From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (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 6913017D374 for ; Tue, 10 Sep 2024 07:22:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=150.107.74.76 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725952924; cv=none; b=TvzahKh9xza9vfHrsEO0Hhm0X/aV52z2ZW5lKoxq2Wdz3L7mk7IyfjPxDkEGhHj0SkRyrNBtwvDr5l7uhA7dsTl5FsHwxlBoZqe2FOpf66jK0zGiSgXBjnQSvrjUPYkE8z7tiHQnKMEBjMRaugjG8/D2/1xpNfGaLn85/hDK57c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725952924; c=relaxed/simple; bh=Qz+HWMixHr0TkuldBWJSnvho7DM/meoSWBHgTf1z3jg=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=EiH9g1l6X1aBqbdT9puxy8VvtpRQB32awmmQ9o5al/9MDhyvV+wGCsprYHOo1AktSNHmv+ZXhW7qcggU6Vnvjms5R9IRSSFl6FoQlN7N98yjvw36h3797sFqNMhpg4ihFsKJ7ubaC2OJLx4OyxhVxqTTLlrAkeP8DyrV+TEejL4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au; spf=pass smtp.mailfrom=ellerman.id.au; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b=iphENexq; arc=none smtp.client-ip=150.107.74.76 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ellerman.id.au Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="iphENexq" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1725952919; bh=Qz+HWMixHr0TkuldBWJSnvho7DM/meoSWBHgTf1z3jg=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=iphENexqZe9/ZJuQmHiRaEn0ojN/WywFBqLg8sghZ8XhuGjQ9EXmRMx7+AbHhZqju f/Yf0LMRKw2+SIsdbwjbWYA2ocrNG7N6yJerQ+bSOE+NjPIUI+8oWFe283TRV16piV aHcM5NcRL5NByW/PPK6u9OP1sldZ3VwUiqJLvarDWjprkTb8XMNyMfLpBwsqRQLpw2 cVrKIQuslBo0GWuExk/LAStJrZOzEkiMRzCmp3cmiBIXdGJeN5nsK1WzoacDFyqKP1 6KeF2fI+xxiXmD+E6oZgJEyQSxj5GLMJNNs7Eu0xqbeHWLRQVQFe6hwOTxsqolaqf8 v7gUGXGMo3/+g== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mail.ozlabs.org (Postfix) with ESMTPSA id 4X2wBG43XYz4wc3; Tue, 10 Sep 2024 17:21:58 +1000 (AEST) From: Michael Ellerman To: "Ryan B. Sullivan" , Joe Lawrence Cc: live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, pmladek@suse.com, mbenes@suse.cz, jikos@kernel.org, jpoimboe@kernel.org, naveen.n.rao@linux.ibm.com, christophe.leroy@csgroup.eu, npiggin@gmail.com Subject: Re: [PATCH] powerpc/ftrace: restore r2 to caller's stack on livepatch sibling call In-Reply-To: References: <87ed6q13xk.fsf@mail.lhotse> <20240815160712.4689-1-rysulliv@redhat.com> <9ec85e72-85dd-e9bc-6531-996413014629@redhat.com> Date: Tue, 10 Sep 2024 17:21:57 +1000 Message-ID: <87bk0wrn1m.fsf@mail.lhotse> Precedence: bulk X-Mailing-List: live-patching@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain "Ryan B. Sullivan" writes: > Hello all, > > Just wanted to ping and see if there was any further feedback or > questions regarding the patch? Hi Ryan, I'd really like a selftest that triggers the sibling call behaviour. As I said upthread I tried writing one but failed. Which you later explained is because the cross-module sibling call is not generated by the compiler but rather by the code being objcopy'ed (or similar). I think it should be possible to trick the compiler into letting us do a cross-module sibling call by doing it in an inline asm block. Obviously that's non-standard, but I think it might work well enough for a test? We have an example of calling a function within an inline asm block in call_do_irq(). I'll try to find time to get that done, but I can't promise when. cheers