From: Xishi Qiu <qiuxishi@huawei.com>
To: Laura Abbott <labbott@fedoraproject.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, Kees Cook <keescook@chromium.org>,
"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH 1/2] arm64: Get existing page protections in split_pmd
Date: Thu, 5 Nov 2015 18:15:14 +0800 [thread overview]
Message-ID: <563B2C32.10307@huawei.com> (raw)
In-Reply-To: <1446587315-18145-2-git-send-email-labbott@fedoraproject.org>
On 2015/11/4 5:48, Laura Abbott wrote:
>
> Rather than always putting the least restrictived permissions
> (PAGE_KERNEL_EXEC) when spliting a pmd into pages, use
> the existing permissions from the pmd for the page.
>
> Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
> ---
> arch/arm64/mm/mmu.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 9211b85..ff41efa 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -75,14 +75,13 @@ static void __init *early_alloc(unsigned long sz)
> static void split_pmd(pmd_t *pmd, pte_t *pte)
> {
> unsigned long pfn = pmd_pfn(*pmd);
> + unsigned long addr = pfn << PAGE_SHIFT;
> + pgprot_t prot = __pgprot(pmd_val(*pmd) ^ addr) | PTE_TYPE_PAGE;
> +
Hi Laura,
I'm not quite understand, I find split_pud() doesn't set the flag
PMD_TYPE_TABLE. If we clear xx_TABLE_BIT, does that means the page
is large page?
And what is the different from the flag xx_TYPE_SECT?
Thanks,
Xishi Qiu
> int i = 0;
>
> do {
> - /*
> - * Need to have the least restrictive permissions available
> - * permissions will be fixed up later
> - */
> - set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
> + set_pte(pte, pfn_pte(pfn, prot));
> pfn++;
> } while (pte++, i++, i < PTRS_PER_PTE);
> }
next prev parent reply other threads:[~2015-11-05 10:18 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-03 21:48 [PATCH 0/2] Support for set_memory_* outside of module space Laura Abbott
2015-11-03 21:48 ` [PATCH 1/2] arm64: Get existing page protections in split_pmd Laura Abbott
2015-11-05 7:07 ` Ard Biesheuvel
2015-11-05 10:15 ` Xishi Qiu [this message]
2015-11-06 1:24 ` Laura Abbott
2015-11-03 21:48 ` [PATCH 2/2] arm64: Allow changing of attributes outside of modules Laura Abbott
2015-11-04 3:17 ` zhong jiang
2015-11-05 7:44 ` Ard Biesheuvel
2015-11-06 1:35 ` Laura Abbott
[not found] ` <563974A8.3060306@huawei.com>
[not found] ` <563A4A74.60900@redhat.com>
2015-11-05 11:10 ` Xishi Qiu
2015-11-06 1:11 ` Laura Abbott
2015-11-05 11:29 ` Xishi Qiu
2015-11-03 23:42 ` [PATCH 0/2] Support for set_memory_* outside of module space Kees Cook
2015-11-04 18:51 ` Laura Abbott
2015-11-04 19:06 ` Kees Cook
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