[SOL] re-enable debug info on SBF

[riptl]

Set SupportsDebugInformation to true for sbf.

[riptl]

There's probably a good reason why this was disabled in the first place. I've tested it with a C program and it works fine though.

[riptl]

Aha! ld.lld: error: canvas.c:(.BTF.ext+0xC0): unrecognized reloc R_BPF_64_NODYLD32

sbf/bpfel+solana doesn't support the R_BPF_64_NODYLD32 reloc required for BPF Type Format section. Looks like an easy fix though.

[riptl]

Another problem is this

https://github.com/solana-labs/llvm-project/blob/321d9c077f20a571f3ec7ba4513b78e7ccf13a71/llvm/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp#L97

This corrupts all relocs in the .rel.debug_line section, which need to be R_BPF_64_ABS32.

I patched that section by hand and got a working Solana .so program with full DWARF info and even a copy of the C source code included in the BTF section. 😃

[riptl]

Debug section relocs work now, @dmakarov would you mind taking a look?

[dmakarov]

Looks good, but I'll run a few more tests before I can merge this.

[riptl]

Thanks – one thing I was concerned about was relocs in the .rodata section. I've yet to test them, I hope I didn't break them.

[dmakarov]

I get the relocation error when a program is loaded to RBPF

ELF error: Relocation failed, unknown type 2

Pretty much all our tests fail with this change.

If you want to test this, build solana-labs/rust with the src/llvm-project submodule updated to include your changes. Once you have the rust compiler binaries, make a symbolic link rust in ~/.cache/solana/v1.23/bpf-tools/ to point to stage1/ subdir in your build of rust ( rust/build/x86_64-apple-darwin/stage1) and then run

cargo test --features="bpf_c,bpf_rust" -- --nocapture --test-threads=1

in solana-labs/solana/programs/bpf

[riptl]

Thanks for verifying, I will investigate this further then. The solution is probably to only use the R_BPF_64_ABS32 relocs for debug sections and otherwise the R_BPF_64_32 variant.

[riptl]

Moved over to #32