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[2.7.103.217]) by smtp.gmail.com with ESMTPSA id j10-20020a05600c190a00b003c6b7f5567csm24812011wmq.0.2022.10.16.11.39.54 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 16 Oct 2022 11:39:54 -0700 (PDT) Message-ID: Date: Sun, 16 Oct 2022 20:39:53 +0200 List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:102.0) Gecko/20100101 Thunderbird/102.3.2 Subject: Re: AMD64 14.0-CURRENT memory layout changes Content-Language: en-US To: freebsd-hackers References: <18733815c5cf1af1e313168629916ee5@gundo.com> From: Paul Floyd In-Reply-To: <18733815c5cf1af1e313168629916ee5@gundo.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4Mr87L0yCdz42QH X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20210112 header.b=SNk2gL+8; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of paulf2718@gmail.com designates 2a00:1450:4864:20::433 as permitted sender) smtp.mailfrom=paulf2718@gmail.com X-Spamd-Result: default: False [-4.00 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.998]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36:c]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20210112]; MIME_GOOD(-0.10)[text/plain]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; ARC_NA(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; RCVD_TLS_LAST(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[2a00:1450:4864:20::433:from]; TO_DN_ALL(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; FREEMAIL_FROM(0.00)[gmail.com]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; MIME_TRACE(0.00)[0:+]; FROM_EQ_ENVFROM(0.00)[]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; FREEMAIL_ENVFROM(0.00)[gmail.com]; MLMMJ_DEST(0.00)[freebsd-hackers@freebsd.org] X-ThisMailContainsUnwantedMimeParts: N On 10/16/22 17:29, Pau Amma wrote: > Jumoing in with some quarterly reports I saw pass that may be related to > either/both: > - > https://www.freebsd.org/status/report-2022-04-2022-06/#_shared_page_address_randomization (not sure this is about rtld) > - > https://www.freebsd.org/status/report-2021-07-2021-09/#_stack_gap_handling_improvements (this one mentions a switch-off sysctl). Hi Pau Amma and Mark Thanks for the info. I now understand the problem. Valgrind needs to intercept sysctl(byname) kern.stacktop and return its own value. I'm already doing this for kern.usrstack. Without interception the guest is getting the stacktop of the host. The host obviously refuses to let the guest mmap over its own stack, resulting in an assert and guest crash. A+ Paul