Re: [PATCH -next v5 4/5] arm64: mm: add support for page table check

[Tong Tiangen <tongtiangen@xxxxxxxxxx>]

在 2022/4/22 14:45, Anshuman Khandual 写道:
> Please change the subject line as
>
> arm64/mm: Enable ARCH_SUPPORTS_PAGE_TABLE_CHECK
>
> OR
>
> arm64/mm: Subscribe ARCH_SUPPORTS_PAGE_TABLE_CHECK
>
> On 4/21/22 13:50, Tong Tiangen wrote:
> > From: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> >
> > As commit d283d422c6c4 ("x86: mm: add x86_64 support for page table
> > check"), add some necessary page table check hooks into routines that
> > modify user page tables.
>
> Please make the commit message comprehensive, which should include
>
> - Enabling ARCH_SUPPORTS_PAGE_TABLE_CHECK on arm64
> - Adding all additional page table helpers required for PAGE_TABLE_CHECK
> - Instrumenting existing page table helpers with page table check hooks

Good suggestion, if i need to do a new version for some other reason i 
think it should be described more comprehensively.

Thanks,
Tong.

> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > Signed-off-by: Tong Tiangen <tongtiangen@xxxxxxxxxx>
> > Reviewed-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> > ---
> >   arch/arm64/Kconfig               |  1 +
> >   arch/arm64/include/asm/pgtable.h | 65 +++++++++++++++++++++++++++++---
> >   2 files changed, 61 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 18a18a0e855d..c1509525ab8e 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -92,6 +92,7 @@ config ARM64
> >   	select ARCH_SUPPORTS_ATOMIC_RMW
> >   	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
> >   	select ARCH_SUPPORTS_NUMA_BALANCING
> > +	select ARCH_SUPPORTS_PAGE_TABLE_CHECK
> >   	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
> >   	select ARCH_WANT_DEFAULT_BPF_JIT
> >   	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> > index 930077f7b572..9f8f97a7cc7c 100644
> > --- a/arch/arm64/include/asm/pgtable.h
> > +++ b/arch/arm64/include/asm/pgtable.h
> > @@ -33,6 +33,7 @@
> >   #include <linux/mmdebug.h>
> >   #include <linux/mm_types.h>
> >   #include <linux/sched.h>
> > +#include <linux/page_table_check.h>
> >   
> >   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> >   #define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE
> > @@ -96,6 +97,7 @@ static inline pteval_t __phys_to_pte_val(phys_addr_t phys)
> >   #define pte_young(pte)		(!!(pte_val(pte) & PTE_AF))
> >   #define pte_special(pte)	(!!(pte_val(pte) & PTE_SPECIAL))
> >   #define pte_write(pte)		(!!(pte_val(pte) & PTE_WRITE))
> > +#define pte_user(pte)		(!!(pte_val(pte) & PTE_USER))
> >   #define pte_user_exec(pte)	(!(pte_val(pte) & PTE_UXN))
> >   #define pte_cont(pte)		(!!(pte_val(pte) & PTE_CONT))
> >   #define pte_devmap(pte)		(!!(pte_val(pte) & PTE_DEVMAP))
> > @@ -312,7 +314,7 @@ static inline void __check_racy_pte_update(struct mm_struct *mm, pte_t *ptep,
> >   		     __func__, pte_val(old_pte), pte_val(pte));
> >   }
> >   
> > -static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
> > +static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
> >   			      pte_t *ptep, pte_t pte)
> >   {
> >   	if (pte_present(pte) && pte_user_exec(pte) && !pte_special(pte))
> > @@ -343,6 +345,13 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
> >   	set_pte(ptep, pte);
> >   }
> >   
> > +static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
> > +			      pte_t *ptep, pte_t pte)
> > +{
> > +	page_table_check_pte_set(mm, addr, ptep, pte);
> > +	return __set_pte_at(mm, addr, ptep, pte);
> > +}
> > +
> >   /*
> >    * Huge pte definitions.
> >    */
> > @@ -454,6 +463,8 @@ static inline int pmd_trans_huge(pmd_t pmd)
> >   #define pmd_dirty(pmd)		pte_dirty(pmd_pte(pmd))
> >   #define pmd_young(pmd)		pte_young(pmd_pte(pmd))
> >   #define pmd_valid(pmd)		pte_valid(pmd_pte(pmd))
> > +#define pmd_user(pmd)		pte_user(pmd_pte(pmd))
> > +#define pmd_user_exec(pmd)	pte_user_exec(pmd_pte(pmd))
> >   #define pmd_cont(pmd)		pte_cont(pmd_pte(pmd))
> >   #define pmd_wrprotect(pmd)	pte_pmd(pte_wrprotect(pmd_pte(pmd)))
> >   #define pmd_mkold(pmd)		pte_pmd(pte_mkold(pmd_pte(pmd)))
> > @@ -501,8 +512,19 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd)
> >   #define pud_pfn(pud)		((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT)
> >   #define pfn_pud(pfn,prot)	__pud(__phys_to_pud_val((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
> >   
> > -#define set_pmd_at(mm, addr, pmdp, pmd)	set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd))
> > -#define set_pud_at(mm, addr, pudp, pud)	set_pte_at(mm, addr, (pte_t *)pudp, pud_pte(pud))
> > +static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
> > +			      pmd_t *pmdp, pmd_t pmd)
> > +{
> > +	page_table_check_pmd_set(mm, addr, pmdp, pmd);
> > +	return __set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd));
> > +}
> > +
> > +static inline void set_pud_at(struct mm_struct *mm, unsigned long addr,
> > +			      pud_t *pudp, pud_t pud)
> > +{
> > +	page_table_check_pud_set(mm, addr, pudp, pud);
> > +	return __set_pte_at(mm, addr, (pte_t *)pudp, pud_pte(pud));
> > +}
> >   
> >   #define __p4d_to_phys(p4d)	__pte_to_phys(p4d_pte(p4d))
> >   #define __phys_to_p4d_val(phys)	__phys_to_pte_val(phys)
> > @@ -643,6 +665,24 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
> >   #define pud_present(pud)	pte_present(pud_pte(pud))
> >   #define pud_leaf(pud)		pud_sect(pud)
> >   #define pud_valid(pud)		pte_valid(pud_pte(pud))
> > +#define pud_user(pud)		pte_user(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) || pte_user_exec(pte));
> > +}
> > +
> > +static inline bool pmd_user_accessible_page(pmd_t pmd)
> > +{
> > +	return pmd_present(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
> > +}
> > +
> > +static inline bool pud_user_accessible_page(pud_t pud)
> > +{
> > +	return pud_present(pud) && pud_user(pud);
> > +}
> > +#endif
> >   
> >   static inline void set_pud(pud_t *pudp, pud_t pud)
> >   {
> > @@ -872,11 +912,21 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
> >   }
> >   #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> >   
> > +static inline pte_t __ptep_get_and_clear(struct mm_struct *mm,
> > +				       unsigned long address, pte_t *ptep)
> > +{
> > +	return __pte(xchg_relaxed(&pte_val(*ptep), 0));
> > +}
> > +
> >   #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
> >   static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
> >   				       unsigned long address, pte_t *ptep)
> >   {
> > -	return __pte(xchg_relaxed(&pte_val(*ptep), 0));
> > +	pte_t pte = __ptep_get_and_clear(mm, address, ptep);
>
> __ptep_get_and_clear() is not required. Please keep the __pte(xchg_relaxed(..),..)
> unchanged as in the case with pmdp_huge_get_and_clear() helper below.
>
>   +
> > +	page_table_check_pte_clear(mm, address, pte);
> > +
> > +	return pte;
> >   }
> >   
> >   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> > @@ -884,7 +934,11 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
> >   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 = pte_pmd(__ptep_get_and_clear(mm, address, (pte_t *)pmdp));
> > +
> > +	page_table_check_pmd_clear(mm, address, pmd);
> > +
> > +	return pmd;
> >   }
> >   #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> >   
> > @@ -918,6 +972,7 @@ 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(xchg_relaxed(&pmd_val(*pmdp), pmd_val(pmd)));
> >   }
> >   #endif
> .