Messages in this thread | | | Date | Mon, 4 Jun 2018 13:13:28 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v12 4/5] arm64: Implement page table free interfaces |
| |
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
| |