I founded that's riscv-pk is not the latest one. And one bug has been fixed in riscv-pk's master branch.
They replace '__clear_cache(0, 0)' with 'asm volatile ("fence.i")'. It was merged in https://github.com/riscv-software-src/riscv-pk/pull/240,
So I wish the submodule riscv-pk could be update.
I founded that's riscv-pk is not the latest one. And one bug has been fixed in riscv-pk's master branch. They replace '__clear_cache(0, 0)' with 'asm volatile ("fence.i")'. It was merged in https://github.com/riscv-software-src/riscv-pk/pull/240, So I wish the submodule riscv-pk could be update.