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 49B0038B for ; Tue, 19 Aug 2025 06:18:34 +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=1755584316; cv=none; b=TEnBCMsBqu8ebQxXV6aHY3Vt6fWazTCDTQZIn2oOjj91dCbu7G+idTr+g00YWLzSqKErop/LtPLw/dMgVvTcrTzAd3DmZ8mjls1RWrzkZqPS8YYyLyQvN/lliBdGAFz+CmMNXWwa/uIu1M0YiKzw+Kl5x+v/r0cPxV0R3nJQM24= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755584316; c=relaxed/simple; bh=MUXSemgemx2RSAJemxhhidrCft+naaehO5l4DQnoJy4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=UUh2deUaU29JanMLuS4l60HJVdBRiqXRQMWpI3esTsS9Y7KfMifAmNH+9dTjJcNab+sqz46JIfZ2/z2KnS9hY2lSgHbEIqLyGwafDHsQE36BgT8JXuAqPO5xyvy0iVs0MkJ8dtEdl53tNGmP+T0CiduPitCrf4EUQLNJjBHF+cs= 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=ZwwTeyWO; 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="ZwwTeyWO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1755584314; 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=A79+ZhsoGDMTj40WO9EJXb2tzabNrvwgqs+8konhKys=; b=ZwwTeyWOHbwhhHaOOnnfOVpD7A2cxgxb2EQuu8f+eJwOUCHgYKPlzD5tN9DeH5JLj8Vk/j 8emC+1VQZg1aQ7RlR2wvt6ygIz2vocBNzXIVGya8C/c+ufYhWaqYwHA24wssaeLrdBNFtg KD58fdAlIfWJjL9f4PPagBGj2ZKWX5M= 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-217-mia76B0vO_auLu_H0x8c0w-1; Tue, 19 Aug 2025 02:18:28 -0400 X-MC-Unique: mia76B0vO_auLu_H0x8c0w-1 X-Mimecast-MFC-AGG-ID: mia76B0vO_auLu_H0x8c0w_1755584306 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 C68E01800286; Tue, 19 Aug 2025 06:18:25 +0000 (UTC) Received: from fweimer-oldenburg.csb.redhat.com (unknown [10.44.32.125]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id F265F1955F24; Tue, 19 Aug 2025 06:18:21 +0000 (UTC) From: Florian Weimer To: Sean Christopherson Cc: Thomas Gleixner , Jens Axboe , LKML , Michael Jeanson , Mathieu Desnoyers , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Wei Liu , Samuel Thibault Subject: Re: BUG: rseq selftests and librseq vs. glibc fail In-Reply-To: (Sean Christopherson's message of "Mon, 18 Aug 2025 17:28:17 -0700") References: <87frdoybk4.ffs@tglx> <87cy8sy2n6.ffs@tglx> <87349oxk2n.ffs@tglx> Date: Tue, 19 Aug 2025 08:18:19 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) 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 3.0 on 10.30.177.17 * Sean Christopherson: >> If I make that: >> >> + if (!*libc_rseq_offset_p || !*libc_rseq_size_p) { >> >> then it makes sense and actually works. The pointer can hardly be NULL, >> even when statically linked, no? > > IIUC, it is indeed the pointers that are set to NULL/0, because for unresolved > symbols, the symbol itself, not its value, is set to '0'. Which makes sense, > because if there is no symbol, then it can't have a value. Right, that's how weak symbol references work. Thanks, Florian