| Message ID | 20191218162402.45610-2-steven.price@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Generic page walk and ptdump | expand |
Steven Price <steven.price@arm.com> writes: > Exposing the pud/pgd levels of the page tables to walk_page_range() means > we may come across the exotic large mappings that come with large areas > of contiguous memory (such as the kernel's linear map). > > For architectures that don't provide all p?d_leaf() macros, provide > generic do nothing default that are suitable where there cannot be leaf > pages at that level. Futher patches will add implementations for > individual architectures. > > The name p?d_leaf() is chosen to minimize the confusion with existing > uses of "large" pages and "huge" pages which do not necessary mean that > the entry is a leaf (for example it may be a set of contiguous entries > that only take 1 TLB slot). For the purpose of walking the page tables > we don't need to know how it will be represented in the TLB, but we do > need to know for sure if it is a leaf of the tree. > > Signed-off-by: Steven Price <steven.price@arm.com> > Acked-by: Mark Rutland <mark.rutland@arm.com> > --- > include/asm-generic/pgtable.h | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h > index 798ea36a0549..e2e2bef07dd2 100644 > --- a/include/asm-generic/pgtable.h > +++ b/include/asm-generic/pgtable.h > @@ -1238,4 +1238,24 @@ static inline bool arch_has_pfn_modify_check(void) > #define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED) > #endif > > +/* > + * p?d_leaf() - true if this entry is a final mapping to a physical address. > + * This differs from p?d_huge() by the fact that they are always available (if > + * the architecture supports large pages at the appropriate level) even > + * if CONFIG_HUGETLB_PAGE is not defined. > + * Only meaningful when called on a valid entry. > + */ > +#ifndef pgd_leaf > +#define pgd_leaf(x) 0 > +#endif > +#ifndef p4d_leaf > +#define p4d_leaf(x) 0 > +#endif > +#ifndef pud_leaf > +#define pud_leaf(x) 0 > +#endif > +#ifndef pmd_leaf > +#define pmd_leaf(x) 0 > +#endif Any reason you made these #defines rather than static inlines? cheers
On 19/12/2019 11:43, Michael Ellerman wrote: > Steven Price <steven.price@arm.com> writes: >> Exposing the pud/pgd levels of the page tables to walk_page_range() means >> we may come across the exotic large mappings that come with large areas >> of contiguous memory (such as the kernel's linear map). >> >> For architectures that don't provide all p?d_leaf() macros, provide >> generic do nothing default that are suitable where there cannot be leaf >> pages at that level. Futher patches will add implementations for >> individual architectures. >> >> The name p?d_leaf() is chosen to minimize the confusion with existing >> uses of "large" pages and "huge" pages which do not necessary mean that >> the entry is a leaf (for example it may be a set of contiguous entries >> that only take 1 TLB slot). For the purpose of walking the page tables >> we don't need to know how it will be represented in the TLB, but we do >> need to know for sure if it is a leaf of the tree. >> >> Signed-off-by: Steven Price <steven.price@arm.com> >> Acked-by: Mark Rutland <mark.rutland@arm.com> >> --- >> include/asm-generic/pgtable.h | 20 ++++++++++++++++++++ >> 1 file changed, 20 insertions(+) >> >> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h >> index 798ea36a0549..e2e2bef07dd2 100644 >> --- a/include/asm-generic/pgtable.h >> +++ b/include/asm-generic/pgtable.h >> @@ -1238,4 +1238,24 @@ static inline bool arch_has_pfn_modify_check(void) >> #define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED) >> #endif >> >> +/* >> + * p?d_leaf() - true if this entry is a final mapping to a physical address. >> + * This differs from p?d_huge() by the fact that they are always available (if >> + * the architecture supports large pages at the appropriate level) even >> + * if CONFIG_HUGETLB_PAGE is not defined. >> + * Only meaningful when called on a valid entry. >> + */ >> +#ifndef pgd_leaf >> +#define pgd_leaf(x) 0 >> +#endif >> +#ifndef p4d_leaf >> +#define p4d_leaf(x) 0 >> +#endif >> +#ifndef pud_leaf >> +#define pud_leaf(x) 0 >> +#endif >> +#ifndef pmd_leaf >> +#define pmd_leaf(x) 0 >> +#endif > > Any reason you made these #defines rather than static inlines? No strong reason - but these have to be #defines in the arch overrides so the #ifndef works, so I was being consistent here. I guess a static inline might avoid warnings although I haven't seen any. Steve
Steven Price <steven.price@arm.com> writes: > On 19/12/2019 11:43, Michael Ellerman wrote: >> Steven Price <steven.price@arm.com> writes: >>> Exposing the pud/pgd levels of the page tables to walk_page_range() means >>> we may come across the exotic large mappings that come with large areas >>> of contiguous memory (such as the kernel's linear map). >>> >>> For architectures that don't provide all p?d_leaf() macros, provide >>> generic do nothing default that are suitable where there cannot be leaf >>> pages at that level. Futher patches will add implementations for >>> individual architectures. >>> >>> The name p?d_leaf() is chosen to minimize the confusion with existing >>> uses of "large" pages and "huge" pages which do not necessary mean that >>> the entry is a leaf (for example it may be a set of contiguous entries >>> that only take 1 TLB slot). For the purpose of walking the page tables >>> we don't need to know how it will be represented in the TLB, but we do >>> need to know for sure if it is a leaf of the tree. >>> >>> Signed-off-by: Steven Price <steven.price@arm.com> >>> Acked-by: Mark Rutland <mark.rutland@arm.com> >>> --- >>> include/asm-generic/pgtable.h | 20 ++++++++++++++++++++ >>> 1 file changed, 20 insertions(+) >>> >>> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h >>> index 798ea36a0549..e2e2bef07dd2 100644 >>> --- a/include/asm-generic/pgtable.h >>> +++ b/include/asm-generic/pgtable.h >>> @@ -1238,4 +1238,24 @@ static inline bool arch_has_pfn_modify_check(void) >>> #define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED) >>> #endif >>> >>> +/* >>> + * p?d_leaf() - true if this entry is a final mapping to a physical address. >>> + * This differs from p?d_huge() by the fact that they are always available (if >>> + * the architecture supports large pages at the appropriate level) even >>> + * if CONFIG_HUGETLB_PAGE is not defined. >>> + * Only meaningful when called on a valid entry. >>> + */ >>> +#ifndef pgd_leaf >>> +#define pgd_leaf(x) 0 >>> +#endif >>> +#ifndef p4d_leaf >>> +#define p4d_leaf(x) 0 >>> +#endif >>> +#ifndef pud_leaf >>> +#define pud_leaf(x) 0 >>> +#endif >>> +#ifndef pmd_leaf >>> +#define pmd_leaf(x) 0 >>> +#endif >> >> Any reason you made these #defines rather than static inlines? > > No strong reason - but these have to be #defines in the arch overrides > so the #ifndef works, so I was being consistent here. We handle that usually just with eg: static inline bool pgd_leaf(pgd_t pgd) { ... } #define pgd_leaf pgd_leaf > I guess a static inline might avoid warnings although I haven't seen > any. If anything I'd expect it to cause warnings, for example if someone is doing pgd_leaf(pmd), but that would be good to catch. cheers
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 798ea36a0549..e2e2bef07dd2 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -1238,4 +1238,24 @@ static inline bool arch_has_pfn_modify_check(void) #define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED) #endif +/* + * p?d_leaf() - true if this entry is a final mapping to a physical address. + * This differs from p?d_huge() by the fact that they are always available (if + * the architecture supports large pages at the appropriate level) even + * if CONFIG_HUGETLB_PAGE is not defined. + * Only meaningful when called on a valid entry. + */ +#ifndef pgd_leaf +#define pgd_leaf(x) 0 +#endif +#ifndef p4d_leaf +#define p4d_leaf(x) 0 +#endif +#ifndef pud_leaf +#define pud_leaf(x) 0 +#endif +#ifndef pmd_leaf +#define pmd_leaf(x) 0 +#endif + #endif /* _ASM_GENERIC_PGTABLE_H */