linux-kernel - Re: arch/arm64/kernel/signal.c:1300: undefined reference to `preserve_gcs

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Message-ID: <aNUZWQdNsyDPGEWc@arm.com>
Date: Thu, 25 Sep 2025 11:28:41 +0100
From: Catalin Marinas <catalin.marinas@....com>
To: kernel test robot <lkp@...el.com>
Cc: Robin Murphy <robin.murphy@....com>, oe-kbuild-all@...ts.linux.dev,
	linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: Re: arch/arm64/kernel/signal.c:1300: undefined reference to
 `preserve_gcs_context'

On Wed, Sep 24, 2025 at 06:30:53PM +0800, kernel test robot wrote:
> FYI, the error/warning still remains.
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   cec1e6e5d1ab33403b809f79cd20d6aff124ccfe
> commit: f00b53f1614f7be554fd28b9594ef4e63e2686c5 arm64: cpufeature: Add GCS to cpucap_is_possible()
> date:   10 months ago
> config: arm64-randconfig-r132-20250924 (https://download.01.org/0day-ci/archive/20250924/202509241856.XvV8zSHD-lkp@intel.com/config)
> compiler: aarch64-linux-gcc (GCC) 10.5.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250924/202509241856.XvV8zSHD-lkp@intel.com/reproduce)

Robin's commit was supposed to fix this.

> 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/202509241856.XvV8zSHD-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    aarch64-linux-ld: Unexpected GOT/PLT entries detected!
>    aarch64-linux-ld: Unexpected run-time procedure linkages detected!
>    aarch64-linux-ld: arch/arm64/kernel/signal.o: in function `setup_sigframe':
> >> arch/arm64/kernel/signal.c:1300: undefined reference to `preserve_gcs_context'
>    aarch64-linux-ld: arch/arm64/kernel/signal.o: in function `restore_sigframe':
> >> arch/arm64/kernel/signal.c:1042: undefined reference to `restore_gcs_context'
> 
> 
> vim +1300 arch/arm64/kernel/signal.c
> 
> bb4891a6c3551f Dave Martin      2017-06-15  1258  
> 20987de3c2c45c Dave Martin      2017-06-15  1259  static int setup_sigframe(struct rt_sigframe_user_layout *user,
> 2e8a1acea8597f Kevin Brodsky    2024-10-29  1260  			  struct pt_regs *regs, sigset_t *set,
> 2e8a1acea8597f Kevin Brodsky    2024-10-29  1261  			  const struct user_access_state *ua_state)
> 2c020ed8d148f7 Catalin Marinas  2012-03-05  1262  {
[...]
> 16f47bb9ac8afe Mark Brown       2024-10-01  1297  	if (system_supports_gcs() && err == 0 && user->gcs_offset) {
> 16f47bb9ac8afe Mark Brown       2024-10-01  1298  		struct gcs_context __user *gcs_ctx =
> 16f47bb9ac8afe Mark Brown       2024-10-01  1299  			apply_user_offset(user, user->gcs_offset);
> 16f47bb9ac8afe Mark Brown       2024-10-01 @1300  		err |= preserve_gcs_context(gcs_ctx);
> 16f47bb9ac8afe Mark Brown       2024-10-01  1301  	}

It looks like the compiler was not able to remove these calls. Is this
compiler-specific?

-- 
Catalin