From 5039e316dde3fb71c79e95e97c5bca8e4724d8f2 Mon Sep 17 00:00:00 2001 From: Dave Young Date: Fri, 20 Dec 2013 18:02:21 +0800 Subject: 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 Acked-by: Borislav Petkov Tested-by: Toshi Kani Signed-off-by: Matt Fleming --- Documentation/ABI/testing/sysfs-kernel-boot_params | 38 ++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-boot_params (limited to 'Documentation/ABI/testing/sysfs-kernel-boot_params') diff --git a/Documentation/ABI/testing/sysfs-kernel-boot_params b/Documentation/ABI/testing/sysfs-kernel-boot_params new file mode 100644 index 000000000000..eca38ce2852d --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-boot_params @@ -0,0 +1,38 @@ +What: /sys/kernel/boot_params +Date: December 2013 +Contact: Dave Young +Description: The /sys/kernel/boot_params directory contains two + files: "data" and "version" and one subdirectory "setup_data". + It is used to export the kernel boot parameters of an x86 + platform to userspace for kexec and debugging purpose. + + If there's no setup_data in boot_params the subdirectory will + not be created. + + "data" file is the binary representation of struct boot_params. + + "version" file is the string representation of boot + protocol version. + + "setup_data" subdirectory contains the setup_data data + structure in boot_params. setup_data is maintained in kernel + as a link list. In "setup_data" subdirectory there's one + subdirectory for each link list node named with the number + of the list nodes. The list node subdirectory contains two + files "type" and "data". "type" file is the string + representation of setup_data type. "data" file is the binary + representation of setup_data payload. + + The whole boot_params directory structure is like below: + /sys/kernel/boot_params + |__ data + |__ setup_data + | |__ 0 + | | |__ data + | | |__ type + | |__ 1 + | |__ data + | |__ type + |__ version + +Users: Kexec -- cgit