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Peter Anvin" Subject: [PATCH 2/2] x86/mm/pti: warn and stop when pti_clone_pagetable() is on 1G page Date: Mon, 30 Nov 2020 23:25:16 +0800 Message-Id: <20201130152516.2387-2-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20201130152516.2387-1-jiangshanlai@gmail.com> References: <20201130152516.2387-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan All callers don't call pti_clone_pagetable() on range that includes pud large page(1G). If it were called in such case, there would be bugs in the caller size, so it worth a warning for robustness. Also add check for pgd_large() & p4d_large() with the same reason, and pgd_large() & p4d_large() are constant 0 which just acts as self-comment in code without overhead. Signed-off-by: Lai Jiangshan --- arch/x86/mm/pti.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index a229320515da..89366fec956b 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -321,10 +321,10 @@ pti_clone_pgtable(unsigned long start, unsigned long end, break; pgd = pgd_offset_k(addr); - if (WARN_ON(pgd_none(*pgd))) + if (WARN_ON(pgd_none(*pgd) || pgd_large(*pgd))) return; p4d = p4d_offset(pgd, addr); - if (WARN_ON(p4d_none(*p4d))) + if (WARN_ON(p4d_none(*p4d) || p4d_large(*p4d))) return; pud = pud_offset(p4d, addr); @@ -333,6 +333,8 @@ pti_clone_pgtable(unsigned long start, unsigned long end, addr = round_up(addr + 1, PUD_SIZE); continue; } + if (WARN_ON(pud_large(*pud))) + return; pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) { -- 2.19.1.6.gb485710b