Commit a2c2e679 authored by Pavel Tatashin's avatar Pavel Tatashin Committed by Will Deacon
Browse files

arm64: hibernate: add trans_pgd public functions 



trans_pgd_create_copy() and trans_pgd_map_page() are going to be
the basis for new shared code that handles page tables for cases
which are between kernels: kexec, and hibernate.

Note: Eventually, get_safe_page() will be moved into a function pointer
passed via argument, but for now keep it as is.

Signed-off-by: default avatarPavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
[will: Keep these functions static until kexec needs them]
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 7ea40889

arch/arm64/kernel/hibernate.c

+60 −33
Original line number Diff line number Diff line
@@ -182,39 +182,15 @@ int arch_hibernation_header_restore(void *addr) 
}

EXPORT_SYMBOL(arch_hibernation_header_restore);



/*

 * Copies length bytes, starting at src_start into an new page,

 * perform cache maintentance, then maps it at the specified address low

 * address as executable.

 *

 * This is used by hibernate to copy the code it needs to execute when

 * overwriting the kernel text. This function generates a new set of page

 * tables, which it loads into ttbr0.

 *

 * Length is provided as we probably only want 4K of data, even on a 64K

 * page system.

 */

static int create_safe_exec_page(void *src_start, size_t length,

static int trans_pgd_map_page(pgd_t *trans_pgd, void *page,

		       unsigned long dst_addr,

				 phys_addr_t *phys_dst_addr)

		       pgprot_t pgprot)

{

	void *page = (void *)get_safe_page(GFP_ATOMIC);

	pgd_t *trans_pgd;

	pgd_t *pgdp;

	pud_t *pudp;

	pmd_t *pmdp;

	pte_t *ptep;



	if (!page)

		return -ENOMEM;



	memcpy(page, src_start, length);

	__flush_icache_range((unsigned long)page, (unsigned long)page + length);



	trans_pgd = (void *)get_safe_page(GFP_ATOMIC);

	if (!trans_pgd)

		return -ENOMEM;



	pgdp = pgd_offset_raw(trans_pgd, dst_addr);

	if (pgd_none(READ_ONCE(*pgdp))) {

		pudp = (void *)get_safe_page(GFP_ATOMIC);
@@ -242,6 +218,44 @@ static int create_safe_exec_page(void *src_start, size_t length, 
	ptep = pte_offset_kernel(pmdp, dst_addr);

	set_pte(ptep, pfn_pte(virt_to_pfn(page), PAGE_KERNEL_EXEC));



	return 0;

}



/*

 * Copies length bytes, starting at src_start into an new page,

 * perform cache maintenance, then maps it at the specified address low

 * address as executable.

 *

 * This is used by hibernate to copy the code it needs to execute when

 * overwriting the kernel text. This function generates a new set of page

 * tables, which it loads into ttbr0.

 *

 * Length is provided as we probably only want 4K of data, even on a 64K

 * page system.

 */

static int create_safe_exec_page(void *src_start, size_t length,

				 unsigned long dst_addr,

				 phys_addr_t *phys_dst_addr)

{

	void *page = (void *)get_safe_page(GFP_ATOMIC);

	pgd_t *trans_pgd;

	int rc;



	if (!page)

		return -ENOMEM;



	memcpy(page, src_start, length);

	__flush_icache_range((unsigned long)page, (unsigned long)page + length);



	trans_pgd = (void *)get_safe_page(GFP_ATOMIC);

	if (!trans_pgd)

		return -ENOMEM;



	rc = trans_pgd_map_page(trans_pgd, page, dst_addr,

				PAGE_KERNEL_EXEC);

	if (rc)

		return rc;



	/*

	 * Load our new page tables. A strict BBM approach requires that we

	 * ensure that TLBs are free of any entries that may overlap with the
@@ -462,6 +476,24 @@ static int copy_page_tables(pgd_t *dst_pgdp, unsigned long start, 
	return 0;

}



static int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,

			  unsigned long end)

{

	int rc;

	pgd_t *trans_pgd = (pgd_t *)get_safe_page(GFP_ATOMIC);



	if (!trans_pgd) {

		pr_err("Failed to allocate memory for temporary page tables.\n");

		return -ENOMEM;

	}



	rc = copy_page_tables(trans_pgd, start, end);

	if (!rc)

		*dst_pgdp = trans_pgd;



	return rc;

}



/*

 * Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().

 *
@@ -483,12 +515,7 @@ int swsusp_arch_resume(void) 
	 * Create a second copy of just the linear map, and use this when

	 * restoring.

	 */

	tmp_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);

	if (!tmp_pg_dir) {

		pr_err("Failed to allocate memory for temporary page tables.\n");

		return -ENOMEM;

	}

	rc = copy_page_tables(tmp_pg_dir, PAGE_OFFSET, PAGE_END);

	rc = trans_pgd_create_copy(&tmp_pg_dir, PAGE_OFFSET, PAGE_END);

	if (rc)

		return rc;

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