fix expose_csr for CSR with address "0"

This change is a quick-and-dirty workaround for the problem when user
wants to expose CSR with address "0" and instead of user-specified name
"csr0" was used.

The problem looks as follows:

riscv013_reg_examine_all eventually calls init_cache_entry for all CSRs.
init_cache_entry eventually results in a call to riscv_reg_gdb_regno_name.

Then in case of non-standard CSRs we have the following logic:

```
// NULL when regno == 0, since names are not generated yet
if (info->reg_names[regno])
    return info->reg_names[regno]
...
if (regno >= GDB_REGNO_CSR0 && regno <= GDB_REGNO_CSR4095) {
    // generate names for all exposed CSRs (the function
    // lazy-initializes all the required names)
    init_custom_csr_names(target);
    // And here we have an error, since we overwrite the name generated
    // by init_custom_csr_names
    info->reg_names[regno] =
        init_reg_name_with_prefix("csr", regno - GDB_REGNO_CSR0);
...
```

The error happens because when initially this function is called with
regno = 0, the first condition false, so we have to go and generate all
the names.

0 files changed, 0 insertions, 0 deletions