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[209.85.167.45]) by smtp.gmail.com with ESMTPSA id s7sm619085lji.20.2019.12.01.06.53.43 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 01 Dec 2019 06:53:43 -0800 (PST) Received: by mail-lf1-f45.google.com with SMTP id q6so2941282lfb.6 for ; Sun, 01 Dec 2019 06:53:43 -0800 (PST) X-Received: by 2002:ac2:555c:: with SMTP id l28mr6278323lfk.52.1575211538956; Sun, 01 Dec 2019 06:45:38 -0800 (PST) MIME-Version: 1.0 References: <20191201015304.cRPsmKUTM%akpm@linux-foundation.org> <20191201090724.GA6629@zn.tnic> In-Reply-To: <20191201090724.GA6629@zn.tnic> From: Linus Torvalds Date: Sun, 1 Dec 2019 06:45:23 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch 064/158] mm: add generic ptdump To: Borislav Petkov Cc: Andrew Morton , alex@ghiti.fr, aou@eecs.berkeley.edu, Ard Biesheuvel , Arnd Bergmann , Andrey Ryabinin , Benjamin Herrenschmidt , Christian Borntraeger , Qian Cai , Catalin Marinas , Dave Hansen , dave.jiang@intel.com, David Miller , Dmitry Vyukov , Alexander Potapenko , Vasily Gorbik , Heiko Carstens , Peter Anvin , James Morse , James Hogan , Kan Liang , Linux-MM , Russell King - ARM Linux , Andrew Lutomirski , Mark Rutland , mawilcox@microsoft.com, Ingo Molnar , mm-commits@vger.kernel.org, Michael Ellerman , n-horiguchi@ah.jp.nec.com, Palmer Dabbelt , Paul Burton , Paul Walmsley , Paul Mackerras , Peter Zijlstra , ralf@linux-mips.org, shashim@codeaurora.org, Steven Price , Thomas Gleixner , vgupta@synopsys.com, Will Deacon , zong.li@sifive.com Content-Type: text/plain; charset="UTF-8" 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 Sun, Dec 1, 2019 at 1:09 AM Borislav Petkov wrote: > > That generic ptdump stuff is probably causing a splat on 32-bit: > > https://lkml.kernel.org/r/20191125144946.GA6628@duo.ucw.cz Hmm. I'm not sure about code generation, but for me that config gives me 60: 55 push %ebp 61: 89 e5 mov %esp,%ebp 63: 57 push %edi 64: 8b 4d 08 mov 0x8(%ebp),%ecx 67: 56 push %esi 68: 53 push %ebx 69: 8b 30 mov (%eax),%esi 6b: 8b 59 10 mov 0x10(%ecx),%ebx so that "ptdump_pte_entry+9" is the "mov (%eax),%esi" And that is "READ_ONCE(*pte)" So the pte pointer itself is broken. Which sounds really odd. Hmm. I've applied the whole series to a local branch, but I'm not merging it into my master branch yet. Can somebody figure out how the page walking could get that broken? Linus