From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) (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 BB7D52459E5; Mon, 12 May 2025 16:02:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747065731; cv=none; b=sZgmuD83+KhvWfLnKDpiVttPxXByTzzrqoDKzekqfsvzEVKscS3VSY50sQ+5sELO++J0RGg/n+AeAjre0XMlv/GiSkJIFu3WPasbSXTI72tj8ltUn15D6pG88O3S3WhEIJPy4ypQ5TaS6cTGrxfPI7d2bR1YFTY2IyY5XY7g2XA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747065731; c=relaxed/simple; bh=+dtNDq8JdWpoZSwzwIh6d8nZ0BLajzNUKA6ws+hcvJs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=pa7QFZ6zNYUom40pRtdIACpfJdpiu1P5ZXC9eHcYgxK5g2OXFC98PXw+gEuTcqdy3QczB6XRJsX97gnQMfcqrjiJkKV933dH7i53Q/tc5ai7fDIlk+NHk+RnzFtYwZ4nzOXsYmtswrR8PwgBK7Y/NQBZsLJ0X4r2cQBdOAUVnmA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=ZmRysR/w; arc=none smtp.client-ip=91.218.175.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="ZmRysR/w" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1747065727; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=I2zAFQNz0bghz2/85QYfjphfPosBf1kHql5f0jIwCo8=; b=ZmRysR/wKLdb7+g1mzsNpBR05OzJPFedyOjTHQDaX+CSf4XO5OaaDRMx9BTaPLzf+m5txr vqo+3HmYchHxiuFWPEXRFWimqTGOPHqVA4+nT7QBHboegUwkmx2rahPA8VGOsk5ilu2qjI epmBe0dsNuc/pMZtzzFUGeFnchzzBow= Date: Tue, 13 May 2025 00:01:50 +0800 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next 1/4] bpf: Allow get_func_[arg|arg_cnt] helpers in raw tracepoint programs To: Alexei Starovoitov Cc: Andrii Nakryiko , Kafai Wan , Song Liu , Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Matt Bobrowski , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Mykola Lysenko , Shuah Khan , LKML , bpf , linux-trace-kernel , Network Development , "open list:KERNEL SELFTEST FRAMEWORK" References: <20250426160027.177173-1-mannkafai@gmail.com> <20250426160027.177173-2-mannkafai@gmail.com> <16eafae1-5014-42a9-b6c4-8be40b26cf31@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Leon Hwang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 2025/5/12 23:25, Alexei Starovoitov wrote: > On Mon, May 12, 2025 at 4:12 AM Leon Hwang wrote: >> [...] >> >> However, since bpf_rdonly_cast() is a kfunc, it causes registers r1–r5 >> to be considered volatile. > > It is not. > See: > BTF_ID_FLAGS(func, bpf_rdonly_cast, KF_FASTCALL) > and relevant commits. Thanks for the reminder — you're right, bpf_rdonly_cast() is marked with KF_FASTCALL, so it doesn't make r1–r5 volatile. Thanks, Leon