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Message-ID: <a59b818d84b74c13a4f25f757eba1f93@AcuMS.aculab.com> Date: Mon, 9 Apr 2018 13:14:58 +0000 From: David Laight <David.Laight@...LAB.COM> To: "'kpark3469@...il.com'" <kpark3469@...il.com>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com> CC: "catalin.marinas@....com" <catalin.marinas@....com>, "keescook@...omium.org" <keescook@...omium.org>, "will.deacon@....com" <will.deacon@....com>, "mark.rutland@....com" <mark.rutland@....com>, "james.morse@....com" <james.morse@....com>, "panand@...hat.com" <panand@...hat.com>, "keun-o.park@...kmatter.ae" <keun-o.park@...kmatter.ae>, "psodagud@...eaurora.org" <psodagud@...eaurora.org>, "jpoimboe@...hat.com" <jpoimboe@...hat.com>, "mingo@...nel.org" <mingo@...nel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: RE: [PATCH v3 3/3] x86: usercopy: reimplement arch_within_stack_frames with unwinder From: kpark3469@...il.com > Sent: 09 April 2018 12:59 > > The old arch_within_stack_frames which used the frame pointer is > now reimplemented to use frame pointer unwinder apis. So the main > functionality is same as before. How much slower does this make the code? Following stack frames using %bp is reasonably quick. I can't imagine some of the other unwinder APIs being any where near that fast. While fine for fault tracebacks, using them during usercopy is likely to have measurable performance impact. David
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