From mboxrd@z Thu Jan 1 00:00:00 1970 From: cpandya@codeaurora.org (Chintan Pandya) Date: Mon, 4 Jun 2018 19:13:18 +0530 Subject: [PATCH v12 4/5] arm64: Implement page table free interfaces In-Reply-To: <20180604121328.GG9482@arm.com> References: <1527856758-27169-1-git-send-email-cpandya@codeaurora.org> <1527856758-27169-5-git-send-email-cpandya@codeaurora.org> <20180604121328.GG9482@arm.com> Message-ID: <98ef3cd0-a9a1-d5b5-f1a6-c0ab8b15ec6a@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 >> --- >> 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 >> #include >> #include >> +#include >> >> #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 -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project