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bh=6j9AGvbK6QZWswMMubEra1MMawrAyneStMphrQrJwmw=; b=O4uH+MLv7Ria1BC4GVqbfWA4aby5n4GH2XEDD5iM4lZ7HO0vP4Q3rJEaUQl8i3CUuiSh+8 6SCz9zFm3WgmTyaPZc1ZXwfHK/2vVZaklhrkdPJzRWJi6uaMFjrZs0psEHPsFX+e5vjN3m /KqBzgzV3KubqqXyj0vPv7Q8Y05f240= Date: Fri, 10 Feb 2023 14:57:03 +0100 From: Borislav Petkov To: "Edgecombe, Rick P" Cc: "bsingharora@gmail.com" , "hpa@zytor.com" , "Syromiatnikov, Eugene" , "peterz@infradead.org" , "rdunlap@infradead.org" , "keescook@chromium.org" , "Yu, Yu-cheng" , "dave.hansen@linux.intel.com" , "kirill.shutemov@linux.intel.com" , "Eranian, Stephane" , "linux-mm@kvack.org" , "fweimer@redhat.com" , "nadav.amit@gmail.com" , "jannh@google.com" , "dethoma@microsoft.com" , "kcc@google.com" , "linux-arch@vger.kernel.org" , "pavel@ucw.cz" , "oleg@redhat.com" , "hjl.tools@gmail.com" , "Yang, Weijiang" , "Lutomirski, Andy" , "linux-doc@vger.kernel.org" , "arnd@arndb.de" , "tglx@linutronix.de" , "Schimpe, Christina" , "mike.kravetz@oracle.com" , "x86@kernel.org" , "akpm@linux-foundation.org" , "jamorris@linux.microsoft.com" , "john.allen@amd.com" , "rppt@kernel.org" , "andrew.cooper3@citrix.com" , "mingo@redhat.com" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" , "gorcunov@gmail.com" Subject: Re: [PATCH v5 11/39] x86/mm: Update pte_modify for _PAGE_COW Message-ID: References: <20230119212317.8324-1-rick.p.edgecombe@intel.com> <20230119212317.8324-12-rick.p.edgecombe@intel.com> <49d20fcd197e85e8475f5170db78780f06396cc0.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <49d20fcd197e85e8475f5170db78780f06396cc0.camel@intel.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9AC33180011 X-Stat-Signature: 3zk3gber9nuc9pk6zmmacd73zbnouk6m X-HE-Tag: 1676037430-25968 X-HE-Meta: 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 xAlVsT42 /MaqeB5pnoLL3cac1MevTpA5szy06yFAXFWGBLwy0qvtgT/WeKqrL+eugq3BZ0MrYq249hJY9oy+is6RlqEFUac+q/YwKe4sKq2M9x81pF1iP7npXfxkkvZ1aziHb3A96FBmPuS9i4bkTkqAnVKF3mwcLLoevLH7V+7Ta9A5S5XJ3JU7l0L3dzmKCaQNCTxS8Q9Inxcn98oUH3UAd/RNbUeaN9VOJJynnIu49IMZcyXcKgwu2qeC7xDJbb7Ui8j7tbceCb1agY+tQfq586RM8fucWptvr1mnts2KrFz6+0fd8ZUelDxyVIvihfecvMHKv50i/UfzssCzwSVjeZ8tsj7g9lXV+x4h7ygqGr2LWYa8M3pw= 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: On Thu, Feb 09, 2023 at 05:09:15PM +0000, Edgecombe, Rick P wrote: > What do you think, can we leave it or give it a new name? Maybe > pte_set_dirty() to be more like the x86-only pte_set_flags() family of > functions? I'd do this (ontop of yours, not built, not tested, etc). It is short and sweet: pte_mkdirty() set both dirty flags pte_modifl() sets only _PAGE_DIRTY No special helpers to lookup what they do, no nothing. Plain and simple. --- diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 7942eff2af50..8ba37380966c 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -392,19 +392,10 @@ static inline pte_t pte_mkexec(pte_t pte) return pte_clear_flags(pte, _PAGE_NX); } -static inline pte_t __pte_mkdirty(pte_t pte, bool soft) -{ - pteval_t dirty = _PAGE_DIRTY; - - if (soft) - dirty |= _PAGE_SOFT_DIRTY; - - return pte_set_flags(pte, dirty); -} - +/* Set _PAGE_SOFT_DIRTY for shadow stack pages. */ static inline pte_t pte_mkdirty(pte_t pte) { - return __pte_mkdirty(pte, true); + return pte_set_flags(pte, _PAGE_DIRTY | _PAGE_SOFT_DIRTY); } static inline pte_t pte_mkyoung(pte_t pte) @@ -749,14 +740,8 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) pte_result = __pte(val); - /* - * Dirty bit is not preserved above so it can be done - * in a special way for the shadow stack case, where it - * may need to set _PAGE_COW. __pte_mkdirty() will do this in - * the case of shadow stack. - */ if (pte_dirty(pte)) - pte_result = __pte_mkdirty(pte_result, false); + pte_result = pte_set_flags(pte_result, _PAGE_DIRTY); return pte_result; } -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette