From patchwork Wed Dec 15 12:51:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: WANG Xuerui X-Patchwork-Id: 12678295 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 0BAF3C433F5 for ; Wed, 15 Dec 2021 13:10:34 +0000 (UTC) Received: from localhost ([::1]:35140 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mxU3E-0003dV-QC for qemu-devel@archiver.kernel.org; Wed, 15 Dec 2021 08:10:32 -0500 Received: from eggs.gnu.org ([209.51.188.92]:52082) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mxTmO-00059K-7W for qemu-devel@nongnu.org; Wed, 15 Dec 2021 07:53:08 -0500 Received: from mail.xen0n.name ([115.28.160.31]:36892 helo=mailbox.box.xen0n.name) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mxTmJ-00048G-AL for qemu-devel@nongnu.org; Wed, 15 Dec 2021 07:53:07 -0500 Received: from ld50.lan (unknown [101.88.31.179]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by mailbox.box.xen0n.name (Postfix) with ESMTPSA id 0A7D8607FB; Wed, 15 Dec 2021 20:52:14 +0800 (CST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=xen0n.name; s=mail; t=1639572734; bh=JzeJXAkASRuv+roZ3M/dcU9DVtYEuUn15KjXtDUyMQg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DaZwN6Whg/y8NHNRNI5sVUUgAZ4cqRDRsqbAWrpLnrmc29gNCBYAXtqdl9xeUhD5j 7EogwXM8Q1ML8KA/bd+t8DL5mivUzDr6Z4oG4PZzJmasG7CfsTtkJtDU5cbbNx6yzc m2fOV8gxOdMkJqJL7SFtJimCrIcAcRxz6n4xEgLM= From: WANG Xuerui To: qemu-devel@nongnu.org Subject: [PATCH v10 28/31] common-user: Add safe syscall handling for loongarch64 hosts Date: Wed, 15 Dec 2021 20:51:33 +0800 Message-Id: <20211215125136.3449717-29-git@xen0n.name> X-Mailer: git-send-email 2.34.0 In-Reply-To: <20211215125136.3449717-1-git@xen0n.name> References: <20211215125136.3449717-1-git@xen0n.name> MIME-Version: 1.0 Received-SPF: pass client-ip=115.28.160.31; envelope-from=git@xen0n.name; helo=mailbox.box.xen0n.name X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , XiaoJuan Yang , Richard Henderson , =?utf-8?q?Philippe_Mathie?= =?utf-8?q?u-Daud=C3=A9?= , Laurent Vivier , WANG Xuerui , =?utf-8?q?Alex_Benn=C3=A9e?= , Song Gao Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Signed-off-by: WANG Xuerui Reviewed-by: Richard Henderson --- .../host/loongarch64/safe-syscall.inc.S | 90 +++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 common-user/host/loongarch64/safe-syscall.inc.S diff --git a/common-user/host/loongarch64/safe-syscall.inc.S b/common-user/host/loongarch64/safe-syscall.inc.S new file mode 100644 index 0000000000..b88a069c45 --- /dev/null +++ b/common-user/host/loongarch64/safe-syscall.inc.S @@ -0,0 +1,90 @@ +/* + * safe-syscall.inc.S : host-specific assembly fragment + * to handle signals occurring at the same time as system calls. + * This is intended to be included by common-user/safe-syscall.S + * + * Ported to LoongArch by WANG Xuerui + * + * Based on safe-syscall.inc.S code for RISC-V, + * originally written by Richard Henderson + * Copyright (C) 2018 Linaro, Inc. + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + + .global safe_syscall_base + .global safe_syscall_start + .global safe_syscall_end + .type safe_syscall_base, @function + .type safe_syscall_start, @function + .type safe_syscall_end, @function + + /* + * This is the entry point for making a system call. The calling + * convention here is that of a C varargs function with the + * first argument an 'int *' to the signal_pending flag, the + * second one the system call number (as a 'long'), and all further + * arguments being syscall arguments (also 'long'). + */ +safe_syscall_base: + .cfi_startproc + /* + * The syscall calling convention is nearly the same as C: + * we enter with a0 == &signal_pending + * a1 == syscall number + * a2 ... a7 == syscall arguments + * and return the result in a0 + * and the syscall instruction needs + * a7 == syscall number + * a0 ... a5 == syscall arguments + * and returns the result in a0 + * Shuffle everything around appropriately. + */ + move $t0, $a0 /* signal_pending pointer */ + move $t1, $a1 /* syscall number */ + move $a0, $a2 /* syscall arguments */ + move $a1, $a3 + move $a2, $a4 + move $a3, $a5 + move $a4, $a6 + move $a5, $a7 + move $a7, $t1 + + /* + * We need to preserve the signal_pending pointer but t0 is + * clobbered by syscalls on LoongArch, so we need to move it + * somewhere else, ideally both preserved across syscalls and + * clobbered by procedure calls so we don't have to allocate a + * stack frame; a6 is just the register we want here. + */ + move $a6, $t0 + + /* + * This next sequence of code works in conjunction with the + * rewind_if_safe_syscall_function(). If a signal is taken + * and the interrupted PC is anywhere between 'safe_syscall_start' + * and 'safe_syscall_end' then we rewind it to 'safe_syscall_start'. + * The code sequence must therefore be able to cope with this, and + * the syscall instruction must be the final one in the sequence. + */ +safe_syscall_start: + /* If signal_pending is non-zero, don't do the call */ + ld.w $t1, $a6, 0 + bnez $t1, 2f + syscall 0 +safe_syscall_end: + /* code path for having successfully executed the syscall */ + li.w $t2, -4096 + bgtu $a0, $t2, 0f + jr $ra + + /* code path setting errno */ +0: sub.d $a0, $zero, $a0 + b safe_syscall_set_errno_tail + + /* code path when we didn't execute the syscall */ +2: li.w $a0, QEMU_ERESTARTSYS + b safe_syscall_set_errno_tail + .cfi_endproc + .size safe_syscall_base, .-safe_syscall_base