From: Anshuman Khandual <anshuman.khandual@arm.com> To: Mark Rutland <mark.rutland@arm.com> Cc: linux-arm-kernel@lists.infradead.org, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64/mm: Remove [PUD|PMD]_TABLE_BIT from [pud|pmd]_bad() Date: Tue, 11 May 2021 09:21:46 +0530 [thread overview] Message-ID: <4a36d7b7-6b27-31cc-d701-ebe3c6e4946e@arm.com> (raw) In-Reply-To: <20210510144337.GA92897@C02TD0UTHF1T.local> On 5/10/21 8:13 PM, Mark Rutland wrote: > On Mon, May 10, 2021 at 04:37:51PM +0530, Anshuman Khandual wrote: >> Semantics wise, [pud|pmd]_bad() have always implied that a given [PUD|PMD] >> entry does not have a pointer to the next level page table. This had been >> made clear in the commit a1c76574f345 ("arm64: mm: use *_sect to check for >> section maps"). Hence explicitly check for a table entry rather than just >> testing a single bit. This basically redefines [pud|pmd]_bad() in terms of >> [pud|pmd]_table() making the semantics clear. >> >> Cc: Catalin Marinas <catalin.marinas@arm.com> >> Cc: Will Deacon <will@kernel.org> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > > I have no strong feelings either way, so: > > Acked-by: Mark Rutland <mark.rutland@arm.com> > > ... that said, I think that the "bad" naming is unclear and misleading, > and it'd be really nice if we could clean that up treewide with > something clearer than "bad". Agreed, the name is misleading. > > It does seem that would roughly fit p??_leaf() if we had But what if the platform does not support huge page aka leaf mapping at the given level ? Also a non table i.e bad entry might not always mean a leaf/section/huge page mapping, it could simply imply that the entry is not just pointing to next level and might be just in an bad intermediate or invalid state. > p??_clear_leaf() and p??_none_or_clear_leaf() helpers. Could you please elaborate how these new helpers might help define pxx_bad() ? > > Thanks, > Mark. > >> --- >> This applies on v5.13-rc1. >> >> arch/arm64/include/asm/pgtable.h | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h >> index 25f5c04b43ce..69f8183bef29 100644 >> --- a/arch/arm64/include/asm/pgtable.h >> +++ b/arch/arm64/include/asm/pgtable.h >> @@ -509,13 +509,12 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, >> >> #define pmd_none(pmd) (!pmd_val(pmd)) >> >> -#define pmd_bad(pmd) (!(pmd_val(pmd) & PMD_TABLE_BIT)) >> - >> #define pmd_table(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \ >> PMD_TYPE_TABLE) >> #define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \ >> PMD_TYPE_SECT) >> #define pmd_leaf(pmd) pmd_sect(pmd) >> +#define pmd_bad(pmd) (!pmd_table(pmd)) >> >> #define pmd_leaf_size(pmd) (pmd_cont(pmd) ? CONT_PMD_SIZE : PMD_SIZE) >> #define pte_leaf_size(pte) (pte_cont(pte) ? CONT_PTE_SIZE : PAGE_SIZE) >> @@ -602,7 +601,7 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) >> pr_err("%s:%d: bad pmd %016llx.\n", __FILE__, __LINE__, pmd_val(e)) >> >> #define pud_none(pud) (!pud_val(pud)) >> -#define pud_bad(pud) (!(pud_val(pud) & PUD_TABLE_BIT)) >> +#define pud_bad(pud) (!pud_table(pud)) >> #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)) >> -- >> 2.20.1 >>
WARNING: multiple messages have this Message-ID (diff)
From: Anshuman Khandual <anshuman.khandual@arm.com> To: Mark Rutland <mark.rutland@arm.com> Cc: linux-arm-kernel@lists.infradead.org, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64/mm: Remove [PUD|PMD]_TABLE_BIT from [pud|pmd]_bad() Date: Tue, 11 May 2021 09:21:46 +0530 [thread overview] Message-ID: <4a36d7b7-6b27-31cc-d701-ebe3c6e4946e@arm.com> (raw) In-Reply-To: <20210510144337.GA92897@C02TD0UTHF1T.local> On 5/10/21 8:13 PM, Mark Rutland wrote: > On Mon, May 10, 2021 at 04:37:51PM +0530, Anshuman Khandual wrote: >> Semantics wise, [pud|pmd]_bad() have always implied that a given [PUD|PMD] >> entry does not have a pointer to the next level page table. This had been >> made clear in the commit a1c76574f345 ("arm64: mm: use *_sect to check for >> section maps"). Hence explicitly check for a table entry rather than just >> testing a single bit. This basically redefines [pud|pmd]_bad() in terms of >> [pud|pmd]_table() making the semantics clear. >> >> Cc: Catalin Marinas <catalin.marinas@arm.com> >> Cc: Will Deacon <will@kernel.org> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > > I have no strong feelings either way, so: > > Acked-by: Mark Rutland <mark.rutland@arm.com> > > ... that said, I think that the "bad" naming is unclear and misleading, > and it'd be really nice if we could clean that up treewide with > something clearer than "bad". Agreed, the name is misleading. > > It does seem that would roughly fit p??_leaf() if we had But what if the platform does not support huge page aka leaf mapping at the given level ? Also a non table i.e bad entry might not always mean a leaf/section/huge page mapping, it could simply imply that the entry is not just pointing to next level and might be just in an bad intermediate or invalid state. > p??_clear_leaf() and p??_none_or_clear_leaf() helpers. Could you please elaborate how these new helpers might help define pxx_bad() ? > > Thanks, > Mark. > >> --- >> This applies on v5.13-rc1. >> >> arch/arm64/include/asm/pgtable.h | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h >> index 25f5c04b43ce..69f8183bef29 100644 >> --- a/arch/arm64/include/asm/pgtable.h >> +++ b/arch/arm64/include/asm/pgtable.h >> @@ -509,13 +509,12 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, >> >> #define pmd_none(pmd) (!pmd_val(pmd)) >> >> -#define pmd_bad(pmd) (!(pmd_val(pmd) & PMD_TABLE_BIT)) >> - >> #define pmd_table(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \ >> PMD_TYPE_TABLE) >> #define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \ >> PMD_TYPE_SECT) >> #define pmd_leaf(pmd) pmd_sect(pmd) >> +#define pmd_bad(pmd) (!pmd_table(pmd)) >> >> #define pmd_leaf_size(pmd) (pmd_cont(pmd) ? CONT_PMD_SIZE : PMD_SIZE) >> #define pte_leaf_size(pte) (pte_cont(pte) ? CONT_PTE_SIZE : PAGE_SIZE) >> @@ -602,7 +601,7 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) >> pr_err("%s:%d: bad pmd %016llx.\n", __FILE__, __LINE__, pmd_val(e)) >> >> #define pud_none(pud) (!pud_val(pud)) >> -#define pud_bad(pud) (!(pud_val(pud) & PUD_TABLE_BIT)) >> +#define pud_bad(pud) (!pud_table(pud)) >> #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)) >> -- >> 2.20.1 >> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-05-11 3:51 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-10 11:07 [PATCH] arm64/mm: Remove [PUD|PMD]_TABLE_BIT from [pud|pmd]_bad() Anshuman Khandual 2021-05-10 11:07 ` Anshuman Khandual 2021-05-10 14:43 ` Mark Rutland 2021-05-10 14:43 ` Mark Rutland 2021-05-11 3:51 ` Anshuman Khandual [this message] 2021-05-11 3:51 ` Anshuman Khandual 2021-05-11 14:07 ` Mark Rutland 2021-05-11 14:07 ` Mark Rutland 2021-05-13 5:14 ` Anshuman Khandual 2021-05-13 5:14 ` Anshuman Khandual 2021-05-14 10:59 ` Catalin Marinas 2021-05-14 10:59 ` Catalin Marinas 2021-05-25 18:58 ` Will Deacon 2021-05-25 18:58 ` Will Deacon
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