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Shutemov" , Ingo Molnar , Steve Wahl Subject: [Patch v3] x86/head/64: remove redundant check on level2_kernel_pgt's _PAGE_PRESENT bit Date: Thu, 23 May 2024 12:35:39 +0000 Message-Id: <20240523123539.14260-1-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.11.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Remove a redundant check on kernel code's PMD _PAGE_PRESENT attribute before fix up. Current process looks like this: pmd in [0, _text) unset _PAGE_PRESENT pmd in [_text, _end] if (_PAGE_PRESENT) fix up delta pmd in (_end, 512) unset _PAGE_PRESENT level2_kernel_pgt compiled with _PAGE_PRESENT set. The check is redundant Signed-off-by: Wei Yang CC: Thomas Gleixner CC: Kirill A. Shutemov CC: Ingo Molnar CC: Steve Wahl Acked-by: Kirill A. Shutemov --- v3: refine the change log per kirill's comment v2: adjust the change log to emphasize the redundant check --- arch/x86/kernel/head64.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index a817ed0724d1..bac33ec19aa2 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -260,8 +260,7 @@ unsigned long __head __startup_64(unsigned long physadd= r, =20 /* fixup pages that are part of the kernel image */ for (; i <=3D pmd_index((unsigned long)_end); i++) - if (pmd[i] & _PAGE_PRESENT) - pmd[i] +=3D load_delta; + pmd[i] +=3D load_delta; =20 /* invalidate pages after the kernel image */ for (; i < PTRS_PER_PMD; i++) --=20 2.34.1