From: James Morse <james.morse@arm.com>
To: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: jmorris@namei.org, sashal@kernel.org, ebiederm@xmission.com,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
corbet@lwn.net, catalin.marinas@arm.com, will@kernel.org,
linux-arm-kernel@lists.infradead.org, marc.zyngier@arm.com,
vladimir.murzin@arm.com, matthias.bgg@gmail.com,
bhsharma@redhat.com, linux-mm@kvack.org, mark.rutland@arm.com
Subject: Re: [PATCH v3 06/17] arm64, hibernate: add trans_pgd public functions
Date: Fri, 6 Sep 2019 16:18:06 +0100 [thread overview]
Message-ID: <bcc3f71f-97d2-dff4-c55a-4798c6e2bede@arm.com> (raw)
In-Reply-To: <20190821183204.23576-7-pasha.tatashin@soleen.com>
Hi Pavel,
On 21/08/2019 19:31, Pavel Tatashin wrote:
> trans_pgd_create_copy() and trans_pgd_map_page() are going to be
> the basis for public interface of new subsystem that handles page
Please don't call this a subsystem. 'sound' and 'mm' are subsystems, this is just some
shared code.
> tables for cases which are between kernels: kexec, and hibernate.
Even though you've baked the get_safe_page() calls into trans_pgd_map_page()?
> diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
> index 750ecc7f2cbe..2e29d620b56c 100644
> --- a/arch/arm64/kernel/hibernate.c
> +++ b/arch/arm64/kernel/hibernate.c
> @@ -182,39 +182,15 @@ int arch_hibernation_header_restore(void *addr)
> +int trans_pgd_map_page(pgd_t *trans_pgd, void *page,
> + unsigned long dst_addr,
> + pgprot_t pgprot)
If this thing is going to be exposed, its name should reflect that its creating a set of
page tables, to map a single page.
A function called 'map_page' with this prototype should 'obviously' map @page at @dst_addr
in @trans_pgd using the provided @pgprot... but it doesn't.
This is what 'create' was doing in the old name, if that wasn't obvious, its because
naming things is hard!
| trans_create_single_page_mapping()?
(might be too verbose)
I think this bites you in patch 8, where you 'generalise' this.
> {
> - void *page = (void *)get_safe_page(GFP_ATOMIC);
> - pgd_t *trans_pgd;
> pgd_t *pgdp;
> pud_t *pudp;
> pmd_t *pmdp;
> pte_t *ptep;
>
> - if (!page)
> - return -ENOMEM;
> -
> - memcpy(page, src_start, length);
> - __flush_icache_range((unsigned long)page, (unsigned long)page + length);
> -
> - trans_pgd = (void *)get_safe_page(GFP_ATOMIC);
> - if (!trans_pgd)
> - return -ENOMEM;
> -
> pgdp = pgd_offset_raw(trans_pgd, dst_addr);
> if (pgd_none(READ_ONCE(*pgdp))) {
> pudp = (void *)get_safe_page(GFP_ATOMIC);
> @@ -242,6 +218,44 @@ static int create_safe_exec_page(void *src_start, size_t length,
> ptep = pte_offset_kernel(pmdp, dst_addr);
> set_pte(ptep, pfn_pte(virt_to_pfn(page), PAGE_KERNEL_EXEC));
>
> + return 0;
> +}
> +
> +/*
> + * Copies length bytes, starting at src_start into an new page,
> + * perform cache maintentance, then maps it at the specified address low
Could you fix the spelling of maintenance as git thinks you've moved it?
> + * address as executable.
> + *
> + * This is used by hibernate to copy the code it needs to execute when
> + * overwriting the kernel text. This function generates a new set of page
> + * tables, which it loads into ttbr0.
> + *
> + * Length is provided as we probably only want 4K of data, even on a 64K
> + * page system.
> + */
> +static int create_safe_exec_page(void *src_start, size_t length,
> + unsigned long dst_addr,
> + phys_addr_t *phys_dst_addr)
> +{
Thanks,
James
next prev parent reply other threads:[~2019-09-06 15:18 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 18:31 [PATCH v3 00/17] arm64: MMU enabled kexec relocation Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 01/17] kexec: quiet down kexec reboot Pavel Tatashin
2019-09-06 15:17 ` James Morse
2019-09-06 15:35 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 02/17] arm64, hibernate: use get_safe_page directly Pavel Tatashin
2019-09-06 15:17 ` James Morse
2019-09-06 15:39 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 03/17] arm64, hibernate: remove gotos in create_safe_exec_page Pavel Tatashin
2019-09-06 15:17 ` James Morse
2019-09-06 15:41 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 04/17] arm64, hibernate: rename dst to page " Pavel Tatashin
2019-09-06 15:17 ` James Morse
2019-09-06 15:41 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 05/17] arm64, hibernate: check pgd table allocation Pavel Tatashin
2019-09-06 15:17 ` James Morse
2019-09-06 15:44 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 06/17] arm64, hibernate: add trans_pgd public functions Pavel Tatashin
2019-09-06 15:18 ` James Morse [this message]
2019-09-06 16:00 ` Pavel Tatashin
2019-10-11 18:16 ` James Morse
2019-08-21 18:31 ` [PATCH v3 07/17] arm64, hibernate: move page handling function to new trans_pgd.c Pavel Tatashin
2019-09-06 15:18 ` James Morse
2019-09-06 17:41 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 08/17] arm64, trans_pgd: make trans_pgd_map_page generic Pavel Tatashin
2019-09-06 15:20 ` James Morse
2019-09-06 18:58 ` Pavel Tatashin
2019-10-11 18:15 ` James Morse
2019-08-21 18:31 ` [PATCH v3 09/17] arm64, trans_pgd: add trans_pgd_create_empty Pavel Tatashin
2019-09-06 15:20 ` James Morse
2019-09-06 19:00 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 10/17] arm64, trans_pgd: adjust trans_pgd_create_copy interface Pavel Tatashin
2019-09-06 15:20 ` James Morse
2019-09-06 19:03 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 11/17] arm64, trans_pgd: add PUD_SECT_RDONLY Pavel Tatashin
2019-09-06 15:21 ` James Morse
2019-09-06 19:04 ` Pavel Tatashin
2019-08-21 18:31 ` [PATCH v3 12/17] arm64, trans_pgd: complete generalization of trans_pgds Pavel Tatashin
2019-09-06 15:23 ` James Morse
2019-09-06 19:06 ` Pavel Tatashin
2019-08-21 18:32 ` [PATCH v3 13/17] kexec: add machine_kexec_post_load() Pavel Tatashin
2019-08-21 18:32 ` [PATCH v3 14/17] arm64, kexec: move relocation function setup and clean up Pavel Tatashin
2019-08-21 18:32 ` [PATCH v3 15/17] arm64, kexec: add expandable argument to relocation function Pavel Tatashin
2019-08-21 18:32 ` [PATCH v3 16/17] arm64, kexec: configure trans_pgd page table for kexec Pavel Tatashin
2019-08-21 18:32 ` [PATCH v3 17/17] arm64, kexec: enable MMU during kexec relocation Pavel Tatashin
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