Commit 8e2759da authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google) Committed by Steven Rostedt (Google)
Browse files

bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled 

Enable kprobe_multi feature if CONFIG_FPROBE is enabled. The pt_regs is
converted from ftrace_regs by ftrace_partial_regs(), thus some registers
may always returns 0. But it should be enough for function entry (access
arguments) and exit (access return value).

Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/173519000417.391279.14011193569589886419.stgit@devnote2


Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: default avatarFlorent Revest <revest@chromium.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 0566cefe

kernel/trace/bpf_trace.c

+14 −13
Original line number Diff line number Diff line
@@ -2561,7 +2561,7 @@ struct bpf_session_run_ctx { 
	void *data;

};



#if defined(CONFIG_FPROBE) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)

#ifdef CONFIG_FPROBE

struct bpf_kprobe_multi_link {

	struct bpf_link link;

	struct fprobe fp;
@@ -2584,6 +2584,13 @@ struct user_syms { 
	char *buf;

};



#ifndef CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS

static DEFINE_PER_CPU(struct pt_regs, bpf_kprobe_multi_pt_regs);

#define bpf_kprobe_multi_pt_regs_ptr()	this_cpu_ptr(&bpf_kprobe_multi_pt_regs)

#else

#define bpf_kprobe_multi_pt_regs_ptr()	(NULL)

#endif



static int copy_user_syms(struct user_syms *us, unsigned long __user *usyms, u32 cnt)

{

	unsigned long __user usymbol;
@@ -2778,7 +2785,7 @@ static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx) 


static int

kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,

			   unsigned long entry_ip, struct pt_regs *regs,

			   unsigned long entry_ip, struct ftrace_regs *fregs,

			   bool is_return, void *data)

{

	struct bpf_kprobe_multi_run_ctx run_ctx = {
@@ -2790,6 +2797,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, 
		.entry_ip = entry_ip,

	};

	struct bpf_run_ctx *old_run_ctx;

	struct pt_regs *regs;

	int err;



	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
@@ -2800,6 +2808,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, 


	migrate_disable();

	rcu_read_lock();

	regs = ftrace_partial_regs(fregs, bpf_kprobe_multi_pt_regs_ptr());

	old_run_ctx = bpf_set_run_ctx(&run_ctx.session_ctx.run_ctx);

	err = bpf_prog_run(link->link.prog, regs);

	bpf_reset_run_ctx(old_run_ctx);
@@ -2816,15 +2825,11 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip, 
			  unsigned long ret_ip, struct ftrace_regs *fregs,

			  void *data)

{

	struct pt_regs *regs = ftrace_get_regs(fregs);

	struct bpf_kprobe_multi_link *link;

	int err;



	if (!regs)

		return 0;



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

	err = kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs, false, data);

	err = kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), fregs, false, data);

	return is_kprobe_session(link->link.prog) ? err : 0;

}
@@ -2834,13 +2839,9 @@ kprobe_multi_link_exit_handler(struct fprobe *fp, unsigned long fentry_ip, 
			       void *data)

{

	struct bpf_kprobe_multi_link *link;

	struct pt_regs *regs = ftrace_get_regs(fregs);



	if (!regs)

		return;



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

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

	kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), fregs, true, data);

}



static int symbols_cmp_r(const void *a, const void *b, const void *priv)
@@ -3101,7 +3102,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr 
	kvfree(cookies);

	return err;

}

#else /* !CONFIG_FPROBE || !CONFIG_DYNAMIC_FTRACE_WITH_REGS */

#else /* !CONFIG_FPROBE */

int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)

{

	return -EOPNOTSUPP;