From patchwork Mon Jun 13 21:45:22 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Henderson X-Patchwork-Id: 9174451 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D96CD6044F for ; Mon, 13 Jun 2016 21:54:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BEE2222230 for ; Mon, 13 Jun 2016 21:54:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B1699264F4; Mon, 13 Jun 2016 21:54:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 1B42522230 for ; Mon, 13 Jun 2016 21:54:41 +0000 (UTC) Received: from localhost ([::1]:59591 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bCZoe-0000O7-GA for patchwork-qemu-devel@patchwork.kernel.org; Mon, 13 Jun 2016 17:54:40 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37893) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bCZgO-0000rs-O0 for qemu-devel@nongnu.org; Mon, 13 Jun 2016 17:46:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bCZgH-0002DR-Pc for qemu-devel@nongnu.org; Mon, 13 Jun 2016 17:46:07 -0400 Received: from mail-qg0-x241.google.com ([2607:f8b0:400d:c04::241]:35897) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bCZgH-0002DN-KL for qemu-devel@nongnu.org; Mon, 13 Jun 2016 17:46:01 -0400 Received: by mail-qg0-x241.google.com with SMTP id 78so3099871qgt.3 for ; Mon, 13 Jun 2016 14:46:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=NzAmt/modA2RZnRory1GYStggfd6t/y4koaLmA+bJ1o=; b=bGAn2rHzDAii6pTsWnwdkRWVsWUB1AmZMx0EYEgG8Wb/W1LU++3aBvKYIZ+YMEIliP ekLk/XHBlZLRx4QD4XZQAMqb4YVXhfk0OKF670g1Dddu9tFfB+5/wQYmpw4ovFzprH2n 1eLtRsViNd/6M9FvmgESh31vlAKYXOEIPzB3voc8pVqTcbPGWU5b1XJUSE7Y1HLqU3xF dAI88bEJZC+iO7XTrwm1ttLvHFaAK4qskMAWRJZ4RQuS6zgjtboZonGOkCp/j7kIDSAS kkgz0k1AFrRfhlnkvEGYc0fOajyfpK4+jU2oUAPQOYLHjwNuTiG4Y0Sh33vzDwOZ58Sa ZPIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references; bh=NzAmt/modA2RZnRory1GYStggfd6t/y4koaLmA+bJ1o=; b=PfshWKdQL4lm/w3ovMjPCbOQujianGbmpEZcgfdi/1xJIca7vsfMEWF4cZJcUPfdbP noEE1irXaoxCR93v5jwnXJmGAZAv1zZeZ9hm+qzyGkwsAIird5d+KKBnYWanAM7Gt7N1 TwJwifVnBpgAcMY3dYok4y5/ezv5Dtqef6CW6sOsLnfinx88OisKKKismYTuUMl8+QjW zWgmqcjNBeDsKEkXWdPNtSvXwdxEuciGM1APYLd3fqHE4sul91xp6SqvNtblovRCNkXI 4kjiV1KR+/7si9MfQTzHSkQbCcG8HaV/FhmPlA6838gBUfOxoFXpCq7obMjrTZk6ao5N xi+g== X-Gm-Message-State: ALyK8tL8mBLjevAQDGKvXlN2aQa4X0VWl9l7saftcJYattucGvzh6zoDC3SMM1u6U0FFjg== X-Received: by 10.140.109.10 with SMTP id k10mr16200546qgf.89.1465854361098; Mon, 13 Jun 2016 14:46:01 -0700 (PDT) Received: from bigtime.com (71-37-54-227.tukw.qwest.net. [71.37.54.227]) by smtp.gmail.com with ESMTPSA id u79sm1432557qka.8.2016.06.13.14.46.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 Jun 2016 14:46:00 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Date: Mon, 13 Jun 2016 14:45:22 -0700 Message-Id: <1465854326-19160-3-git-send-email-rth@twiddle.net> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1465854326-19160-1-git-send-email-rth@twiddle.net> References: <1465854326-19160-1-git-send-email-rth@twiddle.net> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2607:f8b0:400d:c04::241 Subject: [Qemu-devel] [PATCH 2/6] linux-user: Provide safe_syscall for i386 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, riku.voipio@iki.fi Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Signed-off-by: Richard Henderson --- linux-user/host/i386/hostdep.h | 34 ++++++++++ linux-user/host/i386/safe-syscall.inc.S | 110 ++++++++++++++++++++++++++++++++ 2 files changed, 144 insertions(+) create mode 100644 linux-user/host/i386/hostdep.h create mode 100644 linux-user/host/i386/safe-syscall.inc.S diff --git a/linux-user/host/i386/hostdep.h b/linux-user/host/i386/hostdep.h new file mode 100644 index 0000000..9e2b4d7 --- /dev/null +++ b/linux-user/host/i386/hostdep.h @@ -0,0 +1,34 @@ +/* + * hostdep.h : things which are dependent on the host architecture + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#ifndef QEMU_HOSTDEP_H +#define QEMU_HOSTDEP_H + +/* We have a safe-syscall.inc.S */ +#define HAVE_SAFE_SYSCALL + +#ifndef __ASSEMBLER__ + +/* These are defined by the safe-syscall.inc.S file */ +extern char safe_syscall_start[]; +extern char safe_syscall_end[]; + +/* Adjust the signal context to rewind out of safe-syscall if we're in it */ +static inline void rewind_if_in_safe_syscall(void *puc) +{ + struct ucontext *uc = puc; + greg_t *pcreg = &uc->uc_mcontext.gregs[REG_EIP]; + + if (*pcreg > (uintptr_t)safe_syscall_start + && *pcreg < (uintptr_t)safe_syscall_end) { + *pcreg = (uintptr_t)safe_syscall_start; + } +} + +#endif /* __ASSEMBLER__ */ + +#endif diff --git a/linux-user/host/i386/safe-syscall.inc.S b/linux-user/host/i386/safe-syscall.inc.S new file mode 100644 index 0000000..f5f0c64 --- /dev/null +++ b/linux-user/host/i386/safe-syscall.inc.S @@ -0,0 +1,110 @@ +/* + * 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 linux-user/safe-syscall.S + * + * 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 + + /* 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'). + * We return a long which is the syscall's return value, which + * may be negative-errno on failure. Conversion to the + * -1-and-errno-set convention is done by the calling wrapper. + */ +safe_syscall_base: + .cfi_startproc + push %ebp + .cfi_adjust_cfa_offset 4 + .cfi_rel_offset ebp, 0 + push %esi + .cfi_adjust_cfa_offset 4 + .cfi_rel_offset esi, 0 + push %edi + .cfi_adjust_cfa_offset 4 + .cfi_rel_offset edi, 0 + push %ebx + .cfi_adjust_cfa_offset 4 + .cfi_rel_offset ebx, 0 + + /* The syscall calling convention isn't the same as the C one: + * we enter with 0(%esp) == return address + * 4(%esp) == *signal_pending + * 8(%esp) == syscall number + * 12(%esp) ... 32(%esp) == syscall arguments + * and return the result in eax + * and the syscall instruction needs + * eax == syscall number + * ebx, ecx, edx, esi, edi, ebp == syscall arguments + * and returns the result in eax + * Shuffle everything around appropriately. + * Note the 16 bytes that we pushed to save registers. + */ + mov 12+16(%esp), %ebx /* the syscall arguments */ + mov 16+16(%esp), %ecx + mov 20+16(%esp), %edx + mov 24+16(%esp), %esi + mov 28+16(%esp), %edi + mov 32+16(%esp), %ebp + + /* 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 */ + mov 4+16(%esp), %eax /* signal_pending */ + cmp $0, (%eax) + mov 8+16(%esp), %eax /* syscall number */ + jnz 1f + int $0x80 +safe_syscall_end: + /* code path for having successfully executed the syscall */ + pop %ebx + .cfi_remember_state + .cfi_def_cfa_offset 4 + .cfi_restore ebx + pop %edi + .cfi_def_cfa_offset 4 + .cfi_restore edi + pop %esi + .cfi_def_cfa_offset 4 + .cfi_restore esi + pop %ebp + .cfi_def_cfa_offset 4 + .cfi_restore ebp + ret + +1: + /* code path when we didn't execute the syscall */ + .cfi_restore_state + mov $-TARGET_ERESTARTSYS, %eax + pop %ebx + .cfi_remember_state + .cfi_def_cfa_offset 4 + .cfi_restore ebx + pop %edi + .cfi_def_cfa_offset 4 + .cfi_restore edi + pop %esi + .cfi_def_cfa_offset 4 + .cfi_restore esi + pop %ebp + .cfi_def_cfa_offset 4 + .cfi_restore ebp + ret + .cfi_endproc + + .size safe_syscall_base, .-safe_syscall_base