[PATCH v5 3/3] arm64: hibernate: Support DEBUG_PAGEALLOC

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index b4082017c4cb..da4470de1807 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c

@@ -235,6 +235,7 @@ out:
 	return rc;
 }
 
+#define dcache_clean_range(start, end)	__flush_dcache_area(start, (end - start))
 
 int swsusp_arch_suspend(void)
 {

@@ -252,8 +253,14 @@ int swsusp_arch_suspend(void)
 	if (__cpu_suspend_enter(&state)) {
 		ret = swsusp_save();
 	} else {
-		/* Clean kernel to PoC for secondary core startup */
-		__flush_dcache_area(LMADDR(KERNEL_START), KERNEL_END - KERNEL_START);
+		/* Clean kernel core startup/idle code to PoC*/
+		dcache_clean_range(__mmuoff_text_start, __mmuoff_text_end);
+		dcache_clean_range(__mmuoff_data_start, __mmuoff_data_end);
+		dcache_clean_range(__idmap_text_start, __idmap_text_end);
+
+		/* Clean kvm setup code to PoC? */
+		if (el2_reset_needed())
+			dcache_clean_range(__hyp_idmap_text_start, __hyp_idmap_text_end);
 
 		/*
 		 * Tell the hibernation core that we've just restored

@@ -269,6 +276,32 @@ int swsusp_arch_suspend(void)
 	return ret;
 }
 
+static void _copy_pte(pte_t *dst_pte, pte_t *src_pte, unsigned long addr)
+{
+	unsigned long pfn = virt_to_pfn(addr);

+	}
+}
+
 static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
 		    unsigned long end)
 {

@@ -284,13 +317,7 @@ static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
 
 	src_pte = pte_offset_kernel(src_pmd, start);
 	do {
-		if (!pte_none(*src_pte))

-			/*
-			 * Resume will overwrite areas that may be marked
-			 * read only (code, rodata). Clear the RDONLY bit from
-			 * the temporary mappings we use during restore.
-			 */
-			set_pte(dst_pte, __pte(pte_val(*src_pte) & ~PTE_RDONLY));
+		_copy_pte(dst_pte, src_pte, addr);
 	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 
 	return 0;

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index ca6d268e3313..b6c0da84258c 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c

@@ -139,4 +139,42 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
 					__pgprot(0),
 					__pgprot(PTE_VALID));
 }
-#endif
+#ifdef CONFIG_HIBERNATION
+/*
+ * When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
+ * is used to determine if a linear map page has been marked as not-present by
+ * CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
+ * This is based on kern_addr_valid(), which almost does what we need.
+ */
+bool kernel_page_present(struct page *page)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	unsigned long addr = (unsigned long)page_address(page);
+
+	pgd = pgd_offset_k(addr);
+	if (pgd_none(*pgd))
+		return false;
+
+	pud = pud_offset(pgd, addr);
+	if (pud_none(*pud))
+		return false;
+	if (pud_sect(*pud))
+		return true;