From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 98BC3644; Sat, 28 Oct 2023 01:41:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JXa3SL6a" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B761C433C8; Sat, 28 Oct 2023 01:41:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1698457308; bh=culIKFe+JSj9EHA864Ou39mlvl0u+Ctl5H8IvNqq8+M=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=JXa3SL6auUCV66hDM1saY5rjnAQHKpCd8Lc86L4XaH53vvBsK1zjgNIOOgaPxfbaD n6dxp9BV0VEcdnYBq1iXXYjwY+iqNDkNSaBQ3hB6C4CFQLaw9uZv2LDFQAmrDgiDry mL8Z1QfLP0eySvoqWMCUfVG4ci2EMzCHHr6t88IbQUI+IIS52yZD28USV5XoQVRUBZ ZnEW/sn34XwCO/yCWGBevsb3T+toptKWHLaCFg6IYL+8ywqDjw3P3fe9Jbi2c5B6jI 9R+gFPECRDUKtDRw1ebEFOBK5Sv+rU3kgES0M2gA3dJW4yqFnoN0m+H6XDX0QInQRa owC5w0ALTLbkg== Date: Sat, 28 Oct 2023 10:41:44 +0900 From: Masami Hiramatsu (Google) To: Andrii Nakryiko Cc: , , Francis Laniel , , Steven Rostedt Subject: Re: [PATCH] tracing/kprobes: Fix symbol counting logic by looking at modules as well Message-Id: <20231028104144.de23c2287281e9228ce92508@kernel.org> In-Reply-To: <20231027233126.2073148-1-andrii@kernel.org> References: <20231027233126.2073148-1-andrii@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Hi, On Fri, 27 Oct 2023 16:31:26 -0700 Andrii Nakryiko wrote: > Recent changes to count number of matching symbols when creating > a kprobe event failed to take into account kernel modules. As such, it > breaks kprobes on kernel module symbols, by assuming there is no match. > > Fix this my calling module_kallsyms_on_each_symbol() in addition to > kallsyms_on_each_match_symbol() to perform a proper counting. > > Cc: Francis Laniel > Cc: stable@vger.kernel.org > Cc: Masami Hiramatsu > Cc: Steven Rostedt > Fixes: b022f0c7e404 ("tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols") > Signed-off-by: Andrii Nakryiko This fixes "BPF" kprobe event, but not ftrace kprobe events. ftrace kprobe events only checks this if it is in the vmlinux not modules and that's why my selftest passed the original one. Hmm, I need another enhancement like this for the events on offline modules. Thank you, > --- > kernel/trace/trace_kprobe.c | 24 ++++++++++++++++++++---- > 1 file changed, 20 insertions(+), 4 deletions(-) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index effcaede4759..1efb27f35963 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -714,14 +714,30 @@ static int count_symbols(void *data, unsigned long unused) > return 0; > } > > +struct sym_count_ctx { > + unsigned int count; > + const char *name; > +}; > + > +static int count_mod_symbols(void *data, const char *name, unsigned long unused) > +{ > + struct sym_count_ctx *ctx = data; > + > + if (strcmp(name, ctx->name) == 0) > + ctx->count++; > + > + return 0; > +} > + > static unsigned int number_of_same_symbols(char *func_name) > { > - unsigned int count; > + struct sym_count_ctx ctx = { .count = 0, .name = func_name }; > + > + kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count); > > - count = 0; > - kallsyms_on_each_match_symbol(count_symbols, func_name, &count); > + module_kallsyms_on_each_symbol(NULL, count_mod_symbols, &ctx); > > - return count; > + return ctx.count; > } > > static int __trace_kprobe_create(int argc, const char *argv[]) > -- > 2.34.1 > -- Masami Hiramatsu (Google)