Re: [PATCH v3 21/27] plugins: add an API to read registers

["Alex Bennée" <alex.bennee@linaro.org>]

Akihiko Odaki <akihiko.odaki@daynix.com> writes:

> On 2024/02/27 1:56, Alex Bennée wrote:
>> We can only request a list of registers once the vCPU has been
>> initialised so the user needs to use either call the get function on
>> vCPU initialisation or during the translation phase.
>> We don't expose the reg number to the plugin instead hiding it
>> behind
>> an opaque handle. For now this is just the gdb_regnum encapsulated in
>> an anonymous GPOINTER but in future as we add more state for plugins
>> to track we can expand it.
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1706
>> Cc: Akihiko Odaki <akihiko.odaki@daynix.com>
>> Message-Id: <20240103173349.398526-39-alex.bennee@linaro.org>
>> Based-on: <20231025093128.33116-18-akihiko.odaki@daynix.com>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>
> Hi,
>
> Mostly looks good. I have a few trivial comments so please have a look
> at them.

Done

<snip>
>> +        g_array_append_val(find_data, desc);
>> +    }
>> +
>> +    return find_data;
>> +}
>> +
>> +GArray *qemu_plugin_get_registers(void)
>> +{
>> +    g_assert(current_cpu);
>> +
>> +    g_autoptr(GArray) regs = gdb_get_register_list(current_cpu);
>> +    return regs->len ? create_register_handles(current_cpu, regs) : NULL;
>
> Why do you need regs->len check?

Not all guests expose register to gdb so we need to catch that:

  TEST    catch-syscalls-with-libinsn.so on alpha
**
ERROR:../../plugins/api.c:459:qemu_plugin_get_registers: assertion failed: (regs->len)
Aborted

<snip>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro