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bootconfig: Load boot config from the tail of initrd

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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: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu 2020-01-11 01:03:44 +09:00 committed by Steven Rostedt (VMware)
parent 76db5a27a8
commit 7684b8582c
2 changed files with 55 additions and 0 deletions
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1
init/Kconfig
View File

@ -1217,6 +1217,7 @@ endif
config BOOT_CONFIG
bool "Boot config support"
depends on BLK_DEV_INITRD
select LIBXBC
default y
help

54
init/main.c
View File

@ -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();