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Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Cc: Yu-cheng Yu , "Kirill A . Shutemov" Subject: [PATCH v24 11/30] x86/mm: Update pte_modify for _PAGE_COW Date: Thu, 1 Apr 2021 15:10:45 -0700 Message-Id: <20210401221104.31584-12-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210401221104.31584-1-yu-cheng.yu@intel.com> References: <20210401221104.31584-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: DAE97A0000FD X-Stat-Signature: 76nrdw6bkf4f3kugmehzms6i6himb6ki X-Rspamd-Server: rspam02 Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf24; identity=mailfrom; envelope-from=""; helo=mga03.intel.com; client-ip=134.134.136.65 X-HE-DKIM-Result: none/none X-HE-Tag: 1617315084-773406 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The read-only and Dirty PTE has been used to indicate copy-on-write pages= . However, newer x86 processors also regard a read-only and Dirty PTE as a shadow stack page. In order to separate the two, the software-defined _PAGE_COW is created to replace _PAGE_DIRTY for the copy-on-write case, a= nd pte_*() are updated. Pte_modify() changes a PTE to 'newprot', but it doesn't use the pte_*(). Introduce fixup_dirty_pte(), which sets a dirty PTE, based on _PAGE_RW, to either _PAGE_DIRTY or _PAGE_COW. Apply the same changes to pmd_modify(). Signed-off-by: Yu-cheng Yu Reviewed-by: Kirill A. Shutemov --- arch/x86/include/asm/pgtable.h | 37 ++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtabl= e.h index 9c056d5815de..e1739f590ca6 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -799,6 +799,23 @@ static inline pmd_t pmd_mkinvalid(pmd_t pmd) =20 static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask); =20 +static inline pteval_t fixup_dirty_pte(pteval_t pteval) +{ + pte_t pte =3D __pte(pteval); + + /* + * Fix up potential shadow stack page flags because the RO, Dirty + * PTE is special. + */ + if (cpu_feature_enabled(X86_FEATURE_SHSTK)) { + if (pte_dirty(pte)) { + pte =3D pte_mkclean(pte); + pte =3D pte_mkdirty(pte); + } + } + return pte_val(pte); +} + static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { pteval_t val =3D pte_val(pte), oldval =3D val; @@ -809,16 +826,36 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t = newprot) */ val &=3D _PAGE_CHG_MASK; val |=3D check_pgprot(newprot) & ~_PAGE_CHG_MASK; + val =3D fixup_dirty_pte(val); val =3D flip_protnone_guard(oldval, val, PTE_PFN_MASK); return __pte(val); } =20 +static inline int pmd_write(pmd_t pmd); +static inline pmdval_t fixup_dirty_pmd(pmdval_t pmdval) +{ + pmd_t pmd =3D __pmd(pmdval); + + /* + * Fix up potential shadow stack page flags because the RO, Dirty + * PMD is special. + */ + if (cpu_feature_enabled(X86_FEATURE_SHSTK)) { + if (pmd_dirty(pmd)) { + pmd =3D pmd_mkclean(pmd); + pmd =3D pmd_mkdirty(pmd); + } + } + return pmd_val(pmd); +} + static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) { pmdval_t val =3D pmd_val(pmd), oldval =3D val; =20 val &=3D _HPAGE_CHG_MASK; val |=3D check_pgprot(newprot) & ~_HPAGE_CHG_MASK; + val =3D fixup_dirty_pmd(val); val =3D flip_protnone_guard(oldval, val, PHYSICAL_PMD_PAGE_MASK); return __pmd(val); } --=20 2.21.0