selftest/bpf: Fixing powerpc JIT disassembly failure

    Ensure that the trampoline stubs JITed at the tail of the
    epilogue do not expose the dummy trampoline address stored
    in the last 8 bytes(64-bit) and last 4 bytes(32-bit)
    to the disassembly flow. Prevent the disassembler from
    ingesting this memory address, as it may occasionally decode
    into a seemingly valid but incorrect instruction. Fix this
    issue by truncating the last 8/4 bytes from JITed buffers
    before supplying them for disassembly.

    Signed-off-by: Abhishek Dubey [off-list ref]

This looks like a bug fix, but there's no Fixes: tag.  The code being
corrected is the disasm_one_func(text_out, image + pc, func_lens[i]) call
in get_jited_program_text(), which feeds the full JITed function length
(including the trampoline tail holding the dummy trampoline address) to
the disassembler.  That helper and call site were added by commit
b991fc520700.

Should this include:

  Fixes: b991fc520700 ("selftests/bpf: utility function to get program disassembly after jit")


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/27620315552