const data in C result in unsupported BPF relocation R_BPF_INSN_64

[jackcmay]

Problem

Read-only data in C programs result in a R_BPF_INSN_64 relocation that the loader does not recognize.

Code that cause it:

const SolPubkey my_pubkey =  = {.x = {0x4E, 0x2F, 0x5C, 0x61, 0x0A, 0x8D, 0x0A, 0x7C, 0xA8, 0x7F, 0xAB, 0x69, 0xAB, 0x03, 0x7B, 0x0A, 0x52, 0x4C, 0x53, 0xE4, 0xA9, 0x97, 0xE8, 0x0E, 0xA8, 0x5A, 0x48, 0x8B, 0x96, 0xB8, 0xF1, 0x53}};

Warning from the loader:

Error: ELF error: ELF error: Relocation failed, unknown type 1

The workaround is to use #define instead of const:

#define my_pubkey {.x = {0x4E, 0x2F, 0x5C, 0x61, 0x0A, 0x8D, 0x0A, 0x7C, 0xA8, 0x7F, 0xAB, 0x69, 0xAB, 0x03, 0x7B, 0x0D, 0x52, 0x4C, 0x53, 0xE4, 0xA9, 0x97, 0xE8, 0x0E, 0xA8, 0x5A, 0x48, 0x8B, 0x96, 0xB8, 0xF1, 0x53}};

This issue might be related to recent llvm updates

Proposed Solution

Investigate whether we can support R_BPF_INSN_64 and add support for it if possible.

[dmakarov]

I tested the following program

#include <solana_sdk.h>

extern uint64_t entrypoint(const uint8_t *input) {
  const SolPubkey my_pubkey = { .x = {
      0x4E, 0x2F, 0x5C, 0x61,
      0x0A, 0x8D, 0x0A, 0x7C,
      0xA8, 0x7F, 0xAB, 0x69,
      0xAB, 0x03, 0x7B, 0x0A,
      0x52, 0x4C, 0x53, 0xE4,
      0xA9, 0x97, 0xE8, 0x0E,
      0xA8, 0x5A, 0x48, 0x8B,
      0x96, 0xB8, 0xF1, 0x53
    }};

  uint8_t pubkey[] = { \
        0x4E, 0x2F, 0x5C, 0x61, \
        0x0A, 0x8D, 0x0A, 0x7C, \
        0xA8, 0x7F, 0xAB, 0x69, \
        0xAB, 0x03, 0x7B, 0x0A, \
        0x52, 0x4C, 0x53, 0xE4, \
        0xA9, 0x97, 0xE8, 0x0E, \
        0xA8, 0x5A, 0x48, 0x8B, \
        0x96, 0xB8, 0xF1, 0x53  \
  };

  SolPubkey your_pubkey;

  sol_memcpy(&(your_pubkey.x), pubkey, sizeof(pubkey));

  sol_assert(SolPubkey_same(&my_pubkey, &your_pubkey));

  return SUCCESS;
}

It compiles and works without error. Can you give an example of a program that triggers the error ELF error: Relocation failed, unknown type 1?

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