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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id z8si4205708pgh.82.2019.04.19.00.19.00 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 19 Apr 2019 00:19:00 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of peterz@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=efhWri0O; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=peterz@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=M4U9lCHjwX+RI+C+4Qn3GQkY7/2O42PH32K/E1UYiUo=; b=efhWri0OqGFVL87uVOhTf0P8c VSvSxYJhAd6hWo8CmLsODUpgHy2FOdjPhzivpgzeDYDDeiD5oIiDpm5/7IbHgKjlq91wLpWzl1aD2 91I3Ez2HBIUFPqmjTLYnv1ZBwWH/Qw3AsrWa3Rbc4zrTGp/lwd5liclNi1MQEvkxFpGtCo0tFht6C ylKfaemtfAjzZtz7n+nThE01KGuJI1R+8abPHEYloVasqEARRFqBwNStJEX8+DkrmdReR692/NWRH 8Fb/ZC+LcMEtU9ngoXTQZys0EFT/JnwkdRRcHWVA/k49KlOl+ugsAq67JLMjnv0e+1/DskCXYRzRn lv2tg85gQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hHNnJ-0005As-Hx; Fri, 19 Apr 2019 07:18:45 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C26E229B52F44; Fri, 19 Apr 2019 09:18:43 +0200 (CEST) Date: Fri, 19 Apr 2019 09:18:43 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: LKML , Josh Poimboeuf , x86@kernel.org, Andy Lutomirski , Steven Rostedt , Alexander Potapenko , linux-arch@vger.kernel.org, Alexey Dobriyan , Andrew Morton , Pekka Enberg , linux-mm@kvack.org, David Rientjes , Christoph Lameter , Catalin Marinas , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, Mike Rapoport , Akinobu Mita , iommu@lists.linux-foundation.org, Robin Murphy , Christoph Hellwig , Marek Szyprowski , Johannes Thumshirn , David Sterba , Chris Mason , Josef Bacik , linux-btrfs@vger.kernel.org, dm-devel@redhat.com, Mike Snitzer , Alasdair Kergon , intel-gfx@lists.freedesktop.org, Joonas Lahtinen , Maarten Lankhorst , dri-devel@lists.freedesktop.org, David Airlie , Jani Nikula , Daniel Vetter , Rodrigo Vivi Subject: Re: [patch V2 28/29] stacktrace: Provide common infrastructure Message-ID: <20190419071843.GM4038@hirez.programming.kicks-ass.net> References: <20190418084119.056416939@linutronix.de> <20190418084255.652003111@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190418084255.652003111@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Apr 18, 2019 at 10:41:47AM +0200, Thomas Gleixner wrote: > +typedef bool (*stack_trace_consume_fn)(void *cookie, unsigned long addr, > + bool reliable); > +void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, > + struct task_struct *task, struct pt_regs *regs); > +int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, void *cookie, > + struct task_struct *task); This bugs me a little; ideally the _reliable() thing would not exists. Thomas said that the existing __save_stack_trace_reliable() is different enough for the unification to be non-trivial, but maybe Josh can help out? >From what I can see the biggest significant differences are: - it looks at the regs sets on the stack and for FP bails early - bails for khreads and idle (after it does all the hard work!?!) The first (FP checking for exceptions) should probably be reflected in consume_fn(.reliable) anyway -- although that would mean a lot of extra '?' entries where there are none today. And the second (KTHREAD/IDLE) is something that the generic code can easily do before calling into the arch unwinder. Hmm?