powerpc64/bpf: fix handling of BPF stack in exception callback

powerpc64/bpf: fix handling of BPF stack in exception callback

Exception callback reuses the stack frame of exception boundary. When
exception boundary and exception callback programs have different BPF
stack depth, the current stack unwind in exception callback will fail.
Adjust the stack frame size of exception callback, in its prologue,
if its BPF stack depth is different from that of exception boundary.

Reported-by: bot+bpf-ci@kernel.org
Closes: https://lore.kernel.org/bpf/2a310e86a59eb4c44c3ac9e5647814469d9c955580c9c0f1b3d9ca4a44717a34@mail.kernel.org/
Fixes: 11d45eee9f42 ("powerpc64/bpf: Additional NVR handling for bpf_throw")
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260303181031.390073-6-hbathini@linux.ibm.com