From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [patch V2 28/29] stacktrace: Provide common infrastructure Date: Fri, 19 Apr 2019 11:07:17 +0200 Message-ID: <20190419090717.GN7905@worktop.programming.kicks-ass.net> References: <20190418084119.056416939@linutronix.de> <20190418084255.652003111@linutronix.de> <20190419071843.GM4038@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Thomas Gleixner Cc: Mike Snitzer , David Airlie , Catalin Marinas , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, dm-devel@redhat.com, Alexander Potapenko , Christoph Lameter , Christoph Hellwig , Alasdair Kergon , Marek Szyprowski , linux-arch@vger.kernel.org, x86@kernel.org, kasan-dev@googlegroups.com, David Rientjes , Andrey Ryabinin , Alexey Dobriyan , intel-gfx@lists.freedesktop.org, Johannes Thumshirn , Akinobu Mita , Steven Rostedt , Josef Bacik , Rodrigo Vivi , Mike Rapoport , Andy Lutomirski , Josh Poimboeuf List-Id: linux-arch.vger.kernel.org T24gRnJpLCBBcHIgMTksIDIwMTkgYXQgMTA6MzI6MzBBTSArMDIwMCwgVGhvbWFzIEdsZWl4bmVy IHdyb3RlOgo+IE9uIEZyaSwgMTkgQXByIDIwMTksIFBldGVyIFppamxzdHJhIHdyb3RlOgo+ID4g T24gVGh1LCBBcHIgMTgsIDIwMTkgYXQgMTA6NDE6NDdBTSArMDIwMCwgVGhvbWFzIEdsZWl4bmVy IHdyb3RlOgo+ID4gCj4gPiA+ICt0eXBlZGVmIGJvb2wgKCpzdGFja190cmFjZV9jb25zdW1lX2Zu KSh2b2lkICpjb29raWUsIHVuc2lnbmVkIGxvbmcgYWRkciwKPiA+ID4gKyAgICAgICAgICAgICAg ICAgICAgICAgICAgICAgICAgICAgICAgYm9vbCByZWxpYWJsZSk7Cj4gPiAKPiA+ID4gK3ZvaWQg YXJjaF9zdGFja193YWxrKHN0YWNrX3RyYWNlX2NvbnN1bWVfZm4gY29uc3VtZV9lbnRyeSwgdm9p ZCAqY29va2llLAo+ID4gPiArCQkgICAgIHN0cnVjdCB0YXNrX3N0cnVjdCAqdGFzaywgc3RydWN0 IHB0X3JlZ3MgKnJlZ3MpOwo+ID4gPiAraW50IGFyY2hfc3RhY2tfd2Fsa19yZWxpYWJsZShzdGFj a190cmFjZV9jb25zdW1lX2ZuIGNvbnN1bWVfZW50cnksIHZvaWQgKmNvb2tpZSwKPiA+ID4gKwkJ CSAgICAgc3RydWN0IHRhc2tfc3RydWN0ICp0YXNrKTsKPiA+IAo+ID4gVGhpcyBidWdzIG1lIGEg bGl0dGxlOyBpZGVhbGx5IHRoZSBfcmVsaWFibGUoKSB0aGluZyB3b3VsZCBub3QgZXhpc3RzLgo+ ID4gCj4gPiBUaG9tYXMgc2FpZCB0aGF0IHRoZSBleGlzdGluZyBfX3NhdmVfc3RhY2tfdHJhY2Vf cmVsaWFibGUoKSBpcyBkaWZmZXJlbnQKPiA+IGVub3VnaCBmb3IgdGhlIHVuaWZpY2F0aW9uIHRv IGJlIG5vbi10cml2aWFsLCBidXQgbWF5YmUgSm9zaCBjYW4gaGVscAo+ID4gb3V0Pwo+ID4gCj4g PiA+RnJvbSB3aGF0IEkgY2FuIHNlZSB0aGUgYmlnZ2VzdCBzaWduaWZpY2FudCBkaWZmZXJlbmNl cyBhcmU6Cj4gPiAKPiA+ICAtIGl0IGxvb2tzIGF0IHRoZSByZWdzIHNldHMgb24gdGhlIHN0YWNr IGFuZCBmb3IgRlAgYmFpbHMgZWFybHkKPiA+ICAtIGJhaWxzIGZvciBraHJlYWRzIGFuZCBpZGxl IChhZnRlciBpdCBkb2VzIGFsbCB0aGUgaGFyZCB3b3JrIT8hKQo+ID4gCj4gPiBUaGUgZmlyc3Qg KEZQIGNoZWNraW5nIGZvciBleGNlcHRpb25zKSBzaG91bGQgcHJvYmFibHkgYmUgcmVmbGVjdGVk IGluCj4gPiBjb25zdW1lX2ZuKC5yZWxpYWJsZSkgYW55d2F5IC0tIGFsdGhvdWdoIHRoYXQgd291 bGQgbWVhbiBhIGxvdCBvZiBleHRyYQo+ID4gJz8nIGVudHJpZXMgd2hlcmUgdGhlcmUgYXJlIG5v bmUgdG9kYXkuCj4gPiAKPiA+IEFuZCB0aGUgc2Vjb25kIChLVEhSRUFEL0lETEUpIGlzIHNvbWV0 aGluZyB0aGF0IHRoZSBnZW5lcmljIGNvZGUgY2FuCj4gPiBlYXNpbHkgZG8gYmVmb3JlIGNhbGxp bmcgaW50byB0aGUgYXJjaCB1bndpbmRlci4KPiAKPiBBbmQgbG9va2luZyBhdCB0aGUgcG93ZXJw YyB2ZXJzaW9uIG9mIGl0LCB0aGF0IGhhcyBldmVuIG1vcmUgaW50ZXJlc3RpbmcKPiBleHRyYSBj aGVja3MgaW4gdGhhdCBmdW5jdGlvbi4KClJpZ2h0LCBidXQgbm90IGZ1bmRhbWVudGFsbHkgZGlm ZmVyZW50IGZyb20gZGV0ZXJtaW5pbmcgQHJlbGlhYmxlIEkKdGhpbmsuCgpBbnl3YXksIGl0IHdv dWxkIGJlIGdvb2QgaWYgc29tZW9uZSBrbm93bGVkZ2FibGUgY291bGQgaGF2ZSBhIGxvb2sgYXQK dGhpcy4KX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KZHJp LWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBz Oi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:49702 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726834AbfDSWy0 (ORCPT ); Fri, 19 Apr 2019 18:54:26 -0400 Date: Fri, 19 Apr 2019 11:07:17 +0200 From: Peter Zijlstra Subject: Re: [patch V2 28/29] stacktrace: Provide common infrastructure Message-ID: <20190419090717.GN7905@worktop.programming.kicks-ass.net> References: <20190418084119.056416939@linutronix.de> <20190418084255.652003111@linutronix.de> <20190419071843.GM4038@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: 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 Message-ID: <20190419090717._NChbu5jLK6EUbfEM8JHT5iVfiXrPpGuOtJkMij8gzo@z> On Fri, Apr 19, 2019 at 10:32:30AM +0200, Thomas Gleixner wrote: > On Fri, 19 Apr 2019, Peter Zijlstra wrote: > > 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. > > And looking at the powerpc version of it, that has even more interesting > extra checks in that function. Right, but not fundamentally different from determining @reliable I think. Anyway, it would be good if someone knowledgable could have a look at this.