1 files changed, 53 insertions, 7 deletions

diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index b5d603992d40..a9b467763153 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -32,13 +32,23 @@
 #define ALT_ORIG_PTR(a)		__ALT_PTR(a, orig_offset)
 #define ALT_REPL_PTR(a)		__ALT_PTR(a, alt_offset)
 
-int alternatives_applied;
+static int all_alternatives_applied;
+
+static DECLARE_BITMAP(applied_alternatives, ARM64_NCAPS);
 
 struct alt_region {
 	struct alt_instr *begin;
 	struct alt_instr *end;
 };
 
+bool alternative_is_applied(u16 cpufeature)
+{
+	if (WARN_ON(cpufeature >= ARM64_NCAPS))
+		return false;
+
+	return test_bit(cpufeature, applied_alternatives);
+}
+
 /*
  * Check if the target PC is within an alternative block.
  */
@@ -145,7 +155,8 @@ static void clean_dcache_range_nopatch(u64 start, u64 end)
 	} while (cur += d_size, cur < end);
 }
 
-static void __apply_alternatives(void *alt_region, bool is_module)
+static void __apply_alternatives(void *alt_region,  bool is_module,
+				 unsigned long *feature_mask)
 {
 	struct alt_instr *alt;
 	struct alt_region *region = alt_region;
@@ -155,6 +166,9 @@ static void __apply_alternatives(void *alt_region, bool is_module)
 	for (alt = region->begin; alt < region->end; alt++) {
 		int nr_inst;
 
+		if (!test_bit(alt->cpufeature, feature_mask))
+			continue;
+
 		/* Use ARM64_CB_PATCH as an unconditional patch */
 		if (alt->cpufeature < ARM64_CB_PATCH &&
 		    !cpus_have_cap(alt->cpufeature))
@@ -192,6 +206,12 @@ static void __apply_alternatives(void *alt_region, bool is_module)
 		dsb(ish);
 		__flush_icache_all();
 		isb();
+
+		/* Ignore ARM64_CB bit from feature mask */
+		bitmap_or(applied_alternatives, applied_alternatives,
+			  feature_mask, ARM64_NCAPS);
+		bitmap_and(applied_alternatives, applied_alternatives,
+			   cpu_hwcaps, ARM64_NCAPS);
 	}
 }
 
@@ -208,14 +228,19 @@ static int __apply_alternatives_multi_stop(void *unused)
 
 	/* We always have a CPU 0 at this point (__init) */
 	if (smp_processor_id()) {
-		while (!READ_ONCE(alternatives_applied))
+		while (!READ_ONCE(all_alternatives_applied))
 			cpu_relax();
 		isb();
 	} else {
-		BUG_ON(alternatives_applied);
-		__apply_alternatives(&region, false);
+		DECLARE_BITMAP(remaining_capabilities, ARM64_NPATCHABLE);
+
+		bitmap_complement(remaining_capabilities, boot_capabilities,
+				  ARM64_NPATCHABLE);
+
+		BUG_ON(all_alternatives_applied);
+		__apply_alternatives(&region, false, remaining_capabilities);
 		/* Barriers provided by the cache flushing */
-		WRITE_ONCE(alternatives_applied, 1);
+		WRITE_ONCE(all_alternatives_applied, 1);
 	}
 
 	return 0;
@@ -227,6 +252,24 @@ void __init apply_alternatives_all(void)
 	stop_machine(__apply_alternatives_multi_stop, NULL, cpu_online_mask);
 }
 
+/*
+ * This is called very early in the boot process (directly after we run
+ * a feature detect on the boot CPU). No need to worry about other CPUs
+ * here.
+ */
+void __init apply_boot_alternatives(void)
+{
+	struct alt_region region = {
+		.begin	= (struct alt_instr *)__alt_instructions,
+		.end	= (struct alt_instr *)__alt_instructions_end,
+	};
+
+	/* If called on non-boot cpu things could go wrong */
+	WARN_ON(smp_processor_id() != 0);
+
+	__apply_alternatives(&region, false, &boot_capabilities[0]);
+}
+
 #ifdef CONFIG_MODULES
 void apply_alternatives_module(void *start, size_t length)
 {
@@ -234,7 +277,10 @@ void apply_alternatives_module(void *start, size_t length)
 		.begin	= start,
 		.end	= start + length,
 	};
+	DECLARE_BITMAP(all_capabilities, ARM64_NPATCHABLE);
+
+	bitmap_fill(all_capabilities, ARM64_NPATCHABLE);
 
-	__apply_alternatives(&region, true);
+	__apply_alternatives(&region, true, &all_capabilities[0]);
 }
 #endif