arm64: text replication: verify kernel textktext

Verify that the replicated kernel image for the non-boot nodes matches
the boot kernel image, and report differences found. This ensures that
the non-boot modes are running an identical copy of the kernel.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

1 files changed, 37 insertions, 0 deletions

diff --git a/arch/arm64/mm/ktext.c b/arch/arm64/mm/ktext.c
index d29497c37da9..d9d7c0bb064d 100644
--- a/arch/arm64/mm/ktext.c
+++ b/arch/arm64/mm/ktext.c
@@ -124,6 +124,43 @@ void ktext_replication_patch_alternative(__le32 *src, int nr_inst)
 	}
 }
 
+static int __init ktext_replication_check(void)
+{
+	size_t size = _etext - _stext;
+	int nid;
+
+	preempt_disable();
+	pr_info("CPU%u: Checking ktext replication\n", smp_processor_id());
+
+	for_each_node(nid) {
+		if (!kernel_texts[nid])
+			continue;
+
+		if (memcmp(_stext, kernel_texts[nid], size)) {
+			u32 *st, *kt;
+			size_t i, n;
+
+			pr_err("NID%u: kernel text disagreement\n", nid);
+
+			st = (u32 *)_stext;
+			kt = kernel_texts[nid];
+			for (i = n = 0; i < size / 4; i ++) {
+				if (st[i] != kt[i]) {
+					pr_err("Offset 0x%zx: 0x%08x != 0x%08x\n",
+						i * 4, st[i], kt[i]);
+					if (n++ > 8)
+						break;
+				}
+			}
+		}
+	}
+	preempt_enable();
+
+	return 0;
+}
+late_initcall(ktext_replication_check);
+
+
 static bool ktext_enabled = IS_ENABLED(CONFIG_REPLICATE_KTEXT_DEFAULT);
 
 static int __init parse_ktext(char *str)