From: Mike Rapoport <rppt@kernel.org>
To: Ard Biesheuvel <ardb+git@google.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, will@kernel.org,
catalin.marinas@arm.com, mark.rutland@arm.com,
Ard Biesheuvel <ardb@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Liz Prucka <lizprucka@google.com>,
Seth Jenkins <sethjenkins@google.com>,
Kees Cook <kees@kernel.org>, David Hildenbrand <david@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jann Horn <jannh@google.com>,
linux-mm@kvack.org, linux-hardening@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: Re: [PATCH v7 12/15] sh: Drop cache flush of the zero page at boot
Date: Sat, 30 May 2026 19:19:36 +0300 [thread overview]
Message-ID: <ahsOGMc7ys3H_oAt@kernel.org> (raw)
In-Reply-To: <20260529150150.1670604-29-ardb+git@google.com>
On Fri, May 29, 2026 at 05:02:03PM +0200, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> SuperH performs cache maintenance on the zero page during boot,
> presumably because before commit
>
> 6215d9f4470f ("arch, mm: consolidate empty_zero_page")
>
> the zero page did double duty as a boot params region, and was cleared
> separately, as it was not part of BSS. The memset() in question was
> dropped by that commit, but the __flush_wback_region() call remained.
>
> As empty_zero_page[] has been moved to BSS, it can be treated as any
> other BSS memory, and so the cache flush can be dropped.
>
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Cc: Rich Felker <dalias@libc.org>
> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---
> arch/sh/mm/init.c | 3 ---
> 1 file changed, 3 deletions(-)
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2026-05-30 16:19 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-29 15:01 [PATCH v7 00/15] arm64: Unmap linear alias of kernel data/bss Ard Biesheuvel
2026-05-29 15:01 ` [PATCH v7 01/15] arm64: mm: Remove bogus stop condition from map_mem() loop Ard Biesheuvel
2026-05-29 15:01 ` [PATCH v7 02/15] arm64: mm: Drop redundant pgd_t* argument from map_mem() Ard Biesheuvel
2026-05-29 15:01 ` [PATCH v7 03/15] arm64: mm: Check for pud_/pmd_set_huge() failures on kernel mappings Ard Biesheuvel
2026-05-29 15:01 ` [PATCH v7 04/15] arm64: mm: Preserve existing table mappings when mapping DRAM Ard Biesheuvel
2026-05-29 15:01 ` [PATCH v7 05/15] arm64: mm: Preserve non-contiguous descriptors " Ard Biesheuvel
2026-05-29 15:01 ` [PATCH v7 06/15] arm64: mm: Permit contiguous descriptors to be manipulated Ard Biesheuvel
2026-05-29 15:01 ` [PATCH v7 07/15] arm64: kfence: Avoid NOMAP tricks when mapping the early pool Ard Biesheuvel
2026-05-29 15:01 ` [PATCH v7 08/15] arm64: mm: Permit contiguous attribute for preliminary mappings Ard Biesheuvel
2026-05-29 15:02 ` [PATCH v7 09/15] arm64: Move fixmap and kasan page tables to end of kernel image Ard Biesheuvel
2026-05-29 15:02 ` [PATCH v7 10/15] arm64: mm: Don't abuse memblock NOMAP to check for overlaps Ard Biesheuvel
2026-05-29 15:02 ` [PATCH v7 11/15] powerpc/code-patching: Avoid r/w mapping of the zero page Ard Biesheuvel
2026-05-29 15:02 ` [PATCH v7 12/15] sh: Drop cache flush of the zero page at boot Ard Biesheuvel
2026-05-30 16:19 ` Mike Rapoport [this message]
2026-05-29 15:02 ` [PATCH v7 13/15] mm: Make empty_zero_page[] const Ard Biesheuvel
2026-05-29 15:02 ` [PATCH v7 14/15] arm64: mm: Map the kernel data/bss read-only in the linear map Ard Biesheuvel
2026-05-29 15:02 ` [PATCH v7 15/15] arm64: mm: Unmap kernel data/bss entirely from " Ard Biesheuvel
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