Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/…

…git/arm64/linux

Pull arm64 fixes from Will Deacon:
 "Two arm64 fixes for -rc6. They resolve a kernel NULL dereference in
  kexec and bogus kernel page table dumping when userspace is configured
  for 52-bit virtual addressing.

  Summary:

   - Fix kernel oops when attemping kexec_file() with a NULL cmdline

   - Fix page table output in debugfs when ARM64_USER_VA_BITS_52=y"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: kexec_file: handle empty command-line
  arm64: ptdump: Don't iterate kernel page tables using PTRS_PER_PXX

arch/arm64/kernel/machine_kexec_file.c

@@ -120,10 +120,12 @@ static int create_dtb(struct kimage *image,
 {
 	void *buf;
 	size_t buf_size;
+	size_t cmdline_len;
 	int ret;
 
+	cmdline_len = cmdline ? strlen(cmdline) : 0;
 	buf_size = fdt_totalsize(initial_boot_params)
-			+ strlen(cmdline) + DTB_EXTRA_SPACE;
+			+ cmdline_len + DTB_EXTRA_SPACE;
 
 	for (;;) {
 		buf = vmalloc(buf_size);

arch/arm64/mm/dump.c

@@ -286,74 +286,73 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
 
 }
 
-static void walk_pte(struct pg_state *st, pmd_t *pmdp, unsigned long start)
+static void walk_pte(struct pg_state *st, pmd_t *pmdp, unsigned long start,
+		     unsigned long end)
 {
-	pte_t *ptep = pte_offset_kernel(pmdp, 0UL);
-	unsigned long addr;
-	unsigned i;
+	unsigned long addr = start;
+	pte_t *ptep = pte_offset_kernel(pmdp, start);
 
-	for (i = 0; i < PTRS_PER_PTE; i++, ptep++) {
-		addr = start + i * PAGE_SIZE;
+	do {
 		note_page(st, addr, 4, READ_ONCE(pte_val(*ptep)));
-	}
+	} while (ptep++, addr += PAGE_SIZE, addr != end);
 }
 
-static void walk_pmd(struct pg_state *st, pud_t *pudp, unsigned long start)
+static void walk_pmd(struct pg_state *st, pud_t *pudp, unsigned long start,
+		     unsigned long end)
 {
-	pmd_t *pmdp = pmd_offset(pudp, 0UL);
-	unsigned long addr;
-	unsigned i;
+	unsigned long next, addr = start;
+	pmd_t *pmdp = pmd_offset(pudp, start);
 
-	for (i = 0; i < PTRS_PER_PMD; i++, pmdp++) {
+	do {
 		pmd_t pmd = READ_ONCE(*pmdp);
+		next = pmd_addr_end(addr, end);
 
-		addr = start + i * PMD_SIZE;
 		if (pmd_none(pmd) || pmd_sect(pmd)) {
 			note_page(st, addr, 3, pmd_val(pmd));
 		} else {
 			BUG_ON(pmd_bad(pmd));
-			walk_pte(st, pmdp, addr);
+			walk_pte(st, pmdp, addr, next);
 		}
-	}
+	} while (pmdp++, addr = next, addr != end);
 }
 
-static void walk_pud(struct pg_state *st, pgd_t *pgdp, unsigned long start)
+static void walk_pud(struct pg_state *st, pgd_t *pgdp, unsigned long start,
+		     unsigned long end)
 {
-	pud_t *pudp = pud_offset(pgdp, 0UL);
-	unsigned long addr;
-	unsigned i;
+	unsigned long next, addr = start;
+	pud_t *pudp = pud_offset(pgdp, start);
 
-	for (i = 0; i < PTRS_PER_PUD; i++, pudp++) {
+	do {
 		pud_t pud = READ_ONCE(*pudp);
+		next = pud_addr_end(addr, end);
 
-		addr = start + i * PUD_SIZE;
 		if (pud_none(pud) || pud_sect(pud)) {
 			note_page(st, addr, 2, pud_val(pud));
 		} else {
 			BUG_ON(pud_bad(pud));
-			walk_pmd(st, pudp, addr);
+			walk_pmd(st, pudp, addr, next);
 		}
-	}
+	} while (pudp++, addr = next, addr != end);
 }
 
 static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
 		     unsigned long start)
 {
-	pgd_t *pgdp = pgd_offset(mm, 0UL);
-	unsigned i;
-	unsigned long addr;
+	unsigned long end = (start < TASK_SIZE_64) ? TASK_SIZE_64 : 0;
+	unsigned long next, addr = start;
+	pgd_t *pgdp = pgd_offset(mm, start);
 
-	for (i = 0; i < PTRS_PER_PGD; i++, pgdp++) {
+	do {
 		pgd_t pgd = READ_ONCE(*pgdp);
+		next = pgd_addr_end(addr, end);
 
-		addr = start + i * PGDIR_SIZE;
 		if (pgd_none(pgd)) {
 			note_page(st, addr, 1, pgd_val(pgd));
 		} else {
 			BUG_ON(pgd_bad(pgd));
-			walk_pud(st, pgdp, addr);
+			walk_pud(st, pgdp, addr, next);
 		}
-	}
+	} while (pgdp++, addr = next, addr != end);
 }
 
 void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)