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SubjectRe: [PATCH v4 10/17] arm64: trans_pgd: make trans_pgd_map_page generic
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Bikeshedding alarm, please see below.

On 09/09/2019 20:12, Pavel Tatashin wrote:
> kexec is going to use a different allocator, so make
> trans_pgd_map_page to accept allocator as an argument, and also
> kexec is going to use a different map protection, so also pass
> it via argument.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
> ---
> arch/arm64/include/asm/trans_pgd.h | 24 ++++++++++++++++++++++--
> arch/arm64/kernel/hibernate.c | 12 +++++++++++-
> arch/arm64/mm/trans_pgd.c | 17 +++++++++++------
> 3 files changed, 44 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/include/asm/trans_pgd.h b/arch/arm64/include/asm/trans_pgd.h
> index c7b5402b7d87..53f67ec84cdc 100644
> --- a/arch/arm64/include/asm/trans_pgd.h
> +++ b/arch/arm64/include/asm/trans_pgd.h
> @@ -11,10 +11,30 @@
> #include <linux/bits.h>
> #include <asm/pgtable-types.h>
>
> +/*
> + * trans_alloc_page
> + * - Allocator that should return exactly one zeroed page, if this
> + * allocator fails, trans_pgd returns -ENOMEM error.
> + *
> + * trans_alloc_arg
> + * - Passed to trans_alloc_page as an argument
> + */
> +
> +struct trans_pgd_info {
> + void * (*trans_alloc_page)(void *arg);
> + void *trans_alloc_arg;
> +};
> +
> int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
> unsigned long end);
>
> -int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
> - pgprot_t pgprot);
> +/*
> + * Add map entry to trans_pgd for a base-size page at PTE level.
> + * page: page to be mapped.
> + * dst_addr: new VA address for the pages
> + * pgprot: protection for the page.

For consistency please describe all function parameters. From my experience
function parameter description is normally done in the C-file that implements
the logic. Don't ask me why.

> + */
> +int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
> + void *page, unsigned long dst_addr, pgprot_t pgprot);
>
> #endif /* _ASM_TRANS_TABLE_H */
> diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
> index 94ede33bd777..9b75b680ab70 100644
> --- a/arch/arm64/kernel/hibernate.c
> +++ b/arch/arm64/kernel/hibernate.c
> @@ -179,6 +179,12 @@ int arch_hibernation_header_restore(void *addr)
> }
> EXPORT_SYMBOL(arch_hibernation_header_restore);
>
> +static void *
> +hibernate_page_alloc(void *arg)

AFAICS no new line needed here.

> +{
> + return (void *)get_safe_page((gfp_t)(unsigned long)arg);
> +}
> +
> /*
> * Copies length bytes, starting at src_start into an new page,
> * perform cache maintenance, then maps it at the specified address low
> @@ -195,6 +201,10 @@ static int create_safe_exec_page(void *src_start, size_t length,
> unsigned long dst_addr,
> phys_addr_t *phys_dst_addr)
> {
> + struct trans_pgd_info trans_info = {
> + .trans_alloc_page = hibernate_page_alloc,
> + .trans_alloc_arg = (void *)GFP_ATOMIC,
> + };

New line between end of struct and other variables.

With these changes:
Reviewed-by: Matthias Brugger <mbrugger@suse.com>

> void *page = (void *)get_safe_page(GFP_ATOMIC);
> pgd_t *trans_pgd;
> int rc;
> @@ -209,7 +219,7 @@ static int create_safe_exec_page(void *src_start, size_t length,
> if (!trans_pgd)
> return -ENOMEM;
>
> - rc = trans_pgd_map_page(trans_pgd, page, dst_addr,
> + rc = trans_pgd_map_page(&trans_info, trans_pgd, page, dst_addr,
> PAGE_KERNEL_EXEC);
> if (rc)
> return rc;
> diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
> index 5ac712b92439..7521d558a0b9 100644
> --- a/arch/arm64/mm/trans_pgd.c
> +++ b/arch/arm64/mm/trans_pgd.c
> @@ -25,6 +25,11 @@
> #include <linux/mm.h>
> #include <linux/mmzone.h>
>
> +static void *trans_alloc(struct trans_pgd_info *info)
> +{
> + return info->trans_alloc_page(info->trans_alloc_arg);
> +}
> +
> static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr)
> {
> pte_t pte = READ_ONCE(*src_ptep);
> @@ -180,8 +185,8 @@ int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
> return rc;
> }
>
> -int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
> - pgprot_t pgprot)
> +int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
> + void *page, unsigned long dst_addr, pgprot_t pgprot)
> {
> pgd_t *pgdp;
> pud_t *pudp;
> @@ -190,7 +195,7 @@ int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
>
> pgdp = pgd_offset_raw(trans_pgd, dst_addr);
> if (pgd_none(READ_ONCE(*pgdp))) {
> - pudp = (void *)get_safe_page(GFP_ATOMIC);
> + pudp = trans_alloc(info);
> if (!pudp)
> return -ENOMEM;
> pgd_populate(&init_mm, pgdp, pudp);
> @@ -198,7 +203,7 @@ int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
>
> pudp = pud_offset(pgdp, dst_addr);
> if (pud_none(READ_ONCE(*pudp))) {
> - pmdp = (void *)get_safe_page(GFP_ATOMIC);
> + pmdp = trans_alloc(info);
> if (!pmdp)
> return -ENOMEM;
> pud_populate(&init_mm, pudp, pmdp);
> @@ -206,14 +211,14 @@ int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
>
> pmdp = pmd_offset(pudp, dst_addr);
> if (pmd_none(READ_ONCE(*pmdp))) {
> - ptep = (void *)get_safe_page(GFP_ATOMIC);
> + ptep = trans_alloc(info);
> if (!ptep)
> return -ENOMEM;
> pmd_populate_kernel(&init_mm, pmdp, ptep);
> }
>
> ptep = pte_offset_kernel(pmdp, dst_addr);
> - set_pte(ptep, pfn_pte(virt_to_pfn(page), PAGE_KERNEL_EXEC));
> + set_pte(ptep, pfn_pte(virt_to_pfn(page), pgprot));
>
> return 0;
> }
>

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