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Shutemov" Cc: Wei Yang , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar , Steve Wahl Subject: Re: [Patch v2] x86/head/64: remove redundant check on level2_kernel_pgt's _PAGE_PRESENT bit Message-ID: <20240523122604.2owqxj7fmgudewzk@master> Reply-To: Wei Yang References: <20240523083752.11426-1-richard.weiyang@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Thanks for comment. On Thu, May 23, 2024 at 01:33:28PM +0300, Kirill A . Shutemov wrote: >On Thu, May 23, 2024 at 08:37:52AM +0000, Wei Yang wrote: >> This patch tries to remove a redundant check on kernel code's PMD >> _PAGE_PRESENT attribute before fix up. > >Tries? s/This patch tries to r/R/ Will use this one. > >> 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 >> >> Since we have compiled in _PAGE_PRESENT in this page table, it is not >> necessary to check _PAGE_PRESENT again before fixing up delta > >level2_kernel_pgt compiled with _PAGE_PRESENT set. The check is >redundant. > Will use this one, thanks > >-- > Kiryl Shutsemau / Kirill A. Shutemov -- Wei Yang Help you, Help me