arm64: ptdump: Allow all region boundaries to be defined at boot time

Rework the way the address_markers array is populated so that we can
tolerate values that are not compile time constants generally, rather
than keeping track manually of the array indexes in question, and poking
new values into them manually. This will be needed for VMALLOC_END,
which will cease to be a compile time constant after a subsequent patch.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20231213084024.2367360-12-ardb@google.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>

arch/arm64/mm/ptdump.c

@@ -26,34 +26,6 @@
 #include <asm/ptdump.h>
 
 
-enum address_markers_idx {
-	PAGE_OFFSET_NR = 0,
-	PAGE_END_NR,
-#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
-	KASAN_START_NR,
-#endif
-};
-
-static struct addr_marker address_markers[] = {
-	{ PAGE_OFFSET,			"Linear Mapping start" },
-	{ 0 /* PAGE_END */,		"Linear Mapping end" },
-#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
-	{ 0 /* KASAN_SHADOW_START */,	"Kasan shadow start" },
-	{ KASAN_SHADOW_END,		"Kasan shadow end" },
-#endif
-	{ MODULES_VADDR,		"Modules start" },
-	{ MODULES_END,			"Modules end" },
-	{ VMALLOC_START,		"vmalloc() area" },
-	{ VMALLOC_END,			"vmalloc() end" },
-	{ VMEMMAP_START,		"vmemmap start" },
-	{ VMEMMAP_END,			"vmemmap end" },
-	{ PCI_IO_START,			"PCI I/O start" },
-	{ PCI_IO_END,			"PCI I/O end" },
-	{ FIXADDR_TOT_START,		"Fixmap start" },
-	{ FIXADDR_TOP,			"Fixmap end" },
-	{ -1,				NULL },
-};
-
 #define pt_dump_seq_printf(m, fmt, args...)	\
 ({						\
 	if (m)					\
@@ -339,9 +311,8 @@ static void __init ptdump_initialize(void)
 				pg_level[i].mask |= pg_level[i].bits[j].mask;
 }
 
-static struct ptdump_info kernel_ptdump_info = {
+static struct ptdump_info kernel_ptdump_info __ro_after_init = {
 	.mm		= &init_mm,
-	.markers	= address_markers,
 	.base_addr	= PAGE_OFFSET,
 };
 
@@ -375,10 +346,29 @@ void ptdump_check_wx(void)
 
 static int __init ptdump_init(void)
 {
-	address_markers[PAGE_END_NR].start_address = PAGE_END;
+	struct addr_marker m[] = {
+		{ PAGE_OFFSET,		"Linear Mapping start" },
+		{ PAGE_END,		"Linear Mapping end" },
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
-	address_markers[KASAN_START_NR].start_address = KASAN_SHADOW_START;
+		{ KASAN_SHADOW_START,   "Kasan shadow start" },
+		{ KASAN_SHADOW_END,     "Kasan shadow end" },
 #endif
+		{ MODULES_VADDR,	"Modules start" },
+		{ MODULES_END,		"Modules end" },
+		{ VMALLOC_START,	"vmalloc() area" },
+		{ VMALLOC_END,		"vmalloc() end" },
+		{ VMEMMAP_START,	"vmemmap start" },
+		{ VMEMMAP_END,		"vmemmap end" },
+		{ PCI_IO_START,		"PCI I/O start" },
+		{ PCI_IO_END,		"PCI I/O end" },
+		{ FIXADDR_TOT_START,    "Fixmap start" },
+		{ FIXADDR_TOP,	        "Fixmap end" },
+		{ -1,			NULL },
+	};
+	static struct addr_marker address_markers[ARRAY_SIZE(m)] __ro_after_init;
+
+	kernel_ptdump_info.markers = memcpy(address_markers, m, sizeof(m));
+
 	ptdump_initialize();
 	ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
 	return 0;