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arm64: ptdump: Make note_page_flush() range aware

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note_page_flush() calls note_page() with addr == 0 and level == -1 to
dump the last row of a ptdump. addr == 0 (1 << 64 wrapped around)
renders a huge region with enormous size for address spaces with
IA bits < 64. For example the stage-2 page tables and the EFI runtime
page table.

More importantly, the last region of the address space and everything
after the address space up to 1 << 64 are merged into one row of
output. If the last region within the address space is valid, it will
appear to remain valid up to 1 << 64 with the same attributes.

Currently only the EFI runtime ptdump is affected by this, but KVM will
soon fix its stage-2 ptdump by using note_page_flush(). Here is an
example of an EFI runtime ptdump (last row):

0x0000008000000000-0x0000000000000000   17179868672G PGD

With this patch:

0x0000008000000000-0x0001000000000000      261632G PGD

To fix this, cache the end address of a ptdump in ptdump_pg_state so
note_page_flush() can call the final note_page() with the correct end
address.

Fixes: 9d80448ac9 ("efi/arm64: Add debugfs node to dump UEFI runtime page tables")
Signed-off-by: Wei-Lin Chang <weilin.chang@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Wei-Lin Chang 2026-08-14 23:24:57 +01:00 committed by Will Deacon
parent 26b77009ee
commit 902caade3c
2 changed files with 15 additions and 1 deletions
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2
arch/arm64/include/asm/ptdump.h
View File

@ -52,6 +52,8 @@ struct ptdump_pg_state {
const struct addr_marker *marker;
const struct mm_struct *mm;
unsigned long start_address;
/* exclusive end, ULONG_MAX represents an end at 1 << 64 */
unsigned long end_address;
int level;
ptval_t current_prot;
bool check_wx;

14
arch/arm64/mm/ptdump.c
View File

@ -278,9 +278,19 @@ void note_page_pgd(struct ptdump_state *pt_st, unsigned long addr, pgd_t pgd)
void note_page_flush(struct ptdump_state *pt_st)
{
struct ptdump_pg_state *st = container_of(pt_st, struct ptdump_pg_state, ptdump);
unsigned long end = st->end_address;
pte_t pte_zero = {0};
note_page(pt_st, 0, -1, pte_val(pte_zero));
/*
* Address spaces that end at 1 << 64 have end_address == ULONG_MAX,
* but note_page() expects the exclusive end. In this case adjust end
* to the wraparound value 0.
*/
if (end == ULONG_MAX)
end = 0;
note_page(pt_st, end, -1, pte_val(pte_zero));
}
static void arm64_ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm)
@ -303,6 +313,7 @@ void ptdump_walk(struct seq_file *s, struct ptdump_info *info)
.marker = info->markers,
.mm = info->mm,
.pg_level = &kernel_pg_levels[0],
.end_address = end,
.level = -1,
.ptdump = {
.note_page_pte = note_page_pte,
@ -344,6 +355,7 @@ bool ptdump_check_wx(void)
{ -1, NULL},
},
.pg_level = &kernel_pg_levels[0],
.end_address = ~0UL,
.level = -1,
.check_wx = true,
.ptdump = {