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[148.163.158.5]) by mx.google.com with ESMTPS id c4-20020a81c944000000b005e80cc44973si3630462ywl.150.2024.01.15.16.36.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Jan 2024 16:36:03 -0800 (PST) Received-SPF: pass (google.com: domain of iii@linux.ibm.com designates 148.163.158.5 as permitted sender) client-ip=148.163.158.5; Authentication-Results: mx.google.com; dkim=pass header.i=@ibm.com header.s=pp1 header.b=XkdbvgHp; spf=pass (google.com: domain of iii@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=iii@linux.ibm.com; dmarc=pass (p=REJECT sp=NONE dis=NONE) header.from=ibm.com Received: from pps.filterd (m0353725.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 40FNTxSX010544; Tue, 16 Jan 2024 00:36:02 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=t1SC+zmPpc1Y0OU/FyOVQC5ZJl78RtELoSmL2Pk8z88=; b=XkdbvgHpx16Bcpshp6weSMupdHX1W/SQwCNSXDoaSWO/jmuHj588U6Xm5iMUS2++IPY7 C+J+l3qjxhPDaI+/CdqGdMyUtkvkWQfkeEMd5tfcrknsouwpAJLJdPtkz+X5a/kAvWzg 6ZoK6DBudP0yQ+xxXTRpXatADrQw7yW2qK2WYcJSXbj6gC2K/z83Sw7PMiT1OCCuCHSQ FEb5nm+w/FpXKMl4FW8kp0UQth6A3EkGoi0Xi5KIs4I/sP7/6Df5zjzaFJnlT8QiDmzl gMWAXyKVlslCOIAs8+0MjaF2aSFu4pMalvGZ7wcKfU/2+ib1AC1LjjTekSISP3mMoR6i 5Q== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3vncnekb2p-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Jan 2024 00:36:02 +0000 Received: from m0353725.ppops.net (m0353725.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 40FNsO3H002689; Tue, 16 Jan 2024 00:36:02 GMT Received: from ppma12.dal12v.mail.ibm.com (dc.9e.1632.ip4.static.sl-reverse.com [50.22.158.220]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3vncnekb27-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Jan 2024 00:36:02 +0000 Received: from pps.filterd (ppma12.dal12v.mail.ibm.com [127.0.0.1]) by ppma12.dal12v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 40FNHk50014890; Tue, 16 Jan 2024 00:36:00 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 3vm4uskph7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Jan 2024 00:36:00 +0000 Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 40G0ZwAw4063896 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 16 Jan 2024 00:35:59 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D886820043; Tue, 16 Jan 2024 00:35:58 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 366C620040; Tue, 16 Jan 2024 00:35:58 +0000 (GMT) Received: from heavy.boeblingen.de.ibm.com (unknown [9.179.4.64]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 16 Jan 2024 00:35:58 +0000 (GMT) From: Ilya Leoshkevich To: Richard Henderson , Peter Maydell , =?UTF-8?q?Alex=20Benn=C3=A9e?= , David Hildenbrand Cc: Paolo Bonzini , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org, qemu-arm@nongnu.org, qemu-s390x@nongnu.org, Ilya Leoshkevich Subject: [PATCH v3 1/3] linux-user: Allow gdbstub to ignore page protection Date: Tue, 16 Jan 2024 01:31:40 +0100 Message-ID: <20240116003551.75168-2-iii@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240116003551.75168-1-iii@linux.ibm.com> References: <20240116003551.75168-1-iii@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: khQyEJLnj7dh6oK_bGSa1nhVrz2kALtF X-Proofpoint-GUID: cIivWzxTHXKmxZHgbYsOs1hIISBdEjJM X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-01-15_17,2024-01-15_03,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 clxscore=1015 phishscore=0 spamscore=0 lowpriorityscore=0 suspectscore=0 mlxlogscore=961 impostorscore=0 adultscore=0 malwarescore=0 priorityscore=1501 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2401160002 X-TUID: DgE+gV12it+X gdbserver ignores page protection by virtue of using /proc/$pid/mem. Teach qemu gdbstub to do this too. This will not work if /proc is not mounted; accept this limitation. One alternative is to temporarily grant the missing PROT_* bit, but this is inherently racy. Another alternative is self-debugging with ptrace(POKE), which will break if QEMU itself is being debugged - a much more severe limitation. Reviewed-by: Richard Henderson Signed-off-by: Ilya Leoshkevich --- cpu-target.c | 76 +++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 61 insertions(+), 15 deletions(-) diff --git a/cpu-target.c b/cpu-target.c index 5eecd7ea2d7..723f6af5fba 100644 --- a/cpu-target.c +++ b/cpu-target.c @@ -406,6 +406,9 @@ int cpu_memory_rw_debug(CPUState *cpu, vaddr addr, vaddr l, page; void * p; uint8_t *buf = ptr; + ssize_t written; + int ret = -1; + int fd = -1; while (len > 0) { page = addr & TARGET_PAGE_MASK; @@ -413,30 +416,73 @@ int cpu_memory_rw_debug(CPUState *cpu, vaddr addr, if (l > len) l = len; flags = page_get_flags(page); - if (!(flags & PAGE_VALID)) - return -1; + if (!(flags & PAGE_VALID)) { + goto out_close; + } if (is_write) { - if (!(flags & PAGE_WRITE)) - return -1; - /* XXX: this code should not depend on lock_user */ - if (!(p = lock_user(VERIFY_WRITE, addr, l, 0))) - return -1; - memcpy(p, buf, l); - unlock_user(p, addr, l); - } else { - if (!(flags & PAGE_READ)) - return -1; + if (flags & PAGE_WRITE) { + /* XXX: this code should not depend on lock_user */ + p = lock_user(VERIFY_WRITE, addr, l, 0); + if (!p) { + goto out_close; + } + memcpy(p, buf, l); + unlock_user(p, addr, l); + } else { + /* Bypass the host page protection using ptrace. */ + if (fd == -1) { + fd = open("/proc/self/mem", O_WRONLY); + if (fd == -1) { + goto out; + } + } + /* + * If there is a TranslationBlock and we weren't bypassing the + * host page protection, the memcpy() above would SEGV, + * ultimately leading to page_unprotect(). So invalidate the + * translations manually. Both invalidation and pwrite() must + * be under mmap_lock() in order to prevent the creation of + * another TranslationBlock in between. + */ + mmap_lock(); + tb_invalidate_phys_range(addr, addr + l - 1); + written = pwrite(fd, buf, l, (off_t)g2h_untagged(addr)); + mmap_unlock(); + if (written != l) { + goto out_close; + } + } + } else if (flags & PAGE_READ) { /* XXX: this code should not depend on lock_user */ - if (!(p = lock_user(VERIFY_READ, addr, l, 1))) - return -1; + p = lock_user(VERIFY_READ, addr, l, 1); + if (!p) { + goto out_close; + } memcpy(buf, p, l); unlock_user(p, addr, 0); + } else { + /* Bypass the host page protection using ptrace. */ + if (fd == -1) { + fd = open("/proc/self/mem", O_RDONLY); + if (fd == -1) { + goto out; + } + } + if (pread(fd, buf, l, (off_t)g2h_untagged(addr)) != l) { + goto out_close; + } } len -= l; buf += l; addr += l; } - return 0; + ret = 0; +out_close: + if (fd != -1) { + close(fd); + } +out: + return ret; } #endif -- 2.43.0