[PATCH 3/4] arm64: Move the zero page to rodata

Ard Biesheuvel
2026-01-19T16:56:23Z

From: Ard Biesheuvel <ardb@kernel.org>

The zero page should contain only zero bytes, and so mapping it
read-write is unnecessary. Move it to __ro_after_init instead.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/mm/mmu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 2a18637ecc15..d978b07ab7b8 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -68,7 +68,8 @@ long __section(".mmuoff.data.write") __early_cpu_boot_status;
* Empty_zero_page is a special page that is used for zero-initialized data
* and COW.
*/
-unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
+ __ro_after_init __aligned(PAGE_SIZE);
EXPORT_SYMBOL(empty_zero_page);

static DEFINE_SPINLOCK(swapper_pgdir_lock);
--
2.52.0.457.g6b5491de43-goog