From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932309AbdA0N2B (ORCPT ); Fri, 27 Jan 2017 08:28:01 -0500 Received: from mx2.suse.de ([195.135.220.15]:33548 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754879AbdA0N1W (ORCPT ); Fri, 27 Jan 2017 08:27:22 -0500 Subject: Re: [PATCHv2 03/29] asm-generic: introduce __ARCH_USE_5LEVEL_HACK To: "Kirill A. Shutemov" , Linus Torvalds , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , Arnd Bergmann , "H. Peter Anvin" References: <20161227015413.187403-1-kirill.shutemov@linux.intel.com> <20161227015413.187403-4-kirill.shutemov@linux.intel.com> Cc: Andi Kleen , Dave Hansen , Andy Lutomirski , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org From: Vlastimil Babka Message-ID: Date: Fri, 27 Jan 2017 14:24:58 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <20161227015413.187403-4-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/27/2016 02:53 AM, Kirill A. Shutemov wrote: > We are going to introduce to provide > abstraction for properly (in opposite to 5level-fixup.h hack) folded > p4d level. The new header will be included from pgtable-nopud.h. > > If an architecture uses , we cannot use > 5level-fixup.h directly to quickly convert the architecture to 5-level > paging as it would conflict with pgtable-nop4d.h. > > With this patch an architecture can define __ARCH_USE_5LEVEL_HACK before > inclusion to 5level-fixup.h. > > Signed-off-by: Kirill A. Shutemov > --- > include/asm-generic/pgtable-nop4d-hack.h | 62 ++++++++++++++++++++++++++++++++ At risk of bikeshedding and coming from somebody not familiar with this code... IMHO it would be somewhat more intuitive and consistent to name the file "pgtable-nopud-hack.h" as it's about the pud stuff, not p4d stuff, and acts as an alternative implementation to pgtable-nopud.h, not pgtable-nop4d.h Thanks, Vlastimil > include/asm-generic/pgtable-nopud.h | 5 +++ > 2 files changed, 67 insertions(+) > create mode 100644 include/asm-generic/pgtable-nop4d-hack.h > > diff --git a/include/asm-generic/pgtable-nop4d-hack.h b/include/asm-generic/pgtable-nop4d-hack.h > new file mode 100644 > index 000000000000..752fb7511750 > --- /dev/null > +++ b/include/asm-generic/pgtable-nop4d-hack.h > @@ -0,0 +1,62 @@ > +#ifndef _PGTABLE_NOP4D_HACK_H > +#define _PGTABLE_NOP4D_HACK_H > + > +#ifndef __ASSEMBLY__ > +#include > + > +#define __PAGETABLE_PUD_FOLDED > + > +/* > + * Having the pud type consist of a pgd gets the size right, and allows > + * us to conceptually access the pgd entry that this pud is folded into > + * without casting. > + */ > +typedef struct { pgd_t pgd; } pud_t; > + > +#define PUD_SHIFT PGDIR_SHIFT > +#define PTRS_PER_PUD 1 > +#define PUD_SIZE (1UL << PUD_SHIFT) > +#define PUD_MASK (~(PUD_SIZE-1)) > + > +/* > + * The "pgd_xxx()" functions here are trivial for a folded two-level > + * setup: the pud is never bad, and a pud always exists (as it's folded > + * into the pgd entry) > + */ > +static inline int pgd_none(pgd_t pgd) { return 0; } > +static inline int pgd_bad(pgd_t pgd) { return 0; } > +static inline int pgd_present(pgd_t pgd) { return 1; } > +static inline void pgd_clear(pgd_t *pgd) { } > +#define pud_ERROR(pud) (pgd_ERROR((pud).pgd)) > + > +#define pgd_populate(mm, pgd, pud) do { } while (0) > +/* > + * (puds are folded into pgds so this doesn't get actually called, > + * but the define is needed for a generic inline function.) > + */ > +#define set_pgd(pgdptr, pgdval) set_pud((pud_t *)(pgdptr), (pud_t) { pgdval }) > + > +static inline pud_t *pud_offset(pgd_t *pgd, unsigned long address) > +{ > + return (pud_t *)pgd; > +} > + > +#define pud_val(x) (pgd_val((x).pgd)) > +#define __pud(x) ((pud_t) { __pgd(x) }) > + > +#define pgd_page(pgd) (pud_page((pud_t){ pgd })) > +#define pgd_page_vaddr(pgd) (pud_page_vaddr((pud_t){ pgd })) > + > +/* > + * allocating and freeing a pud is trivial: the 1-entry pud is > + * inside the pgd, so has no extra memory associated with it. > + */ > +#define pud_alloc_one(mm, address) NULL > +#define pud_free(mm, x) do { } while (0) > +#define __pud_free_tlb(tlb, x, a) do { } while (0) > + > +#undef pud_addr_end > +#define pud_addr_end(addr, end) (end) > + > +#endif /* __ASSEMBLY__ */ > +#endif /* _PGTABLE_NOP4D_HACK_H */ > diff --git a/include/asm-generic/pgtable-nopud.h b/include/asm-generic/pgtable-nopud.h > index 810431d8351b..5e49430a30a4 100644 > --- a/include/asm-generic/pgtable-nopud.h > +++ b/include/asm-generic/pgtable-nopud.h > @@ -3,6 +3,10 @@ > > #ifndef __ASSEMBLY__ > > +#ifdef __ARCH_USE_5LEVEL_HACK > +#include > +#else > + > #define __PAGETABLE_PUD_FOLDED > > /* > @@ -58,4 +62,5 @@ static inline pud_t * pud_offset(pgd_t * pgd, unsigned long address) > #define pud_addr_end(addr, end) (end) > > #endif /* __ASSEMBLY__ */ > +#endif /* !__ARCH_USE_5LEVEL_HACK */ > #endif /* _PGTABLE_NOPUD_H */ >