RandomX fails to build as shared library on AArch64 due to non-PIC assembly symbol (ADR relocation error)

[coffnix]

Environment

• OS: Macaroni OS MARK
• Distribution family: Gentoo-based
• Kernel: Linux 6.19.11 PREEMPT
• Architecture: aarch64
• libc: glibc 2.40

CPU

• SoC: CIX P1 CD8160
• Vendor: Cix Technology Group Co., Ltd.
• CPUs: 12
• Topology: 8x Cortex-A720 + 4x Cortex-A520
• Features include: AES, PMULL, SHA1, SHA2, SHA3, SM3, SM4, SVE, SVE2, BF16, I8MM

Memory

• RAM: 30 GiB
• Swap: 15 GiB

Compiler

• GCC: 14.3.0
• Target: aarch64-unknown-linux-gnu
• Thread model: posix
• Default PIE enabled
• Default SSP enabled
• Configured with --with-arch=armv9.2-a --with-tune=cortex-a720

Toolchain

• CMake
• Ninja
• GCC-based Gentoo toolchain

Build context

• Building RandomX as a shared library (librandomx.so)
• Compiler flags include -march=armv8-a+crypto
• Issue reproduced on AArch64 during shared library build
• Build mode: shared library (BUILD_SHARED_LIBS=ON)

Describe the bug

Building RandomX as a shared library on AArch64 fails with a linker error related to non-PIC assembly code.

The issue is caused by the use of adr with a globally exported symbol in jit_compiler_a64_static.S, which results in an invalid relocation type when building a shared object.

---

Error

relocation R_AARCH64_ADR_PREL_LO21 against symbol `randomx_program_aarch64_aes_lut_pointers' which may bind externally can not be used when making a shared object

---

Root cause

The symbol randomx_program_aarch64_aes_lut_pointers is declared as global and accessed via adr:

adr x19, DECL(randomx_program_aarch64_aes_lut_pointers)

This generates a PC-relative relocation that is not valid for externally visible symbols in shared libraries.

At the same time, the symbol is referenced from C++:

(uint8_t*)randomx_program_aarch64_aes_lut_pointers

---

Fix

Marking the symbol as hidden resolves the issue while preserving functionality:

.global DECL(randomx_program_aarch64_aes_lut_pointers)
.hidden DECL(randomx_program_aarch64_aes_lut_pointers)

This keeps the symbol usable internally while preventing problematic relocations when linking as a shared object.

---

Notes

Removing .global entirely avoids the relocation error but breaks linkage from C++.

Using .hidden is the correct fix, as it preserves symbol visibility where needed while ensuring compatibility with shared library builds.

Patch

This patch marks the symbol randomx_program_aarch64_aes_lut_pointers as hidden while keeping it global, ensuring compatibility with shared library builds on AArch64 without breaking internal references.

opi6plus /var/overlay/overlay-local/dev-libs/randomx # cat files/randomx-aarch64-shared-fix.patch
--- a/src/jit_compiler_a64_static.S
+++ b/src/jit_compiler_a64_static.S
@@ -44,6 +44,7 @@
 	.global DECL(randomx_program_aarch64_v2_FE_mix)
 	.global DECL(randomx_program_aarch64_v1_FE_mix)
 	.global DECL(randomx_program_aarch64_v2_FE_mix_soft_aes)
+	.hidden DECL(randomx_program_aarch64_aes_lut_pointers)
 	.global DECL(randomx_program_aarch64_aes_lut_pointers)
 	.global DECL(randomx_program_aarch64_vm_instructions_end_light)
 	.global DECL(randomx_program_aarch64_vm_instructions_end_light_tweak)

[SChernykh]

If you have a patch, why didn't you create a PR then?

[coffnix]

If you have a patch, why didn't you create a PR then?

yo @SChernykh I prefer to open an issue first to discuss the problem along with a proposed fix, instead of submitting a PR right away.

This way, maintainers can validate whether the approach aligns with the project’s design and constraints before code is introduced. In my experience with open source projects, this helps avoid submitting changes that might not be suitable from a broader perspective.

If the proposed solution is confirmed to be appropriate, I’m happy to follow up with a proper PR.

[SChernykh]

It's a one-line fix, just create the PR. Passing CI is all that will be needed to approve it.

[coffnix]

I tested it here on my fork, it worked, I will now submit a PR. Thanks for the feedback!