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

["Clément Leger" <cleger@kalray.eu>]

Hi Ahmad,

----- On 24 Jun, 2020, at 08:17, Ahmad Fatoum a.fatoum@pengutronix.de wrote:

> On 6/23/20 9:35 PM, Clement Leger wrote:
>> From: Clement Leger <clement.leger@kalray.eu>
>> 
>> In order to boot elfs files, add bootm command support for kvx. This support
>> can boot elf files using bootm elf support. initrd and device-tree handling
>> is also included and loads them after the elf file load address.
>> 
>> Signed-off-by: Clement Leger <cleger@kalray.eu>
>> ---
>>  arch/kvx/Kconfig                   |   5 ++
>>  arch/kvx/configs/generic_defconfig |   3 +-
>>  arch/kvx/include/asm/bootm.h       |  11 +++
>>  arch/kvx/include/asm/elf.h         |   3 +
>>  arch/kvx/lib/Makefile              |   2 +-
>>  arch/kvx/lib/bootm.c               | 134 +++++++++++++++++++++++++++++
>>  6 files changed, 156 insertions(+), 2 deletions(-)
>>  create mode 100644 arch/kvx/include/asm/bootm.h
>>  create mode 100644 arch/kvx/lib/bootm.c
>> 
>> diff --git a/arch/kvx/Kconfig b/arch/kvx/Kconfig
>> index 5463bb4f1..3327021e1 100644
>> --- a/arch/kvx/Kconfig
>> +++ b/arch/kvx/Kconfig
>> @@ -1,9 +1,14 @@
>>  config KVX
>>  	bool
>>  	select 64BIT
>> +	select BOOTM
>> +	select BOOTM_ELF
>> +	select BOOTM_OFTREE
>> +	select BOOTM_INITRD
>>  	select CLKDEV_LOOKUP
>>  	select COMMON_CLK
>>  	select COMMON_CLK_OF_PROVIDER
>> +	select ELF
>>  	select FLEXIBLE_BOOTARGS
>>  	select GENERIC_FIND_NEXT_BIT
>>  	select LIBFDT
>> diff --git a/arch/kvx/configs/generic_defconfig
>> b/arch/kvx/configs/generic_defconfig
>> index f9ff773a0..816217174 100644
>> --- a/arch/kvx/configs/generic_defconfig
>> +++ b/arch/kvx/configs/generic_defconfig
>> @@ -1,7 +1,8 @@
>>  CONFIG_AUTO_COMPLETE=y
>>  CONFIG_BAUDRATE=115200
>> -# CONFIG_BOOTM is not set
>>  CONFIG_CLOCKSOURCE_KVX=y
>> +CONFIG_CMD_BOOT=y
>> +CONFIG_CMD_BOOTM=y
>>  CONFIG_CMD_CMP=y
>>  CONFIG_CMD_OF_DUMP=y
>>  CONFIG_CMD_POWEROFF=y
>> diff --git a/arch/kvx/include/asm/bootm.h b/arch/kvx/include/asm/bootm.h
>> new file mode 100644
>> index 000000000..7ad7e2e87
>> --- /dev/null
>> +++ b/arch/kvx/include/asm/bootm.h
>> @@ -0,0 +1,11 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Copyright (C) 2019 Kalray Inc.
>> + */
>> +
>> +#ifndef _ASM_KVX_BOOTM_H
>> +#define _ASM_KVX_BOOTM_H
>> +
>> +#define LINUX_BOOT_PARAM_MAGIC 0x31564752414E494CULL
>> +
>> +#endif /* _ASM_KVX_BOOTM_H */
>> diff --git a/arch/kvx/include/asm/elf.h b/arch/kvx/include/asm/elf.h
>> index 7cc09d7ba..2975ad1b9 100644
>> --- a/arch/kvx/include/asm/elf.h
>> +++ b/arch/kvx/include/asm/elf.h
>> @@ -11,6 +11,9 @@
>>   */
>>  #include <linux/types.h>
>>  
>> +#define EM_KVX		256
>> +
>> +#define ELF_ARCH	EM_KVX
>>  #define ELF_CLASS	ELFCLASS32
>>  #define ELF_DATA	ELFDATA2MSB
>>  
>> diff --git a/arch/kvx/lib/Makefile b/arch/kvx/lib/Makefile
>> index 352e7034a..6e56462da 100644
>> --- a/arch/kvx/lib/Makefile
>> +++ b/arch/kvx/lib/Makefile
>> @@ -3,4 +3,4 @@
>>  # Copyright (C) 2019 Kalray Inc.
>>  #
>>  
>> -obj-y	+= cpuinfo.o board.o dtb.o poweroff.o
>> +obj-y	+= cpuinfo.o board.o dtb.o poweroff.o bootm.o
>> diff --git a/arch/kvx/lib/bootm.c b/arch/kvx/lib/bootm.c
>> new file mode 100644
>> index 000000000..02bd0b5cf
>> --- /dev/null
>> +++ b/arch/kvx/lib/bootm.c
>> @@ -0,0 +1,134 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * This file is subject to the terms and conditions of the GNU General Public
>> + * License.  See the file "COPYING" in the main directory of this archive
>> + * for more details.
>> + *
>> + * Copyright (C) 2019 Kalray Inc.
>> + */
>> +
>> +#include <elf.h>
>> +#include <boot.h>
>> +#include <init.h>
>> +#include <bootm.h>
>> +#include <binfmt.h>
>> +#include <common.h>
>> +#include <libfile.h>
>> +#include <linux/kernel.h>
>> +
>> +#include <asm/cache.h>
>> +#include <asm/bootm.h>
>> +
>> +typedef void __noreturn (*boot_func_entry)(unsigned long, void *);
>> +
>> +static int do_boot_entry(struct image_data *data, boot_func_entry entry,
>> +			 void *fdt_load_addr)
>> +{
>> +	printf("starting elf (entry at %p)\n", entry);
>> +
>> +	if (data->dryrun)
>> +		return 0;
>> +
>> +	shutdown_barebox();
>> +
>> +	/* flushes instruction and clear dcache caches before execution */
>> +	sync_dcache_icache();
>> +	dcache_inval();
> 
> 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.

> 
>> +
>> +	/**
>> +	 * 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.                           |                             |
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