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AFNElJ9ExR/voAeJOnEBa5yhwWeWUOFF/wULhb4+vMKpD71jJqFSxwHwrbKCNmhOLOog9QOSuIGIGbu2wQ==@kvack.org X-Gm-Message-State: AOJu0YxM9FQ4xtmRe/NQVsNGBafmz5P//OHnx9dLd++lx3EbaE/1WRFv ixz9PgDGkJHpP4DDZnDWY+rqaX9um6aFhdIeCIBum2LsL2qc5FsYOcQTe60IrkOOm3sOrR+TTQ= = X-Received: from edpg3.prod.google.com ([2002:aa7:d1c3:0:b0:68b:f715:5345]) (user=ardb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:a29b:10b0:683:be46:c20c with SMTP id 4fb4d7f45d1cf-68c8a65763dmr15813a12.16.1780066952419; Fri, 29 May 2026 08:02:32 -0700 (PDT) Date: Fri, 29 May 2026 17:02:03 +0200 In-Reply-To: <20260529150150.1670604-17-ardb+git@google.com> Mime-Version: 1.0 References: <20260529150150.1670604-17-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=1322; i=ardb@kernel.org; h=from:subject; bh=4saoJOhT3cEc7dpWXJZksxFCf7gWJDz5CDZcsy0RHE0=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIUtyVe4Vpn2a3EuL7z5c9yPshq/FTf8NSmKzXz68s33ZB ld1mYh7HaUsDGJcDLJiiiwCs/++23l6olSt8yxZmDmsTCBDGLg4BWAibDIM/2u5Yv7kFfP5v2Ww OfqOx3NBpOKey7t5vhR6LI5Y9SY78z3D/5SO1Jh354yPPvIQfsjEWFAfIL3vxawn2VI8ya8XJ21 dxwwA X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260529150150.1670604-29-ardb+git@google.com> Subject: [PATCH v7 12/15] sh: Drop cache flush of the zero page at boot From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, Ard Biesheuvel , Ryan Roberts , Anshuman Khandual , Kevin Brodsky , Liz Prucka , Seth Jenkins , Kees Cook , Mike Rapoport , David Hildenbrand , Andrew Morton , Jann Horn , linux-mm@kvack.org, linux-hardening@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , Geert Uytterhoeven Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: 77j558i45bfhuzse94yqd585fj5xb7to X-Rspamd-Queue-Id: 2FB64160019 X-Rspamd-Server: rspam07 X-Rspam-User: X-HE-Tag: 1780066953-34939 X-HE-Meta: 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 WJ1GbQb+ 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ard Biesheuvel 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 Cc: Rich Felker Cc: John Paul Adrian Glaubitz Cc: Mike Rapoport Cc: Geert Uytterhoeven Signed-off-by: Ard Biesheuvel --- arch/sh/mm/init.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c index 4e40d5e96be9..110308bdef01 100644 --- a/arch/sh/mm/init.c +++ b/arch/sh/mm/init.c @@ -331,9 +331,6 @@ void __init mem_init(void) /* Set this up early, so we can take care of the zero page */ cpu_cache_init(); - /* clear the zero-page */ - __flush_wback_region(empty_zero_page, PAGE_SIZE); - vsyscall_init(); pr_info("virtual kernel memory layout:\n" -- 2.54.0.823.g6e5bcc1fc9-goog