From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
hch@infradead.org, akpm@linux-foundation.org
Subject: Re: [RFC V1 00/31] mm/mmap: Drop protection_map[] and platform's __SXXX/__PXXX requirements
Date: Mon, 31 Jan 2022 09:05:43 +0530 [thread overview]
Message-ID: <45a5562d-9eaa-b9ea-62e0-4518e5a09046@arm.com> (raw)
In-Reply-To: <YfKSXXTZOa9FYug8@kernel.org>
On 1/27/22 6:08 PM, Mike Rapoport wrote:
> Hi Anshuman,
>
> On Mon, Jan 24, 2022 at 06:26:37PM +0530, Anshuman Khandual wrote:
>> protection_map[] is an array based construct that translates given vm_flags
>> combination. This array contains page protection map, which is populated by
>> the platform via [__S000 .. __S111] and [__P000 .. __P111] exported macros.
>> Primary usage for protection_map[] is for vm_get_page_prot(), which is used
>> to determine page protection value for a given vm_flags. vm_get_page_prot()
>> implementation, could again call platform overrides arch_vm_get_page_prot()
>> and arch_filter_pgprot(). Some platforms override protection_map[] that was
>> originally built with __SXXX/__PXXX with different runtime values.
>>
>> Currently there are multiple layers of abstraction i.e __SXXX/__PXXX macros
>> , protection_map[], arch_vm_get_page_prot() and arch_filter_pgprot() built
>> between the platform and generic MM, finally defining vm_get_page_prot().
>>
>> Hence this series proposes to drop all these abstraction levels and instead
>> just move the responsibility of defining vm_get_page_prot() to the platform
>> itself making it clean and simple.
>>
>> This first introduces ARCH_HAS_VM_GET_PAGE_PROT which enables the platforms
>> to define custom vm_get_page_prot(). This starts converting platforms that
>> either change protection_map[] or define the overrides arch_filter_pgprot()
>> or arch_vm_get_page_prot() which enables for those constructs to be dropped
>> off completely. This series then converts remaining platforms which enables
>> for __SXXX/__PXXX constructs to be dropped off completely. Finally it drops
>> the generic vm_get_page_prot() and then ARCH_HAS_VM_GET_PAGE_PROT as every
>> platform now defines their own vm_get_page_prot().
>
> I generally like the idea, I just think the conversion can be more straight
> forward. Rather than adding ARCH_HAS_VM_GET_PAGE_PROT and then dropping it,
> why won't me make the generic vm_get_page_prot() __weak, then add per-arch
> implementation and in the end drop the generic one?
>
Is not the ARCH_HAS_ config based switch over a relatively better method ?
IIUC some existing platform overrides could have been implemented via __weak
identifier, although ARCH_HAS_ method was preferred. But I might be missing
something here.
prev parent reply other threads:[~2022-01-31 3:35 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-24 12:56 [RFC V1 00/31] mm/mmap: Drop protection_map[] and platform's __SXXX/__PXXX requirements Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 01/31] mm/debug_vm_pgtable: Directly use vm_get_page_prot() Anshuman Khandual
2022-01-26 7:15 ` Christoph Hellwig
2022-01-27 4:16 ` Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 02/31] mm/mmap: Clarify protection_map[] indices Anshuman Khandual
2022-01-26 7:16 ` Christoph Hellwig
2022-01-27 4:07 ` Anshuman Khandual
2022-01-27 12:39 ` Mike Rapoport
2022-01-31 3:25 ` Anshuman Khandual
2022-02-05 9:10 ` Firo Yang
2022-02-09 3:23 ` Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 03/31] mm/mmap: Add new config ARCH_HAS_VM_GET_PAGE_PROT Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 04/31] powerpc/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT Anshuman Khandual
2022-02-03 18:15 ` Mike Rapoport
2022-02-04 2:57 ` Anshuman Khandual
2022-02-04 4:44 ` Mike Rapoport
2022-01-24 12:56 ` [RFC V1 05/31] arm64/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 06/31] sparc/mm: " Anshuman Khandual
2022-01-24 12:58 ` David Miller
2022-01-24 18:21 ` Khalid Aziz
2022-01-24 12:56 ` [RFC V1 07/31] mips/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 08/31] m68k/mm: " Anshuman Khandual
2022-01-24 14:13 ` Andreas Schwab
2022-01-25 3:42 ` Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 09/31] arm/mm: " Anshuman Khandual
2022-01-24 17:06 ` Russell King (Oracle)
2022-01-25 3:36 ` Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 10/31] x86/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 11/31] mm/mmap: Drop protection_map[] Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 12/31] mm/mmap: Drop arch_filter_pgprot() Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 13/31] mm/mmap: Drop arch_vm_get_page_pgprot() Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 14/31] s390/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 15/31] riscv/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 16/31] alpha/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 17/31] sh/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 18/31] arc/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 19/31] csky/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 20/31] extensa/mm: " Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 21/31] parisc/mm: " Anshuman Khandual
2022-01-25 16:53 ` Rolf Eike Beer
2022-01-27 4:06 ` Anshuman Khandual
2022-01-24 12:56 ` [RFC V1 22/31] openrisc/mm: " Anshuman Khandual
2022-02-05 6:58 ` [OpenRISC] " Stafford Horne
2022-01-24 12:57 ` [RFC V1 23/31] um/mm: " Anshuman Khandual
2022-01-24 12:57 ` [RFC V1 24/31] microblaze/mm: " Anshuman Khandual
2022-01-24 12:57 ` [RFC V1 25/31] nios2/mm: " Anshuman Khandual
2022-01-26 16:38 ` Dinh Nguyen
2022-01-24 12:57 ` [RFC V1 26/31] hexagon/mm: " Anshuman Khandual
2022-01-24 12:57 ` [RFC V1 27/31] nds32/mm: " Anshuman Khandual
2022-01-24 12:57 ` [RFC V1 28/31] ia64/mm: " Anshuman Khandual
2022-01-24 12:57 ` [RFC V1 29/31] mm/mmap: Drop generic vm_get_page_prot() Anshuman Khandual
2022-01-24 12:57 ` [RFC V1 30/31] mm/mmap: Drop ARCH_HAS_VM_GET_PAGE_PROT Anshuman Khandual
2022-01-24 12:57 ` [RFC V1 31/31] mm/mmap: Define macros for vm_flags access permission combinations Anshuman Khandual
2022-02-03 5:24 ` Anshuman Khandual
2022-01-27 12:38 ` [RFC V1 00/31] mm/mmap: Drop protection_map[] and platform's __SXXX/__PXXX requirements Mike Rapoport
2022-01-31 3:35 ` Anshuman Khandual [this message]
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