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[133.167.126.250]) by smtp.gmail.com with ESMTPSA id ij14-20020a17090af80e00b0029bcf877eabsm1473763pjb.10.2024.03.13.07.59.34 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Mar 2024 07:59:36 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Precedence: bulk X-Mailing-List: linux-toolchains@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.500.171.1.1\)) Subject: Re: [POC 5/5] x86_64: invoke SFrame based stack tracer for user space From: Tatsuyuki Ishi In-Reply-To: <20240313105228.2a6bbd2f@gandalf.local.home> Date: Wed, 13 Mar 2024 22:58:18 +0800 Cc: Peter Zijlstra , Indu Bhagat , linux-toolchains@vger.kernel.org, daandemeyer@meta.com, andrii@kernel.org, kris.van.hees@oracle.com, elena.zannoni@oracle.com, nick.alcock@oracle.com Content-Transfer-Encoding: quoted-printable Message-Id: References: <20230501200410.3973453-1-indu.bhagat@oracle.com> <20230501200410.3973453-6-indu.bhagat@oracle.com> <20230502105353.GO1597476@hirez.programming.kicks-ass.net> <20230502112720.0c0d011b@gandalf.local.home> <4CDF4EB4-C8AF-43DB-88AB-DB4BB76995F2@gmail.com> <20240313105228.2a6bbd2f@gandalf.local.home> To: Steven Rostedt X-Mailer: Apple Mail (2.3774.500.171.1.1) > On Mar 13, 2024, at 22:52, Steven Rostedt wrote: >=20 > The simple answer is to call irq_work. That will trigger an interrupt = when > irqs are enabled again (returning from NMI and just before entering = user > space). >=20 > The return from the irq_work can do the proper ptrace path. >=20 Yeah, that makes sense. Thanks! Not sure how much overhead a self-IPI causes, compared to forging an = IRET, but we can probably measure that later. Tatsuyuki