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Date:   Mon, 23 May 2022 21:17:03 -0700 (PDT)
Subject:     Re: [PATCH -next v7 6/6] riscv/mm: Enable ARCH_SUPPORTS_PAGE_TABLE_CHECK
In-Reply-To: <20220507110114.4128854-7-tongtiangen@huawei.com>
CC:     tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
        pasha.tatashin@soleen.com, anshuman.khandual@arm.com,
        akpm@linux-foundation.org, catalin.marinas@arm.com,
        Will Deacon <will@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        aou@eecs.berkeley.edu, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
        linux-riscv@lists.infradead.org, tongtiangen@huawei.com,
        wangkefeng.wang@huawei.com, guohanjun@huawei.com
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     tongtiangen@huawei.com
Message-ID: <mhng-7c6392da-5321-4fc6-b0af-c6b41b300a6a@palmer-mbp2014>
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On Sat, 07 May 2022 04:01:14 PDT (-0700), tongtiangen@huawei.com 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@huawei.com>
> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>

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@rivosinc.com>

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!

> ---
>  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 */