From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) (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 ABB951DA628 for ; Fri, 23 Jan 2026 19:05:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769195150; cv=none; b=tSyZq2DdSw7d48QQumf1c5cNx9gb1IQsztOarvpIBPKWxgZf4fSdZMPlt9C4KvdFeKV7LzyOnpAf4ZSU81+SIMFCzNKcH0n4WuvK1BYgB6oZwI1FAwuRu5AasnFdtGsW1SFsnrpYJFDbbJYOBwQQeVkKoC3qM7Wr3DVHgW+ZlI0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769195150; c=relaxed/simple; bh=vEgGnmKQ3/w5bJ2jiMRqtltEJGbTjhrRKZ1ALWspsHA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=IFjj1rD/uUlp0twW0XmDoLB/IKhqQSM4ZC2v2lS9/Bd8zKU0/ak2djfyUWwK9Tk7HRtPj5RidjKdqPjizwaRci3/V5n70Fkmvde7GxC3q7I3wKmbnPm752C27b0GGwax8iajoXt0Z/h2xRAjM7ok3sm5HDE2gyjXBe/F7RT6zDo= 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=BnNEXmSY; arc=none smtp.client-ip=91.218.175.174 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="BnNEXmSY" Message-ID: <8cc92e34-c77f-4293-a0a3-9f13e3440716@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1769195145; 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=932oIGiEPEF7l80f+ZE1KYAU4eKnL27ViShR3j7TwJ4=; b=BnNEXmSYbxqeWRdNFsZogBmS2P4Bt9MiXIaNwmVl4OAX4eR47MN80677moo7mUgCrG4fTv yJ8DH554Cr/svQCtCML8gFMUuK9WX+bjVFqZ7A7BQHPUiWpJJLvq4PzaRiF5KmxxgEd0yS Ty3AK3FvlN4cYWYARWIjeyLS3o6xTLw= Date: Fri, 23 Jan 2026 11:05:40 -0800 Precedence: bulk X-Mailing-List: dwarves@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v2 dwarves 2/5] btf_encoder: Add true_signature feature support for "."-suffixed functions Content-Language: en-GB To: Alan Maguire , mattbobrowski@google.com Cc: ihor.solodrai@linux.dev, eddyz87@gmail.com, jolsa@kernel.org, andrii@kernel.org, ast@kernel.org, david.faust@oracle.com, dwarves@vger.kernel.org, bpf@vger.kernel.org References: <20260123172650.4062362-1-alan.maguire@oracle.com> <20260123172650.4062362-3-alan.maguire@oracle.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <20260123172650.4062362-3-alan.maguire@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 1/23/26 9:26 AM, Alan Maguire wrote: > Currently we collate function information by name and add functions > provided there are no inconsistencies across various representations. > > For true_signature support - where we wish to add the real signature > of a function even if it differs from source level - we need to do > a few things: > > 1. For "."-suffixed functions, we need to match from DWARF->ELF; > we can do this via the address associated with the function. > In doing this, we can then be confident that the debug info > for foo.isra.0 is the right info for the function at that > address. > > 2. When adding saved functions we need to look for such cases > and provided they do not violate other constraints around BTF > representation - unexpected reg usage for function, uncertain > parameter location or ambiguous address - we add them with > their "."-suffixed name. The latter can be used as a signal > that the function is transformed from the original. > > Doing this adds 500 functions to BTF. These are traceable with > their "."-suffix names and because we have excluded ambiguous > address cases we know exactly which function address they refer > to. > > Signed-off-by: Alan Maguire Acked-by: Yonghong Song