bpf, arm64: Fix tailcall hierarchy

This patch fixes a tailcall issue caused by abusing the tailcall in
bpf2bpf feature on arm64 like the way of "bpf, x64: Fix tailcall
hierarchy".

On arm64, when a tail call happens, it uses tail_call_cnt_ptr to
increment tail_call_cnt, too.

At the prologue of main prog, it has to initialize tail_call_cnt and
prepare tail_call_cnt_ptr.

At the prologue of subprog, it pushes x26 register twice, and does not
initialize tail_call_cnt.

At the epilogue, it pops x26 twice, no matter whether it is main prog or
subprog.

Fixes: d4609a5d8c70 ("bpf, arm64: Keep tail call count across bpf2bpf calls")
Acked-by: Puranjay Mohan <[email protected]>
Signed-off-by: Leon Hwang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>

0 files changed, 0 insertions, 0 deletions