linux/kernel/ksysfs.c
Hari Bathini 692f66f26a crash: move crashkernel parsing and vmcore related code under CONFIG_CRASH_CORE
Patch series "kexec/fadump: remove dependency with CONFIG_KEXEC and
reuse crashkernel parameter for fadump", v4.

Traditionally, kdump is used to save vmcore in case of a crash.  Some
architectures like powerpc can save vmcore using architecture specific
support instead of kexec/kdump mechanism.  Such architecture specific
support also needs to reserve memory, to be used by dump capture kernel.
crashkernel parameter can be a reused, for memory reservation, by such
architecture specific infrastructure.

This patchset removes dependency with CONFIG_KEXEC for crashkernel
parameter and vmcoreinfo related code as it can be reused without kexec
support.  Also, crashkernel parameter is reused instead of
fadump_reserve_mem to reserve memory for fadump.

The first patch moves crashkernel parameter parsing and vmcoreinfo
related code under CONFIG_CRASH_CORE instead of CONFIG_KEXEC_CORE.  The
second patch reuses the definitions of append_elf_note() & final_note()
functions under CONFIG_CRASH_CORE in IA64 arch code.  The third patch
removes dependency on CONFIG_KEXEC for firmware-assisted dump (fadump)
in powerpc.  The next patch reuses crashkernel parameter for reserving
memory for fadump, instead of the fadump_reserve_mem parameter.  This
has the advantage of using all syntaxes crashkernel parameter supports,
for fadump as well.  The last patch updates fadump kernel documentation
about use of crashkernel parameter.

This patch (of 5):

Traditionally, kdump is used to save vmcore in case of a crash.  Some
architectures like powerpc can save vmcore using architecture specific
support instead of kexec/kdump mechanism.  Such architecture specific
support also needs to reserve memory, to be used by dump capture kernel.
crashkernel parameter can be a reused, for memory reservation, by such
architecture specific infrastructure.

But currently, code related to vmcoreinfo and parsing of crashkernel
parameter is built under CONFIG_KEXEC_CORE.  This patch introduces
CONFIG_CRASH_CORE and moves the above mentioned code under this config,
allowing code reuse without dependency on CONFIG_KEXEC.  There is no
functional change with this patch.

Link: http://lkml.kernel.org/r/149035338104.6881.4550894432615189948.stgit@hbathini.in.ibm.com
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-08 17:15:11 -07:00

272 lines
6.3 KiB
C

/*
* kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
* are not related to any other subsystem
*
* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
*
* This file is release under the GPLv2
*
*/
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/kexec.h>
#include <linux/profile.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/capability.h>
#include <linux/compiler.h>
#include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */
#define KERNEL_ATTR_RO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
#define KERNEL_ATTR_RW(_name) \
static struct kobj_attribute _name##_attr = \
__ATTR(_name, 0644, _name##_show, _name##_store)
/* current uevent sequence number */
static ssize_t uevent_seqnum_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
}
KERNEL_ATTR_RO(uevent_seqnum);
#ifdef CONFIG_UEVENT_HELPER
/* uevent helper program, used during early boot */
static ssize_t uevent_helper_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%s\n", uevent_helper);
}
static ssize_t uevent_helper_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
if (count+1 > UEVENT_HELPER_PATH_LEN)
return -ENOENT;
memcpy(uevent_helper, buf, count);
uevent_helper[count] = '\0';
if (count && uevent_helper[count-1] == '\n')
uevent_helper[count-1] = '\0';
return count;
}
KERNEL_ATTR_RW(uevent_helper);
#endif
#ifdef CONFIG_PROFILING
static ssize_t profiling_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", prof_on);
}
static ssize_t profiling_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
int ret;
if (prof_on)
return -EEXIST;
/*
* This eventually calls into get_option() which
* has a ton of callers and is not const. It is
* easiest to cast it away here.
*/
profile_setup((char *)buf);
ret = profile_init();
if (ret)
return ret;
ret = create_proc_profile();
if (ret)
return ret;
return count;
}
KERNEL_ATTR_RW(profiling);
#endif
#ifdef CONFIG_KEXEC_CORE
static ssize_t kexec_loaded_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", !!kexec_image);
}
KERNEL_ATTR_RO(kexec_loaded);
static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", kexec_crash_loaded());
}
KERNEL_ATTR_RO(kexec_crash_loaded);
static ssize_t kexec_crash_size_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%zu\n", crash_get_memory_size());
}
static ssize_t kexec_crash_size_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
unsigned long cnt;
int ret;
if (kstrtoul(buf, 0, &cnt))
return -EINVAL;
ret = crash_shrink_memory(cnt);
return ret < 0 ? ret : count;
}
KERNEL_ATTR_RW(kexec_crash_size);
#endif /* CONFIG_KEXEC_CORE */
#ifdef CONFIG_CRASH_CORE
static ssize_t vmcoreinfo_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
return sprintf(buf, "%pa %x\n", &vmcore_base,
(unsigned int)sizeof(vmcoreinfo_note));
}
KERNEL_ATTR_RO(vmcoreinfo);
#endif /* CONFIG_CRASH_CORE */
/* whether file capabilities are enabled */
static ssize_t fscaps_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", file_caps_enabled);
}
KERNEL_ATTR_RO(fscaps);
#ifndef CONFIG_TINY_RCU
int rcu_expedited;
static ssize_t rcu_expedited_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
}
static ssize_t rcu_expedited_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
if (kstrtoint(buf, 0, &rcu_expedited))
return -EINVAL;
return count;
}
KERNEL_ATTR_RW(rcu_expedited);
int rcu_normal;
static ssize_t rcu_normal_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
}
static ssize_t rcu_normal_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
if (kstrtoint(buf, 0, &rcu_normal))
return -EINVAL;
return count;
}
KERNEL_ATTR_RW(rcu_normal);
#endif /* #ifndef CONFIG_TINY_RCU */
/*
* Make /sys/kernel/notes give the raw contents of our kernel .notes section.
*/
extern const void __start_notes __weak;
extern const void __stop_notes __weak;
#define notes_size (&__stop_notes - &__start_notes)
static ssize_t notes_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t off, size_t count)
{
memcpy(buf, &__start_notes + off, count);
return count;
}
static struct bin_attribute notes_attr __ro_after_init = {
.attr = {
.name = "notes",
.mode = S_IRUGO,
},
.read = &notes_read,
};
struct kobject *kernel_kobj;
EXPORT_SYMBOL_GPL(kernel_kobj);
static struct attribute * kernel_attrs[] = {
&fscaps_attr.attr,
&uevent_seqnum_attr.attr,
#ifdef CONFIG_UEVENT_HELPER
&uevent_helper_attr.attr,
#endif
#ifdef CONFIG_PROFILING
&profiling_attr.attr,
#endif
#ifdef CONFIG_KEXEC_CORE
&kexec_loaded_attr.attr,
&kexec_crash_loaded_attr.attr,
&kexec_crash_size_attr.attr,
#endif
#ifdef CONFIG_CRASH_CORE
&vmcoreinfo_attr.attr,
#endif
#ifndef CONFIG_TINY_RCU
&rcu_expedited_attr.attr,
&rcu_normal_attr.attr,
#endif
NULL
};
static struct attribute_group kernel_attr_group = {
.attrs = kernel_attrs,
};
static int __init ksysfs_init(void)
{
int error;
kernel_kobj = kobject_create_and_add("kernel", NULL);
if (!kernel_kobj) {
error = -ENOMEM;
goto exit;
}
error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
if (error)
goto kset_exit;
if (notes_size > 0) {
notes_attr.size = notes_size;
error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
if (error)
goto group_exit;
}
return 0;
group_exit:
sysfs_remove_group(kernel_kobj, &kernel_attr_group);
kset_exit:
kobject_put(kernel_kobj);
exit:
return error;
}
core_initcall(ksysfs_init);