fix: resolve memory access violation in io_addr test

[owlxiao]

This PR aims to resolve memory access violation in io_addr test.

The io_addr regression test was failing with memory access violation errors:

Memory access violation from 0x80 to 0x88, curent flags=1, access flags=2
Error: exception: invalid memory address

This issue occurs because, during the io_addr test, the io_mpm_addr is periodically read to obtain test data. In the main test program, this region is reserved with READ-ONLY permissions.

  RT_CHECK(vx_mem_alloc(device, addr_buf_size, VX_MEM_READ, &usr_test_buffer));
  RT_CHECK(vx_mem_address(usr_test_buffer, &usr_test_addr));
  RT_CHECK(vx_mem_reserve(device, io_base_addr, addr_buf_size, VX_MEM_READ, &io_test_buffer));
  RT_CHECK(vx_mem_alloc(device, src_buf_size, VX_MEM_READ, &src_buffer));
  RT_CHECK(vx_mem_address(src_buffer, &kernel_arg.src_addr));
  RT_CHECK(vx_mem_alloc(device, dst_buf_size, VX_MEM_WRITE, &dst_buffer));
  RT_CHECK(vx_mem_address(dst_buffer, &kernel_arg.dst_addr));

However, at the end of each kernel execution, the program calls vx_perf_dump to export performance counters, and vx_perf_dump writes the corresponding counter values to io_mpm_addr.

.section .text
.type _Exit, @function
.global _Exit
_Exit:
  call vx_perf_dump
  li t0, IO_MPM_EXITCODE
  sw a0, 0(t0)
  fence
  .insn r RISCV_CUSTOM0, 0, 0, x0, x0, x0  # tmc x0

void vx_perf_dump() {
    int core_id = vx_core_id();
    uint32_t * const csr_mem = (uint32_t*)(IO_MPM_ADDR + 64 * sizeof(uint32_t) * core_id);
    DUMP_CSRS(0);
    //DUMP_CSRS(1); reserved for exitcode
    DUMP_CSRS(2);
    DUMP_CSRS(3);
    ...
}

Since the region still has READ-ONLY permissions at that point, this results in an error.

[tinebp]

Can you please share the command line to reproduce this bug?