Commit 7684b858 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
Browse files

bootconfig: Load boot config from the tail of initrd 

Load the extended boot config data from the tail of initrd
image. If there is an SKC data there, it has
[(u32)size][(u32)checksum] header (in really, this is a
footer) at the end of initrd. If the checksum (simple sum
of bytes) is match, this starts parsing it from there.

Link: http://lkml.kernel.org/r/157867222435.17873.9936667353335606867.stgit@devnote2



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 76db5a27

init/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -1217,6 +1217,7 @@ endif 


config BOOT_CONFIG

	bool "Boot config support"

	depends on BLK_DEV_INITRD

	select LIBXBC

	default y

	help

init/main.c

+54 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/initrd.h>

#include <linux/memblock.h>

#include <linux/acpi.h>

#include <linux/bootconfig.h>

#include <linux/console.h>

#include <linux/nmi.h>

#include <linux/percpu.h>
@@ -245,6 +246,58 @@ static int __init loglevel(char *str) 


early_param("loglevel", loglevel);



#ifdef CONFIG_BOOT_CONFIG

u32 boot_config_checksum(unsigned char *p, u32 size)

{

	u32 ret = 0;



	while (size--)

		ret += *p++;



	return ret;

}



static void __init setup_boot_config(void)

{

	u32 size, csum;

	char *data, *copy;

	u32 *hdr;



	if (!initrd_end)

		return;



	hdr = (u32 *)(initrd_end - 8);

	size = hdr[0];

	csum = hdr[1];



	if (size >= XBC_DATA_MAX)

		return;



	data = ((void *)hdr) - size;

	if ((unsigned long)data < initrd_start)

		return;



	if (boot_config_checksum((unsigned char *)data, size) != csum)

		return;



	copy = memblock_alloc(size + 1, SMP_CACHE_BYTES);

	if (!copy) {

		pr_err("Failed to allocate memory for boot config\n");

		return;

	}



	memcpy(copy, data, size);

	copy[size] = '\0';



	if (xbc_init(copy) < 0)

		pr_err("Failed to parse boot config\n");

	else

		pr_info("Load boot config: %d bytes\n", size);

}

#else

#define setup_boot_config()	do { } while (0)

#endif



/* Change NUL term back to "=", to make "param" the whole string. */

static int __init repair_env_string(char *param, char *val,

				    const char *unused, void *arg)
@@ -595,6 +648,7 @@ asmlinkage __visible void __init start_kernel(void) 
	pr_notice("%s", linux_banner);

	early_security_init();

	setup_arch(&command_line);

	setup_boot_config();

	setup_command_line(command_line);

	setup_nr_cpu_ids();

	setup_per_cpu_areas();