From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5919AC6FD1B for ; Tue, 7 Mar 2023 18:03:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231185AbjCGSDc (ORCPT ); Tue, 7 Mar 2023 13:03:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37812 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231610AbjCGSDF (ORCPT ); Tue, 7 Mar 2023 13:03:05 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B8F3ACE3F for ; Tue, 7 Mar 2023 09:56:17 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 0922DB819BB for ; Tue, 7 Mar 2023 17:56:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75019C4339C; Tue, 7 Mar 2023 17:56:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678211774; bh=SImXVM1pVWr+m/iM8SNl9XtBcn1kvgY9BQxWI+guvak=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iSHahpwWo55hJWhnogflx9ifeW1gwapssA7EMSskQd04qozZ2Mg2Mz7C5S0ra2RAE +mKH1yxbdVxDKXuF1trZZWHxZQ9xhNyheRJCP05YbU29aVJ5goZUtpw0qnRPuQbSHL FhXy9Sk2YMXATYqBIdJAmfsdomx4ME1cUtzhDSMA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andy Chiu , Guo Ren , Palmer Dabbelt Subject: [PATCH 6.2 0973/1001] riscv: ftrace: Fixup panic by disabling preemption Date: Tue, 7 Mar 2023 18:02:25 +0100 Message-Id: <20230307170104.449974155@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170022.094103862@linuxfoundation.org> References: <20230307170022.094103862@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Andy Chiu commit 8547649981e6631328cd64f583667501ae385531 upstream. In RISCV, we must use an AUIPC + JALR pair to encode an immediate, forming a jump that jumps to an address over 4K. This may cause errors if we want to enable kernel preemption and remove dependency from patching code with stop_machine(). For example, if a task was switched out on auipc. And, if we changed the ftrace function before it was switched back, then it would jump to an address that has updated 11:0 bits mixing with previous XLEN:12 part. p: patched area performed by dynamic ftrace ftrace_prologue: p| REG_S ra, -SZREG(sp) p| auipc ra, 0x? ------------> preempted ... change ftrace function ... p| jalr -?(ra) <------------- switched back p| REG_L ra, -SZREG(sp) func: xxx ret Fixes: afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT") Signed-off-by: Andy Chiu Signed-off-by: Guo Ren Link: https://lore.kernel.org/r/20230112090603.1295340-2-guoren@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt Signed-off-by: Greg Kroah-Hartman --- arch/riscv/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -138,7 +138,7 @@ config RISCV select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL select HAVE_FUNCTION_GRAPH_TRACER - select HAVE_FUNCTION_TRACER if !XIP_KERNEL + select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION config ARCH_MMAP_RND_BITS_MIN default 18 if 64BIT