On Mon, 2024-01-08 at 03:13 +0000, Huang, Kai wrote: > 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 <[email protected]> > > --- > > 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 <[email protected]> >
Another argument of range-based free function is, theoretically you can build the identical mapping table using different x86_mapping_info on different ranges, thus it makes less sense to use one 'struct x86_mapping_info *info' to free the entire page table, albeit in this implementation only the 'free_pgt_page()' callback is used. _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
