init: initialize jump labels before command line option parsing
authorDan Williams <>
Fri, 19 Apr 2019 00:50:44 +0000 (17:50 -0700)
committerLinus Torvalds <>
Fri, 19 Apr 2019 16:46:05 +0000 (09:46 -0700)
When a module option, or core kernel argument, toggles a static-key it
requires jump labels to be initialized early.  While x86, PowerPC, and
ARM64 arrange for jump_label_init() to be called before parse_args(),
ARM does not.

  Kernel command line: rdinit=/sbin/init page_alloc.shuffle=1 panic=-1 console=ttyAMA0,115200 page_alloc.shuffle=1
  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 0 at ./include/linux/jump_label.h:303
  static_key_enable(): static key 'page_alloc_shuffle_key+0x0/0x4' used
  before call to jump_label_init()
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted
  5.1.0-rc4-next-20190410-00003-g3367c36ce744 #1
  Hardware name: ARM Integrator/CP (Device Tree)
  [<c0011c68>] (unwind_backtrace) from [<c000ec48>] (show_stack+0x10/0x18)
  [<c000ec48>] (show_stack) from [<c07e9710>] (dump_stack+0x18/0x24)
  [<c07e9710>] (dump_stack) from [<c001bb1c>] (__warn+0xe0/0x108)
  [<c001bb1c>] (__warn) from [<c001bb88>] (warn_slowpath_fmt+0x44/0x6c)
  [<c001bb88>] (warn_slowpath_fmt) from [<c0b0c4a8>]
  [<c0b0c4a8>] (page_alloc_shuffle) from [<c0b0c550>] (shuffle_store+0x28/0x48)
  [<c0b0c550>] (shuffle_store) from [<c003e6a0>] (parse_args+0x1f4/0x350)
  [<c003e6a0>] (parse_args) from [<c0ac3c00>] (start_kernel+0x1c0/0x488)

Move the fallback call to jump_label_init() to occur before

The redundant calls to jump_label_init() in other archs are left intact
in case they have static key toggling use cases that are even earlier
than option parsing.

Signed-off-by: Dan Williams <>
Reported-by: Guenter Roeck <>
Reviewed-by: Kees Cook <>
Cc: Mathieu Desnoyers <>
Cc: Thomas Gleixner <>
Cc: Mike Rapoport <>
Cc: Russell King <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>

index 598e278b46f743d777e6f9375ac1c932896ef99c..7d4025d665eb95ee439ddb4e5e564aff8fa09c24 100644 (file)
@@ -582,6 +582,8 @@ asmlinkage __visible void __init start_kernel(void)
        pr_notice("Kernel command line: %s\n", boot_command_line);
+       /* parameters may set static keys */
+       jump_label_init();
        after_dashes = parse_args("Booting kernel",
                                  static_command_line, __start___param,
@@ -591,8 +593,6 @@ asmlinkage __visible void __init start_kernel(void)
                parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
                           NULL, set_init_arg);
-       jump_label_init();
         * These use large bootmem allocations and must precede
         * kmem_cache_init()