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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.
This commit is contained in:
Parshintsev Anatoly 2025-01-30 20:22:03 +03:00
parent 5de7310881
commit 3999025add
1 changed files with 2 additions and 2 deletions
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4
src/target/riscv/riscv_reg.c
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@ -56,7 +56,6 @@ static const char * const default_reg_names[GDB_REGNO_COUNT] = {
[GDB_REGNO_T5] = "t5",
[GDB_REGNO_T6] = "t6",
[GDB_REGNO_PC] = "pc",
[GDB_REGNO_CSR0] = "csr0",
[GDB_REGNO_PRIV] = "priv",
[GDB_REGNO_FT0] = "ft0",
[GDB_REGNO_FT1] = "ft1",
@ -196,7 +195,8 @@ const char *riscv_reg_gdb_regno_name(const struct target *target, enum gdb_regno
}
if (regno >= GDB_REGNO_CSR0 && regno <= GDB_REGNO_CSR4095) {
init_custom_csr_names(target);
info->reg_names[regno] = init_reg_name_with_prefix("csr", regno - GDB_REGNO_CSR0);
if (!info->reg_names[regno])
info->reg_names[regno] = init_reg_name_with_prefix("csr", regno - GDB_REGNO_CSR0);
return info->reg_names[regno];
}
assert(!"Encountered uninitialized entry in reg_names table");