From patchwork Sat Jan 7 13:35:43 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 13092162 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 808A2C54EBC for ; Sat, 7 Jan 2023 13:36:39 +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=yRAGKk1ewQAnD3wL1I6jo/aU/uFQFmilmlv7T917RPI=; b=dTjY07xASn7ZB+ E8LoSbcNXTbQic8r5pfvWfK4xHdQ50eE7BNowzUidUUNtdmkkO5bHTBYES2YpwxHY+qICJy3fC2nL dW1YazQMHNs4IyZoGjZsF4l9h6gkaddiOfoYNRY/M0A6URsnLsrcIRcGTFpqhm+cCox0d9hkMNoeJ oSNAgV7B/+u0fiaqAecZxI9qQJ0WhimEoJJ3cDeRnLHG5ZKvNe79OewkjUmiQjkstco/bjy5gEK/0 HYySgd3zz0K06lFg4F5Yu5S20BLxsLQfBq8+conqNn/ngo0jY8GAUmbWGZ9jl86roIFTQYxgwZwX2 nV7Pcol7nDhVeZBO1yoA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pE9Mr-005KhF-2Z; Sat, 07 Jan 2023 13:36:16 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pE9Mn-005Kfr-CC for linux-riscv@lists.infradead.org; Sat, 07 Jan 2023 13:36:10 +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 E30BA60C09; Sat, 7 Jan 2023 13:36:08 +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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230107_053609_484749_A8CC9D04 X-CRM114-Status: GOOD ( 12.82 ) 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 --- 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 config ARCH_MMAP_RND_BITS_MIN default 18 if 64BIT