From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v9 3/4] arm64: Implement page table free interfaces
Date: Wed, 23 May 2018 15:01:58 +0100 [thread overview]
Message-ID: <20180523140157.GG26965@arm.com> (raw)
In-Reply-To: <1525074094-25839-4-git-send-email-cpandya@codeaurora.org>
Hi Chintan,
[as a side note: I'm confused on the status of this patch series, as part
of it was reposted separately by Toshi. Please can you work together?]
On Mon, Apr 30, 2018 at 01:11:33PM +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
>
> Signed-off-by: Chintan Pandya <cpandya@codeaurora•org>
> ---
> arch/arm64/mm/mmu.c | 29 +++++++++++++++++++++++++----
> 1 file changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index da98828..0f651db 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)
> @@ -973,12 +974,32 @@ 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);
> + pmd_t *table;
> +
> + if (pmd_present(READ_ONCE(*pmdp))) {
Might also be worth checking pmd_table here, just in case. (same for pud)
> + table = __va(pmd_val(*pmdp));
Can you avoid dereferencing *pmdp twice, and instead READ_ONCE into a local
variable, please? (same for pud)
> + pmd_clear(pmdp);
> + __flush_tlb_kernel_pgtable(addr);
> + free_page((unsigned long) table);
Shouldn't this be pte_free_kernel, to pair with pte_alloc_kernel which
was used to allocate the page in the first place? (similarly for pud)
> + }
> + 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;
> + int i;
> +
> + if (pud_present(READ_ONCE(*pudp))) {
> + table = __va(pud_val(*pudp));
> + for (i = 0; i < PTRS_PER_PMD; i++)
> + pmd_free_pte_page(&table[i], addr + (i * PMD_SIZE));
I think it would be cleaner to write this as a do { ... } while, for
consistency with the ioremap and vmalloc code.
Will
next prev parent reply other threads:[~2018-05-23 14:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-30 7:41 [PATCH v9 0/4] Fix issues with huge mapping in ioremap for ARM64 Chintan Pandya
2018-04-30 7:41 ` [PATCH v9 1/4] ioremap: Update pgtable free interfaces with addr Chintan Pandya
2018-04-30 7:41 ` [PATCH v9 2/4] arm64: tlbflush: Introduce __flush_tlb_kernel_pgtable Chintan Pandya
2018-04-30 7:41 ` [PATCH v9 3/4] arm64: Implement page table free interfaces Chintan Pandya
2018-05-23 14:01 ` Will Deacon [this message]
2018-05-23 14:34 ` Kani, Toshi
2018-05-24 7:03 ` Chintan Pandya
2018-05-24 7:34 ` Chintan Pandya
2018-04-30 7:41 ` [PATCH v9 4/4] Revert "arm64: Enforce BBM for huge IO/VMAP mappings" Chintan Pandya
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