Now that all the handling is in place to deal with read-only page tables
at runtime, do a pass over the kernel page tables at boot to remap all
the page table pages read-only that were allocated early.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
arch/arm64/mm/mmu.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 971501535757..b1212f6d48f2 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -559,8 +559,23 @@ static void __init map_mem(pgd_t *pgdp)
memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
}
+static void mark_pgtables_ro(const pmd_t *pmdp, int level, int num_entries)
+{
+ while (num_entries--) {
+ if (pmd_valid(*pmdp) && pmd_table(*pmdp)) {
+ pmd_t *next = __va(__pmd_to_phys(*pmdp));
+
+ if (level < 2)
+ mark_pgtables_ro(next, level + 1, PTRS_PER_PMD);
+ set_pgtable_ro(next);
+ }
+ pmdp++;
+ }
+}
+
void mark_rodata_ro(void)
{
+ int pgd_level = 4 - CONFIG_PGTABLE_LEVELS;
unsigned long section_size;
/*
@@ -571,6 +586,11 @@ void mark_rodata_ro(void)
update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
section_size, PAGE_KERNEL_RO);
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+ mark_pgtables_ro((pmd_t *)&tramp_pg_dir, pgd_level, PTRS_PER_PGD);
+#endif
+ mark_pgtables_ro((pmd_t *)&swapper_pg_dir, pgd_level, PTRS_PER_PGD);
+
debug_checkwx();
}
--
2.30.2
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