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Message-ID: <84f626ba-6abf-42f0-b520-8b622c21bb73@lucifer.local>
Date: Wed, 9 Oct 2024 15:25:25 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: linux-mm@...ck.org, Arnd Bergmann <arnd@...db.de>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Andreas Larsson <andreas@...sler.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Christian Brauner <brauner@...nel.org>, Christoph Hellwig <hch@....de>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Damien Le Moal <dlemoal@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        Greg Ungerer <gerg@...ux-m68k.org>, Helge Deller <deller@....de>,
        Kees Cook <kees@...nel.org>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Matt Turner <mattst88@...il.com>, Max Filippov <jcmvbkbc@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>, Michal Hocko <mhocko@...e.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Richard Henderson <richard.henderson@...aro.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Vladimir Murzin <vladimir.murzin@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        linux-stm32@...md-mailman.stormreply.com, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 2/5] asm-generic: move MAP_* flags from mman-common.h to
 mman.h

On Wed, Sep 25, 2024 at 09:06:12PM +0000, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
>
> powerpc and sparc include asm-generic/mman-common.h to get the MAP_* flags
> 0x008000 through 0x4000000, but those flags are all different on alpha,
> mips, parisc and xtensa.
>
> Add duplicate definitions for these along with the MAP_* flags for 0x100
> through 0x4000 that are already different on powerpc and sparc, as a
> preparation for actually sharing mman-common.h with all architectures.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  arch/powerpc/include/uapi/asm/mman.h   | 16 ++++++++++++++++
>  arch/sparc/include/uapi/asm/mman.h     | 15 +++++++++++++++
>  include/uapi/asm-generic/mman-common.h | 16 ----------------
>  include/uapi/asm-generic/mman.h        | 21 +++++++++++++++++++++
>  include/uapi/linux/mman.h              |  5 +++++
>  5 files changed, 57 insertions(+), 16 deletions(-)
>
> diff --git a/arch/powerpc/include/uapi/asm/mman.h b/arch/powerpc/include/uapi/asm/mman.h
> index c0c737215b00..d57b347c37fe 100644
> --- a/arch/powerpc/include/uapi/asm/mman.h
> +++ b/arch/powerpc/include/uapi/asm/mman.h
> @@ -13,6 +13,11 @@
>
>  #define PROT_SAO	0x10		/* Strong Access Ordering */
>
> +/* 0x01 - 0x03 are defined in linux/mman.h */
> +#define MAP_TYPE	0x0f		/* Mask for type of mapping */
> +#define MAP_FIXED	0x10		/* Interpret addr exactly */
> +#define MAP_ANONYMOUS	0x20		/* don't use a file */
> +
>  #define MAP_RENAME      MAP_ANONYMOUS   /* In SunOS terminology */
>  #define MAP_NORESERVE   0x40            /* don't reserve swap pages */
>  #define MAP_LOCKED	0x80
> @@ -21,6 +26,17 @@
>  #define MAP_DENYWRITE	0x0800		/* ETXTBSY */
>  #define MAP_EXECUTABLE	0x1000		/* mark it as an executable */
>
> +#define MAP_POPULATE		0x008000	/* populate (prefault) pagetables */
> +#define MAP_NONBLOCK		0x010000	/* do not block on IO */
> +#define MAP_STACK		0x020000	/* give out an address that is best suited for process/thread stacks */
> +#define MAP_HUGETLB		0x040000	/* create a huge page mapping */
> +#define MAP_SYNC		0x080000 /* perform synchronous page faults for the mapping */
> +#define MAP_FIXED_NOREPLACE	0x100000	/* MAP_FIXED which doesn't unmap underlying mapping */
> +
> +#define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be
> +					 * uninitialized */
> +
> +
>
>  #define MCL_CURRENT     0x2000          /* lock all currently mapped pages */
>  #define MCL_FUTURE      0x4000          /* lock all additions to address space */
> diff --git a/arch/sparc/include/uapi/asm/mman.h b/arch/sparc/include/uapi/asm/mman.h
> index cec9f4109687..afb86698cdb1 100644
> --- a/arch/sparc/include/uapi/asm/mman.h
> +++ b/arch/sparc/include/uapi/asm/mman.h
> @@ -8,6 +8,11 @@
>
>  #define PROT_ADI	0x10		/* ADI enabled */
>
> +/* 0x01 - 0x03 are defined in linux/mman.h */
> +#define MAP_TYPE	0x0f		/* Mask for type of mapping */
> +#define MAP_FIXED	0x10		/* Interpret addr exactly */
> +#define MAP_ANONYMOUS	0x20		/* don't use a file */
> +
>  #define MAP_RENAME      MAP_ANONYMOUS   /* In SunOS terminology */
>  #define MAP_NORESERVE   0x40            /* don't reserve swap pages */
>  #define MAP_INHERIT     0x80            /* SunOS doesn't do this, but... */
> @@ -18,6 +23,16 @@
>  #define MAP_DENYWRITE	0x0800		/* ETXTBSY */
>  #define MAP_EXECUTABLE	0x1000		/* mark it as an executable */
>
> +#define MAP_POPULATE		0x008000	/* populate (prefault) pagetables */
> +#define MAP_NONBLOCK		0x010000	/* do not block on IO */
> +#define MAP_STACK		0x020000	/* give out an address that is best suited for process/thread stacks */
> +#define MAP_HUGETLB		0x040000	/* create a huge page mapping */
> +#define MAP_SYNC		0x080000 /* perform synchronous page faults for the mapping */
> +#define MAP_FIXED_NOREPLACE	0x100000	/* MAP_FIXED which doesn't unmap underlying mapping */
> +
> +#define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be
> +					 * uninitialized */
> +
>  #define MCL_CURRENT     0x2000          /* lock all currently mapped pages */
>  #define MCL_FUTURE      0x4000          /* lock all additions to address space */
>  #define MCL_ONFAULT	0x8000		/* lock all pages that are faulted in */
> diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
> index 792ad5599d9c..8d66d2dabaa8 100644
> --- a/include/uapi/asm-generic/mman-common.h
> +++ b/include/uapi/asm-generic/mman-common.h
> @@ -17,22 +17,6 @@
>  #define PROT_GROWSDOWN	0x01000000	/* mprotect flag: extend change to start of growsdown vma */
>  #define PROT_GROWSUP	0x02000000	/* mprotect flag: extend change to end of growsup vma */
>
> -/* 0x01 - 0x03 are defined in linux/mman.h */
> -#define MAP_TYPE	0x0f		/* Mask for type of mapping */
> -#define MAP_FIXED	0x10		/* Interpret addr exactly */
> -#define MAP_ANONYMOUS	0x20		/* don't use a file */
> -

Hm, maybe I'm missing something, but why are we duplicating these?

> -/* 0x0100 - 0x4000 flags are defined in asm-generic/mman.h */
> -#define MAP_POPULATE		0x008000	/* populate (prefault) pagetables */
> -#define MAP_NONBLOCK		0x010000	/* do not block on IO */
> -#define MAP_STACK		0x020000	/* give out an address that is best suited for process/thread stacks */
> -#define MAP_HUGETLB		0x040000	/* create a huge page mapping */
> -#define MAP_SYNC		0x080000 /* perform synchronous page faults for the mapping */
> -#define MAP_FIXED_NOREPLACE	0x100000	/* MAP_FIXED which doesn't unmap underlying mapping */
> -
> -#define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be
> -					 * uninitialized */
> -
>  /*
>   * Flags for mlock
>   */
> diff --git a/include/uapi/asm-generic/mman.h b/include/uapi/asm-generic/mman.h
> index 57e8195d0b53..f26f9b4c03e1 100644
> --- a/include/uapi/asm-generic/mman.h
> +++ b/include/uapi/asm-generic/mman.h
> @@ -4,12 +4,33 @@
>
>  #include <asm-generic/mman-common.h>
>
> +/*
> + * 0x01 - 0x03 are defined in linux/mman.h
> + * 0x04 - 0x200000 are architecture specific
> + * 0x200000 - 0x2000000 are available for common assignments in linux/mman.h
> + * 0x4000000 - 0x80000000 are used for hugepage encodings
> + */
> +#define MAP_TYPE	0x0f		/* Mask for type of mapping */
> +#define MAP_FIXED	0x10		/* Interpret addr exactly */
> +#define MAP_ANONYMOUS	0x20		/* don't use a file */
> +
>  #define MAP_GROWSDOWN	0x0100		/* stack-like segment */
>  #define MAP_DENYWRITE	0x0800		/* ETXTBSY */
>  #define MAP_EXECUTABLE	0x1000		/* mark it as an executable */
>  #define MAP_LOCKED	0x2000		/* pages are locked */
>  #define MAP_NORESERVE	0x4000		/* don't check for reservations */
>
> +#define MAP_POPULATE		0x008000	/* populate (prefault) pagetables */
> +#define MAP_NONBLOCK		0x010000	/* do not block on IO */
> +#define MAP_STACK		0x020000	/* give out an address that is best suited for process/thread stacks */
> +#define MAP_HUGETLB		0x040000	/* create a huge page mapping */
> +#define MAP_SYNC		0x080000 /* perform synchronous page faults for the mapping */
> +#define MAP_FIXED_NOREPLACE	0x100000	/* MAP_FIXED which doesn't unmap underlying mapping */
> +
> +#define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be
> +					 * uninitialized */
> +
> +
>  /*
>   * Bits [26:31] are reserved, see asm-generic/hugetlb_encode.h
>   * for MAP_HUGETLB usage
> diff --git a/include/uapi/linux/mman.h b/include/uapi/linux/mman.h
> index e89d00528f2f..b70cb06dd7ef 100644
> --- a/include/uapi/linux/mman.h
> +++ b/include/uapi/linux/mman.h
> @@ -18,6 +18,11 @@
>  #define MAP_PRIVATE	0x02		/* Changes are private */
>  #define MAP_SHARED_VALIDATE 0x03	/* share + validate extension flags */
>  #define MAP_DROPPABLE	0x08		/* Zero memory under memory pressure. */
> +/*
> + * 0x10 through 0x200000 are used for architecture specific definitions
> + * in asm/mman.h, numbers 0x400000 through 0x2000000 are currently
> + * available on all architectures.
> + */

Nice to add this documentation!

>
>  /*
>   * Huge page size encoding when MAP_HUGETLB is specified, and a huge page
> --
> 2.39.2
>

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