On 6/8/21 9:54 AM, Kunihiko Hayashi wrote:
Hi,
[...]
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
Shouldn't the post-relocation env update happen in env_relocate() ?
Usually env_relocate() calls env_load() that uses relocated gd->env_addr. It's no problem.
If CONFIG_SYS_TEXT_BASE is zero, gd->reloc_off becomes illegal. CONFIG_SYS_RELOC_GD_ENV_ADDR should be disabled in that case.
Sorry this isn't wrong.
But then, if CONFIG_SYS_TEXT_BASE is zero, the env shouldn't be relocated or how should it behave ?
I think the env should be relocated if CONFIG_SYS_RELOC_GD_ENV_ADDR=y regardless of CONFIG_SYS_TEXT_BASE.
If CONFIG_POSITION_INDEPENDENT=y and CONFIG_SYS_TEXT_BASE is zero, there is something wrong with the calculation of the relocation address about env.
Ah, got it.
gd->reloc_off is relocated address offset from zero, however, gd->env_addr has still non-relocated address.
| gd->env_addr += gd->reloc_off;
I think the env should be relocated if CONFIG_SYS_RELOC_GD_ENV_ADDR=y. But this code sets gd->env_addr incorrectly.
In that case, there is a non-relocated <textbase> address instead of CONFIG_SYS_TEXT_BASE.
This should be "gd->env_addr = (gd->env_addr - <textbase>) + gd->reloc_off", However, I'm not sure how we get non-relocated <textbase> address.
Maybe what you need to do is store current $pc register when you enter U-Boot very early on, in _start function, and then use it here ? Although, I am not entirely sure whether this is still possible on arm64.