[PATCH] handle renamed init_level4_pgt -> init_top_pgt

[Jeff Mahoney]

Linux 4.13 renamed init_level4_pgt to init_top_pgt in preparation for
introducing 5-level page tables.  This patch follows the rename if
the lookup for init_level4_pgt fails.  It also checks to see if
5-level page tables are enabled and bails if it discovers they are.

Signed-off-by: Jeff Mahoney <jeffm at suse.com>
---
 arch/x86_64.c  | 24 +++++++++++++++++++++---
 makedumpfile.c |  6 ++++++
 makedumpfile.h |  2 ++
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/arch/x86_64.c b/arch/x86_64.c
index 08dd6b2..9b09035 100644
--- a/arch/x86_64.c
+++ b/arch/x86_64.c
@@ -259,16 +259,26 @@ vtop4_x86_64(unsigned long vaddr)
 {
 	unsigned long page_dir, pml4, pgd_paddr, pgd_pte, pmd_paddr, pmd_pte;
 	unsigned long pte_paddr, pte;
+	unsigned long init_level4_pgt;
 
-	if (SYMBOL(init_level4_pgt) == NOT_FOUND_SYMBOL) {
+	if (SYMBOL(init_level4_pgt) != NOT_FOUND_SYMBOL)
+		init_level4_pgt = SYMBOL(init_level4_pgt);
+	else if (SYMBOL(init_top_pgt) != NOT_FOUND_SYMBOL)
+		init_level4_pgt = SYMBOL(init_top_pgt);
+	else {
 		ERRMSG("Can't get the symbol of init_level4_pgt.\n");
 		return NOT_PADDR;
 	}
 
+	if (SYMBOL(level4_kernel_pgt) != NOT_FOUND_SYMBOL) {
+		ERRMSG("Kernel is built with 5-level page tables\n");
+		return NOT_PADDR;
+	}
+
 	/*
 	 * Get PGD.
 	 */
-	page_dir = SYMBOL(init_level4_pgt) - __START_KERNEL_map + info->phys_base;
+	page_dir = init_level4_pgt - __START_KERNEL_map + info->phys_base;
 	if (is_xen_memory()) {
 		page_dir = ptom_xen(page_dir);
 		if (page_dir == NOT_PADDR)
@@ -549,8 +559,16 @@ find_vmemmap_x86_64()
 	struct vmap_pfns *vmapp, *vmaphead = NULL, *cur, *tail;
 
 	init_level4_pgt = SYMBOL(init_level4_pgt);
+	if (init_level4_pgt == NOT_FOUND_SYMBOL)
+		init_level4_pgt = SYMBOL(init_top_pgt);
+
 	if (init_level4_pgt == NOT_FOUND_SYMBOL) {
-		ERRMSG("init_level4_pgt not found\n");
+		ERRMSG("init_level4_pgt/init_top_pgt not found\n");
+		return FAILED;
+	}
+
+	if (SYMBOL(level4_kernel_pgt) != NOT_FOUND_SYMBOL) {
+		ERRMSG("kernel is configured for 5-level page tables\n");
 		return FAILED;
 	}
 	pagestructsize = size_table.page;
diff --git a/makedumpfile.c b/makedumpfile.c
index f85003a..6e5ec34 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -1486,6 +1486,8 @@ get_symbol_info(void)
 	SYMBOL_INIT(_stext, "_stext");
 	SYMBOL_INIT(swapper_pg_dir, "swapper_pg_dir");
 	SYMBOL_INIT(init_level4_pgt, "init_level4_pgt");
+	SYMBOL_INIT(level4_kernel_pgt, "level4_kernel_pgt");
+	SYMBOL_INIT(init_top_pgt, "init_top_pgt");
 	SYMBOL_INIT(vmlist, "vmlist");
 	SYMBOL_INIT(vmap_area_list, "vmap_area_list");
 	SYMBOL_INIT(node_online_map, "node_online_map");
@@ -2105,6 +2107,8 @@ write_vmcoreinfo_data(void)
 	WRITE_SYMBOL("_stext", _stext);
 	WRITE_SYMBOL("swapper_pg_dir", swapper_pg_dir);
 	WRITE_SYMBOL("init_level4_pgt", init_level4_pgt);
+	WRITE_SYMBOL("level4_kernel_pgt", level4_kernel_pgt);
+	WRITE_SYMBOL("init_top_pgt", init_top_pgt);
 	WRITE_SYMBOL("vmlist", vmlist);
 	WRITE_SYMBOL("vmap_area_list", vmap_area_list);
 	WRITE_SYMBOL("node_online_map", node_online_map);
@@ -2500,6 +2504,8 @@ read_vmcoreinfo(void)
 	READ_SYMBOL("_stext", _stext);
 	READ_SYMBOL("swapper_pg_dir", swapper_pg_dir);
 	READ_SYMBOL("init_level4_pgt", init_level4_pgt);
+	READ_SYMBOL("level4_kernel_pgt", level4_kernel_pgt);
+	READ_SYMBOL("init_top_pgt", init_top_pgt);
 	READ_SYMBOL("vmlist", vmlist);
 	READ_SYMBOL("vmap_area_list", vmap_area_list);
 	READ_SYMBOL("node_online_map", node_online_map);
diff --git a/makedumpfile.h b/makedumpfile.h
index 8a05794..9357e47 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -1517,6 +1517,8 @@ struct symbol_table {
 	unsigned long long	_stext;
 	unsigned long long	swapper_pg_dir;
 	unsigned long long	init_level4_pgt;
+	unsigned long long	level4_kernel_pgt;
+	unsigned long long	init_top_pgt;
 	unsigned long long	vmlist;
 	unsigned long long	vmap_area_list;
 	unsigned long long	phys_base;


-- 
Jeff Mahoney
SUSE Labs