[PATCH v3 12/17] arm64, trans_pgd: complete generalization of trans_pgds

[Pavel Tatashin <pasha.tatashin@soleen.com>]

Make the last private functions in page table copy path generlized for use
outside of hibernate.

Switch to use the provided allocator, flags, and source page table. Also,
unify all copy function implementations to reduce the possibility of bugs.
All page table levels are implemented symmetrically.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
---
 arch/arm64/mm/trans_pgd.c | 200 +++++++++++++++++++++-----------------
 1 file changed, 109 insertions(+), 91 deletions(-)

diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
index efd42509d069..ccd9900f8edb 100644
--- a/arch/arm64/mm/trans_pgd.c
+++ b/arch/arm64/mm/trans_pgd.c
@@ -27,139 +27,157 @@ static void *trans_alloc(struct trans_pgd_info *info)
 	return page;
 }
 
-static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr)
+static int copy_pte(struct trans_pgd_info *info, pte_t *dst_ptep,
+		    pte_t *src_ptep, unsigned long start, unsigned long end)
 {
-	pte_t pte = READ_ONCE(*src_ptep);
-
-	if (pte_valid(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_ptep, pte_mkwrite(pte));
-	} else if (debug_pagealloc_enabled() && !pte_none(pte)) {
-		/*
-		 * debug_pagealloc will removed the PTE_VALID bit if
-		 * the page isn't in use by the resume kernel. It may have
-		 * been in use by the original kernel, in which case we need
-		 * to put it back in our copy to do the restore.
-		 *
-		 * Before marking this entry valid, check the pfn should
-		 * be mapped.
-		 */
-		BUG_ON(!pfn_valid(pte_pfn(pte)));
-
-		set_pte(dst_ptep, pte_mkpresent(pte_mkwrite(pte)));
-	}
-}
-
-static int copy_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp, unsigned long start,
-		    unsigned long end)
-{
-	pte_t *src_ptep;
-	pte_t *dst_ptep;
 	unsigned long addr = start;
+	int i = pte_index(addr);
 
-	dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
-	if (!dst_ptep)
-		return -ENOMEM;
-	pmd_populate_kernel(&init_mm, dst_pmdp, dst_ptep);
-	dst_ptep = pte_offset_kernel(dst_pmdp, start);
-
-	src_ptep = pte_offset_kernel(src_pmdp, start);
 	do {
-		_copy_pte(dst_ptep, src_ptep, addr);
-	} while (dst_ptep++, src_ptep++, addr += PAGE_SIZE, addr != end);
+		pte_t src_pte = READ_ONCE(src_ptep[i]);
+
+		if (pte_none(src_pte))
+			continue;
+		if (info->trans_flags & TRANS_MKWRITE)
+			src_pte = pte_mkwrite(src_pte);
+		if (info->trans_flags & TRANS_MKVALID)
+			src_pte = pte_mkpresent(src_pte);
+		if (info->trans_flags & TRANS_CHECKPFN) {
+			if (!pfn_valid(pte_pfn(src_pte)))
+				return -ENXIO;
+		}
+		set_pte(&dst_ptep[i], src_pte);
+	} while (addr += PAGE_SIZE, i++, addr != end && i < PTRS_PER_PTE);
 
 	return 0;
 }
 
-static int copy_pmd(pud_t *dst_pudp, pud_t *src_pudp, unsigned long start,
-		    unsigned long end)
+static int copy_pmd(struct trans_pgd_info *info, pmd_t *dst_pmdp,
+		    pmd_t *src_pmdp, unsigned long start, unsigned long end)
 {
-	pmd_t *src_pmdp;
-	pmd_t *dst_pmdp;
 	unsigned long next;
 	unsigned long addr = start;
+	int i = pmd_index(addr);
+	int rc;
 
-	if (pud_none(READ_ONCE(*dst_pudp))) {
-		dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
-		if (!dst_pmdp)
-			return -ENOMEM;
-		pud_populate(&init_mm, dst_pudp, dst_pmdp);
-	}
-	dst_pmdp = pmd_offset(dst_pudp, start);
-
-	src_pmdp = pmd_offset(src_pudp, start);
 	do {
-		pmd_t pmd = READ_ONCE(*src_pmdp);
+		pmd_t src_pmd = READ_ONCE(src_pmdp[i]);
+		pmd_t dst_pmd = READ_ONCE(dst_pmdp[i]);
+		pte_t *dst_ptep, *src_ptep;
 
 		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
+		if (pmd_none(src_pmd))
+			continue;
+
+		if (!pmd_table(src_pmd)) {
+			if (info->trans_flags & TRANS_MKWRITE)
+				pmd_val(src_pmd) &= ~PMD_SECT_RDONLY;
+			set_pmd(&dst_pmdp[i], src_pmd);
 			continue;
-		if (pmd_table(pmd)) {
-			if (copy_pte(dst_pmdp, src_pmdp, addr, next))
+		}
+
+		if (pmd_none(dst_pmd)) {
+			pte_t *t = trans_alloc(info);
+
+			if (!t)
 				return -ENOMEM;
-		} else {
-			set_pmd(dst_pmdp,
-				__pmd(pmd_val(pmd) & ~PMD_SECT_RDONLY));
+
+			__pmd_populate(&dst_pmdp[i], __pa(t), PTE_TYPE_PAGE);
+			dst_pmd = READ_ONCE(dst_pmdp[i]);
 		}
-	} while (dst_pmdp++, src_pmdp++, addr = next, addr != end);
+
+		src_ptep = __va(pmd_page_paddr(src_pmd));
+		dst_ptep = __va(pmd_page_paddr(dst_pmd));
+
+		rc = copy_pte(info, dst_ptep, src_ptep, addr, next);
+		if (rc)
+			return rc;
+	} while (addr = next, i++, addr != end && i < PTRS_PER_PMD);
 
 	return 0;
 }
 
-static int copy_pud(pgd_t *dst_pgdp, pgd_t *src_pgdp, unsigned long start,
-		    unsigned long end)
+static int copy_pud(struct trans_pgd_info *info, pud_t *dst_pudp,
+		    pud_t *src_pudp, unsigned long start, unsigned long end)
 {
-	pud_t *dst_pudp;
-	pud_t *src_pudp;
 	unsigned long next;
 	unsigned long addr = start;
+	int i = pud_index(addr);
+	int rc;
 
-	if (pgd_none(READ_ONCE(*dst_pgdp))) {
-		dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
-		if (!dst_pudp)
-			return -ENOMEM;
-		pgd_populate(&init_mm, dst_pgdp, dst_pudp);
-	}
-	dst_pudp = pud_offset(dst_pgdp, start);
-
-	src_pudp = pud_offset(src_pgdp, start);
 	do {
-		pud_t pud = READ_ONCE(*src_pudp);
+		pud_t src_pud = READ_ONCE(src_pudp[i]);
+		pud_t dst_pud = READ_ONCE(dst_pudp[i]);
+		pmd_t *dst_pmdp, *src_pmdp;
 
 		next = pud_addr_end(addr, end);
-		if (pud_none(pud))
+		if (pud_none(src_pud))
 			continue;
-		if (pud_table(pud)) {
-			if (copy_pmd(dst_pudp, src_pudp, addr, next))
+
+		if (!pud_table(src_pud)) {
+			if (info->trans_flags & TRANS_MKWRITE)
+				pud_val(src_pud) &= ~PUD_SECT_RDONLY;
+			set_pud(&dst_pudp[i], src_pud);
+			continue;
+		}
+
+		if (pud_none(dst_pud)) {
+			pmd_t *t = trans_alloc(info);
+
+			if (!t)
 				return -ENOMEM;
-		} else {
-			set_pud(dst_pudp,
-				__pud(pud_val(pud) & ~PUD_SECT_RDONLY));
+
+			__pud_populate(&dst_pudp[i], __pa(t), PMD_TYPE_TABLE);
+			dst_pud = READ_ONCE(dst_pudp[i]);
 		}
-	} while (dst_pudp++, src_pudp++, addr = next, addr != end);
+
+		src_pmdp = __va(pud_page_paddr(src_pud));
+		dst_pmdp = __va(pud_page_paddr(dst_pud));
+
+		rc = copy_pmd(info, dst_pmdp, src_pmdp, addr, next);
+		if (rc)
+			return rc;
+	} while (addr = next, i++, addr != end && i < PTRS_PER_PUD);
 
 	return 0;
 }
 
-static int copy_page_tables(pgd_t *dst_pgdp, unsigned long start,
-			    unsigned long end)
+static int copy_pgd(struct trans_pgd_info *info, pgd_t *dst_pgdp,
+		    pgd_t *src_pgdp, unsigned long start, unsigned long end)
 {
 	unsigned long next;
 	unsigned long addr = start;
-	pgd_t *src_pgdp = pgd_offset_k(start);
+	int i = pgd_index(addr);
+	int rc;
 
-	dst_pgdp = pgd_offset_raw(dst_pgdp, start);
 	do {
+		pgd_t src_pgd;
+		pgd_t dst_pgd;
+		pud_t *dst_pudp, *src_pudp;
+
+		src_pgd = READ_ONCE(src_pgdp[i]);
+		dst_pgd = READ_ONCE(dst_pgdp[i]);
 		next = pgd_addr_end(addr, end);
-		if (pgd_none(READ_ONCE(*src_pgdp)))
+		if (pgd_none(src_pgd))
 			continue;
-		if (copy_pud(dst_pgdp, src_pgdp, addr, next))
-			return -ENOMEM;
-	} while (dst_pgdp++, src_pgdp++, addr = next, addr != end);
+
+		if (pgd_none(dst_pgd)) {
+			pud_t *t = trans_alloc(info);
+
+			if (!t)
+				return -ENOMEM;
+
+			__pgd_populate(&dst_pgdp[i], __pa(t), PUD_TYPE_TABLE);
+			dst_pgd = READ_ONCE(dst_pgdp[i]);
+		}
+
+		src_pudp = __va(pgd_page_paddr(src_pgd));
+		dst_pudp = __va(pgd_page_paddr(dst_pgd));
+
+		rc = copy_pud(info, dst_pudp, src_pudp, addr, next);
+		if (rc)
+			return rc;
+	} while (addr = next, i++, addr != end && i < PTRS_PER_PGD);
 
 	return 0;
 }
@@ -186,7 +204,7 @@ int trans_pgd_create_copy(struct trans_pgd_info *info, pgd_t **trans_pgd,
 	if (rc)
 		return rc;
 
-	return copy_page_tables(*trans_pgd, start, end);
+	return copy_pgd(info, *trans_pgd, from_table, start, end);
 }
 
 int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
-- 
2.23.0


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