diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index b12e4437bf0a247f3269919969a432a88da37e6e..f3fea3928efce873a5fe3290d08a2ae3a92826cc 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1469,6 +1469,7 @@ static void add_cpu_to_masks(int cpu)
 }
 
 /* Activate a secondary processor. */
+__no_stack_protector
 void start_secondary(void *unused)
 {
 	unsigned int cpu = raw_smp_processor_id();
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index 08eb06301791d7ad4a44b867e2498904813c5f6f..6f495fca9d79574463f95cd9b4bbc521800b5ab6 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -251,6 +251,18 @@
  */
 #define __noreturn                      __attribute__((__noreturn__))
 
+/*
+ * Optional: only supported since GCC >= 11.1, clang >= 7.0.
+ *
+ *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fstack_005fprotector-function-attribute
+ *   clang: https://clang.llvm.org/docs/AttributeReference.html#no-stack-protector-safebuffers
+ */
+#if __has_attribute(__no_stack_protector__)
+# define __no_stack_protector		__attribute__((__no_stack_protector__))
+#else
+# define __no_stack_protector
+#endif
+
 /*
  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute
  * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute
diff --git a/init/main.c b/init/main.c
index 2b466bd041104f56047fdb96107f55633c8470e5..86b31c0f485692789af49d8581f13360e262df76 100644
--- a/init/main.c
+++ b/init/main.c
@@ -874,7 +874,8 @@ void __init __weak arch_call_rest_init(void)
 	rest_init();
 }
 
-asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
+asmlinkage __visible __init __no_sanitize_address __noreturn __no_stack_protector
+void start_kernel(void)
 {
 	char *command_line;
 	char *after_dashes;
@@ -1076,6 +1077,7 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
 	arch_call_rest_init();
 
 	prevent_tail_call_optimization();
+	unreachable();
 }
 
 /* Call all constructor functions linked into the kernel. */