Re: [gustavoars:for-next/cast-function 1/3] kernel/trace/ftrace.c:7029:6: error: no previous prototype for function 'arch_ftrace_ops_list_func'

[Steven Rostedt]

On Thu, 14 Oct 2021 07:33:21 +0800
kernel test robot <lkp@xxxxxxxxx> wrote:

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git for-next/cast-function
> head:   eed09ebd6f47aeb92b3fe3b8d338b2a55e534928
> commit: f9d45e65ef7f67bdb39c15d09bc6021f197d893e [1/3] ftrace: Fix -Wcast-function-type warnings on powerpc64
> config: i386-buildonly-randconfig-r002-20211013 (attached as .config)
> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project b6a8c695542b2987eb9a203d5663a0740cb4725f)
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git/commit/?id=f9d45e65ef7f67bdb39c15d09bc6021f197d893e
>         git remote add gustavoars https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git
>         git fetch --no-tags gustavoars for-next/cast-function
>         git checkout f9d45e65ef7f67bdb39c15d09bc6021f197d893e
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=i386 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> 
> All errors (new ones prefixed by >>):
> 
>    kernel/trace/ftrace.c:297:5: error: no previous prototype for function '__register_ftrace_function' [-Werror,-Wmissing-prototypes]
>    int __register_ftrace_function(struct ftrace_ops *ops)
>        ^
>    kernel/trace/ftrace.c:297:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
>    int __register_ftrace_function(struct ftrace_ops *ops)
>    ^
>    static 
>    kernel/trace/ftrace.c:340:5: error: no previous prototype for function '__unregister_ftrace_function' [-Werror,-Wmissing-prototypes]
>    int __unregister_ftrace_function(struct ftrace_ops *ops)
>        ^
>    kernel/trace/ftrace.c:340:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
>    int __unregister_ftrace_function(struct ftrace_ops *ops)
>    ^
>    static 
>    kernel/trace/ftrace.c:579:5: error: no previous prototype for function 'ftrace_profile_pages_init' [-Werror,-Wmissing-prototypes]
>    int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
>        ^
>    kernel/trace/ftrace.c:579:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
>    int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
>    ^
>    static 
>    kernel/trace/ftrace.c:3871:15: error: no previous prototype for function 'arch_ftrace_match_adjust' [-Werror,-Wmissing-prototypes]
>    char * __weak arch_ftrace_match_adjust(char *str, const char *search)
>                  ^
>    kernel/trace/ftrace.c:3871:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
>    char * __weak arch_ftrace_match_adjust(char *str, const char *search)
>    ^
>    static 
> >> kernel/trace/ftrace.c:7029:6: error: no previous prototype for function 'arch_ftrace_ops_list_func' [-Werror,-Wmissing-prototypes]  
>    void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
>         ^
>    kernel/trace/ftrace.c:7029:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
>    void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
>    ^
>    static 
>    5 errors generated.
> 
> 
> vim +/arch_ftrace_ops_list_func +7029 kernel/trace/ftrace.c
> 
>   7011	
>   7012	/*
>   7013	 * Some archs only support passing ip and parent_ip. Even though
>   7014	 * the list function ignores the op parameter, we do not want any
>   7015	 * C side effects, where a function is called without the caller
>   7016	 * sending a third parameter.
>   7017	 * Archs are to support both the regs and ftrace_ops at the same time.
>   7018	 * If they support ftrace_ops, it is assumed they support regs.
>   7019	 * If call backs want to use regs, they must either check for regs
>   7020	 * being NULL, or CONFIG_DYNAMIC_FTRACE_WITH_REGS.
>   7021	 * Note, CONFIG_DYNAMIC_FTRACE_WITH_REGS expects a full regs to be saved.
>   7022	 * An architecture can pass partial regs with ftrace_ops and still
>   7023	 * set the ARCH_SUPPORTS_FTRACE_OPS.
>   7024	 *
>   7025	 * In vmlinux.lds.h, ftrace_ops_list_func() is defined to be
>   7026	 * arch_ftrace_ops_list_func.
>   7027	 */
>   7028	#if ARCH_SUPPORTS_FTRACE_OPS
> > 7029	void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,  
>   7030				       struct ftrace_ops *op, struct ftrace_regs *fregs)
>   7031	{
>   7032		__ftrace_ops_list_func(ip, parent_ip, NULL, fregs);
>   7033	}
>   7034	#else
>   7035	void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
>   7036	{
>   7037		__ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
>   7038	}
>   7039	#endif
>   7040	NOKPROBE_SYMBOL(arch_ftrace_ops_list_func);
>   7041	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

This should fix this issue as well as some of the other ones reported on
this commit.

[ I'll be adding this update to my own version in my tree ]

-- Steve

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index b86f52683b6f..8771c435f34b 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -178,7 +178,8 @@
 			ftrace_ops_list_func = arch_ftrace_ops_list_func;
 #else
 # ifdef CONFIG_FUNCTION_TRACER
-#  define MCOUNT_REC()	ftrace_stub_graph = ftrace_stub;
+#  define MCOUNT_REC()	ftrace_stub_graph = ftrace_stub;	\
+			ftrace_ops_list_func = arch_ftrace_ops_list_func;
 # else
 #  define MCOUNT_REC()
 # endif
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 832e65f06754..871b51bec170 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -30,16 +30,25 @@
 #define ARCH_SUPPORTS_FTRACE_OPS 0
 #endif
 
+#ifdef CONFIG_FUNCTION_TRACER
+struct ftrace_ops;
 /*
  * If the arch's mcount caller does not support all of ftrace's
  * features, then it must call an indirect function that
  * does. Or at least does enough to prevent any unwelcome side effects.
+ *
+ * Also define the function prototype that these architectures use
+ * to call the ftrace_ops_list_func().
  */
 #if !ARCH_SUPPORTS_FTRACE_OPS
 # define FTRACE_FORCE_LIST_FUNC 1
+void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
 #else
 # define FTRACE_FORCE_LIST_FUNC 0
+void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+			       struct ftrace_ops *op, struct ftrace_regs *fregs);
 #endif
+#endif /* CONFIG_FUNCTION_TRACER */
 
 /* Main tracing buffer and events set up */
 #ifdef CONFIG_TRACING
@@ -88,8 +97,6 @@ extern int
 ftrace_enable_sysctl(struct ctl_table *table, int write,
 		     void *buffer, size_t *lenp, loff_t *ppos);
 
-struct ftrace_ops;
-
 #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
 
 struct ftrace_regs {