[PATCH] env: Leave invalid env for nowhere location

[Kunihiko Hayashi]

Hi Marek,
Sorry for rate reply.

On 2021/05/25 16:35, Marek Vasut wrote:
> On 5/12/21 4:09 PM, Kunihiko Hayashi wrote:
>> When CONFIG_ENV_IS_NOWHERE is enabled, env_nowhere_init() sets ENV_INVALID
>> to gd->env_valid, and sets default_environment before relocation to
>> gd->env_addr. After that, env_init() switches gd->env_valid to ENV_VALID
>> by the previous fix.
>>
>> If gd->env_valid is ENV_INVALID, env_get_char() returns relocated
>> default_environment, however, env_get_char() returns gd->env_addr before
>> relocation since gd->env_valid is ENV_VALID, and access to gd->env_addr
>> will cause a fault.
>>
>> This leaves gd->env_valid as ENV_INVALID for "nowhere" location.
> 
> So do I understand this correctly that _after_ relocation, env_init() is
> called and env_init() does not update gd->env_addr to the relocated one?

In my understandings, env_init() belongs to init_sequence_f[]
and env_init() is called before relocation.

> I would expect that after relocation, if all you have is env_nowhere
> driver, the env_nowhere_init() is called again from the first for() loop
> of env_init() [1], which would set gd->env_valid to ENV_INVALID [1], and
> that for() loop would exit with ret = -ENOENT [2], so then the last part
> of env_init() would check for ret == -ENOENT and update gd->env_addr to
> relocated default_environment [3].
> 
> 324  int env_init(void)
> 325  {
> 326    struct env_driver *drv;
> 327    int ret = -ENOENT;
> 328    int prio;
> 329
> 330    for (prio = 0; (drv = env_driver_lookup(ENVOP_INIT, prio)); prio++) {
>            /* Part [1] */
> 331      if (!drv->init || !(ret = drv->init()))
> 332        env_set_inited(drv->location);
> 333      if (ret == -ENOENT)
> 334        env_set_inited(drv->location);
> 335
> 336      debug("%s: Environment %s init done (ret=%d)\n", __func__,
> 337            drv->name, ret);
> 338
>            /* Part [2] */
> 339      if (gd->env_valid == ENV_INVALID)
> 340        ret = -ENOENT;
> 341    }
> 342
> 343    if (!prio)
> 344      return -ENODEV;
> 345
>          /* Part [3] */
> 346    if (ret == -ENOENT) {
>            /* This should be relocated default_environment address */
> 347      gd->env_addr = (ulong)&default_environment[0];
> 348      gd->env_valid = ENV_VALID;
> 349
> 350      return 0;
> 351    }
> 352
> 353    return ret;
> 354  }
> 
> Or am I missing something obvious ?

These are called before relocation, and update gd->env_addr to non-relocated
default_environment by [3].

After that, gd->env_addr is relocated in initr_reloc_global_data()
if CONFIG_SYS_RELOC_GD_ENV_ADDR is defined.

| #ifdef CONFIG_SYS_RELOC_GD_ENV_ADDR
| 	/*
| 	 * Relocate the early env_addr pointer unless we know it is not inside
| 	 * the binary. Some systems need this and for the rest, it doesn't hurt.
| 	 */
| 	gd->env_addr += gd->reloc_off;
| #endif


However, I misunderstood my situation.
gd->reloc_off doesn't have the proper value because CONFIG_SYS_TEXT_BASE
is zero due to CONFIG_POSITION_INDENENDENT=y.

gd->reloc_off is calculated with CONFIG_SYS_TEXT_BASE in setup_reloc().

| 	gd->reloc_off = gd->relocaddr - CONFIG_SYS_TEXT_BASE;

gd->env_addr is added with gd->reloc_off (== gd->relocaddr - 0),
as a result, gd->env_addr has wrong address.

In this case, I think the proper solution is to undefine
CONFIG_SYS_RELOC_GD_ENV_ADDR.

My patch isn't necessary no longer and your patch also works with
"nowhere".

Thank you,

---
Best Regards
Kunihiko Hayashi