Re: [PATCH -next v7 6/6] riscv/mm: Enable ARCH_SUPPORTS_PAGE_TABLE_CHECK

[Tong Tiangen]

在 2022/5/24 12:17, Palmer Dabbelt 写道:
> On Sat, 07 May 2022 04:01:14 PDT (-0700), tongtiangen@xxxxxxxxxx wrote:
> > As commit d283d422c6c4 ("x86: mm: add x86_64 support for page table 
> > check")
> > , enable ARCH_SUPPORTS_PAGE_TABLE_CHECK on riscv.
> >
> > Add additional page table check stubs for page table helpers, these stubs
> > can be used to check the existing page table entries.
> >
> > Signed-off-by: Tong Tiangen <tongtiangen@xxxxxxxxxx>
> > Reviewed-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
>
> This doesn't build on rv32 (or presumably any other 32-bit arch) 
> something like this should do it
>
>     diff --git a/arch/riscv/include/asm/pgtable.h 
> b/arch/riscv/include/asm/pgtable.h
>     index 2b18e4410c4d..ea658ed6a1b1 100644
>     --- a/arch/riscv/include/asm/pgtable.h
>     +++ b/arch/riscv/include/asm/pgtable.h
>     @@ -690,11 +690,13 @@ static inline bool 
> pmd_user_accessible_page(pmd_t pmd)
>          return pmd_leaf(pmd) && pmd_user(pmd);
>      }
>     +#ifdef CONFIG_64BIT
>      static inline bool pud_user_accessible_page(pud_t pud)
>      {
>          return pud_leaf(pud) && pud_user(pud);
>      }
>     -#endif
>     +#endif /* CONFIG_64BIT */
>     +#endif /* CONFIG_PAGE_TABLE_CHECK */
>      #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>      static inline int pmd_trans_huge(pmd_t pmd)
>     diff --git a/mm/page_table_check.c b/mm/page_table_check.c
>     index 3692bea2ea2c..ac9bddfa1398 100644
>     --- a/mm/page_table_check.c
>     +++ b/mm/page_table_check.c
>     @@ -165,6 +165,7 @@ void __page_table_check_pmd_clear(struct 
> mm_struct *mm, unsigned long addr,
>      }
>      EXPORT_SYMBOL(__page_table_check_pmd_clear);
>     +#if CONFIG_PGTABLE_LEVELS > 3
>      void __page_table_check_pud_clear(struct mm_struct *mm, unsigned 
> long addr,
>                        pud_t pud)
>      {
>     @@ -177,6 +178,7 @@ void __page_table_check_pud_clear(struct 
> mm_struct *mm, unsigned long addr,
>          }
>      }
>      EXPORT_SYMBOL(__page_table_check_pud_clear);
>     +#endif
>      void __page_table_check_pte_set(struct mm_struct *mm, unsigned long 
> addr,
>                      pte_t *ptep, pte_t pte)
>     @@ -208,6 +210,7 @@ void __page_table_check_pmd_set(struct mm_struct 
> *mm, unsigned long addr,
>      }
>      EXPORT_SYMBOL(__page_table_check_pmd_set);
>     +#if CONFIG_PGTABLE_LEVELS > 3
>      void __page_table_check_pud_set(struct mm_struct *mm, unsigned long 
> addr,
>                      pud_t *pudp, pud_t pud)
>      {
>     @@ -222,6 +225,7 @@ void __page_table_check_pud_set(struct mm_struct 
> *mm, unsigned long addr,
>          }
>      }
>      EXPORT_SYMBOL(__page_table_check_pud_set);
>     +#endif
>      void __page_table_check_pte_clear_range(struct mm_struct *mm,
>                          unsigned long addr,
>
> with those changes this passes my tests, so
>
> Acked-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
>
> Feel free to take this along with the rest of them if that's easier, the 
> RISC-V bits are pretty light-weight.  Also happy to do some sort of 
> shared tag once the other issues get sorted out.
>
> Thanks!

Hi, palmer, thanks for you reply.

I fixed the issue on riscv32 a few days ago. It seems that it can also 
solve the issue you said.

https://lore.kernel.org/lkml/20220517074548.2227779-2-tongtiangen@xxxxxxxxxx/

Thanks,
Tong.
> > ---
> >  arch/riscv/Kconfig               |  1 +
> >  arch/riscv/include/asm/pgtable.h | 71 +++++++++++++++++++++++++++++---
> >  2 files changed, 66 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 715390feb6ea..bb9fde09eea5 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -38,6 +38,7 @@ config RISCV
> >      select ARCH_SUPPORTS_ATOMIC_RMW
> >      select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
> >      select ARCH_SUPPORTS_HUGETLBFS if MMU
> > +    select ARCH_SUPPORTS_PAGE_TABLE_CHECK
> >      select ARCH_USE_MEMTEST
> >      select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
> >      select ARCH_WANT_FRAME_POINTERS
> > diff --git a/arch/riscv/include/asm/pgtable.h 
> > b/arch/riscv/include/asm/pgtable.h
> > index 046b44225623..62e733c85836 100644
> > --- a/arch/riscv/include/asm/pgtable.h
> > +++ b/arch/riscv/include/asm/pgtable.h
> > @@ -114,6 +114,8 @@
> >  #include <asm/pgtable-32.h>
> >  #endif /* CONFIG_64BIT */
> >
> > +#include <linux/page_table_check.h>
> > +
> >  #ifdef CONFIG_XIP_KERNEL
> >  #define XIP_FIXUP(addr) ({                            \
> >      uintptr_t __a = (uintptr_t)(addr);                    \
> > @@ -315,6 +317,11 @@ static inline int pte_exec(pte_t pte)
> >      return pte_val(pte) & _PAGE_EXEC;
> >  }
> >
> > +static inline int pte_user(pte_t pte)
> > +{
> > +    return pte_val(pte) & _PAGE_USER;
> > +}
> > +
> >  static inline int pte_huge(pte_t pte)
> >  {
> >      return pte_present(pte) && (pte_val(pte) & _PAGE_LEAF);
> > @@ -446,7 +453,7 @@ static inline void set_pte(pte_t *ptep, pte_t pteval)
> >
> >  void flush_icache_pte(pte_t pte);
> >
> > -static inline void set_pte_at(struct mm_struct *mm,
> > +static inline void __set_pte_at(struct mm_struct *mm,
> >      unsigned long addr, pte_t *ptep, pte_t pteval)
> >  {
> >      if (pte_present(pteval) && pte_exec(pteval))
> > @@ -455,10 +462,17 @@ static inline void set_pte_at(struct mm_struct *mm,
> >      set_pte(ptep, pteval);
> >  }
> >
> > +static inline void set_pte_at(struct mm_struct *mm,
> > +    unsigned long addr, pte_t *ptep, pte_t pteval)
> > +{
> > +    page_table_check_pte_set(mm, addr, ptep, pteval);
> > +    __set_pte_at(mm, addr, ptep, pteval);
> > +}
> > +
> >  static inline void pte_clear(struct mm_struct *mm,
> >      unsigned long addr, pte_t *ptep)
> >  {
> > -    set_pte_at(mm, addr, ptep, __pte(0));
> > +    __set_pte_at(mm, addr, ptep, __pte(0));
> >  }
> >
> >  #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
> > @@ -479,7 +493,11 @@ static inline int ptep_set_access_flags(struct 
> > vm_area_struct *vma,
> >  static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
> >                         unsigned long address, pte_t *ptep)
> >  {
> > -    return __pte(atomic_long_xchg((atomic_long_t *)ptep, 0));
> > +    pte_t pte = __pte(atomic_long_xchg((atomic_long_t *)ptep, 0));
> > +
> > +    page_table_check_pte_clear(mm, address, pte);
> > +
> > +    return pte;
> >  }
> >
> >  #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
> > @@ -546,6 +564,13 @@ static inline unsigned long pmd_pfn(pmd_t pmd)
> >      return ((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT);
> >  }
> >
> > +#define __pud_to_phys(pud)  (pud_val(pud) >> _PAGE_PFN_SHIFT << 
> > PAGE_SHIFT)
> > +
> > +static inline unsigned long pud_pfn(pud_t pud)
> > +{
> > +    return ((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT);
> > +}
> > +
> >  static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
> >  {
> >      return pte_pmd(pte_modify(pmd_pte(pmd), newprot));
> > @@ -567,6 +592,11 @@ static inline int pmd_young(pmd_t pmd)
> >      return pte_young(pmd_pte(pmd));
> >  }
> >
> > +static inline int pmd_user(pmd_t pmd)
> > +{
> > +    return pte_user(pmd_pte(pmd));
> > +}
> > +
> >  static inline pmd_t pmd_mkold(pmd_t pmd)
> >  {
> >      return pte_pmd(pte_mkold(pmd_pte(pmd)));
> > @@ -600,15 +630,39 @@ static inline pmd_t pmd_mkdirty(pmd_t pmd)
> >  static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
> >                  pmd_t *pmdp, pmd_t pmd)
> >  {
> > -    return set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd));
> > +    page_table_check_pmd_set(mm, addr, pmdp, pmd);
> > +    return __set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd));
> > +}
> > +
> > +static inline int pud_user(pud_t pud)
> > +{
> > +    return pte_user(pud_pte(pud));
> >  }
> >
> >  static inline void set_pud_at(struct mm_struct *mm, unsigned long addr,
> >                  pud_t *pudp, pud_t pud)
> >  {
> > -    return set_pte_at(mm, addr, (pte_t *)pudp, pud_pte(pud));
> > +    page_table_check_pud_set(mm, addr, pudp, pud);
> > +    return __set_pte_at(mm, addr, (pte_t *)pudp, pud_pte(pud));
> > +}
> > +
> > +#ifdef CONFIG_PAGE_TABLE_CHECK
> > +static inline bool pte_user_accessible_page(pte_t pte)
> > +{
> > +    return pte_present(pte) && pte_user(pte);
> > +}
> > +
> > +static inline bool pmd_user_accessible_page(pmd_t pmd)
> > +{
> > +    return pmd_leaf(pmd) && pmd_user(pmd);
> >  }
> >
> > +static inline bool pud_user_accessible_page(pud_t pud)
> > +{
> > +    return pud_leaf(pud) && pud_user(pud);
> > +}
> > +#endif
> > +
> >  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> >  static inline int pmd_trans_huge(pmd_t pmd)
> >  {
> > @@ -634,7 +688,11 @@ static inline int 
> > pmdp_test_and_clear_young(struct vm_area_struct *vma,
> >  static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
> >                      unsigned long address, pmd_t *pmdp)
> >  {
> > -    return pte_pmd(ptep_get_and_clear(mm, address, (pte_t *)pmdp));
> > +    pmd_t pmd = __pmd(atomic_long_xchg((atomic_long_t *)pmdp, 0));
> > +
> > +    page_table_check_pmd_clear(mm, address, pmd);
> > +
> > +    return pmd;
> >  }
> >
> >  #define __HAVE_ARCH_PMDP_SET_WRPROTECT
> > @@ -648,6 +706,7 @@ static inline void pmdp_set_wrprotect(struct 
> > mm_struct *mm,
> >  static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
> >                  unsigned long address, pmd_t *pmdp, pmd_t pmd)
> >  {
> > +    page_table_check_pmd_set(vma->vm_mm, address, pmdp, pmd);
> >      return __pmd(atomic_long_xchg((atomic_long_t *)pmdp, pmd_val(pmd)));
> >  }
> >  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> .