RISC-V: Add page table dump support for uefi

Extend the current page table dump support in RISC-V to include efi
pages as well.

Here is the output of efi runtime page table mappings.

---[ UEFI runtime start ]---
0x0000000020002000-0x0000000020003000 0x00000000be732000 4K PTE D A . . . W R V
0x0000000020018000-0x0000000020019000 0x00000000be738000 4K PTE D A . . . W R V
0x000000002002c000-0x000000002002d000 0x00000000be73c000 4K PTE D A . . . W R V
0x0000000020031000-0x0000000020032000 0x00000000bff61000 4K PTE D A . . X W R V
---[ UEFI runtime end ]---

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/mm/ptdump.c

@@ -3,6 +3,7 @@
  * Copyright (C) 2019 SiFive
  */
 
+#include <linux/efi.h>
 #include <linux/init.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
@@ -49,6 +50,14 @@ struct addr_marker {
 	const char *name;
 };
 
+/* Private information for debugfs */
+struct ptd_mm_info {
+	struct mm_struct		*mm;
+	const struct addr_marker	*markers;
+	unsigned long base_addr;
+	unsigned long end;
+};
+
 static struct addr_marker address_markers[] = {
 #ifdef CONFIG_KASAN
 	{KASAN_SHADOW_START,	"Kasan shadow start"},
@@ -68,6 +77,28 @@ static struct addr_marker address_markers[] = {
 	{-1, NULL},
 };
 
+static struct ptd_mm_info kernel_ptd_info = {
+	.mm		= &init_mm,
+	.markers	= address_markers,
+	.base_addr	= KERN_VIRT_START,
+	.end		= ULONG_MAX,
+};
+
+#ifdef CONFIG_EFI
+static struct addr_marker efi_addr_markers[] = {
+		{ 0,		"UEFI runtime start" },
+		{ SZ_1G,	"UEFI runtime end" },
+		{ -1,		NULL }
+};
+
+static struct ptd_mm_info efi_ptd_info = {
+	.mm		= &efi_mm,
+	.markers	= efi_addr_markers,
+	.base_addr	= 0,
+	.end		= SZ_2G,
+};
+#endif
+
 /* Page Table Entry */
 struct prot_bits {
 	u64 mask;
@@ -245,22 +276,22 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr,
 	}
 }
 
-static void ptdump_walk(struct seq_file *s)
+static void ptdump_walk(struct seq_file *s, struct ptd_mm_info *pinfo)
 {
 	struct pg_state st = {
 		.seq = s,
-		.marker = address_markers,
+		.marker = pinfo->markers,
 		.level = -1,
 		.ptdump = {
 			.note_page = note_page,
 			.range = (struct ptdump_range[]) {
-				{KERN_VIRT_START, ULONG_MAX},
+				{pinfo->base_addr, pinfo->end},
 				{0, 0}
 			}
 		}
 	};
 
-	ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
+	ptdump_walk_pgd(&st.ptdump, pinfo->mm, NULL);
 }
 
 void ptdump_check_wx(void)
@@ -293,7 +324,7 @@ void ptdump_check_wx(void)
 
 static int ptdump_show(struct seq_file *m, void *v)
 {
-	ptdump_walk(m);
+	ptdump_walk(m, m->private);
 
 	return 0;
 }
@@ -308,8 +339,13 @@ static int ptdump_init(void)
 		for (j = 0; j < ARRAY_SIZE(pte_bits); j++)
 			pg_level[i].mask |= pte_bits[j].mask;
 
-	debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
+	debugfs_create_file("kernel_page_tables", 0400, NULL, &kernel_ptd_info,
 			    &ptdump_fops);
+#ifdef CONFIG_EFI
+	if (efi_enabled(EFI_RUNTIME_SERVICES))
+		debugfs_create_file("efi_page_tables", 0400, NULL, &efi_ptd_info,
+				    &ptdump_fops);
+#endif
 
 	return 0;
 }