| Message ID | 20190701064026.970-2-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fix vmalloc_to_page for huge vmap mappings | expand |
On Mon, Jul 01, 2019 at 04:40:24PM +1000, Nicholas Piggin wrote: > walk_page_range() is going to be allowed to walk page tables other than > those of user space. For this it needs to know when it has reached a > 'leaf' entry in the page tables. This information will be provided by the > p?d_large() functions/macros. > > For arm64, we already have p?d_sect() macros which we can reuse for > p?d_large(). > > pud_sect() is defined as a dummy function when CONFIG_PGTABLE_LEVELS < 3 > or CONFIG_ARM64_64K_PAGES is defined. However when the kernel is > configured this way then architecturally it isn't allowed to have a > large page that this level, and any code using these page walking macros > is implicitly relying on the page size/number of levels being the same as > the kernel. So it is safe to reuse this for p?d_large() as it is an > architectural restriction. > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Signed-off-by: Steven Price <steven.price@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
On 01/07/2019 07:40, Nicholas Piggin wrote: > walk_page_range() is going to be allowed to walk page tables other than > those of user space. For this it needs to know when it has reached a > 'leaf' entry in the page tables. This information will be provided by the > p?d_large() functions/macros. > > For arm64, we already have p?d_sect() macros which we can reuse for > p?d_large(). > > pud_sect() is defined as a dummy function when CONFIG_PGTABLE_LEVELS < 3 > or CONFIG_ARM64_64K_PAGES is defined. However when the kernel is > configured this way then architecturally it isn't allowed to have a > large page that this level, and any code using these page walking macros > is implicitly relying on the page size/number of levels being the same as > the kernel. So it is safe to reuse this for p?d_large() as it is an > architectural restriction. > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Signed-off-by: Steven Price <steven.price@arm.com> Hi Nicolas, This appears to my patch which I originally posted as part of converting x86/arm64 to use a generic page walk code[1]. I'm not sure that this patch makes much sense on its own, in particular it was working up to having a generic macro[2] which means the _large() macros could be used across all architectures. Also as a matter of courtesy please can you ensure the authorship information is preserved when posting other people's patches (there should be a From: line with my name on). You should also include your own Signed-off-by: line (see submitting-patches[3]) after mine. Apologies to anyone that has been following my patch series, I've been on holiday so not actively working on it. My aim is to combine the series with a generic ptdump implementation[4] which should improve the diff state. I should be able to post that in the next few weeks. Thanks, Steve [1] Series: https://patchwork.kernel.org/cover/10883885/ Last posting of this patch: https://patchwork.kernel.org/patch/10883899/ [2] https://patchwork.kernel.org/patch/10883965/ [3] https://www.kernel.org/doc/html/latest/process/submitting-patches.html#developer-s-certificate-of-origin-1-1 [4] RFC version here: https://lore.kernel.org/lkml/20190417143423.26665-1-steven.price@arm.com/ > --- > arch/arm64/include/asm/pgtable.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index fca26759081a..0e973201bc16 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -417,6 +417,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > PMD_TYPE_TABLE) > #define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \ > PMD_TYPE_SECT) > +#define pmd_large(pmd) pmd_sect(pmd) > > #if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS < 3 > #define pud_sect(pud) (0) > @@ -499,6 +500,7 @@ static inline void pte_unmap(pte_t *pte) { } > #define pud_none(pud) (!pud_val(pud)) > #define pud_bad(pud) (!(pud_val(pud) & PUD_TABLE_BIT)) > #define pud_present(pud) pte_present(pud_pte(pud)) > +#define pud_large(pud) pud_sect(pud) > #define pud_valid(pud) pte_valid(pud_pte(pud)) > > static inline void set_pud(pud_t *pudp, pud_t pud) >
Steven Price's on July 1, 2019 7:57 pm: > On 01/07/2019 07:40, Nicholas Piggin wrote: >> walk_page_range() is going to be allowed to walk page tables other than >> those of user space. For this it needs to know when it has reached a >> 'leaf' entry in the page tables. This information will be provided by the >> p?d_large() functions/macros. >> >> For arm64, we already have p?d_sect() macros which we can reuse for >> p?d_large(). >> >> pud_sect() is defined as a dummy function when CONFIG_PGTABLE_LEVELS < 3 >> or CONFIG_ARM64_64K_PAGES is defined. However when the kernel is >> configured this way then architecturally it isn't allowed to have a >> large page that this level, and any code using these page walking macros >> is implicitly relying on the page size/number of levels being the same as >> the kernel. So it is safe to reuse this for p?d_large() as it is an >> architectural restriction. >> >> Cc: Catalin Marinas <catalin.marinas@arm.com> >> Cc: Will Deacon <will.deacon@arm.com> >> Signed-off-by: Steven Price <steven.price@arm.com> > > Hi Nicolas, > > This appears to my patch which I originally posted as part of converting > x86/arm64 to use a generic page walk code[1]. Hey, yeah it is, I'd intended to mark you as the author but must have forgot to change it in git. > I'm not sure that this > patch makes much sense on its own, in particular it was working up to > having a generic macro[2] which means the _large() macros could be used > across all architectures. It goes with this series which makes _large macros usable for archs that define HUGE_VMAP. I posted the same thing earlier and Anshuman noted you'd done it too so I deferred to yours (I thought it would go via arm64 tree and that this would just allow Andrew to easily reconcile the merge). If your series is not going upstream this time then the changelog probably doesn't make so much sense, so I could just send my version to the arm64 tree. Thanks, Nick
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index fca26759081a..0e973201bc16 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -417,6 +417,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, PMD_TYPE_TABLE) #define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \ PMD_TYPE_SECT) +#define pmd_large(pmd) pmd_sect(pmd) #if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS < 3 #define pud_sect(pud) (0) @@ -499,6 +500,7 @@ static inline void pte_unmap(pte_t *pte) { } #define pud_none(pud) (!pud_val(pud)) #define pud_bad(pud) (!(pud_val(pud) & PUD_TABLE_BIT)) #define pud_present(pud) pte_present(pud_pte(pud)) +#define pud_large(pud) pud_sect(pud) #define pud_valid(pud) pte_valid(pud_pte(pud)) static inline void set_pud(pud_t *pudp, pud_t pud)
walk_page_range() is going to be allowed to walk page tables other than those of user space. For this it needs to know when it has reached a 'leaf' entry in the page tables. This information will be provided by the p?d_large() functions/macros. For arm64, we already have p?d_sect() macros which we can reuse for p?d_large(). pud_sect() is defined as a dummy function when CONFIG_PGTABLE_LEVELS < 3 or CONFIG_ARM64_64K_PAGES is defined. However when the kernel is configured this way then architecturally it isn't allowed to have a large page that this level, and any code using these page walking macros is implicitly relying on the page size/number of levels being the same as the kernel. So it is safe to reuse this for p?d_large() as it is an architectural restriction. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Steven Price <steven.price@arm.com> --- arch/arm64/include/asm/pgtable.h | 2 ++ 1 file changed, 2 insertions(+)