On Sat, 2023-12-23 at 02:52 +0300, Kirill A. Shutemov wrote:
> The helper complements kernel_ident_mapping_init(): it frees the
> identity mapping that was previously allocated. It will be used in the
> error path to free a partially allocated mapping or if the mapping is no
> longer needed.
>
> The caller provides a struct x86_mapping_info with the free_pgd_page()
> callback hooked up and the pgd_t to free.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
> arch/x86/include/asm/init.h | 3 ++
> arch/x86/mm/ident_map.c | 73 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 76 insertions(+)
>
> diff --git a/arch/x86/include/asm/init.h b/arch/x86/include/asm/init.h
> index cc9ccf61b6bd..14d72727d7ee 100644
> --- a/arch/x86/include/asm/init.h
> +++ b/arch/x86/include/asm/init.h
> @@ -6,6 +6,7 @@
>
> struct x86_mapping_info {
> void *(*alloc_pgt_page)(void *); /* allocate buf for page table */
> + void (*free_pgt_page)(void *, void *); /* free buf for page table */
> void *context; /* context for alloc_pgt_page */
> unsigned long page_flag; /* page flag for PMD or PUD entry */
> unsigned long offset; /* ident mapping offset */
> @@ -16,4 +17,6 @@ struct x86_mapping_info {
> int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
> unsigned long pstart, unsigned long pend);
>
> +void kernel_ident_mapping_free(struct x86_mapping_info *info, pgd_t *pgd);
Maybe range-based free function can provide more flexibility (e.g., you can
directly call the free function to cleanup in kernel_ident_mapping_init()
internally when something goes wrong), but I guess this is sufficient for
current use case (and perhaps the majority use cases).
Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx>
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