From nobody Tue Sep 16 03:29:28 2025 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 0EA8BC46467 for ; Sat, 7 Jan 2023 13:36:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232401AbjAGNgS (ORCPT ); Sat, 7 Jan 2023 08:36:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230350AbjAGNgL (ORCPT ); Sat, 7 Jan 2023 08:36:11 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EDA7115D for ; Sat, 7 Jan 2023 05:36:11 -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 AA480B80EBF for ; Sat, 7 Jan 2023 13:36:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6882AC433F1; Sat, 7 Jan 2023 13:36:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673098568; bh=V792wXFwxvPtjCh6mve4UN0IqpgiVRIo4oWLOTpVhcc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s7tw01/FJa7C+JS9FZn2vOZ1EHRhzYsw4UqVMHAqi+KSlSeQe11jXV0Z0nBNBHqUq lgt/sMmwoJSGgpgzejN67lpJZYcSogDUvOGDUXWwVIT4DgT/cRD16fPc9UTPCmi+M3 LXQc5TwDcZqfJmuhyWwCYXbCbdaXZRZtxGZrDaotUQjfmSzMfrtgKyLnx/c0z1QlvW SlCvNWugTwm827ZEnjOS9zXnUeUmAPZmAG4/tr6Ra6Ne1jM2RMlo9eDIxJn/XVp+jW IM5OA0GxZjo74KJ36V6CHx9C+G9PFmAUJPuZ7ZDQb39yb+hZ4RBUViYyGBNvu7V6nl 0CjAy+71op0kA== From: guoren@kernel.org To: anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, conor.dooley@microchip.com, heiko@sntech.de, rostedt@goodmis.org, mhiramat@kernel.org, jolsa@redhat.com, bp@suse.de, jpoimboe@kernel.org, suagrfillet@gmail.com, andy.chiu@sifive.com, e.shatokhin@yadro.com, guoren@kernel.org Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH -next V6 1/7] riscv: ftrace: Fixup panic by disabling preemption Date: Sat, 7 Jan 2023 08:35:43 -0500 Message-Id: <20230107133549.4192639-2-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20230107133549.4192639-1-guoren@kernel.org> References: <20230107133549.4192639-1-guoren@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andy Chiu 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 MCOU= NT") Signed-off-by: Andy Chiu Signed-off-by: Guo Ren --- arch/riscv/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index e2b656043abf..ee0d39b26794 100644 --- 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 =20 config ARCH_MMAP_RND_BITS_MIN default 18 if 64BIT --=20 2.36.1