RUST compiled code for riscv32imc-unknown-none-elf doesn't provide custom instruction in object dump code

Hi,
code for riscv32imc-unknown-none-elf target successfully compiles and generates the output file. Using riscv32-unknown-elf-objdump generated object dump file.

Object dump comprises of .insn instead of actual custom instruction
110e2: 00e6850b .insn 4, 0x00e6850b

Any help is much appreciated.

Thanks