x86: Export x86 boot_params to sysfs

kexec-tools use boot_params for getting the 1st kernel hardware_subarch,
the kexec kernel EFI runtime support also needs to read the old efi_info
from boot_params. Currently it exists in debugfs which is not a good
place for such infomation. Per HPA, we should avoid "sploit debugfs".

In this patch /sys/kernel/boot_params are exported, also the setup_data is
exported as a subdirectory. kexec-tools is using debugfs for hardware_subarch
for a long time now so we're not removing it yet.

Structure is like below:

/sys/kernel/boot_params
|__ data                /* boot_params in binary*/
|__ setup_data
|   |__ 0               /* the first setup_data node */
|   |   |__ data        /* setup_data node 0 in binary*/
|   |   |__ type        /* setup_data type of setup_data node 0, hex string */
[snip]
|__ version             /* boot protocal version (in hex, "0x" prefixed)*/

Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 9b0a34e2cd79..510cca5c5390 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_X86_64)	+= sys_x86_64.o x8664_ksyms_64.o
 obj-y			+= syscall_$(BITS).o
 obj-$(CONFIG_X86_64)	+= vsyscall_64.o
 obj-$(CONFIG_X86_64)	+= vsyscall_emu_64.o
+obj-$(CONFIG_SYSFS)	+= ksysfs.o
 obj-y			+= bootflag.o e820.o
 obj-y			+= pci-dma.o quirks.o topology.o kdebugfs.o
 obj-y			+= alternative.o i8253.o pci-nommu.o hw_breakpoint.o