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(p200300cbc7045d00d8c2fbf6a608957a.dip0.t-ipconnect.de. [2003:cb:c704:5d00:d8c2:fbf6:a608:957a]) by smtp.gmail.com with ESMTPSA id s7-20020a5d6a87000000b00207aad420c4sm12434616wru.101.2022.04.19.05.46.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Apr 2022 05:46:53 -0700 (PDT) Message-ID: Date: Tue, 19 Apr 2022 14:46:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Hugh Dickins , Linus Torvalds , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Jann Horn , Michal Hocko , Nadav Amit , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Liang Zhang , Pedro Gomes , Oded Gabbay , Catalin Marinas , Will Deacon , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Gerald Schaefer , linux-mm@kvack.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org References: <20220329164329.208407-1-david@redhat.com> <20220329164329.208407-4-david@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v2 3/8] x86/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE In-Reply-To: <20220329164329.208407-4-david@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: DD6991A000B X-Stat-Signature: pohyxtoyyjqhseoezzw5fjhohfctpiay Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=RnKtPUGk; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf19.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com X-HE-Tag: 1650372415-741728 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 29.03.22 18:43, David Hildenbrand wrote: > Let's use bit 3 to remember PG_anon_exclusive in swap ptes. > > Signed-off-by: David Hildenbrand > --- Looks like I ignored that 32bit uses a different (undocumented) swap layout and bit 3 falls into the swp type. We'll restrict this to x86-64 for now, just like for the other architectures. The following seems to fly. @Andrew, let me know if you prefer a v3. >From bafb5ba914e89ad20c46f4e841a36909e610b81e Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 9 Mar 2022 09:47:29 +0100 Subject: [PATCH] x86/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on x86_64 Let's use bit 3 to remember PG_anon_exclusive in swap ptes. Signed-off-by: David Hildenbrand --- arch/x86/include/asm/pgtable.h | 17 +++++++++++++++++ arch/x86/include/asm/pgtable_64.h | 4 +++- arch/x86/include/asm/pgtable_64_types.h | 5 +++++ 3 files changed, 25 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 62ab07e24aef..a1c555abed26 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -1291,6 +1291,23 @@ static inline void update_mmu_cache_pud(struct vm_area_struct *vma, unsigned long addr, pud_t *pud) { } +#ifdef _PAGE_SWP_EXCLUSIVE +#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE +static inline pte_t pte_swp_mkexclusive(pte_t pte) +{ + return pte_set_flags(pte, _PAGE_SWP_EXCLUSIVE); +} + +static inline int pte_swp_exclusive(pte_t pte) +{ + return pte_flags(pte) & _PAGE_SWP_EXCLUSIVE; +} + +static inline pte_t pte_swp_clear_exclusive(pte_t pte) +{ + return pte_clear_flags(pte, _PAGE_SWP_EXCLUSIVE); +} +#endif /* _PAGE_SWP_EXCLUSIVE */ #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY static inline pte_t pte_swp_mksoft_dirty(pte_t pte) diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h index 56d0399a0cd1..e479491da8d5 100644 --- a/arch/x86/include/asm/pgtable_64.h +++ b/arch/x86/include/asm/pgtable_64.h @@ -186,7 +186,7 @@ static inline void native_pgd_clear(pgd_t *pgd) * * | ... | 11| 10| 9|8|7|6|5| 4| 3|2| 1|0| <- bit number * | ... |SW3|SW2|SW1|G|L|D|A|CD|WT|U| W|P| <- bit names - * | TYPE (59-63) | ~OFFSET (9-58) |0|0|X|X| X| X|F|SD|0| <- swp entry + * | TYPE (59-63) | ~OFFSET (9-58) |0|0|X|X| X| E|F|SD|0| <- swp entry * * G (8) is aliased and used as a PROT_NONE indicator for * !present ptes. We need to start storing swap entries above @@ -203,6 +203,8 @@ static inline void native_pgd_clear(pgd_t *pgd) * F (2) in swp entry is used to record when a pagetable is * writeprotected by userfaultfd WP support. * + * E (3) in swp entry is used to rememeber PG_anon_exclusive. + * * Bit 7 in swp entry should be 0 because pmd_present checks not only P, * but also L and G. * diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 91ac10654570..70e360a2e5fb 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -163,4 +163,9 @@ extern unsigned int ptrs_per_p4d; #define PGD_KERNEL_START ((PAGE_SIZE / 2) / sizeof(pgd_t)) +/* + * We borrow bit 3 to remember PG_anon_exclusive. + */ +#define _PAGE_SWP_EXCLUSIVE _PAGE_PWT + #endif /* _ASM_X86_PGTABLE_64_DEFS_H */ -- 2.35.1 -- Thanks, David / dhildenb