[SOLVED] Use .obj created by MASM (ml64) with gcc on linux

I have a .obj file that is created by ml64 and then used by a vsxproj to compile a windows dll. The C part simply acts as a pass-through to one function in the masm code.

Is it possible to do the same with gcc so I can compile a linux .so file?

Edit:

objdump -f test.obj returns:

test.obj :
file format pe-x86-64
architecture: i386:x86-64, flags 0x0000003d :
HAS RELOC, HAS LINENO, HAS DEBUG, HAS SYMS, HAS LOCALS
start address 0X0000000000000000

Trying objcopy -I pe-x86-64 -O elf64-x86-64 test.obj test.o gives :

objcopy: test.o: (null)unsupported
objcopy: test.o: sorry, cannot handle this file

Edit2: gcc output:

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 11.3.0-1ubuntu1~22.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-11 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-11-xKiWfi/gcc-11-11.3.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-xKiWfi/gcc-11-11.3.0/debian/tmp-gcn/usr --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.3.0 (Ubuntu 11.3.0-1ubuntu1~22.04) 
COLLECT_GCC_OPTIONS='-v' '-shared' '-o' 'EmulatorCore.so' '-fPIC' '-Wall' '-g' '-m64' '-mtune=generic' '-march=x86-64' '-dumpdir' 'EmulatorCore.so-'
 /usr/lib/gcc/x86_64-linux-gnu/11/cc1 -quiet -v -imultiarch x86_64-linux-gnu core.c -quiet -dumpdir EmulatorCore.so- -dumpbase core.c -dumpbase-ext .c -m64 -mtune=generic -march=x86-64 -g -Wall -version -fPIC -fasynchronous-unwind-tables -fstack-protector-strong -Wformat-security -fstack-clash-protection -fcf-protection -o /tmp/ccNiOQu1.s
GNU C17 (Ubuntu 11.3.0-1ubuntu1~22.04) version 11.3.0 (x86_64-linux-gnu)
    compiled by GNU C version 11.3.0, GMP version 6.2.1, MPFR version 4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/11/include-fixed"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-linux-gnu/11/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
GNU C17 (Ubuntu 11.3.0-1ubuntu1~22.04) version 11.3.0 (x86_64-linux-gnu)
    compiled by GNU C version 11.3.0, GMP version 6.2.1, MPFR version 4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 3f6cb05d963ad324b8f9442822c95179
COLLECT_GCC_OPTIONS='-v' '-shared' '-o' 'EmulatorCore.so' '-fPIC' '-Wall' '-g' '-m64' '-mtune=generic' '-march=x86-64' '-dumpdir' 'EmulatorCore.so-'
 as -v --gdwarf-5 --64 -o /tmp/ccs6mQj9.o /tmp/ccNiOQu1.s
GNU assembler version 2.38 (x86_64-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.38
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/11/:/usr/lib/gcc/x86_64-linux-gnu/11/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/11/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/11/:/usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/11/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/11/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-shared' '-o' 'EmulatorCore.so' '-fPIC' '-Wall' '-g' '-m64' '-mtune=generic' '-march=x86-64' '-dumpdir' 'EmulatorCore.so.'
 /usr/lib/gcc/x86_64-linux-gnu/11/collect2 -plugin /usr/lib/gcc/x86_64-linux-gnu/11/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper -plugin-opt=-fresolution=/tmp/cc2PLxAY.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu --as-needed -shared -z relro -o EmulatorCore.so /usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/11/crtbeginS.o -L/usr/lib/gcc/x86_64-linux-gnu/11 -L/usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/11/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/11/../../.. /tmp/ccs6mQj9.o core.obj -lgcc --push-state --as-needed -lgcc_s --pop-state -lc -lgcc --push-state --as-needed -lgcc_s --pop-state /usr/lib/gcc/x86_64-linux-gnu/11/crtendS.o /usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu/crtn.o
COLLECT_GCC_OPTIONS='-v' '-shared' '-o' 'EmulatorCore.so' '-fPIC' '-Wall' '-g' '-m64' '-mtune=generic' '-march=x86-64' '-dumpdir' 'EmulatorCore.so.'

I'm using a simple wrapper to adjust to the calling convention

#include <stdint.h>

extern int32_t asm_func(void* state);

int wrapper(void *state)
{
  int32_t toReturn = 0;

  __asm__ volatile(
     "mov %rdi, %rsi \t\n"
     "call asm_func  \t\n");

  return toReturn;
}

int32_t fnEmulatorCode(void* state) {
  return wrapper(state);
}