From patchwork Wed Sep 21 03:49:08 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 12983187 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 B0A9BC32771 for ; Wed, 21 Sep 2022 03:49:37 +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=tMUIrXYARdkAzq3MzooJ5fs3m2n/KU+UK2pGf3uT41U=; b=yL4F/cTp64LSjL lqCfXVyS+Np9L4P0/9dL1xIwzMjVUQgQA4AqMivA9oOs6kDm0GeqhWEuOL9eYgRGt/qpj1G/5pL+U mRAOciFkPCNJgrVK3NkCGs7iK65tG2aaCdsOfORnFl/xyzrAvb4ofyhrToWWyIZDeqr2jkVvr7o5U QZ9mKiHLJp2m3ongm/Tr3l0g2QYMctC8KKQXtGnuqKLKslGEMGSPP8+GkxdHVcBotdNWLvWK7GnSl qhCbaN57kZ70hYLmbz+So8opcujxjmT+XmG9P2kdVW527BQ24xkUoDXzwF1dfzb5QFxWUIOcqhywi Euteu/5eXMgbvhlHTXCQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oaqjp-008egd-45; Wed, 21 Sep 2022 03:49:29 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oaqjm-008efd-GI for linux-riscv@lists.infradead.org; Wed, 21 Sep 2022 03:49:27 +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 dfw.source.kernel.org (Postfix) with ESMTPS id B8CB662835; Wed, 21 Sep 2022 03:49:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 912DAC433B5; Wed, 21 Sep 2022 03:49:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1663732165; bh=Iig2bmqX2xPq4svTTL0eg2AIxZh7cd/4Rrn/f1KZwI8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JHv1P1cxYrDQ4irReok/MJi/zVEpjKmZTJ5o+uOxY+sowAozNgRUvjCOC4p/6jkZe mDaYv8lsmlaXSvNX1+GPOTpn/RH43YPt0aa8SaC/5b98jdoOToRRih/iEVmma+u5t/ L1UlDuGFbE6XfETSX0EAiNblpJN9I37skiKYqgiuvB38Wz7OajoXml9xTQFI2LXwtG TLJVKEWjG6szoWPzw7QkGt9DEioQtHXGCNH4h5iBKJ64qkALtKQJiTqZKHvg0iDL7p xGg95iOdZmyaqvmPt5jb5UyqfV1w5oGPoWa9d7bj1r60TgKCcuoGy025PhjvOQpkkB 9nspWJn2399UQ== From: guoren@kernel.org To: arnd@arndb.de, palmer@rivosinc.com, rostedt@goodmis.org, andy.chiu@sifive.com, greentime.hu@sifive.com, zong.li@sifive.com, jrtc27@jrtc27.com, mingo@redhat.com, palmer@dabbelt.com Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, guoren@kernel.org Subject: [PATCH V2 1/3] riscv: ftrace: Fixup panic by disabling preemption Date: Tue, 20 Sep 2022 23:49:08 -0400 Message-Id: <20220921034910.3142465-2-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220921034910.3142465-1-guoren@kernel.org> References: <20220921034910.3142465-1-guoren@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220920_204926_604082_80A4CEF6 X-CRM114-Status: GOOD ( 15.22 ) 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 ed66c31e4655..b3454c843932 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -272,7 +272,7 @@ 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