From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 BA31D2DFF1D for ; Thu, 6 Nov 2025 07:51:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762415493; cv=none; b=AHPJ/wy3XjyaLulPz5U6mm9UJ5IyKPK2H8Czs6lESjmDXAe/IAfablhntfJcwDLcgp+uVVKwGP3Hek2dLd3D+Ne88T/VyoxWUKcdN5DkjFPdgvPcEgQ15uv/Cnv03Px7DQB4A7gjJ4Z/uvGL21mPAjohUnZc07eBJMTnLB0bksk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762415493; c=relaxed/simple; bh=K65aaEqq/YB61r4p7ihT0ItAeEpKgQgbAjU3OugTSoM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=EFd9UsRoO29ecsAxp46sptJ25jb61fcNXjZA/aXmU/weJE6cQ4rt2DNKpbrubznJGXNtsWH0VA+MVc3Hs6z4f7++0YcIUAmrtPS7GdhWxWYVkJAEh6HzM6glyvBo+NLufMfCzH75xPEmGCl/cmah+C/e7734Pja3MKG28qG3zME= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=f8VJ+nfa; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="f8VJ+nfa" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1762415490; 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: in-reply-to:in-reply-to:references:references; bh=p/narQH7oBzjR+CHzap2CS6luEPNI9uaK+xgrYacn+w=; b=f8VJ+nfaVlZo6E6oiajGdSYmRwVZts0co/zxkRoICNDQcEI5deoCMTxw2FinT0yQ/V9Wxb i3pq7tdIc8N1TWa2YFlI2jk8JXeyGxETj/hJztQqFVIIvS3+vSlzWZnuVdho7Zhh7zAdPS G3yVlIrq1dY/b8mrfZXnuWjujgvgBHI= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-53-ecT11MeyOWeocyapa6M-Fg-1; Thu, 06 Nov 2025 02:51:27 -0500 X-MC-Unique: ecT11MeyOWeocyapa6M-Fg-1 X-Mimecast-MFC-AGG-ID: ecT11MeyOWeocyapa6M-Fg_1762415486 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4019F180047F; Thu, 6 Nov 2025 07:51:26 +0000 (UTC) Received: from fweimer-oldenburg.csb.redhat.com (unknown [10.45.224.98]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8C20C18002B6; Thu, 6 Nov 2025 07:51:24 +0000 (UTC) From: Florian Weimer To: Indu Bhagat Cc: Fangrui Song , linux-toolchains@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Concerns about SFrame viability for userspace stack walking In-Reply-To: <9c11b765-66df-46f3-b4ea-a0c7f52dac35@oracle.com> (Indu Bhagat's message of "Wed, 5 Nov 2025 16:44:24 -0800") References: <3xd4fqvwflefvsjjoagytoi3y3sf7lxqjremhe2zo5tounihe4@3ftafgryadsr> <2d713719-709d-4b46-8234-2dfe948b836a@oracle.com> <9c11b765-66df-46f3-b4ea-a0c7f52dac35@oracle.com> User-Agent: Gnus/5.13 (Gnus v5.13) Date: Thu, 06 Nov 2025 08:51:22 +0100 Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 * Indu Bhagat: > PLT stubs may use stack (push to stack). As per the document "A null > frame (MODE = 8) is the simplest possible frame, with no allocated > stack of either kind (hence no saved registers)". So null frame can > be used for PLT only if the functions invoking the PLT stub were using > an RBP-based frame. Isnt it ? I think I said this before, but I don't think new toolchain features need to support lazy binding. Without lazy bindings, the PLT stubs do not change the stack pointer or frame pointer and just make a tail call. Do you see a need for continued support of lazy binding? Thanks, Florian