[jpoimboe:sframe 5/10] arch/x86/events/core.c:2856:6: warning: no previous prototype for function '__perf_callchain_user'

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git sframe
head:   ec004e900e02c9c85cf8c89d4c26d4168a6c5d18
commit: f19cd074272c3fd160c2d637cc0f65cfffad1e81 [5/10] perf/x86: Add HAVE_PERF_CALLCHAIN_DEFERRED
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20231110/202311100457.J76Vb8Yp-lkp@intel.com/config)
compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231110/202311100457.J76Vb8Yp-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/202311100457.J76Vb8Yp-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> arch/x86/events/core.c:2856:6: warning: no previous prototype for function '__perf_callchain_user' [-Wmissing-prototypes]
   void __perf_callchain_user(struct perf_callchain_entry_ctx *entry,
        ^
   arch/x86/events/core.c:2856:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void __perf_callchain_user(struct perf_callchain_entry_ctx *entry,
   ^
   static 
   1 warning generated.


vim +/__perf_callchain_user +2856 arch/x86/events/core.c

  2855	
> 2856	void __perf_callchain_user(struct perf_callchain_entry_ctx *entry,
  2857				   struct pt_regs *regs, bool atomic)
  2858	{
  2859		struct stack_frame frame;
  2860		const struct stack_frame __user *fp;
  2861	
  2862		if (perf_guest_state()) {
  2863			/* TODO: We don't support guest os callchain now */
  2864			return;
  2865		}
  2866	
  2867		/*
  2868		 * We don't know what to do with VM86 stacks.. ignore them for now.
  2869		 */
  2870		if (regs->flags & (X86_VM_MASK | PERF_EFLAGS_VM))
  2871			return;
  2872	
  2873		fp = (void __user *)regs->bp;
  2874	
  2875		perf_callchain_store(entry, regs->ip);
  2876	
  2877		if (atomic && !nmi_uaccess_okay())
  2878			return;
  2879	
  2880		if (atomic)
  2881			pagefault_disable();
  2882	
  2883		if (__perf_callchain_user32(regs, entry))
  2884			goto done;
  2885	
  2886		while (entry->nr < entry->max_stack) {
  2887			if (!valid_user_frame(fp, sizeof(frame)))
  2888				break;
  2889	
  2890			if (__get_user(frame.next_frame, &fp->next_frame))
  2891				break;
  2892			if (__get_user(frame.return_address, &fp->return_address))
  2893				break;
  2894	
  2895			perf_callchain_store(entry, frame.return_address);
  2896			fp = (void __user *)frame.next_frame;
  2897		}
  2898	done:
  2899		if (atomic)
  2900			pagefault_enable();
  2901	}
  2902	

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