1 files changed, 32 insertions, 11 deletions

diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index 414288a558c8..5c4bce4ac381 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -107,32 +107,53 @@ static u32 get_alt_insn(struct alt_instr *alt, __le32 *insnptr, __le32 *altinsnp
 	return insn;
 }
 
+static void patch_alternative(struct alt_instr *alt,
+			      __le32 *origptr, __le32 *updptr, int nr_inst)
+{
+	__le32 *replptr;
+	int i;
+
+	replptr = ALT_REPL_PTR(alt);
+	for (i = 0; i < nr_inst; i++) {
+		u32 insn;
+
+		insn = get_alt_insn(alt, origptr + i, replptr + i);
+		updptr[i] = cpu_to_le32(insn);
+	}
+}
+
 static void __apply_alternatives(void *alt_region, bool use_linear_alias)
 {
 	struct alt_instr *alt;
 	struct alt_region *region = alt_region;
-	__le32 *origptr, *replptr, *updptr;
+	__le32 *origptr, *updptr;
+	alternative_cb_t alt_cb;
 
 	for (alt = region->begin; alt < region->end; alt++) {
-		u32 insn;
-		int i, nr_inst;
+		int nr_inst;
 
-		if (!cpus_have_cap(alt->cpufeature))
+		/* Use ARM64_CB_PATCH as an unconditional patch */
+		if (alt->cpufeature < ARM64_CB_PATCH &&
+		    !cpus_have_cap(alt->cpufeature))
 			continue;
 
-		BUG_ON(alt->alt_len != alt->orig_len);
+		if (alt->cpufeature == ARM64_CB_PATCH)
+			BUG_ON(alt->alt_len != 0);
+		else
+			BUG_ON(alt->alt_len != alt->orig_len);
 
 		pr_info_once("patching kernel code\n");
 
 		origptr = ALT_ORIG_PTR(alt);
-		replptr = ALT_REPL_PTR(alt);
 		updptr = use_linear_alias ? lm_alias(origptr) : origptr;
-		nr_inst = alt->alt_len / sizeof(insn);
+		nr_inst = alt->orig_len / AARCH64_INSN_SIZE;
 
-		for (i = 0; i < nr_inst; i++) {
-			insn = get_alt_insn(alt, origptr + i, replptr + i);
-			updptr[i] = cpu_to_le32(insn);
-		}
+		if (alt->cpufeature < ARM64_CB_PATCH)
+			alt_cb = patch_alternative;
+		else
+			alt_cb  = ALT_REPL_PTR(alt);
+
+		alt_cb(alt, origptr, updptr, nr_inst);
 
 		flush_icache_range((uintptr_t)origptr,
 				   (uintptr_t)(origptr + nr_inst));