From nobody Sun Apr 6 21:56:59 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=reject dis=none) header.from=linux.ibm.com ARC-Seal: i=1; a=rsa-sha256; t=1736368048; cv=none; d=zohomail.com; s=zohoarc; b=QafAKb3tI1HxYUBxJskUH+zyDfjF1WtuV6LB+Ad4zn9U7cijZzsgTJZJQLh02P/1Ta09AqMkR13maANywwJFYWhNzF9aJG/ZWqu2wXxpAtZBSPP2qYNnTt9FqEg6+G6ViyAsOiSoDxvCWuOQTQLC09mKAO+Taz5B9EU4J2RLcyE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1736368048; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=WBuOr1ZSrRUBNaILva5B47YmUMZfjdf9mHbEGsDD8W8=; b=N3uU4XDTKPLrWSF8YZ9FSj+C9JViJjk0gCDcczw3fTBnJOyoilHSYVI2bMd6IAjyR3QgVQAXdqyqYtJd2JW0ghlDjSNtcCyA9L08+WzHDf7ddgJxQLvlLMEqbTvWZrNbbG8y6SPiod/PZZO97NrtXkhQVD79mCla/wJPmRtCdtw= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=reject dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1736368048735433.85015656204405; Wed, 8 Jan 2025 12:27:28 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tVcdf-0007Eq-RX; Wed, 08 Jan 2025 15:26:52 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tVcda-0007DT-9e for qemu-devel@nongnu.org; Wed, 08 Jan 2025 15:26:46 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tVcdY-0006rv-91 for qemu-devel@nongnu.org; Wed, 08 Jan 2025 15:26:45 -0500 Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 508FuFvW006940; Wed, 8 Jan 2025 20:26:34 GMT Received: from ppma11.dal12v.mail.ibm.com (db.9e.1632.ip4.static.sl-reverse.com [50.22.158.219]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 441hupvcp5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 08 Jan 2025 20:26:33 +0000 (GMT) Received: from pps.filterd (ppma11.dal12v.mail.ibm.com [127.0.0.1]) by ppma11.dal12v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 508HipTi026176; Wed, 8 Jan 2025 20:26:32 GMT Received: from smtprelay07.fra02v.mail.ibm.com ([9.218.2.229]) by ppma11.dal12v.mail.ibm.com (PPS) with ESMTPS id 43yj129a9v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 08 Jan 2025 20:26:32 +0000 Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 508KQV5Z55837068 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 8 Jan 2025 20:26:31 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 22C4D20043; Wed, 8 Jan 2025 20:26:31 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 834AF20040; Wed, 8 Jan 2025 20:26:30 +0000 (GMT) Received: from heavy.ibm.com (unknown [9.179.24.127]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 8 Jan 2025 20:26:30 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=WBuOr1ZSrRUBNaILv a5B47YmUMZfjdf9mHbEGsDD8W8=; b=YiDUAj/3WtJIznFs5NDQhWOWs2YKLipzm AxvI+s8ISxLafP07+3dpl+3iMGmDsRMxZZyso41jBbKMbKlwyQ4Dn1l2SgMIouP4 d3A2bIkzwgnOO5FKySighh6yW6Nzbw59DnDtMLQVkEY4CbioBLSl+XVNbc8tQLmN pNizGt8OrBdaIw73z/Ev9HsmG45nSvIi6rrkilx0opFEgXnGqIvplPhj4tQZ0hsx sB7XKzcbcS1nVBxyCMAdo1b1pGAdNj1DqAGdVgCDtGwOWe0pirT+OR3jKsGGZ8GN 4FhuxbvPBcIoxaiNuqqwwZjeyfT9jbEG/4Yz2qQ+svTbvnXRL0XJA== From: Ilya Leoshkevich To: Warner Losh , Riku Voipio , Laurent Vivier , Paolo Bonzini , Richard Henderson , =?UTF-8?q?Alex=20Benn=C3=A9e?= Cc: Kyle Evans , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org, Ilya Leoshkevich Subject: [PATCH v4 5/9] user: Introduce host_interrupt_signal Date: Wed, 8 Jan 2025 21:05:00 +0100 Message-ID: <20250108202625.149869-6-iii@linux.ibm.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250108202625.149869-1-iii@linux.ibm.com> References: <20250108202625.149869-1-iii@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: p7hemIlFg6SZ5jX0YtsjntCohlWsiQQI X-Proofpoint-GUID: p7hemIlFg6SZ5jX0YtsjntCohlWsiQQI X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-15_01,2024-10-11_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 clxscore=1015 mlxscore=0 malwarescore=0 priorityscore=1501 lowpriorityscore=0 spamscore=0 bulkscore=0 impostorscore=0 mlxlogscore=999 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501080163 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=148.163.156.1; envelope-from=iii@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, 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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @ibm.com) X-ZM-MESSAGEID: 1736368051330116600 Content-Type: text/plain; charset="utf-8" Attaching to the gdbstub of a running process requires stopping its threads. For threads that run on a CPU, cpu_exit() is enough, but the only way to grab attention of a thread that is stuck in a long-running syscall is to interrupt it with a signal. Reserve a host realtime signal for this, just like it's already done for TARGET_SIGABRT on Linux. This may reduce the number of available guest realtime signals by one, but this is acceptable, since there are quite a lot of them, and it's unlikely that there are apps that need them all. Set signal_pending for the safe_sycall machinery to prevent invoking the syscall. This is a lie, since we don't queue a guest signal, but process_pending_signals() can handle the absence of pending signals. The syscall returns with QEMU_ERESTARTSYS errno, which arranges for the automatic restart. This is important, because it helps avoiding disturbing poorly written guests. Reviewed-by: Warner Losh Signed-off-by: Ilya Leoshkevich --- bsd-user/signal.c | 12 ++++++++++++ include/user/signal.h | 2 ++ linux-user/signal.c | 25 ++++++++++++++++++++----- 3 files changed, 34 insertions(+), 5 deletions(-) diff --git a/bsd-user/signal.c b/bsd-user/signal.c index 8c51f6ce653..ff2ccbbf605 100644 --- a/bsd-user/signal.c +++ b/bsd-user/signal.c @@ -51,6 +51,8 @@ static inline int sas_ss_flags(TaskState *ts, unsigned lo= ng sp) on_sig_stack(ts, sp) ? SS_ONSTACK : 0; } =20 +int host_interrupt_signal =3D SIGRTMAX; + /* * The BSD ABIs use the same signal numbers across all the CPU architectur= es, so * (unlike Linux) these functions are just the identity mapping. This migh= t not @@ -491,6 +493,12 @@ static void host_signal_handler(int host_sig, siginfo_= t *info, void *puc) uintptr_t pc =3D 0; bool sync_sig =3D false; =20 + if (host_sig =3D=3D host_interrupt_signal) { + ts->signal_pending =3D 1; + cpu_exit(thread_cpu); + return; + } + /* * Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special * handling wrt signal blocking and unwinding. @@ -854,6 +862,9 @@ void signal_init(void) =20 for (i =3D 1; i <=3D TARGET_NSIG; i++) { host_sig =3D target_to_host_signal(i); + if (host_sig =3D=3D host_interrupt_signal) { + continue; + } sigaction(host_sig, NULL, &oact); if (oact.sa_sigaction =3D=3D (void *)SIG_IGN) { sigact_table[i - 1]._sa_handler =3D TARGET_SIG_IGN; @@ -872,6 +883,7 @@ void signal_init(void) sigaction(host_sig, &act, NULL); } } + sigaction(host_interrupt_signal, &act, NULL); } =20 static void handle_pending_signal(CPUArchState *env, int sig, diff --git a/include/user/signal.h b/include/user/signal.h index 19b6b9e5ddc..7fa33b05d91 100644 --- a/include/user/signal.h +++ b/include/user/signal.h @@ -20,4 +20,6 @@ */ int target_to_host_signal(int sig); =20 +extern int host_interrupt_signal; + #endif diff --git a/linux-user/signal.c b/linux-user/signal.c index bffbef235cd..81a98c6d02f 100644 --- a/linux-user/signal.c +++ b/linux-user/signal.c @@ -517,6 +517,8 @@ static int core_dump_signal(int sig) } } =20 +int host_interrupt_signal; + static void signal_table_init(const char *rtsig_map) { int hsig, tsig, count; @@ -580,10 +582,10 @@ static void signal_table_init(const char *rtsig_map) * Attempts for configure "missing" signals via sigaction will be * silently ignored. * - * Reserve one signal for internal usage (see below). + * Reserve two signals for internal usage (see below). */ =20 - hsig =3D SIGRTMIN + 1; + hsig =3D SIGRTMIN + 2; for (tsig =3D TARGET_SIGRTMIN; hsig <=3D SIGRTMAX && tsig <=3D TARGET_NSIG; hsig++, tsig++) { @@ -604,12 +606,17 @@ static void signal_table_init(const char *rtsig_map) host_to_target_signal_table[SIGABRT] =3D 0; for (hsig =3D SIGRTMIN; hsig <=3D SIGRTMAX; hsig++) { if (!host_to_target_signal_table[hsig]) { - host_to_target_signal_table[hsig] =3D TARGET_SIGABRT; - break; + if (host_interrupt_signal) { + host_to_target_signal_table[hsig] =3D TARGET_SIGABRT; + break; + } else { + host_interrupt_signal =3D hsig; + } } } if (hsig > SIGRTMAX) { - fprintf(stderr, "No rt signals left for SIGABRT mapping\n"); + fprintf(stderr, + "No rt signals left for interrupt and SIGABRT mapping\n"); exit(EXIT_FAILURE); } =20 @@ -689,6 +696,8 @@ void signal_init(const char *rtsig_map) } sigact_table[tsig - 1]._sa_handler =3D thand; } + + sigaction(host_interrupt_signal, &act, NULL); } =20 /* Force a synchronously taken signal. The kernel force_sig() function @@ -1036,6 +1045,12 @@ static void host_signal_handler(int host_sig, siginf= o_t *info, void *puc) bool sync_sig =3D false; void *sigmask; =20 + if (host_sig =3D=3D host_interrupt_signal) { + ts->signal_pending =3D 1; + cpu_exit(thread_cpu); + return; + } + /* * Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special * handling wrt signal blocking and unwinding. Non-spoofed SIGILL, --=20 2.47.1