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 08ACD2AF00 for ; Sun, 26 Jan 2025 14:40:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737902411; cv=none; b=Bw3hIMCehusdoX19eCfgzGpUyPgVmCjzdpGfDtH7Z/HQIs3zgwWedvBEJoMNSTD81x9zw1QTMLYVIdoT5EorP672kNNL24E/1QhG1B6PY3gf/YWLgnlGoLS22+v6Mtpf2zNbzuhIHjOb93NyVk2id1Flo09HxA2Bq09wlgjRXYk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737902411; c=relaxed/simple; bh=Of6s/34NuA/HPkSmdPrlVHZZnoDx8kQdpML1kh+efqY=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=ICWaWe6DorJPEemuHQo8jw2HuGlyB4QkCJwhv73QSo8EFFhR9mgRmTqaqKThfgMk5Xx8p5r6oYK4Z9QnniYUif2f2Ho+vQsBKhJMQp/17qmhX6bs82fVE3PPIooiFdu/WOZlIZ+O19Y/Xkav99IrLJXiu2iL9j0wZT5ZENGwNf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=a6Z1ZhXN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="a6Z1ZhXN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 680DCC4CED3; Sun, 26 Jan 2025 14:40:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737902409; bh=Of6s/34NuA/HPkSmdPrlVHZZnoDx8kQdpML1kh+efqY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=a6Z1ZhXNIBlQS+vgmffLTnv4K4LZgWkkoNm7vDRs1wsx2mE2cUwmlCtIrDbV5gQaz 9VRU+o/stI6WqgHvrENVQf15AKiScyd8vAFHbjsYwjYxkUNfdHazvseZLFN7J7DsVG xwalIPPZ8i38b+ERk1Uz2JBXwOhEgeKxTInK5x5AwHgC0zCcL3SL12OqVBb4Ji8H50 sENOTnulzVwIGWr3fveeyMQPXFHQt/HX7FNXEZe5LLs+o0bcIEr1ni3z3xLVW8vB0z 7v3KiqmzwFTO/NHKhkHQxgB8FSFckIBl6aLzuTzELJ+YzrtCJ6hE+h91NkZKdtJfyZ TPhAzZaLzJksA== Date: Sun, 26 Jan 2025 23:40:05 +0900 From: Masami Hiramatsu (Google) To: Jiri Olsa Cc: Sven Schnelle , Martin KaFai Lau , Ilya Leoshkevich , bpf Subject: Re: [TEST FAILURE] bpf: s390: missed/kprobe_recursion Message-Id: <20250126234005.70cb3b43193b08ed8a211553@kernel.org> In-Reply-To: References: <3c841f0a-772a-406c-9888-f8e71826daff@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit On Fri, 24 Jan 2025 16:41:38 +0100 Jiri Olsa wrote: > On Fri, Jan 24, 2025 at 12:23:35PM +0100, Jiri Olsa wrote: > > On Thu, Jan 23, 2025 at 02:32:38PM -0800, Martin KaFai Lau wrote: > > > Hi Jiri, > > > > > > The "missed/kprobe_recursion" fails consistently on s390. It seems to start > > > failing after the recent bpf and bpf-next tree ffwd. > > > > > > An example: > > > https://github.com/kernel-patches/bpf/actions/runs/12934431612/job/36076956920 > > > > > > Can you help to take a look? > > > > > > afaict, it only happens on s390 so far, so cc IIya if there is any recent > > > change that may ring the bell. > > > > hi, > > I need to check more but I wonder it's the: > > 7495e179b478 s390/tracing: Enable HAVE_FTRACE_GRAPH_FUNC > > > > which seems to add recursion check and bail out before we have > > a chance to trigger it in bpf code > > so the test attaches bpf program test1 to bpf_fentry_test1 via kprobe.multi > > SEC("kprobe.multi/bpf_fentry_test1") > int test1(struct pt_regs *ctx) > { > bpf_kfunc_common_test(); > return 0; > } > > and several other programs are attached to bpf_kfunc_common_test function > > > I can't test this on s390, but looks like following is happening: > > kprobe.multi uses fprobe, so the test kernel path goes: > > bpf_fentry_test1 > ftrace_graph_func > function_graph_enter_regs > fprobe_entry > kprobe_multi_link_prog_run > test1 (bpf program) > bpf_kfunc_common_test > kprobe_ftrace_handler > kprobe_perf_func > trace_call_bpf > -> bpf_prog_active check fails, missed count is incremented > > > kprobe_ftrace_handler calls/takes ftrace_test_recursion_trylock (ftrace recursion lock) > > but s390 now calls/takes ftrace_test_recursion_trylock already in ftrace_graph_func, > so s390 stops at kprobe_ftrace_handler and does not get to trace_call_bpf to increment > prog->missed counters Oops, good catch! I missed to remove it from s390. We've already moved it in function_graph_enter_regs(). > > adding Sven, Masami, any idea? > > if the ftrace_test_recursion_trylock is needed ftrace_graph_func on s390, then > I think we will need to fix our test to skip s390 arch Yes. Please try this patch; >From 12fcda79d0b1082449d5f7cfb8039b0237cf246d Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Sun, 26 Jan 2025 23:38:59 +0900 Subject: [PATCH] s390: fgraph: Fix to remove ftrace_test_recursion_trylock() Fix to remove ftrace_test_recursion_trylock() from ftrace_graph_func() because commit d576aec24df9 ("fgraph: Get ftrace recursion lock in function_graph_enter") has been moved it to function_graph_enter_regs() already. Reported-by: Jiri Olsa Fixes: d576aec24df9 ("fgraph: Get ftrace recursion lock in function_graph_enter") Signed-off-by: Masami Hiramatsu (Google) --- arch/s390/kernel/ftrace.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index c0b2c97efefb..63ba6306632e 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -266,18 +266,13 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs) { unsigned long *parent = &arch_ftrace_regs(fregs)->regs.gprs[14]; - int bit; if (unlikely(ftrace_graph_is_dead())) return; if (unlikely(atomic_read(¤t->tracing_graph_pause))) return; - bit = ftrace_test_recursion_trylock(ip, *parent); - if (bit < 0) - return; if (!function_graph_enter_regs(*parent, ip, 0, parent, fregs)) *parent = (unsigned long)&return_to_handler; - ftrace_test_recursion_unlock(bit); } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ -- 2.43.0 Thank you, -- Masami Hiramatsu (Google)