Re: [PATCH 4/4] kvx: add support for elf loading using bootm

["Clément Leger" <cleger@kalray.eu>]

Hi Ahmad

----- On 29 Jun, 2020, at 10:15, Ahmad Fatoum a.fatoum@pengutronix.de wrote:

> Hello,
> 
> On 6/24/20 9:15 AM, Clément Leger wrote:
>>> You already flushed out the dcache contents to the point of unification.
>>> What do you gain by invalidating it?
>> 
>> Indeed, this is not strictly necessary, it just allow to boot the elf without a
>> dirty D-cache. But actually, the booted program should invalidate its D-cache
>> before fetching any data to avoid using cached data. I can remove it since
>> this is only for some buggy programs.
> 
> Why would use of cached data hurt here? If you keep the MMU throughout, you
> should only need to invalidate the data cache when doing DMA. Am I missing
> something?

You are actually right, since barebox loaded the program by itself, the D-cache
contains the expected data even for the loaded program.
BTW, MMU is not enabled yet in barebox.

> 
> Either way, I've no preference (except for naming it the same as on ARM,
> see previous mail).

Sorry, I missed the points you made on my previous patchset, my mailer marked
all the mail has read :/. I will make another more through review.

Regards,

Clément

> 
> Cheers
> Ahmad
> 
>> 
>>>
>>>> +
>>>> +	/**
>>>> +	 * Parameters passing
>>>> +	 * r0: boot magic
>>>> +	 * r1: device tree pointer
>>>> +	 */
>>>> +	entry(LINUX_BOOT_PARAM_MAGIC, (void *) fdt_load_addr);
>>>> +
>>>> +	/* should never return ! */
>>>> +	panic("Returned from boot program !\n");
>>>> +
>>>> +	return -EINVAL;
>>>> +}
>>>> +
>>>> +static int do_boot_elf(struct image_data *data, struct elf_image *elf)
>>>> +{
>>>> +	int ret;
>>>> +	void *fdt;
>>>> +	boot_func_entry entry;
>>>> +	unsigned long load_addr, initrd_address;
>>>> +
>>>> +	/* load initrd after the elf */
>>>> +	load_addr = PAGE_ALIGN((unsigned long) elf->high_addr);
>>>> +	if (bootm_has_initrd(data)) {
>>>> +		if (data->initrd_address != UIMAGE_INVALID_ADDRESS)
>>>> +			initrd_address = data->initrd_address;
>>>> +		else
>>>> +			initrd_address = load_addr;
>>>> +
>>>> +		printf("Loading initrd at 0x%lx\n", initrd_address);
>>>> +		ret = bootm_load_initrd(data, initrd_address);
>>>> +		if (ret) {
>>>> +			printf("Failed to load initrd\n");
>>>> +			return ret;
>>>> +		}
>>>> +
>>>> +		if (data->initrd_address == UIMAGE_INVALID_ADDRESS) {
>>>> +			load_addr += resource_size(data->initrd_res);
>>>> +			load_addr = PAGE_ALIGN(load_addr);
>>>> +		}
>>>> +	}
>>>> +
>>>> +	fdt = bootm_get_devicetree(data);
>>>> +	if (IS_ERR(fdt)) {
>>>> +		printf("Failed to load dtb\n");
>>>> +		return PTR_ERR(fdt);
>>>> +	}
>>>> +
>>>> +	printf("Loading device tree at %lx\n", load_addr);
>>>> +	/* load device tree after the initrd if any */
>>>> +	ret = bootm_load_devicetree(data, fdt, load_addr);
>>>> +	if (ret) {
>>>> +		printf("Failed to load device tree: %d\n", ret);
>>>> +		goto err_free_fdt;
>>>> +	}
>>>> +
>>>> +	entry = (boot_func_entry) data->os_address;
>>>> +
>>>> +	ret = do_boot_entry(data, entry, fdt);
>>>> +
>>>> +err_free_fdt:
>>>> +	free(fdt);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int do_bootm_elf(struct image_data *data)
>>>> +{
>>>> +	int ret;
>>>> +
>>>> +	ret = bootm_load_os(data, data->os_address);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	return do_boot_elf(data, data->elf);
>>>> +}
>>>> +
>>>> +static struct image_handler elf_handler = {
>>>> +	.name = "ELF",
>>>> +	.bootm = do_bootm_elf,
>>>> +	.filetype = filetype_elf,
>>>> +};
>>>> +
>>>> +static struct binfmt_hook binfmt_elf_hook = {
>>>> +	.type = filetype_elf,
>>>> +	.exec = "bootm",
>>>> +};
>>>> +
>>>> +static int kvx_register_image_handler(void)
>>>> +{
>>>> +	register_image_handler(&elf_handler);
>>>> +
>>>> +	binfmt_register(&binfmt_elf_hook);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +late_initcall(kvx_register_image_handler);
>>>>
>>>
>>> --
>>> Pengutronix e.K.                           |                             |
>>> Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
>>> 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
>>> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
>> 
> 
> --
> Pengutronix e.K.                           |                             |
> Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
> 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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