From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 BF982846C for ; Fri, 10 Mar 2023 14:34:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B671C433A0; Fri, 10 Mar 2023 14:34:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678458840; bh=7rkYHDJciWNfgZyu6i07Kh5yKCdXU0eh9RjC3XuqjkA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=itRW43sOMxRI6qPC6s/g30GAq9D9yQMI5sb96Pdij9rPjvtOYp37fupSxZhhpPv1b eSV9cvn5JYXM7q1LmhkNKxEtkL3HKtNRGYVPa6YuuFT5+NAnqqgR7OuBsqCfqo2MD+ SpC0uZfjMZLVO9gxsTzDzcIwPZW9zvQ2F8mN1jLA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nathan Lynch , Michael Ellerman , Sasha Levin Subject: [PATCH 5.4 162/357] powerpc/rtas: ensure 4KB alignment for rtas_data_buf Date: Fri, 10 Mar 2023 14:37:31 +0100 Message-Id: <20230310133741.866880429@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133733.973883071@linuxfoundation.org> References: <20230310133733.973883071@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Nathan Lynch [ Upstream commit 836b5b9fcc8e09cea7e8a59a070349a00e818308 ] Some RTAS functions that have work area parameters impose alignment requirements on the work area passed to them by the OS. Examples include: - ibm,configure-connector - ibm,update-nodes - ibm,update-properties 4KB is the greatest alignment required by PAPR for such buffers. rtas_data_buf used to have a __page_aligned attribute in the arch/ppc64 days, but that was changed to __cacheline_aligned for unknown reasons by commit 033ef338b6e0 ("powerpc: Merge rtas.c into arch/powerpc/kernel"). That works out to 128-byte alignment on ppc64, which isn't right. This was found by inspection and I'm not aware of any real problems caused by this. Either current RTAS implementations don't enforce the alignment constraints, or rtas_data_buf is always being placed at a 4KB boundary by accident (or both, perhaps). Use __aligned(SZ_4K) to ensure the rtas_data_buf has alignment appropriate for all users. Signed-off-by: Nathan Lynch Fixes: 033ef338b6e0 ("powerpc: Merge rtas.c into arch/powerpc/kernel") Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230125-b4-powerpc-rtas-queue-v3-6-26929c8cce78@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/rtas.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 8e61984b368d1..ee810df7d522d 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -53,7 +53,7 @@ EXPORT_SYMBOL(rtas); DEFINE_SPINLOCK(rtas_data_buf_lock); EXPORT_SYMBOL_GPL(rtas_data_buf_lock); -char rtas_data_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned; +char rtas_data_buf[RTAS_DATA_BUF_SIZE] __aligned(SZ_4K); EXPORT_SYMBOL_GPL(rtas_data_buf); unsigned long rtas_rmo_buf; -- 2.39.2