Commit e4630fdd authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

x86/power/64: Always create temporary identity mapping correctly 



The low-level resume-from-hibernation code on x86-64 uses
kernel_ident_mapping_init() to create the temoprary identity mapping,
but that function assumes that the offset between kernel virtual
addresses and physical addresses is aligned on the PGD level.

However, with a randomized identity mapping base, it may be aligned
on the PUD level and if that happens, the temporary identity mapping
created by set_up_temporary_mappings() will not reflect the actual
kernel identity mapping and the image restoration will fail as a
result (leading to a kernel panic most of the time).

To fix this problem, rework kernel_ident_mapping_init() to support
unaligned offsets between KVA and PA up to the PMD level and make
set_up_temporary_mappings() use it as approprtiate.

Reported-and-tested-by: default avatarThomas Garnier <thgarnie@google.com>
Reported-by: default avatarBorislav Petkov <bp@suse.de>
Suggested-by: default avatarYinghai Lu <yinghai@kernel.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarYinghai Lu <yinghai@kernel.org>
parent c226fab4

arch/x86/include/asm/init.h

+2 −2
Original line number Diff line number Diff line
@@ -5,10 +5,10 @@ struct x86_mapping_info { 
	void *(*alloc_pgt_page)(void *); /* allocate buf for page table */

	void *context;			 /* context for alloc_pgt_page */

	unsigned long pmd_flag;		 /* page flag for PMD entry */

	bool kernel_mapping;		 /* kernel mapping or ident mapping */

	unsigned long offset;		 /* ident mapping offset */

};



int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,

				unsigned long addr, unsigned long end);

				unsigned long pstart, unsigned long pend);



#endif /* _ASM_X86_INIT_H */

arch/x86/mm/ident_map.c

+11 −8
Original line number Diff line number Diff line
@@ -3,15 +3,17 @@ 
 * included by both the compressed kernel and the regular kernel.

 */



static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,

static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,

			   unsigned long addr, unsigned long end)

{

	addr &= PMD_MASK;

	for (; addr < end; addr += PMD_SIZE) {

		pmd_t *pmd = pmd_page + pmd_index(addr);



		if (!pmd_present(*pmd))

			set_pmd(pmd, __pmd(addr | pmd_flag));

		if (pmd_present(*pmd))

			continue;



		set_pmd(pmd, __pmd((addr - info->offset) | info->pmd_flag));

	}

}
@@ -30,13 +32,13 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, 


		if (pud_present(*pud)) {

			pmd = pmd_offset(pud, 0);

			ident_pmd_init(info->pmd_flag, pmd, addr, next);

			ident_pmd_init(info, pmd, addr, next);

			continue;

		}

		pmd = (pmd_t *)info->alloc_pgt_page(info->context);

		if (!pmd)

			return -ENOMEM;

		ident_pmd_init(info->pmd_flag, pmd, addr, next);

		ident_pmd_init(info, pmd, addr, next);

		set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));

	}
@@ -44,14 +46,15 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, 
}



int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,

			      unsigned long addr, unsigned long end)

			      unsigned long pstart, unsigned long pend)

{

	unsigned long addr = pstart + info->offset;

	unsigned long end = pend + info->offset;

	unsigned long next;

	int result;

	int off = info->kernel_mapping ? pgd_index(__PAGE_OFFSET) : 0;



	for (; addr < end; addr = next) {

		pgd_t *pgd = pgd_page + pgd_index(addr) + off;

		pgd_t *pgd = pgd_page + pgd_index(addr);

		pud_t *pud;



		next = (addr & PGDIR_MASK) + PGDIR_SIZE;

arch/x86/power/hibernate_64.c

+1 −1
Original line number Diff line number Diff line
@@ -87,7 +87,7 @@ static int set_up_temporary_mappings(void) 
	struct x86_mapping_info info = {

		.alloc_pgt_page	= alloc_pgt_page,

		.pmd_flag	= __PAGE_KERNEL_LARGE_EXEC,

		.kernel_mapping = true,

		.offset		= __PAGE_OFFSET,

	};

	unsigned long mstart, mend;

	pgd_t *pgd;

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