tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   b86a6a241b7c60ca7a6ca4fb3c0d2aedbbf2c1b6
commit: 52e7c52d2ded5908e6a4f8a7248e5fa6e0d6809a [5770/7050] RISC-V: Stop relying on GCC's register allocator's hueristics
config: riscv-allnoconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 9.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout 52e7c52d2ded5908e6a4f8a7248e5fa6e0d6809a
        # save the attached .config to linux build tree
        GCC_VERSION=9.2.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   arch/riscv/kernel/stacktrace.c: In function 'walk_stackframe':
>> arch/riscv/kernel/stacktrace.c:78:8: error: 'sp_in_global' undeclared (first use in this function)
      78 |   sp = sp_in_global;
         |        ^~~~~~~~~~~~
   arch/riscv/kernel/stacktrace.c:78:8: note: each undeclared identifier is reported only once for each function it appears in

vim +/sp_in_global +78 arch/riscv/kernel/stacktrace.c

    67	
    68	static void notrace walk_stackframe(struct task_struct *task,
    69		struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
    70	{
    71		unsigned long sp, pc;
    72		unsigned long *ksp;
    73	
    74		if (regs) {
    75			sp = user_stack_pointer(regs);
    76			pc = instruction_pointer(regs);
    77		} else if (task == NULL || task == current) {
  > 78			sp = sp_in_global;
    79			pc = (unsigned long)walk_stackframe;
    80		} else {
    81			/* task blocked in __switch_to */
    82			sp = task->thread.sp;
    83			pc = task->thread.ra;
    84		}
    85	
    86		if (unlikely(sp & 0x7))
    87			return;
    88	
    89		ksp = (unsigned long *)sp;
    90		while (!kstack_end(ksp)) {
    91			if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
    92				break;
    93			pc = (*ksp++) - 0x4;
    94		}
    95	}
    96	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org