From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D7459AD24; Fri, 23 May 2025 00:58:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747961927; cv=none; b=m8f2znCNr5mRRz2+mCK34Ap+WUok1oRsyO0f27bVxI2uX/ViJ1xuhobTFfdveNuwe9QuLodFVFjPDUm+qCWU9nfQSv8pOkjMPPpJ4BExo1WoP09RL6NxpK+GLSsG+RZSKVWkKxcB+bBmNMW0P4r85QK55DSQJIYchazT9Wgsm/s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747961927; c=relaxed/simple; bh=G3lDgalSES4+LUeMJSVcq2Vx7YAnMSifKDBUKcnxS90=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=O4voYlqKjm2SUrQ6XNcgRMBrH8656EW5dolfMxrqP6Ki3Zn8+HG1OEIHr1C/6c/U5vINZ6wIZ6tHHx59yKUNYpL3O7a0/lUkOks4FQ8Q6KlHZ3ou9xKSIG54CYYsX8znObrW8GxtW8g76RsxP6+TigCxcF8Ye/zZi71+3+42CaM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=ihKSeQkN; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="ihKSeQkN" Received: from [192.168.7.202] ([71.202.166.45]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 54N0vVCN3229952 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Thu, 22 May 2025 17:57:32 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 54N0vVCN3229952 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025042001; t=1747961853; bh=hLCy7IahoOH+nrCcvZn3wBZZBx3mRCPW8+yytgbmYQw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ihKSeQkNPrDweyMMjCBfaJhlyRciuvUlfc8SB/DlqpiHjoItCE5lKKDlZXgy4ERzw 1nm9VfJ7NFhJPibwdALiazQfGVv2qJKEtpqINUZEyvXcK/dImDUgLLK5Zs88RCzHXd z90CHhiqmdhJv6r0GE4LkQ6N89TrpMnDMYdp0tM/B3ABEqhzn0eXWufmcxrwXznVhq t6B96xiMQWiwQotC4Y6Idy6oJe7SoCBZSPSXuW6oza3ueZ8Bu5ivApj78Hcwj4Gxq9 qcUJF3abmIDUavsjQq2kisAj6nagLuTUhiUZ3bqZtzp9QYuPpUp0S6/8p3frf/GpB5 ERObCGKHWKoKQ== Message-ID: <97a86550-844d-41c8-bc5e-b3b7b20ef6c9@zytor.com> Date: Thu, 22 May 2025 17:57:31 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/1] x86/fred/signal: Prevent single-step upon ERETU completion To: Andrew Cooper , Dave Hansen , linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, peterz@infradead.org, stable@vger.kernel.org References: <20250522171754.3082061-1-xin@zytor.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; keydata= xsDNBGUPz1cBDACS/9yOJGojBFPxFt0OfTWuMl0uSgpwk37uRrFPTTLw4BaxhlFL0bjs6q+0 2OfG34R+a0ZCuj5c9vggUMoOLdDyA7yPVAJU0OX6lqpg6z/kyQg3t4jvajG6aCgwSDx5Kzg5 Rj3AXl8k2wb0jdqRB4RvaOPFiHNGgXCs5Pkux/qr0laeFIpzMKMootGa4kfURgPhRzUaM1vy bsMsL8vpJtGUmitrSqe5dVNBH00whLtPFM7IbzKURPUOkRRiusFAsw0a1ztCgoFczq6VfAVu raTye0L/VXwZd+aGi401V2tLsAHxxckRi9p3mc0jExPc60joK+aZPy6amwSCy5kAJ/AboYtY VmKIGKx1yx8POy6m+1lZ8C0q9b8eJ8kWPAR78PgT37FQWKYS1uAroG2wLdK7FiIEpPhCD+zH wlslo2ETbdKjrLIPNehQCOWrT32k8vFNEMLP5G/mmjfNj5sEf3IOKgMTMVl9AFjsINLHcxEQ 6T8nGbX/n3msP6A36FDfdSEAEQEAAc0WWGluIExpIDx4aW5Aenl0b3IuY29tPsLBDQQTAQgA NxYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89XBQkFo5qAAhsDBAsJCAcFFQgJCgsFFgID AQAACgkQa70OVx2uN1HUpgv/cM2fsFCQodLArMTX5nt9yqAWgA5t1srri6EgS8W3F+3Kitge tYTBKu6j5BXuXaX3vyfCm+zajDJN77JHuYnpcKKr13VcZi1Swv6Jx1u0II8DOmoDYLb1Q2ZW v83W55fOWJ2g72x/UjVJBQ0sVjAngazU3ckc0TeNQlkcpSVGa/qBIHLfZraWtdrNAQT4A1fa sWGuJrChBFhtKbYXbUCu9AoYmmbQnsx2EWoJy3h7OjtfFapJbPZql+no5AJ3Mk9eE5oWyLH+ QWqtOeJM7kKvn/dBudokFSNhDUw06e7EoVPSJyUIMbYtUO7g2+Atu44G/EPP0yV0J4lRO6EA wYRXff7+I1jIWEHpj5EFVYO6SmBg7zF2illHEW31JAPtdDLDHYcZDfS41caEKOQIPsdzQkaQ oW2hchcjcMPAfyhhRzUpVHLPxLCetP8vrVhTvnaZUo0xaVYb3+wjP+D5j/3+hwblu2agPsaE vgVbZ8Fx3TUxUPCAdr/p73DGg57oHjgezsDNBGUPz1gBDAD4Mg7hMFRQqlzotcNSxatlAQNL MadLfUTFz8wUUa21LPLrHBkUwm8RujehJrzcVbPYwPXIO0uyL/F///CogMNx7Iwo6by43KOy g89wVFhyy237EY76j1lVfLzcMYmjBoTH95fJC/lVb5Whxil6KjSN/R/y3jfG1dPXfwAuZ/4N cMoOslWkfZKJeEut5aZTRepKKF54T5r49H9F7OFLyxrC/uI9UDttWqMxcWyCkHh0v1Di8176 jjYRNTrGEfYfGxSp+3jYL3PoNceIMkqM9haXjjGl0W1B4BidK1LVYBNov0rTEzyr0a1riUrp Qk+6z/LHxCM9lFFXnqH7KWeToTOPQebD2B/Ah5CZlft41i8L6LOF/LCuDBuYlu/fI2nuCc8d m4wwtkou1Y/kIwbEsE/6RQwRXUZhzO6llfoN96Fczr/RwvPIK5SVMixqWq4QGFAyK0m/1ap4 bhIRrdCLVQcgU4glo17vqfEaRcTW5SgX+pGs4KIPPBE5J/ABD6pBnUUAEQEAAcLA/AQYAQgA JhYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89ZBQkFo5qAAhsMAAoJEGu9DlcdrjdR4C0L /RcjolEjoZW8VsyxWtXazQPnaRvzZ4vhmGOsCPr2BPtMlSwDzTlri8BBG1/3t/DNK4JLuwEj OAIE3fkkm+UG4Kjud6aNeraDI52DRVCSx6xff3bjmJsJJMb12mWglN6LjdF6K+PE+OTJUh2F dOhslN5C2kgl0dvUuevwMgQF3IljLmi/6APKYJHjkJpu1E6luZec/lRbetHuNFtbh3xgFIJx 2RpgVDP4xB3f8r0I+y6ua+p7fgOjDLyoFjubRGed0Be45JJQEn7A3CSb6Xu7NYobnxfkwAGZ Q81a2XtvNS7Aj6NWVoOQB5KbM4yosO5+Me1V1SkX2jlnn26JPEvbV3KRFcwV5RnDxm4OQTSk PYbAkjBbm+tuJ/Sm+5Yp5T/BnKz21FoCS8uvTiziHj2H7Cuekn6F8EYhegONm+RVg3vikOpn gao85i4HwQTK9/D1wgJIQkdwWXVMZ6q/OALaBp82vQ2U9sjTyFXgDjglgh00VRAHP7u1Rcu4 l75w1xInsg== In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/22/2025 10:53 AM, Andrew Cooper wrote: > This was a behaviour intentionally changed in FRED so traps wouldn't get > lost if an exception where to occur. > > What precise case is triggering this? Following is the test code: // SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (C) 2025 Intel Corporation */ #define _GNU_SOURCE #include #include #include #include #include #include static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_sigaction = handler; sa.sa_flags = SA_SIGINFO | flags; sigemptyset(&sa.sa_mask); if (sigaction(sig, &sa, 0)) err(1, "sigaction"); return; } static void sigtrap(int sig, siginfo_t *info, void *ctx_void) { ucontext_t *ctx = (ucontext_t *)ctx_void; static unsigned long last_trap_ip; static unsigned int loop_count_on_same_ip; if (last_trap_ip == ctx->uc_mcontext.gregs[REG_RIP]) { printf("trapped on %016lx\n", last_trap_ip); if (++loop_count_on_same_ip > 10) { printf("trap loop detected, test failed\n"); exit(2); } return; } loop_count_on_same_ip = 0; last_trap_ip = ctx->uc_mcontext.gregs[REG_RIP]; printf("trapped on %016lx\n", last_trap_ip); } int main(int argc, char *argv[]) { sethandler(SIGTRAP, sigtrap, 0); asm volatile("push $0x302\n\t" "popf\n\t" "nop\n\t" "nop\n\t" "push $0x202\n\t" "popf\n\t"); printf("test passed\n"); } W/o the fix when FRED enabled, I get: xin@fred-ubt:~$ ./lass_test trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trapped on 00000000004012fe trap loop detected, test failed W/ the fix when FRED enabled: [xin@dev ~]$ ./lass_test trapped on 00000000004012fe trapped on 00000000004012ff trapped on 0000000000401304 trapped on 0000000000401305 test passed Obviously the test passes on IDT. As Dave asked, I will integrate this test into selftests. Thanks! Xin