kernel/trace/bpf_trace.c

+13 −2
Original line number Diff line number Diff line
@@ -2644,12 +2644,23 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, 
	return err;

}



static void

static int

kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,

			  struct pt_regs *regs, void *data)

{

	struct bpf_kprobe_multi_link *link;



	link = container_of(fp, struct bpf_kprobe_multi_link, fp);

	kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);

	return 0;

}



static void

kprobe_multi_link_exit_handler(struct fprobe *fp, unsigned long fentry_ip,

			       struct pt_regs *regs, void *data)

{

	struct bpf_kprobe_multi_link *link;



	link = container_of(fp, struct bpf_kprobe_multi_link, fp);

	kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);

}
@@ -2848,7 +2859,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr 
		goto error;



	if (flags & BPF_F_KPROBE_MULTI_RETURN)

		link->fp.exit_handler = kprobe_multi_link_handler;

		link->fp.exit_handler = kprobe_multi_link_exit_handler;

	else

		link->fp.entry_handler = kprobe_multi_link_handler;

kernel/trace/fprobe.c

+9 −5
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip, 
	struct rethook_node *rh = NULL;

	struct fprobe *fp;

	void *entry_data = NULL;

	int bit;

	int bit, ret;



	fp = container_of(ops, struct fprobe, ops);

	if (fprobe_disabled(fp))
@@ -52,11 +52,15 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip, 
	}



	if (fp->entry_handler)

		fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);

		ret = fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);



	if (rh)

	/* If entry_handler returns !0, nmissed is not counted. */

	if (rh) {

		if (ret)

			rethook_recycle(rh);

		else

			rethook_hook(rh, ftrace_get_regs(fregs), true);



	}

out:

	ftrace_test_recursion_unlock(bit);

}

lib/test_fprobe.c

+5 −2
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32)) 
	return nest(value + 2);

}



static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip,

static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,

				     struct pt_regs *regs, void *data)

{

	KUNIT_EXPECT_FALSE(current_test, preemptible());
@@ -51,6 +51,8 @@ static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, 
			*(u32 *)data = entry_val;

	} else

		KUNIT_EXPECT_NULL(current_test, data);



	return 0;

}



static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
@@ -74,10 +76,11 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, 
		KUNIT_EXPECT_NULL(current_test, data);

}



static notrace void nest_entry_handler(struct fprobe *fp, unsigned long ip,

static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,

				     struct pt_regs *regs, void *data)

{

	KUNIT_EXPECT_FALSE(current_test, preemptible());

	return 0;

}



static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip,

samples/fprobe/fprobe_example.c

+3 −2
Original line number Diff line number Diff line
@@ -48,7 +48,7 @@ static void show_backtrace(void) 
	stack_trace_print(stacks, len, 24);

}



static void sample_entry_handler(struct fprobe *fp, unsigned long ip,

static int sample_entry_handler(struct fprobe *fp, unsigned long ip,

				struct pt_regs *regs, void *data)

{

	if (use_trace)
@@ -62,6 +62,7 @@ static void sample_entry_handler(struct fprobe *fp, unsigned long ip, 
	nhit++;

	if (stackdump)

		show_backtrace();

	return 0;

}



static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs,