Hi Pavel, On 26/03/2020 03:24, Pavel Tatashin wrote: > From: James Morse <james.morse@xxxxxxx> > > To resume from hibernate, the contents of memory are restored from > the swap image. This may overwrite any page, including the running > kernel and its page tables. > > Hibernate copies the code it uses to do the restore into a single > page that it knows won't be overwritten, and maps it with page tables > built from pages that won't be overwritten. > > Today the address it uses for this mapping is arbitrary, but to allow > kexec to reuse this code, it needs to be idmapped. To idmap the page > we must avoid the kernel helpers that have VA_BITS baked in. > > Convert create_single_mapping() to take a single PA, and idmap it. > The page tables are built in the reverse order to normal using > pfn_pte() to stir in any bits between 52:48. T0SZ is always increased > to cover 48bits, or 52 if the copy code has bits 52:48 in its PA. > > Pasha: The original patch from James > inux-arm-kernel/20200115143322.214247-4-james.morse@xxxxxxx -EBROKENLINK The convention is to use a 'Link:' tag in the signed-off area. e.g. 5a3577039cbe > Adopted it to trans_pgd, so it can be commonly used by both Kexec > and Hibernate. Some minor clean-ups. Please describe your changes just before your SoB. This means each author sign's off on the stuff above their SoB, and its obvious who made which changes. Search for 'Lucky K Maintainer' in process/submitting-patches.rst for an example. > diff --git a/arch/arm64/include/asm/trans_pgd.h b/arch/arm64/include/asm/trans_pgd.h > index 97a7ea73b289..4912d3caf0ca 100644 > --- a/arch/arm64/include/asm/trans_pgd.h > +++ b/arch/arm64/include/asm/trans_pgd.h > @@ -32,4 +32,7 @@ int trans_pgd_create_copy(struct trans_pgd_info *info, pgd_t **trans_pgd, > int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd, > void *page, unsigned long dst_addr, pgprot_t pgprot); This trans_pgd_map_page() used to be create_single_mapping(), which is where the original patch made its changes. You should only need one of these, not both. > +int trans_pgd_idmap_page(struct trans_pgd_info *info, phys_addr_t *trans_ttbr0, > + unsigned long *t0sz, void *page); > + > #endif /* _ASM_TRANS_TABLE_H */ > diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c > index 37d7d1c60f65..c2517d1af2af 100644 > --- a/arch/arm64/mm/trans_pgd.c > +++ b/arch/arm64/mm/trans_pgd.c > @@ -242,3 +242,52 @@ int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd, > > return 0; > } > + > +/* > + * The page we want to idmap may be outside the range covered by VA_BITS that > + * can be built using the kernel's p?d_populate() helpers. As a one off, for a > + * single page, we build these page tables bottom up and just assume that will > + * need the maximum T0SZ. > + * > + * Returns 0 on success, and -ENOMEM on failure. > + * On success trans_ttbr0 contains page table with idmapped page, t0sz is set to > + * maxumum T0SZ for this page. maxumum > + */ Thanks, James _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
