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Date: Fri, 22 Apr 2022 11:35:13 +0530 From: Anshuman Khandual <anshuman.khandual@....com> To: Tong Tiangen <tongtiangen@...wei.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, Pasha Tatashin <pasha.tatashin@...een.com>, Andrew Morton <akpm@...ux-foundation.org>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu> Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org, linux-riscv@...ts.infradead.org, Kefeng Wang <wangkefeng.wang@...wei.com>, Guohanjun <guohanjun@...wei.com> Subject: Re: [PATCH -next v5 3/5] mm: page_table_check: add hooks to public helpers On 4/21/22 13:50, Tong Tiangen wrote: > Move ptep_clear() to the include/linux/pgtable.h and add page table check > relate hooks to some helpers, it's prepare for support page table check > feature on new architecture. Could instrumenting generic page table helpers (fallback instances when its corresponding __HAVE_ARCH_XXX is not defined on the platform), might add all the page table check hooks into paths on platforms which have not subscribed ARCH_SUPPORTS_PAGE_TABLE_CHECK in the first place ? Although these looks have !CONFIG_PAGE_TABLE_CHECK fallback stubs in the header, hence a build problem gets avoided. > > Signed-off-by: Tong Tiangen <tongtiangen@...wei.com> > Acked-by: Pasha Tatashin <pasha.tatashin@...een.com> > --- > arch/x86/include/asm/pgtable.h | 10 ---------- > include/linux/pgtable.h | 26 ++++++++++++++++++-------- > 2 files changed, 18 insertions(+), 18 deletions(-) > > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > index 564abe42b0f7..51cd39858f81 100644 > --- a/arch/x86/include/asm/pgtable.h > +++ b/arch/x86/include/asm/pgtable.h > @@ -1073,16 +1073,6 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, > return pte; > } > > -#define __HAVE_ARCH_PTEP_CLEAR AFICS X86 is the only platform subscribing __HAVE_ARCH_PTEP_CLEAR. Hence if this is getting dropped for generic ptep_clear(), then no need to add back #ifnded __HAVE_ARCH_PTEP_CLEAR construct. Generic ptep_clear() is the only definition for all platforms ? Also if this patch is trying to drop off __HAVE_ARCH_PTEP_CLEAR along with other page table check related changes, it needs to be done via a separate patch instead. > -static inline void ptep_clear(struct mm_struct *mm, unsigned long addr, > - pte_t *ptep) > -{ > - if (IS_ENABLED(CONFIG_PAGE_TABLE_CHECK)) > - ptep_get_and_clear(mm, addr, ptep); > - else > - pte_clear(mm, addr, ptep); > -} > - > #define __HAVE_ARCH_PTEP_SET_WRPROTECT > static inline void ptep_set_wrprotect(struct mm_struct *mm, > unsigned long addr, pte_t *ptep) > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h > index 49ab8ee2d6d7..10d2d91edf20 100644 > --- a/include/linux/pgtable.h > +++ b/include/linux/pgtable.h > @@ -12,6 +12,7 @@ > #include <linux/bug.h> > #include <linux/errno.h> > #include <asm-generic/pgtable_uffd.h> > +#include <linux/page_table_check.h> > > #if 5 - defined(__PAGETABLE_P4D_FOLDED) - defined(__PAGETABLE_PUD_FOLDED) - \ > defined(__PAGETABLE_PMD_FOLDED) != CONFIG_PGTABLE_LEVELS > @@ -272,14 +273,6 @@ static inline bool arch_has_hw_pte_young(void) > } > #endif > > -#ifndef __HAVE_ARCH_PTEP_CLEAR > -static inline void ptep_clear(struct mm_struct *mm, unsigned long addr, > - pte_t *ptep) > -{ > - pte_clear(mm, addr, ptep); > -} > -#endif > - > #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR > static inline pte_t ptep_get_and_clear(struct mm_struct *mm, > unsigned long address, > @@ -287,10 +280,22 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, > { > pte_t pte = *ptep; > pte_clear(mm, address, ptep); > + page_table_check_pte_clear(mm, address, pte); > return pte; > } > #endif > > +#ifndef __HAVE_ARCH_PTEP_CLEAR > +static inline void ptep_clear(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep) > +{ > + if (IS_ENABLED(CONFIG_PAGE_TABLE_CHECK)) > + ptep_get_and_clear(mm, addr, ptep); > + else > + pte_clear(mm, addr, ptep); Could not this be reworked to avoid IS_ENABLED() ? This is confusing. If the page table hooks can be added to all potential page table paths via generic helpers, irrespective of CONFIG_PAGE_TABLE_CHECK option, there is no rationale for doing a IS_ENABLED() check here. > +} > +#endif > + > #ifndef __HAVE_ARCH_PTEP_GET > static inline pte_t ptep_get(pte_t *ptep) > { > @@ -360,7 +365,10 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm, > pmd_t *pmdp) > { > pmd_t pmd = *pmdp; > + > pmd_clear(pmdp); > + page_table_check_pmd_clear(mm, address, pmd); > + > return pmd; > } > #endif /* __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR */ > @@ -372,6 +380,8 @@ static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm, > pud_t pud = *pudp; > > pud_clear(pudp); > + page_table_check_pud_clear(mm, address, pud); > + > return pud; > } > #endif /* __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR */
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