[broonie-ci:arm64-gcs 37/46] arch/arm64/mm/gcs.c:137:5: warning: no previous prototype for function 'arch_set_shadow_stack_status'

[broonie-ci:arm64-gcs 37/46] arch/arm64/mm/gcs.c:137:5: warning: no previous prototype for function 'arch_set_shadow_stack_status'

[kernel test robot]

Hi Mark,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/ci.git arm64-gcs
head:   b74369f3118f3aa07e067adae1f42db39f143397
commit: d21b0b3e80f82892db3e57c60aebdd4c53519e3c [37/46] arm64: Add Kconfig for Guarded Control Stack (GCS)
config: arm64-randconfig-r006-20230715 (https://download.01.org/0day-ci/archive/20230715/202307152153.qVglN5AE-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce: (https://download.01.org/0day-ci/archive/20230715/202307152153.qVglN5AE-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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307152153.qVglN5AE-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> arch/arm64/mm/gcs.c:137:5: warning: no previous prototype for function 'arch_set_shadow_stack_status' [-Wmissing-prototypes]
   int arch_set_shadow_stack_status(struct task_struct *task, unsigned long arg)
       ^
   arch/arm64/mm/gcs.c:137:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int arch_set_shadow_stack_status(struct task_struct *task, unsigned long arg)
   ^
   static 
>> arch/arm64/mm/gcs.c:189:5: warning: no previous prototype for function 'arch_get_shadow_stack_status' [-Wmissing-prototypes]
   int arch_get_shadow_stack_status(struct task_struct *task,
       ^
   arch/arm64/mm/gcs.c:189:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int arch_get_shadow_stack_status(struct task_struct *task,
   ^
   static 
   2 warnings generated.


vim +/arch_set_shadow_stack_status +137 arch/arm64/mm/gcs.c

688ff8cacd9951 Mark Brown 2023-04-05  136  
688ff8cacd9951 Mark Brown 2023-04-05 @137  int arch_set_shadow_stack_status(struct task_struct *task, unsigned long arg)
688ff8cacd9951 Mark Brown 2023-04-05  138  {
688ff8cacd9951 Mark Brown 2023-04-05  139  	unsigned long gcs, size;
688ff8cacd9951 Mark Brown 2023-04-05  140  
688ff8cacd9951 Mark Brown 2023-04-05  141  	if (!system_supports_gcs())
688ff8cacd9951 Mark Brown 2023-04-05  142  		return -EINVAL;
688ff8cacd9951 Mark Brown 2023-04-05  143  
688ff8cacd9951 Mark Brown 2023-04-05  144  	if (is_compat_thread(task_thread_info(task)))
688ff8cacd9951 Mark Brown 2023-04-05  145  		return -EINVAL;
688ff8cacd9951 Mark Brown 2023-04-05  146  
688ff8cacd9951 Mark Brown 2023-04-05  147  	/* Reject unknown flags */
688ff8cacd9951 Mark Brown 2023-04-05  148  	if (arg & ~PR_SHADOW_STACK_SUPPORTED_STATUS_MASK)
688ff8cacd9951 Mark Brown 2023-04-05  149  		return -EINVAL;
688ff8cacd9951 Mark Brown 2023-04-05  150  
688ff8cacd9951 Mark Brown 2023-04-05  151  	/* If the task has been locked block any attempted changes */
688ff8cacd9951 Mark Brown 2023-04-05  152  	if (task->thread.gcs_el0_mode & PR_SHADOW_STACK_LOCK)
688ff8cacd9951 Mark Brown 2023-04-05  153  		return -EBUSY;
688ff8cacd9951 Mark Brown 2023-04-05  154  
688ff8cacd9951 Mark Brown 2023-04-05  155  	/* Drop flags other than lock if disabling */
688ff8cacd9951 Mark Brown 2023-04-05  156  	if (!(arg & PR_SHADOW_STACK_ENABLE))
688ff8cacd9951 Mark Brown 2023-04-05  157  		arg &= ~PR_SHADOW_STACK_LOCK;
688ff8cacd9951 Mark Brown 2023-04-05  158  
688ff8cacd9951 Mark Brown 2023-04-05  159  	/* If we are enabling GCS then make sure we have a stack */
688ff8cacd9951 Mark Brown 2023-04-05  160  	if (arg & PR_SHADOW_STACK_ENABLE) {
688ff8cacd9951 Mark Brown 2023-04-05  161  		if (!task_gcs_el0_enabled(task)) {
688ff8cacd9951 Mark Brown 2023-04-05  162  			/* Do not allow GCS to be reenabled */
688ff8cacd9951 Mark Brown 2023-04-05  163  			if (task->thread.gcs_base)
688ff8cacd9951 Mark Brown 2023-04-05  164  				return -EINVAL;
688ff8cacd9951 Mark Brown 2023-04-05  165  
688ff8cacd9951 Mark Brown 2023-04-05  166  			size = gcs_size(0);
688ff8cacd9951 Mark Brown 2023-04-05  167  			gcs = alloc_gcs(task->thread.gcspr_el0, size,
688ff8cacd9951 Mark Brown 2023-04-05  168  					0, 0);
688ff8cacd9951 Mark Brown 2023-04-05  169  			if (!gcs)
688ff8cacd9951 Mark Brown 2023-04-05  170  				return -ENOMEM;
688ff8cacd9951 Mark Brown 2023-04-05  171  
688ff8cacd9951 Mark Brown 2023-04-05  172  			task->thread.gcspr_el0 = gcs + size - sizeof(u64);
688ff8cacd9951 Mark Brown 2023-04-05  173  			task->thread.gcs_base = gcs;
688ff8cacd9951 Mark Brown 2023-04-05  174  			task->thread.gcs_size = size;
688ff8cacd9951 Mark Brown 2023-04-05  175  			if (task == current)
688ff8cacd9951 Mark Brown 2023-04-05  176  				write_sysreg_s(task->thread.gcspr_el0,
688ff8cacd9951 Mark Brown 2023-04-05  177  					       SYS_GCSPR_EL0);
688ff8cacd9951 Mark Brown 2023-04-05  178  
688ff8cacd9951 Mark Brown 2023-04-05  179  		}
688ff8cacd9951 Mark Brown 2023-04-05  180  	}
688ff8cacd9951 Mark Brown 2023-04-05  181  
688ff8cacd9951 Mark Brown 2023-04-05  182  	task->thread.gcs_el0_mode = arg;
688ff8cacd9951 Mark Brown 2023-04-05  183  	if (task == current)
688ff8cacd9951 Mark Brown 2023-04-05  184  		gcs_set_el0_mode(task);
688ff8cacd9951 Mark Brown 2023-04-05  185  
688ff8cacd9951 Mark Brown 2023-04-05  186  	return 0;
688ff8cacd9951 Mark Brown 2023-04-05  187  }
688ff8cacd9951 Mark Brown 2023-04-05  188  
688ff8cacd9951 Mark Brown 2023-04-05 @189  int arch_get_shadow_stack_status(struct task_struct *task,

:::::: The code at line 137 was first introduced by commit
:::::: 688ff8cacd99518f46a420dbb4a02de6e671e5ae arm64/gcs: Implement shadow stack prctl() interface

:::::: TO: Mark Brown <broonie@kernel.org>
:::::: CC: Mark Brown <broonie@kernel.org>

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