Subject: [PATCH V4 04/11] arm64: dump: De-constify VA_START and KASAN_SHADOW_START

From: Steve Capper <[email-masked]>
Date: Mon, 29 Jul 2019 17:21:10 +0100

The kernel page table dumper assumes that the placement of VA regions is
constant and determined at compile time. As we are about to introduce
variable VA logic, we need to be able to determine certain regions at
boot time.

Specifically the VA_START and KASAN_SHADOW_START will depend on whether
or not the system is booted with 52-bit kernel VAs.

This patch adds logic to the kernel page table dumper s.t. these regions
can be computed at boot time.

Signed-off-by: Steve Capper <[email-masked]>

---

Changed in V3 - simplified the scope of de-constifying to just VA_START
and KASAN_SHADOW_START.
---
 arch/arm64/mm/dump.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index 6f0b9f8ddf55..afe7e1460557 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -25,11 +25,20 @@
 #include <asm/pgtable-hwdef.h>
 #include <asm/ptdump.h>
 
-static const struct addr_marker address_markers[] = {
+
+enum address_markers_idx {
+	PAGE_OFFSET_NR = 0,
+	VA_START_NR,
+#ifdef CONFIG_KASAN
+	KASAN_START_NR,
+#endif
+};
+
+static struct addr_marker address_markers[] = {
 	{ PAGE_OFFSET,			"Linear Mapping start" },
-	{ VA_START,			"Linear Mapping end" },
+	{ 0 /* VA_START */,		"Linear Mapping end" },
 #ifdef CONFIG_KASAN
-	{ KASAN_SHADOW_START,		"Kasan shadow start" },
+	{ 0 /* KASAN_SHADOW_START */,	"Kasan shadow start" },
 	{ KASAN_SHADOW_END,		"Kasan shadow end" },
 #endif
 	{ MODULES_VADDR,		"Modules start" },
@@ -402,6 +411,10 @@ void ptdump_check_wx(void)
 
 static int ptdump_init(void)
 {
+	address_markers[VA_START_NR].start_address = VA_START;
+#ifdef CONFIG_KASAN
+	address_markers[KASAN_START_NR].start_address = KASAN_SHADOW_START;
+#endif
 	ptdump_initialize();
 	ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
 	return 0;
-- 
2.20.1

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