arm64: Fix 5-level paging support in kexec/hibernate trampoline

Add the missing code to allocate P4D level page tables when cloning the the kernel page tables. This fixes a crash that may be observed when attempting to resume from hibernation on an LPA2 capable system with 4k pages, which therefore uses 5 levels of paging. Presumably, kexec is equally affected. Signed-off-by: Ard Biesheuvel <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Will Deacon <[email protected]>
torvalds · Feb 4, 2025 · 3648027 · 3648027
1 parent 2014c95
commit 3648027
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
@@ -162,6 +162,13 @@ static int copy_p4d(struct trans_pgd_info *info, pgd_t *dst_pgdp,
 	unsigned long next;
 	unsigned long addr = start;
 
+	if (pgd_none(READ_ONCE(*dst_pgdp))) {
+		dst_p4dp = trans_alloc(info);
+		if (!dst_p4dp)
+			return -ENOMEM;
+		pgd_populate(NULL, dst_pgdp, dst_p4dp);
+	}
+
 	dst_p4dp = p4d_offset(dst_pgdp, start);
 	src_p4dp = p4d_offset(src_pgdp, start);
 	do {