| Message ID | 1527856758-27169-5-git-send-email-cpandya@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jun 01, 2018 at 06:09:17PM +0530, Chintan Pandya wrote: > Implement pud_free_pmd_page() and pmd_free_pte_page(). > > Implementation requires, > 1) Clearing off the current pud/pmd entry > 2) Invalidate TLB which could have previously > valid but not stale entry > 3) Freeing of the un-used next level page tables Please can you rewrite this describing the problem that you're solving, rather than a brief summary of some requirements? > Signed-off-by: Chintan Pandya <cpandya@codeaurora.org> > --- > arch/arm64/mm/mmu.c | 38 ++++++++++++++++++++++++++++++++++---- > 1 file changed, 34 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 8ae5d7a..6e7e16c 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -45,6 +45,7 @@ > #include <asm/memblock.h> > #include <asm/mmu_context.h> > #include <asm/ptdump.h> > +#include <asm/tlbflush.h> > > #define NO_BLOCK_MAPPINGS BIT(0) > #define NO_CONT_MAPPINGS BIT(1) > @@ -977,12 +978,41 @@ int pmd_clear_huge(pmd_t *pmdp) > return 1; > } > > -int pud_free_pmd_page(pud_t *pud, unsigned long addr) > +int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr) > { > - return pud_none(*pud); > + pte_t *table; > + pmd_t pmd; > + > + pmd = READ_ONCE(*pmdp); > + if (pmd_present(pmd)) { > + table = pmd_page_vaddr(pmd); > + pmd_clear(pmdp); > + __flush_tlb_kernel_pgtable(addr); > + pte_free_kernel(NULL, table); > + } > + return 1; > } > > -int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) > +int pud_free_pmd_page(pud_t *pudp, unsigned long addr) > { > - return pmd_none(*pmd); > + pmd_t *table; > + pmd_t *entry; > + pud_t pud; > + unsigned long next, end; > + > + pud = READ_ONCE(*pudp); > + if (pud_present(pud)) { Just some stylistic stuff, but please can you rewrite this as: if (!pud_present(pud) || VM_WARN_ON(!pud_table(pud))) return 1; similarly for the pmd/pte code above. > + table = pud_page_vaddr(pud); > + entry = table; Could you rename entry -> pmdp, please? > + next = addr; > + end = addr + PUD_SIZE; > + do { > + pmd_free_pte_page(entry, next); > + } while (entry++, next += PMD_SIZE, next != end); > + > + pud_clear(pudp); > + __flush_tlb_kernel_pgtable(addr); > + pmd_free(NULL, table); > + } > + return 1; So with these patches, we only ever return 1 from these helpers. It looks like the same is true for x86, so how about we make them void and move the calls inside the conditionals in lib/ioremap.c? Obviously, this would be a separate patch on the end. Will
On 6/4/2018 5:43 PM, Will Deacon wrote: > On Fri, Jun 01, 2018 at 06:09:17PM +0530, Chintan Pandya wrote: >> Implement pud_free_pmd_page() and pmd_free_pte_page(). >> >> Implementation requires, >> 1) Clearing off the current pud/pmd entry >> 2) Invalidate TLB which could have previously >> valid but not stale entry >> 3) Freeing of the un-used next level page tables > > Please can you rewrite this describing the problem that you're solving, > rather than a brief summary of some requirements? Okay. I'll fix this in v13. > >> Signed-off-by: Chintan Pandya <cpandya@codeaurora.org> >> --- >> arch/arm64/mm/mmu.c | 38 ++++++++++++++++++++++++++++++++++---- >> 1 file changed, 34 insertions(+), 4 deletions(-) >> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 8ae5d7a..6e7e16c 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -45,6 +45,7 @@ >> #include <asm/memblock.h> >> #include <asm/mmu_context.h> >> #include <asm/ptdump.h> >> +#include <asm/tlbflush.h> >> >> #define NO_BLOCK_MAPPINGS BIT(0) >> #define NO_CONT_MAPPINGS BIT(1) >> @@ -977,12 +978,41 @@ int pmd_clear_huge(pmd_t *pmdp) >> return 1; >> } >> >> -int pud_free_pmd_page(pud_t *pud, unsigned long addr) >> +int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr) >> { >> - return pud_none(*pud); >> + pte_t *table; >> + pmd_t pmd; >> + >> + pmd = READ_ONCE(*pmdp); >> + if (pmd_present(pmd)) { >> + table = pmd_page_vaddr(pmd); >> + pmd_clear(pmdp); >> + __flush_tlb_kernel_pgtable(addr); >> + pte_free_kernel(NULL, table); >> + } >> + return 1; >> } >> >> -int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) >> +int pud_free_pmd_page(pud_t *pudp, unsigned long addr) >> { >> - return pmd_none(*pmd); >> + pmd_t *table; >> + pmd_t *entry; >> + pud_t pud; >> + unsigned long next, end; >> + >> + pud = READ_ONCE(*pudp); >> + if (pud_present(pud)) { > > Just some stylistic stuff, but please can you rewrite this as: > > if (!pud_present(pud) || VM_WARN_ON(!pud_table(pud))) > return 1; > > similarly for the pmd/pte code above. Okay. v13 will have this. > >> + table = pud_page_vaddr(pud); >> + entry = table; > > Could you rename entry -> pmdp, please? Sure. > >> + next = addr; >> + end = addr + PUD_SIZE; >> + do { >> + pmd_free_pte_page(entry, next); >> + } while (entry++, next += PMD_SIZE, next != end); >> + >> + pud_clear(pudp); >> + __flush_tlb_kernel_pgtable(addr); >> + pmd_free(NULL, table); >> + } >> + return 1; > > So with these patches, we only ever return 1 from these helpers. It looks > like the same is true for x86, so how about we make them void and move the > calls inside the conditionals in lib/ioremap.c? Obviously, this would be a > separate patch on the end. That sounds valid code churn to me. But since x86 discussion is not concluded yet, I would wait to share until that gets resolved. May be not in v13 but separate effort. Would that be okay to you ? > > Will > Chintan
On Mon, Jun 04, 2018 at 07:13:18PM +0530, Chintan Pandya wrote: > On 6/4/2018 5:43 PM, Will Deacon wrote: > >On Fri, Jun 01, 2018 at 06:09:17PM +0530, Chintan Pandya wrote: > >>+ next = addr; > >>+ end = addr + PUD_SIZE; > >>+ do { > >>+ pmd_free_pte_page(entry, next); > >>+ } while (entry++, next += PMD_SIZE, next != end); > >>+ > >>+ pud_clear(pudp); > >>+ __flush_tlb_kernel_pgtable(addr); > >>+ pmd_free(NULL, table); > >>+ } > >>+ return 1; > > > >So with these patches, we only ever return 1 from these helpers. It looks > >like the same is true for x86, so how about we make them void and move the > >calls inside the conditionals in lib/ioremap.c? Obviously, this would be a > >separate patch on the end. > > That sounds valid code churn to me. But since x86 discussion is not > concluded yet, I would wait to share until that gets resolved. May be > not in v13 but separate effort. Would that be okay to you ? Yes, fine by me. Will
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 8ae5d7a..6e7e16c 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -45,6 +45,7 @@ #include <asm/memblock.h> #include <asm/mmu_context.h> #include <asm/ptdump.h> +#include <asm/tlbflush.h> #define NO_BLOCK_MAPPINGS BIT(0) #define NO_CONT_MAPPINGS BIT(1) @@ -977,12 +978,41 @@ int pmd_clear_huge(pmd_t *pmdp) return 1; } -int pud_free_pmd_page(pud_t *pud, unsigned long addr) +int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr) { - return pud_none(*pud); + pte_t *table; + pmd_t pmd; + + pmd = READ_ONCE(*pmdp); + if (pmd_present(pmd)) { + table = pmd_page_vaddr(pmd); + pmd_clear(pmdp); + __flush_tlb_kernel_pgtable(addr); + pte_free_kernel(NULL, table); + } + return 1; } -int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) +int pud_free_pmd_page(pud_t *pudp, unsigned long addr) { - return pmd_none(*pmd); + pmd_t *table; + pmd_t *entry; + pud_t pud; + unsigned long next, end; + + pud = READ_ONCE(*pudp); + if (pud_present(pud)) { + table = pud_page_vaddr(pud); + entry = table; + next = addr; + end = addr + PUD_SIZE; + do { + pmd_free_pte_page(entry, next); + } while (entry++, next += PMD_SIZE, next != end); + + pud_clear(pudp); + __flush_tlb_kernel_pgtable(addr); + pmd_free(NULL, table); + } + return 1; }
Implement pud_free_pmd_page() and pmd_free_pte_page(). Implementation requires, 1) Clearing off the current pud/pmd entry 2) Invalidate TLB which could have previously valid but not stale entry 3) Freeing of the un-used next level page tables Signed-off-by: Chintan Pandya <cpandya@codeaurora.org> --- arch/arm64/mm/mmu.c | 38 ++++++++++++++++++++++++++++++++++---- 1 file changed, 34 insertions(+), 4 deletions(-)