From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Wei-Lin Chang <weilin.chang@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Will Deacon <will@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.12 1273/1376] arm64: ptdump: Make note_page_flush() range aware
Date: Sat, 12 Sep 2026 09:01:39 +0200
Message-ID: <20260912065635.911109432@linuxfoundation.org>
In-Reply-To: <20260912065607.535295758@linuxfoundation.org>
References: <20260912065607.535295758@linuxfoundation.org>
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6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wei-Lin Chang <weilin.chang@arm.com>

[ Upstream commit 902caade3cfd60f99bf71b355e7c86344bd831e5 ]

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: 9d80448ac92b ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm64/include/asm/ptdump.h |  2 ++
 arch/arm64/mm/ptdump.c          | 14 +++++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h
index 01033c1d38dc2..8bf87ac9bb4ba 100644
--- a/arch/arm64/include/asm/ptdump.h
+++ b/arch/arm64/include/asm/ptdump.h
@@ -50,6 +50,8 @@ 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;
 	u64 current_prot;
 	bool check_wx;
diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
index cafaff8056b14..93a872582ede8 100644
--- a/arch/arm64/mm/ptdump.c
+++ b/arch/arm64/mm/ptdump.c
@@ -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));
 }
 
 void ptdump_walk(struct seq_file *s, struct ptdump_info *info)
@@ -296,6 +306,7 @@ 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,
@@ -337,6 +348,7 @@ bool ptdump_check_wx(void)
 			{ -1, NULL},
 		},
 		.pg_level = &kernel_pg_levels[0],
+		.end_address = ~0UL,
 		.level = -1,
 		.check_wx = true,
 		.ptdump = {
-- 
2.53.0