jump_labels: Mark __jump_label_transform() as __always_inlined to wor…

…k around aggressive compiler un-inlining

In randconfig testing, certain UBSAN and CC Kconfig combinations
with GCC 10.3.0:

  CONFIG_X86_32=y

  CONFIG_CC_OPTIMIZE_FOR_SIZE=y

  CONFIG_UBSAN=y
  # CONFIG_UBSAN_TRAP is not set
  # CONFIG_UBSAN_BOUNDS is not set
  CONFIG_UBSAN_SHIFT=y
  # CONFIG_UBSAN_DIV_ZERO is not set
  CONFIG_UBSAN_UNREACHABLE=y
  CONFIG_UBSAN_BOOL=y
  # CONFIG_UBSAN_ENUM is not set
  # CONFIG_UBSAN_ALIGNMENT is not set
  # CONFIG_UBSAN_SANITIZE_ALL is not set

... produce this build warning (and build error if
CONFIG_SECTION_MISMATCH_WARN_ONLY=y is set):

  WARNING: modpost: vmlinux.o(.text+0x4c1cc): Section mismatch in reference from the function __jump_label_transform() to the function .init.text:text_poke_early()
  The function __jump_label_transform() references
  the function __init text_poke_early().
  This is often because __jump_label_transform lacks a __init
  annotation or the annotation of text_poke_early is wrong.

  ERROR: modpost: Section mismatches detected.

The problem is that __jump_label_transform() gets uninlined by GCC,
despite there being only a single local scope user of the 'static inline'
function.

Mark the function __always_inline instead, to work around this compiler
bug/artifact.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/jump_label.c

@@ -79,9 +79,10 @@ __jump_label_patch(struct jump_entry *entry, enum jump_label_type type)
 	return (struct jump_label_patch){.code = code, .size = size};
 }
 
-static inline void __jump_label_transform(struct jump_entry *entry,
-					  enum jump_label_type type,
-					  int init)
+static __always_inline void
+__jump_label_transform(struct jump_entry *entry,
+		       enum jump_label_type type,
+		       int init)
 {
 	const struct jump_label_patch jlp = __jump_label_patch(entry, type);