Core fails to load on glibc 2.41+: "cannot enable executable stack as shared object requires"

[veralvx]

melonds_libretro.so is linked with an executable stack. glibc 2.41 stopped granting that at dlopen time, so on any distribution shipping that glibc or newer, RetroArch cannot load the core.

Log:

[INFO] [Core] Loading dynamic libretro core from: ".../melonds_libretro.so".
[ERROR] [Core] Failed to open libretro core: ".../melonds_libretro.so"
[ERROR] [Core] Error(s): .../melonds_libretro.so: cannot enable executable
        stack as shared object requires: Invalid argument

RetroArch 1.22.2, x86_64, glibc 2.41+.

Cause

src/ARMJIT_x64/ARMJIT_Linkage.S and src/ARMJIT_A64/ARMJIT_Linkage.S are assembled without a .note.GNU-stack section. Given an input object without that note, the linker assumes an executable stack is needed and marks the whole shared object RWE. Makefile:548 builds these files through $(CC) -x assembler-with-cpp, so the mark lands in the core.

Assembling the current:

$ gcc -fPIC -x assembler-with-cpp -c -o before.o src/ARMJIT_x64/ARMJIT_Linkage.S
$ gcc -shared -fPIC -o libbefore.so before.o stub.c
/usr/bin/ld: warning: before.o: missing .note.GNU-stack section implies
executable stack
$ readelf -lW libbefore.so | grep GNU_STACK
  GNU_STACK  0x000000 0x0000000000000000 0x0000000000000000 ... RWE 0x10

glibc 2.41's release notes describe the change.

Fix

PR: #218

Upstream melonDS added the note to both files in 3ab752b (2023-10-22) and refined the platform guards in 2a86ee7 and 63e4b68. Here, ARMJIT_Linkage.S has not changed since 436b3c4 (2021-03-12), so the fix never arrived.

Adding the same four lines to each file produces GNU_STACK RW, and the core loads. Patch and test procedure are in the pull request.