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

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

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?

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

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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