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>
This commit is contained in:
Dave Young
Matt Fleming
parent
456a29ddad
commit
5039e316dd
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@ -0,0 +1,38 @@
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What: /sys/kernel/boot_params
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Date: December 2013
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Contact: Dave Young <dyoung@redhat.com>
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Description: The /sys/kernel/boot_params directory contains two
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files: "data" and "version" and one subdirectory "setup_data".
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It is used to export the kernel boot parameters of an x86
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platform to userspace for kexec and debugging purpose.
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If there's no setup_data in boot_params the subdirectory will
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not be created.
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"data" file is the binary representation of struct boot_params.
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"version" file is the string representation of boot
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protocol version.
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"setup_data" subdirectory contains the setup_data data
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structure in boot_params. setup_data is maintained in kernel
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as a link list. In "setup_data" subdirectory there's one
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subdirectory for each link list node named with the number
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of the list nodes. The list node subdirectory contains two
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files "type" and "data". "type" file is the string
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representation of setup_data type. "data" file is the binary
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representation of setup_data payload.
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The whole boot_params directory structure is like below:
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/sys/kernel/boot_params
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|__ data
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|__ setup_data
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| |__ 0
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| | |__ data
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| | |__ type
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| |__ 1
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| |__ data
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| |__ type
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|__ version
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Users: Kexec
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@ -29,6 +29,7 @@ obj-$(CONFIG_X86_64) += sys_x86_64.o x8664_ksyms_64.o
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obj-y += syscall_$(BITS).o
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obj-$(CONFIG_X86_64) += vsyscall_64.o
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obj-$(CONFIG_X86_64) += vsyscall_emu_64.o
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obj-$(CONFIG_SYSFS) += ksysfs.o
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obj-y += bootflag.o e820.o
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obj-y += pci-dma.o quirks.o topology.o kdebugfs.o
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obj-y += alternative.o i8253.o pci-nommu.o hw_breakpoint.o
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@ -0,0 +1,339 @@
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/*
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* Architecture specific sysfs attributes in /sys/kernel
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*
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* Copyright (C) 2007, Intel Corp.
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* Huang Ying <ying.huang@intel.com>
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* Copyright (C) 2013, 2013 Red Hat, Inc.
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* Dave Young <dyoung@redhat.com>
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*
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* This file is released under the GPLv2
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*/
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#include <linux/kobject.h>
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#include <linux/string.h>
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#include <linux/sysfs.h>
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#include <linux/init.h>
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#include <linux/stat.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <asm/setup.h>
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static ssize_t version_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "0x%04x\n", boot_params.hdr.version);
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}
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static struct kobj_attribute boot_params_version_attr = __ATTR_RO(version);
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static ssize_t boot_params_data_read(struct file *fp, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t off, size_t count)
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{
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memcpy(buf, (void *)&boot_params + off, count);
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return count;
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}
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static struct bin_attribute boot_params_data_attr = {
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.attr = {
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.name = "data",
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.mode = S_IRUGO,
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},
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.read = boot_params_data_read,
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.size = sizeof(boot_params),
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};
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static struct attribute *boot_params_version_attrs[] = {
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&boot_params_version_attr.attr,
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NULL,
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};
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static struct bin_attribute *boot_params_data_attrs[] = {
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&boot_params_data_attr,
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NULL,
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};
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static struct attribute_group boot_params_attr_group = {
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.attrs = boot_params_version_attrs,
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.bin_attrs = boot_params_data_attrs,
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};
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static int kobj_to_setup_data_nr(struct kobject *kobj, int *nr)
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{
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const char *name;
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name = kobject_name(kobj);
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return kstrtoint(name, 10, nr);
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}
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static int get_setup_data_paddr(int nr, u64 *paddr)
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{
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int i = 0;
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struct setup_data *data;
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u64 pa_data = boot_params.hdr.setup_data;
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while (pa_data) {
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if (nr == i) {
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*paddr = pa_data;
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return 0;
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}
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data = ioremap_cache(pa_data, sizeof(*data));
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if (!data)
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return -ENOMEM;
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pa_data = data->next;
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iounmap(data);
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i++;
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}
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return -EINVAL;
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}
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static int __init get_setup_data_size(int nr, size_t *size)
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{
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int i = 0;
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struct setup_data *data;
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u64 pa_data = boot_params.hdr.setup_data;
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while (pa_data) {
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data = ioremap_cache(pa_data, sizeof(*data));
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if (!data)
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return -ENOMEM;
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if (nr == i) {
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*size = data->len;
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iounmap(data);
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return 0;
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}
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pa_data = data->next;
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iounmap(data);
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i++;
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}
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return -EINVAL;
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}
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static ssize_t type_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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int nr, ret;
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u64 paddr;
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struct setup_data *data;
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ret = kobj_to_setup_data_nr(kobj, &nr);
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if (ret)
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return ret;
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ret = get_setup_data_paddr(nr, &paddr);
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if (ret)
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return ret;
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data = ioremap_cache(paddr, sizeof(*data));
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if (!data)
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return -ENOMEM;
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ret = sprintf(buf, "0x%x\n", data->type);
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iounmap(data);
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return ret;
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}
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static ssize_t setup_data_data_read(struct file *fp,
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struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf,
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loff_t off, size_t count)
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{
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int nr, ret = 0;
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u64 paddr;
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struct setup_data *data;
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void *p;
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ret = kobj_to_setup_data_nr(kobj, &nr);
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if (ret)
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return ret;
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ret = get_setup_data_paddr(nr, &paddr);
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if (ret)
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return ret;
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data = ioremap_cache(paddr, sizeof(*data));
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if (!data)
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return -ENOMEM;
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if (off > data->len) {
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ret = -EINVAL;
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goto out;
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}
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if (count > data->len - off)
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count = data->len - off;
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if (!count)
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goto out;
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ret = count;
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p = ioremap_cache(paddr + sizeof(*data), data->len);
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if (!p) {
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ret = -ENOMEM;
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goto out;
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}
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memcpy(buf, p + off, count);
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iounmap(p);
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out:
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iounmap(data);
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return ret;
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}
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static struct kobj_attribute type_attr = __ATTR_RO(type);
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static struct bin_attribute data_attr = {
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.attr = {
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.name = "data",
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.mode = S_IRUGO,
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},
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.read = setup_data_data_read,
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};
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static struct attribute *setup_data_type_attrs[] = {
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&type_attr.attr,
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NULL,
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};
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static struct bin_attribute *setup_data_data_attrs[] = {
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&data_attr,
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NULL,
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};
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static struct attribute_group setup_data_attr_group = {
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.attrs = setup_data_type_attrs,
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.bin_attrs = setup_data_data_attrs,
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};
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static int __init create_setup_data_node(struct kobject *parent,
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struct kobject **kobjp, int nr)
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{
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int ret = 0;
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size_t size;
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struct kobject *kobj;
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char name[16]; /* should be enough for setup_data nodes numbers */
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snprintf(name, 16, "%d", nr);
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kobj = kobject_create_and_add(name, parent);
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if (!kobj)
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return -ENOMEM;
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ret = get_setup_data_size(nr, &size);
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if (ret)
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goto out_kobj;
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data_attr.size = size;
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ret = sysfs_create_group(kobj, &setup_data_attr_group);
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if (ret)
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goto out_kobj;
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*kobjp = kobj;
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return 0;
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out_kobj:
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kobject_put(kobj);
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return ret;
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}
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static void __init cleanup_setup_data_node(struct kobject *kobj)
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{
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sysfs_remove_group(kobj, &setup_data_attr_group);
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kobject_put(kobj);
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}
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static int __init get_setup_data_total_num(u64 pa_data, int *nr)
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{
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int ret = 0;
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struct setup_data *data;
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*nr = 0;
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while (pa_data) {
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*nr += 1;
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data = ioremap_cache(pa_data, sizeof(*data));
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if (!data) {
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ret = -ENOMEM;
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goto out;
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}
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pa_data = data->next;
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iounmap(data);
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}
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out:
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return ret;
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}
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static int __init create_setup_data_nodes(struct kobject *parent)
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{
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struct kobject *setup_data_kobj, **kobjp;
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u64 pa_data;
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int i, j, nr, ret = 0;
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pa_data = boot_params.hdr.setup_data;
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if (!pa_data)
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return 0;
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setup_data_kobj = kobject_create_and_add("setup_data", parent);
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if (!setup_data_kobj) {
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ret = -ENOMEM;
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goto out;
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}
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ret = get_setup_data_total_num(pa_data, &nr);
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if (ret)
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goto out_setup_data_kobj;
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kobjp = kmalloc(sizeof(*kobjp) * nr, GFP_KERNEL);
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if (!kobjp) {
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ret = -ENOMEM;
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goto out_setup_data_kobj;
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}
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for (i = 0; i < nr; i++) {
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ret = create_setup_data_node(setup_data_kobj, kobjp + i, i);
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if (ret)
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goto out_clean_nodes;
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}
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kfree(kobjp);
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return 0;
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out_clean_nodes:
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for (j = i - 1; j > 0; j--)
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cleanup_setup_data_node(*(kobjp + j));
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kfree(kobjp);
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out_setup_data_kobj:
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kobject_put(setup_data_kobj);
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out:
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return ret;
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}
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static int __init boot_params_ksysfs_init(void)
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{
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int ret;
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struct kobject *boot_params_kobj;
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boot_params_kobj = kobject_create_and_add("boot_params",
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kernel_kobj);
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if (!boot_params_kobj) {
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ret = -ENOMEM;
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goto out;
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}
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ret = sysfs_create_group(boot_params_kobj, &boot_params_attr_group);
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if (ret)
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goto out_boot_params_kobj;
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ret = create_setup_data_nodes(boot_params_kobj);
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if (ret)
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goto out_create_group;
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return 0;
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out_create_group:
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sysfs_remove_group(boot_params_kobj, &boot_params_attr_group);
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out_boot_params_kobj:
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kobject_put(boot_params_kobj);
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out:
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return ret;
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}
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arch_initcall(boot_params_ksysfs_init);
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