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jump_labels: Mark __jump_label_transform() as __always_inlined to work 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>
This commit is contained in:
Ingo Molnar 2021-07-13 06:16:05 +02:00
parent 7fef2edf7c
commit e48a12e546
1 changed files with 4 additions and 3 deletions
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7
arch/x86/kernel/jump_label.c
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@ -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}; return (struct jump_label_patch){.code = code, .size = size};
} }
static inline void __jump_label_transform(struct jump_entry *entry, static __always_inline void
enum jump_label_type type, __jump_label_transform(struct jump_entry *entry,
int init) enum jump_label_type type,
int init)
{ {
const struct jump_label_patch jlp = __jump_label_patch(entry, type); const struct jump_label_patch jlp = __jump_label_patch(entry, type);