Re: [PATCH v2 bpf-next 2/3] bpf: introduce helper bpf_get_branch_snapshot

On Fri, Aug 27, 2021 at 11:10:39PM +0800, kernel test robot wrote:

All errors (new ones prefixed by >>):

   riscv32-linux-ld: kernel/bpf/trampoline.o: in function `.L57':

quoted

quoted

trampoline.c:(.text+0x34c): undefined reference to `__SCK__perf_snapshot_branch_stack'

   riscv32-linux-ld: kernel/bpf/trampoline.o: in function `.L61':
   trampoline.c:(.text+0x360): undefined reference to `bpf_perf_branch_snapshot'

This a build with PERF_EVENTS=n, I suppose you'd better make calling
perf_snapshot_branch_stack() dependent on having that :-)