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[217.140.110.172]) by mx.google.com with ESMTP id f13si7129905eda.21.2019.07.23.02.57.53 for ; Tue, 23 Jul 2019 02:57:53 -0700 (PDT) Received-SPF: pass (google.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) client-ip=217.140.110.172; Authentication-Results: mx.google.com; spf=pass (google.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D39B8337; Tue, 23 Jul 2019 02:57:52 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 639E93F71A; Tue, 23 Jul 2019 02:57:50 -0700 (PDT) Date: Tue, 23 Jul 2019 10:57:48 +0100 From: Mark Rutland To: Steven Price Cc: linux-mm@kvack.org, Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Dave Hansen , Ingo Molnar , James Morse , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Peter Zijlstra , Thomas Gleixner , Will Deacon , x86@kernel.org, "H. Peter Anvin" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "Liang, Kan" , Andrew Morton Subject: Re: [PATCH v9 19/21] mm: Add generic ptdump Message-ID: <20190723095747.GB8085@lakrids.cambridge.arm.com> References: <20190722154210.42799-1-steven.price@arm.com> <20190722154210.42799-20-steven.price@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190722154210.42799-20-steven.price@arm.com> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) 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 Mon, Jul 22, 2019 at 04:42:08PM +0100, Steven Price wrote: > Add a generic version of page table dumping that architectures can > opt-in to > > Signed-off-by: Steven Price [...] > +#ifdef CONFIG_KASAN > +/* > + * This is an optimization for KASAN=y case. Since all kasan page tables > + * eventually point to the kasan_early_shadow_page we could call note_page() > + * right away without walking through lower level page tables. This saves > + * us dozens of seconds (minutes for 5-level config) while checking for > + * W+X mapping or reading kernel_page_tables debugfs file. > + */ > +static inline bool kasan_page_table(struct ptdump_state *st, void *pt, > + unsigned long addr) > +{ > + if (__pa(pt) == __pa(kasan_early_shadow_pmd) || > +#ifdef CONFIG_X86 > + (pgtable_l5_enabled() && > + __pa(pt) == __pa(kasan_early_shadow_p4d)) || > +#endif > + __pa(pt) == __pa(kasan_early_shadow_pud)) { > + st->note_page(st, addr, 5, pte_val(kasan_early_shadow_pte[0])); > + return true; > + } > + return false; Having you tried this with CONFIG_DEBUG_VIRTUAL? The kasan_early_shadow_pmd is a kernel object rather than a linear map object, so you should use __pa_symbol for that. It's a bit horrid to have to test multiple levels in one function; can't we check the relevant level inline in each of the test_p?d funcs? They're optional anyway, so they only need to be defined for CONFIG_KASAN. Thanks, Mark. > +} > +#else > +static inline bool kasan_page_table(struct ptdump_state *st, void *pt, > + unsigned long addr) > +{ > + return false; > +} > +#endif > + > +static int ptdump_test_p4d(unsigned long addr, unsigned long next, > + p4d_t *p4d, struct mm_walk *walk) > +{ > + struct ptdump_state *st = walk->private; > + > + if (kasan_page_table(st, p4d, addr)) > + return 1; > + return 0; > +} > +static int ptdump_test_pud(unsigned long addr, unsigned long next, > + pud_t *pud, struct mm_walk *walk) > +{ > + struct ptdump_state *st = walk->private; > + > + if (kasan_page_table(st, pud, addr)) > + return 1; > + return 0; > +} > + > +static int ptdump_test_pmd(unsigned long addr, unsigned long next, > + pmd_t *pmd, struct mm_walk *walk) > +{ > + struct ptdump_state *st = walk->private; > + > + if (kasan_page_table(st, pmd, addr)) > + return 1; > + return 0; > +} > + > +static int ptdump_hole(unsigned long addr, unsigned long next, > + struct mm_walk *walk) > +{ > + struct ptdump_state *st = walk->private; > + > + st->note_page(st, addr, -1, 0); > + > + return 0; > +} > + > +void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm) > +{ > + struct mm_walk walk = { > + .mm = mm, > + .pgd_entry = ptdump_pgd_entry, > + .p4d_entry = ptdump_p4d_entry, > + .pud_entry = ptdump_pud_entry, > + .pmd_entry = ptdump_pmd_entry, > + .pte_entry = ptdump_pte_entry, > + .test_p4d = ptdump_test_p4d, > + .test_pud = ptdump_test_pud, > + .test_pmd = ptdump_test_pmd, > + .pte_hole = ptdump_hole, > + .private = st > + }; > + const struct ptdump_range *range = st->range; > + > + down_read(&mm->mmap_sem); > + while (range->start != range->end) { > + walk_page_range(range->start, range->end, &walk); > + range++; > + } > + up_read(&mm->mmap_sem); > + > + /* Flush out the last page */ > + st->note_page(st, 0, 0, 0); > +} > -- > 2.20.1 >