From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 26D1617736 for ; Mon, 7 Aug 2023 22:09:39 +0000 (UTC) Received: from mail-ed1-x532.google.com (mail-ed1-x532.google.com [IPv6:2a00:1450:4864:20::532]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70CB7448C; Mon, 7 Aug 2023 15:09:10 -0700 (PDT) Received: by mail-ed1-x532.google.com with SMTP id 4fb4d7f45d1cf-5227e5d9d96so6641472a12.2; Mon, 07 Aug 2023 15:09:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1691446094; x=1692050894; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=M6+h3JPtffH3KCnU+FPVbWvNYGtSA/UOocgPTJJmPrM=; b=dhwsK4bB5MaJTm9+mzIvA5OXXQvBIIJkM3LHvM0/KCirJESPqHr/1ROandY8hhMcF1 Ypy8TqMIwmFozUDcajbUy72oPZj2xQxT+0oJ8sz02MO9GCY+MyJ70npaJmzZK+24sBFH OBDsvT0M/XL5XYy9mQV5wowXxgCvtqK+Wq7TSdrX3/d5hjMj8LiDD/yY1PtpBbgAGzJz X+fmNKB+as6A60nEV0fRcHN4yM/RDpgZANcjIrRq1qxlo3TvobWe5w6o4mPncr93v6nh mzCEzEJuHBg8G+09kfF8qQI59MEuXUWjhguHVj0KzUCxFHXOlExxnb3wVqBndwc4ir7z Q/AQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691446094; x=1692050894; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=M6+h3JPtffH3KCnU+FPVbWvNYGtSA/UOocgPTJJmPrM=; b=Q96FQii6I8/rbMQWhCcppCpDv6ZsSYSr0XzQCeaG25vj9Z59qtk637BEfrCahrArHv Whx0gUGGQ2V9ZKrAVh+qqSzwJMr8LcjzbB884Rs54WLPVYY+ZVfDfE42dUaJP85Vro5L N8sN/xcVdshSwuNVj0SI8PuQvxpuyoYzpTdCBTU5FRV0PIAeWxbjNqT47PLUWDoA+dG6 TbHqzQ4JQajnSHKVjEJczAKZOkOcx2jw/kDar2itm1yzcpT22Ks+98d5JwUunYYjieiH kKcz6bKXs5AgxmYwRGH7iT1XO1LH7TdGqjVrxF5gng+3WtOn/9axAFrzB2t5TnEXdhfG zQRA== X-Gm-Message-State: AOJu0Yx86rLPgd8Afs2wtJXHY65cMN96y0VeftIqLx+BlbqcbxRv+rX7 1Q0k43g+ajAhNcLYTHfixmk= X-Google-Smtp-Source: AGHT+IHcFeSC/KLA5gbHHDoZ38Wjuek7W2QjlW9lOhBV5LyfzbSNg41cd2VqVgu1h/MLxxqARpsyCQ== X-Received: by 2002:a05:6402:110a:b0:523:7b1:3718 with SMTP id u10-20020a056402110a00b0052307b13718mr7820189edv.14.1691446093469; Mon, 07 Aug 2023 15:08:13 -0700 (PDT) Received: from krava ([83.240.60.134]) by smtp.gmail.com with ESMTPSA id d13-20020a50fe8d000000b0051e1660a34esm5637299edt.51.2023.08.07.15.08.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Aug 2023 15:08:13 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Tue, 8 Aug 2023 00:08:11 +0200 To: "Masami Hiramatsu (Google)" Cc: Alexei Starovoitov , Steven Rostedt , Florent Revest , linux-trace-kernel@vger.kernel.org, LKML , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov , Arnaldo Carvalho de Melo , Daniel Borkmann , Alan Maguire , Mark Rutland , Peter Zijlstra , Thomas Gleixner Subject: Re: [RFC PATCH v2 6/6] bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled Message-ID: References: <169139090386.324433.6412259486776991296.stgit@devnote2> <169139097360.324433.2521527070503682979.stgit@devnote2> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <169139097360.324433.2521527070503682979.stgit@devnote2> X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Mon, Aug 07, 2023 at 03:49:33PM +0900, Masami Hiramatsu (Google) wrote: > From: Masami Hiramatsu (Google) > > 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). > > Signed-off-by: Masami Hiramatsu (Google) > --- > kernel/trace/bpf_trace.c | 22 +++++++++------------- > 1 file changed, 9 insertions(+), 13 deletions(-) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 99c5f95360f9..0725272a3de2 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -2460,7 +2460,7 @@ static int __init bpf_event_init(void) > fs_initcall(bpf_event_init); > #endif /* CONFIG_MODULES */ > > -#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +#ifdef CONFIG_FPROBE > struct bpf_kprobe_multi_link { > struct bpf_link link; > struct fprobe fp; > @@ -2482,6 +2482,8 @@ struct user_syms { > char *buf; > }; > > +static DEFINE_PER_CPU(struct pt_regs, bpf_kprobe_multi_pt_regs); > + > static int copy_user_syms(struct user_syms *us, unsigned long __user *usyms, u32 cnt) > { > unsigned long __user usymbol; > @@ -2623,13 +2625,14 @@ 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) > { > struct bpf_kprobe_multi_run_ctx run_ctx = { > .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)) { > @@ -2639,6 +2642,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, > > migrate_disable(); > rcu_read_lock(); > + regs = ftrace_partial_regs(fregs, this_cpu_ptr(&bpf_kprobe_multi_pt_regs)); you did check for !regs when returned from ftrace_get_regs, why don't we need to check it in here? both ftrace_partial_regs and ftrace_get_regs call arch_ftrace_get_regs on x86 also also I can't find the place ensuring fregs->regs.cs != 0 for FL_SAVE_REGS flag as stated in arch_ftrace_get_regs, any hint? thanks, jirka > old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx); > err = bpf_prog_run(link->link.prog, regs); > bpf_reset_run_ctx(old_run_ctx); > @@ -2656,13 +2660,9 @@ kprobe_multi_link_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 0; > > link = container_of(fp, struct bpf_kprobe_multi_link, fp); > - kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs); > + kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), fregs); > return 0; > } > > @@ -2672,13 +2672,9 @@ 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); > + kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), fregs); > } > > static int symbols_cmp_r(const void *a, const void *b, const void *priv) > @@ -2918,7 +2914,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr > kvfree(cookies); > return err; > } > -#else /* !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; >