linux-kernel - [tip:core/rseq 40/42] arch/arm64/kernel/entry-common.c:103:9: error: implicit declaration of function 'exit_to_user_mode_prepare'; did you mean 'arch_exit_to_user_mode

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Message-ID: <202511030013.EmYk0XGN-lkp@intel.com>
Date: Mon, 3 Nov 2025 00:41:13 +0800
From: kernel test robot <lkp@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: [tip:core/rseq 40/42] arch/arm64/kernel/entry-common.c:103:9: error:
 implicit declaration of function 'exit_to_user_mode_prepare'; did you mean
 'arch_exit_to_user_mode_prepare'?

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core/rseq
head:   69c8e3d1610588d677faaa6035e1bd5de9431d6e
commit: d589306403107aa3ba5f014cb7d17b3d5db3cf94 [40/42] entry: Split up exit_to_user_mode_prepare()
config: arm64-randconfig-003-20251102 (https://download.01.org/0day-ci/archive/20251103/202511030013.EmYk0XGN-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251103/202511030013.EmYk0XGN-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511030013.EmYk0XGN-lkp@intel.com/

All errors (new ones prefixed by >>):

   arch/arm64/kernel/entry-common.c: In function 'arm64_exit_to_user_mode':
>> arch/arm64/kernel/entry-common.c:103:9: error: implicit declaration of function 'exit_to_user_mode_prepare'; did you mean 'arch_exit_to_user_mode_prepare'? [-Werror=implicit-function-declaration]
     103 |         exit_to_user_mode_prepare(regs);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~
         |         arch_exit_to_user_mode_prepare
   cc1: some warnings being treated as errors


vim +103 arch/arm64/kernel/entry-common.c

bc29b71f53b13c Mark Rutland 2021-08-02   93  
bc29b71f53b13c Mark Rutland 2021-08-02   94  /*
bc29b71f53b13c Mark Rutland 2021-08-02   95   * Handle IRQ/context state management when exiting to user mode.
bc29b71f53b13c Mark Rutland 2021-08-02   96   * After this function returns it is not safe to call regular kernel code,
59598b42eb52c7 Mukesh Ojha  2022-10-29   97   * instrumentable code, or any code which may trigger an exception.
bc29b71f53b13c Mark Rutland 2021-08-02   98   */
997d79eb938e98 Mark Rutland 2024-02-06   99  
b3cf07851b6c4a Jinjie Ruan  2025-08-15  100  static __always_inline void arm64_exit_to_user_mode(struct pt_regs *regs)
4d1c2ee2709fd6 Mark Rutland 2021-08-02  101  {
97d935faacde47 Mark Rutland 2024-02-06  102  	local_irq_disable();
ab1e29acdb33c9 Eric Chan    2023-05-31 @103  	exit_to_user_mode_prepare(regs);
b3cf07851b6c4a Jinjie Ruan  2025-08-15  104  	local_daif_mask();
e130338eed5de0 Mark Rutland 2021-08-02  105  	mte_check_tfsr_exit();
b3cf07851b6c4a Jinjie Ruan  2025-08-15  106  	exit_to_user_mode();
e130338eed5de0 Mark Rutland 2021-08-02  107  }
e130338eed5de0 Mark Rutland 2021-08-02  108  

:::::: The code at line 103 was first introduced by commit
:::::: ab1e29acdb33c971e1af8ed8ec427bd1deff5f32 arm64: lockdep: enable checks for held locks when returning to userspace

:::::: TO: Eric Chan <ericchancf@...gle.com>
:::::: CC: Catalin Marinas <catalin.marinas@....com>

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki