From patchwork Tue Nov 29 03:32:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 13058172 X-Patchwork-Delegate: palmer@dabbelt.com 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 B13E6C4332F for ; Tue, 29 Nov 2022 03:32:58 +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=ByPjF29oKXkDw7l28Nip7xumMhn82u5LdK07nrXUdns=; b=SexgH962TAQQTW pB/J9Deb8lVMkeUNnnfCOBjd/Kov4oClo+bkHKsbEl9xk4qSm6zEMvBei22qGFIX2ivi1G4MBj+BP Wj3DeK19gwdLsawpEaNP12ShcUIlFQlCQcHjt3cIj3YRMZwkGFAVbKUMJl8DuqHUxapBeNqh7pG6i 43Qn0SWHY37EDVnJQ+beR7NZIzmJ+K1CDU3Kt4pwgCQ3A+PVAAZzKDpycHtI9UhgvkrS6NtoRW2gX QIUx0wAIuzjIhBO5uYNYgjqKT5N/Qyu1olLFjNhziw+z3P/ImCdP5BrzKfhKqXRevuYVl9CH6VVBL IqofVys1hZi8FzdDjZ2Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ozrMZ-005jmP-2l; Tue, 29 Nov 2022 03:32:51 +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 1ozrMV-005jko-LP for linux-riscv@lists.infradead.org; Tue, 29 Nov 2022 03:32:49 +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 33A7061563; Tue, 29 Nov 2022 03:32:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C086AC43470; Tue, 29 Nov 2022 03:32:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669692766; bh=vVvv9Dl3Ond8/L8UdaSALSgt+hLH0wBtdq85SQamt6I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XJESHQJrO4KYoVBp10iKOSvt6JEN5l5QRp2/fnu5LqhygqWwVS5LRUa2dxb8G4xVv SzuT+lOHQQNsxnQ/CROZ3O1QoouPaN8f4poLM+BUVgcBV666AeQrhAJLgg1N8MPefB 3PgRsRvVRvnUB9cj4fzlbU8ybPL6oqbvpJcgbl7e8W5Eu6DMJSzKjcuBXdmKlW5oBT Ku6nh+IWFEZ9JGXaIhXVgNc/iGRJ9frv2qfljSZDBcGGuqSSOahOGa5qXICACpeKsm UigBuAckMEKodDT0rxVjtVgJw5qlX/k6khQ/e2cSVBoSEe+7by74josWmh1rAdSmsu GauCgW4LJiILg== 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, mark.rutland@arm.com Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Guo Ren Subject: [PATCH V4 1/7] riscv: ftrace: Fixup panic by disabling preemption Date: Mon, 28 Nov 2022 22:32:24 -0500 Message-Id: <20221129033230.255947-2-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20221129033230.255947-1-guoren@kernel.org> References: <20221129033230.255947-1-guoren@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221128_193247_829123_2D621E44 X-CRM114-Status: GOOD ( 14.63 ) 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: afc76b8b8011 ("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