Re: [PATCH v3 1/2] fgraph: Enhance funcgraph-retval with BTF-based type-aware output

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

Hi Donglin,

kernel test robot noticed the following build errors:

[auto build test ERROR on trace/for-next]
[also build test ERROR on linus/master v6.18 next-20251212]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Donglin-Peng/fgraph-Enhance-funcgraph-retval-with-BTF-based-type-aware-output/20251209-201633
base:   https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace for-next
patch link:    https://lore.kernel.org/r/20251209121349.525641-2-dolinux.peng%40gmail.com
patch subject: [PATCH v3 1/2] fgraph: Enhance funcgraph-retval with BTF-based type-aware output
config: arm-randconfig-002-20251214 (https://download.01.org/0day-ci/archive/20251214/202512140850.JdD1lPmn-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 10.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251214/202512140850.JdD1lPmn-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/202512140850.JdD1lPmn-lkp@intel.com/

All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: kernel/trace/trace_functions_graph.o: in function `trim_retval':
>> kernel/trace/trace_functions_graph.c:888: undefined reference to `btf_find_func_proto'


vim +888 kernel/trace/trace_functions_graph.c

   872	
   873	static void trim_retval(unsigned long func, unsigned long *retval, bool *print_retval,
   874				int *fmt)
   875	{
   876		const struct btf_type *t;
   877		char name[KSYM_NAME_LEN];
   878		struct btf *btf;
   879		u32 v, msb;
   880		int kind;
   881	
   882		if (!IS_ENABLED(CONFIG_DEBUG_INFO_BTF))
   883			return;
   884	
   885		if (lookup_symbol_name(func, name))
   886			return;
   887	
 > 888		t = btf_find_func_proto(name, &btf);
   889		if (IS_ERR_OR_NULL(t))
   890			return;
   891	
   892		t = btf_type_skip_modifiers(btf, t->type, NULL);
   893		kind = t ? BTF_INFO_KIND(t->info) : BTF_KIND_UNKN;
   894		switch (kind) {
   895		case BTF_KIND_UNKN:
   896			*print_retval = false;
   897			break;
   898		case BTF_KIND_STRUCT:
   899		case BTF_KIND_UNION:
   900		case BTF_KIND_ENUM:
   901		case BTF_KIND_ENUM64:
   902			if (kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION)
   903				*fmt = RETVAL_FMT_HEX;
   904			else
   905				*fmt = RETVAL_FMT_DEC;
   906	
   907			if (t->size > sizeof(unsigned long)) {
   908				*fmt |= RETVAL_FMT_TRUNC;
   909			} else {
   910				msb = BITS_PER_BYTE * t->size - 1;
   911				*retval &= GENMASK(msb, 0);
   912			}
   913			break;
   914		case BTF_KIND_INT:
   915			v = *(u32 *)(t + 1);
   916			if (BTF_INT_ENCODING(v) == BTF_INT_BOOL) {
   917				*fmt = RETVAL_FMT_BOOL;
   918				msb = 0;
   919			} else {
   920				if (BTF_INT_ENCODING(v) == BTF_INT_SIGNED)
   921					*fmt = RETVAL_FMT_DEC;
   922				else
   923					*fmt = RETVAL_FMT_HEX;
   924	
   925				if (t->size > sizeof(unsigned long)) {
   926					*fmt |= RETVAL_FMT_TRUNC;
   927					msb = BITS_PER_LONG - 1;
   928				} else {
   929					msb = BTF_INT_BITS(v) - 1;
   930				}
   931			}
   932			*retval &= GENMASK(msb, 0);
   933			break;
   934		default:
   935			*fmt = RETVAL_FMT_HEX;
   936			break;
   937		}
   938	}
   939	

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