From patchwork Wed Nov 23 15:39:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 13053877 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 055BAC4332F for ; Wed, 23 Nov 2022 15:40:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=7+TdWRSWhXwQPFvlkp6TCrgNF/+SPn5Nv+YOLm1bwM4=; b=z28NFE4WdmQTHK M3xRAlKATFEjoOeJ1rZiS6p6O8ruZVJJApi+9aABNtZVb8aYH4Nb3xxSqquCbGzari9TuPxm6tnCu XC5IanETrVGb0PUV1df2nTdMvmUbsw6N6CKzTFfvBLKB2vs+R8iYxtBWsPaXmvdIs2dpFArN8xpj7 eLfXKujXu7V4nw4mntSd2TlRBd37/NZriOxaoBMTFKmdjV63L65SgrqIagxQ/v+KqjLefQXtQYI7L 0ux+z9h3dbd3CgkCP7IQkPto/u6/Hdo1vuPLYles0sJO6IdYDGreh/wDnAYwIgJzh7IwnlUlEzQLr 3fw/KUDSbH8m9WkEVnDQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oxrrK-000X4g-Hf; Wed, 23 Nov 2022 15:40:22 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oxrrA-000Wvj-Bb for linux-riscv@lists.infradead.org; Wed, 23 Nov 2022 15:40:14 +0000 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 B6B42B8216C; Wed, 23 Nov 2022 15:40:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADDE3C433D7; Wed, 23 Nov 2022 15:40:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669218009; bh=klemdwhmvdHm8UXMNKhz8vGyWWFdhO3duaUDPADUSqA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BSGNtn91mrpp3bPJslAbgOWWcK/5+OU23WPXON7/FejtddmER7EHhkkS7MhuXO4ca W0AcRvSsbkvIBDYZ6REPQVDE5h+PZtldLD6nC5VqrbD0EDTg2YR0+Dk0WiZ2b1lo5T f+ILD5bLCug436RG/pF8ojzCrvAiCKp/ef8gLaAr6Ty4naE0Evd41erwlbMMHxZkxG mwAovIg1UoZDcga8X/4pR/UGIhVdbR0rf5SuCrL3GrWxVvheYVzmWL+OvdtnvYTO1m YKOlNf2BVVW8AlIORzuzO1o5NNbkYrJ8z96wXJmgqc+AGB1J9EFf6srFoptvADgZoj SLOnrRYMjC/MA== 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 Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Guo Ren Subject: [PATCH V3 1/5] riscv: ftrace: Fixup panic by disabling preemption Date: Wed, 23 Nov 2022 10:39:46 -0500 Message-Id: <20221123153950.2911981-2-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20221123153950.2911981-1-guoren@kernel.org> References: <20221123153950.2911981-1-guoren@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221123_074012_670116_58F9F262 X-CRM114-Status: GOOD ( 14.72 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org 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: fc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT") Signed-off-by: Andy Chiu Signed-off-by: Guo Ren --- @Andy, could you give the patch a Signed-off-by? I just copy your most important comment, so the first author should be you. First, let's fix the problem caused by my previous patch, and you can continue your ftrace preemption work. --- arch/riscv/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 7cd981f96f48..1d0e5838b11b 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -280,7 +280,7 @@ config ARCH_RV64I 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 select SWIOTLB if MMU endchoice