diff mbox series

[v2,18/19] arm64: ptdump: Disregard unaddressable VA space

Message ID 20221124123932.2648991-19-ardb@kernel.org (mailing list archive)
State New, archived
Headers show
Series arm64: Enable LPA2 support for 4k and 16k pages | expand

Commit Message

Ard Biesheuvel Nov. 24, 2022, 12:39 p.m. UTC 
Configurations built with support for 52-bit virtual addressing can also
run on CPUs that only support 48 bits of VA space, in which case only
that part of swapper_pg_dir that represents the 48-bit addressable
region is relevant, and everything else is ignored by the hardware.

Our software pagetable walker has little in the way of input address
validation, and so it will happily start a walk from an address that is
not representable by the number of paging levels that are actually
active, resulting in lots of bogus output from the page table dumper
unless we take care to start at a valid address.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/mm/ptdump.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
index 9bc4066c5bf3..ca38ac2637b5 100644
--- a/arch/arm64/mm/ptdump.c
+++ b/arch/arm64/mm/ptdump.c
@@ -358,7 +358,7 @@  void ptdump_check_wx(void)
 		.ptdump = {
 			.note_page = note_page,
 			.range = (struct ptdump_range[]) {
-				{PAGE_OFFSET, ~0UL},
+				{_PAGE_OFFSET(vabits_actual), ~0UL},
 				{0, 0}
 			}
 		}
@@ -380,6 +380,8 @@  static int __init ptdump_init(void)
 	address_markers[KASAN_START_NR].start_address = KASAN_SHADOW_START;
 #endif
 	ptdump_initialize();
+	if (vabits_actual < VA_BITS)
+		kernel_ptdump_info.base_addr = _PAGE_OFFSET(vabits_actual);
 	ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
 	return 0;
 }