On Fri, Dec 15, 2023 at 04:45:49PM -0800, Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@xxxxxxxxxx>
>
> The func_addr used to be NULL for indirect trampolines used by struct_ops.
> Now func_addr is a valid function pointer.
> Hence use BPF_TRAMP_F_INDIRECT flag to detect such condition.
>
> Fixes: 2cd3e3772e41 ("x86/cfi,bpf: Fix bpf_struct_ops CFI")
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> ---
> arch/s390/net/bpf_jit_comp.c | 3 ++-
> tools/testing/selftests/bpf/DENYLIST.s390x | 2 --
> 2 files changed, 2 insertions(+), 3 deletions(-)
IIUC F_INDIRECT trampolines are called via C function pointers, and
func_addr does not participate in any call chains, but is rather used
as a source of CFI information. So returning to %r14 is the right
thing to do.
Thanks!
Reviewed-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
