arm64: trans_pgd: make trans_pgd_map_page generic

kexec is going to use a different allocator, so make
trans_pgd_map_page to accept allocator as an argument, and also
kexec is going to use a different map protection, so also pass
it via argument.

Signed-off-by: Pavel Tatashin <[e-mail]>
Reviewed-by: Matthias Brugger <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Will Deacon <[e-mail]>

arch/arm64/include/asm/trans_pgd.h

···
 #include <linux/types.h>
 #include <asm/pgtable-types.h>
 
+/*
+ * trans_alloc_page
+ *	- Allocator that should return exactly one zeroed page, if this
+ *	  allocator fails, trans_pgd_create_copy() and trans_pgd_map_page()
+ *	  return -ENOMEM error.
+ *
+ * trans_alloc_arg
+ *	- Passed to trans_alloc_page as an argument
+ */
+
+struct trans_pgd_info {
+	void * (*trans_alloc_page)(void *arg);
+	void *trans_alloc_arg;
+};
+
 int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
 			  unsigned long end);
 
-int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
-		       pgprot_t pgprot);
+int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
+		       void *page, unsigned long dst_addr, pgprot_t pgprot);
 
 #endif /* _ASM_TRANS_TABLE_H */

arch/arm64/kernel/hibernate.c

···
 }
 EXPORT_SYMBOL(arch_hibernation_header_restore);
 
+static void *hibernate_page_alloc(void *arg)
+{
+	return (void *)get_safe_page((gfp_t)(unsigned long)arg);
+}
+
 /*
  * Copies length bytes, starting at src_start into an new page,
  * perform cache maintenance, then maps it at the specified address low
···
 				 unsigned long dst_addr,
 				 phys_addr_t *phys_dst_addr)
 {
+	struct trans_pgd_info trans_info = {
+		.trans_alloc_page	= hibernate_page_alloc,
+		.trans_alloc_arg	= (void *)GFP_ATOMIC,
+	};
+
 	void *page = (void *)get_safe_page(GFP_ATOMIC);
 	pgd_t *trans_pgd;
 	int rc;
···
 	if (!trans_pgd)
 		return -ENOMEM;
 
-	rc = trans_pgd_map_page(trans_pgd, page, dst_addr,
+	rc = trans_pgd_map_page(&trans_info, trans_pgd, page, dst_addr,
 				PAGE_KERNEL_EXEC);
 	if (rc)
 		return rc;

arch/arm64/mm/trans_pgd.c

···
 #include <linux/mm.h>
 #include <linux/mmzone.h>
 
+static void *trans_alloc(struct trans_pgd_info *info)
+{
+	return info->trans_alloc_page(info->trans_alloc_arg);
+}
+
 static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr)
 {
 	pte_t pte = READ_ONCE(*src_ptep);
···
 	return rc;
 }
 
-int trans_pgd_map_page(pgd_t *trans_pgd, void *page,
-		       unsigned long dst_addr,
-		       pgprot_t pgprot)
+/*
+ * Add map entry to trans_pgd for a base-size page at PTE level.
+ * info:	contains allocator and its argument
+ * trans_pgd:	page table in which new map is added.
+ * page:	page to be mapped.
+ * dst_addr:	new VA address for the page
+ * pgprot:	protection for the page.
+ *
+ * Returns 0 on success, and -ENOMEM on failure.
+ */
+int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
+		       void *page, unsigned long dst_addr, pgprot_t pgprot)
 {
 	pgd_t *pgdp;
 	p4d_t *p4dp;
···
 
 	pgdp = pgd_offset_pgd(trans_pgd, dst_addr);
 	if (pgd_none(READ_ONCE(*pgdp))) {
-		p4dp = (void *)get_safe_page(GFP_ATOMIC);
+		p4dp = trans_alloc(info);
 		if (!pgdp)
 			return -ENOMEM;
 		pgd_populate(&init_mm, pgdp, p4dp);
···
 
 	p4dp = p4d_offset(pgdp, dst_addr);
 	if (p4d_none(READ_ONCE(*p4dp))) {
-		pudp = (void *)get_safe_page(GFP_ATOMIC);
+		pudp = trans_alloc(info);
 		if (!pudp)
 			return -ENOMEM;
 		p4d_populate(&init_mm, p4dp, pudp);
···
 
 	pudp = pud_offset(p4dp, dst_addr);
 	if (pud_none(READ_ONCE(*pudp))) {
-		pmdp = (void *)get_safe_page(GFP_ATOMIC);
+		pmdp = trans_alloc(info);
 		if (!pmdp)
 			return -ENOMEM;
 		pud_populate(&init_mm, pudp, pmdp);
···
 
 	pmdp = pmd_offset(pudp, dst_addr);
 	if (pmd_none(READ_ONCE(*pmdp))) {
-		ptep = (void *)get_safe_page(GFP_ATOMIC);
+		ptep = trans_alloc(info);
 		if (!ptep)
 			return -ENOMEM;
 		pmd_populate_kernel(&init_mm, pmdp, ptep);
 	}
 
 	ptep = pte_offset_kernel(pmdp, dst_addr);
-	set_pte(ptep, pfn_pte(virt_to_pfn(page), PAGE_KERNEL_EXEC));
+	set_pte(ptep, pfn_pte(virt_to_pfn(page), pgprot));
 
 	return 0;
 }