Thread (32 messages) 32 messages, 10 authors, 7d ago

Re: [PATCH v7 12/15] sh: Drop cache flush of the zero page at boot

From: Mike Rapoport <rppt@kernel.org>
Date: 2026-05-30 16:19:58
Also in: linux-arm-kernel, linux-hardening, linux-mm, linux-sh, lkml

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.
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