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Message-ID: <20251106045107.17813-3-sourabhjain@linux.ibm.com>
Date: Thu, 6 Nov 2025 10:21:04 +0530
From: Sourabh Jain <sourabhjain@...ux.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: Sourabh Jain <sourabhjain@...ux.ibm.com>,
Aditya Gupta <adityag@...ux.ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>, Baoquan he <bhe@...hat.com>,
Dave Young <dyoung@...hat.com>, Hari Bathini <hbathini@...ux.ibm.com>,
Jiri Bohac <jbohac@...e.cz>, Madhavan Srinivasan <maddy@...ux.ibm.com>,
Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
Pingfan Liu <piliu@...hat.com>,
"Ritesh Harjani (IBM)" <ritesh.list@...il.com>,
Shivang Upadhyay <shivangu@...ux.ibm.com>,
Vivek Goyal <vgoyal@...hat.com>, linuxppc-dev@...ts.ozlabs.org,
kexec@...ts.infradead.org
Subject: [PATCH v2 2/5] kexec: move sysfs entries to /sys/kernel/kexec
Several kexec and kdump sysfs entries are currently placed directly
under /sys/kernel/, which clutters the directory and makes it harder to
identify unrelated entries. To improve organization and readability,
these entries are now moved under a dedicated directory,
/sys/kernel/kexec.
For backward compatibility, symlinks are created at the old locations
so that existing tools and scripts continue to work. These symlinks can
be removed in the future once users have switched to the new path.
While creating symlinks, entries are added in /sys/kernel/ that point
to their new locations under /sys/kernel/kexec/. If an error occurs
while adding a symlink, it is logged but does not stop initialization
of the remaining kexec sysfs symlinks.
The /sys/kernel/<crash_elfcorehdr_size | kexec/crash_elfcorehdr_size>
entry is now controlled by CONFIG_CRASH_DUMP instead of
CONFIG_VMCORE_INFO, as CONFIG_CRASH_DUMP also enables
CONFIG_VMCORE_INFO.
Cc: Aditya Gupta <adityag@...ux.ibm.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Baoquan he <bhe@...hat.com>
Cc: Dave Young <dyoung@...hat.com>
Cc: Hari Bathini <hbathini@...ux.ibm.com>
Cc: Jiri Bohac <jbohac@...e.cz>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: Mahesh J Salgaonkar <mahesh@...ux.ibm.com>
Cc: Pingfan Liu <piliu@...hat.com>
Cc: Ritesh Harjani (IBM) <ritesh.list@...il.com>
Cc: Shivang Upadhyay <shivangu@...ux.ibm.com>
Cc: Vivek Goyal <vgoyal@...hat.com>
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: kexec@...ts.infradead.org
Signed-off-by: Sourabh Jain <sourabhjain@...ux.ibm.com>
---
kernel/kexec_core.c | 118 ++++++++++++++++++++++++++++++++++++++++++++
kernel/ksysfs.c | 68 +------------------------
2 files changed, 119 insertions(+), 67 deletions(-)
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index fa00b239c5d9..2e12a164e870 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -41,6 +41,7 @@
#include <linux/objtool.h>
#include <linux/kmsg_dump.h>
#include <linux/dma-map-ops.h>
+#include <linux/sysfs.h>
#include <asm/page.h>
#include <asm/sections.h>
@@ -1229,3 +1230,120 @@ int kernel_kexec(void)
kexec_unlock();
return error;
}
+
+static ssize_t loaded_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%d\n", !!kexec_image);
+}
+static struct kobj_attribute loaded_attr = __ATTR_RO(loaded);
+
+#ifdef CONFIG_CRASH_DUMP
+static ssize_t crash_loaded_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%d\n", kexec_crash_loaded());
+}
+static struct kobj_attribute crash_loaded_attr = __ATTR_RO(crash_loaded);
+
+static ssize_t crash_size_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ ssize_t size = crash_get_memory_size();
+
+ if (size < 0)
+ return size;
+
+ return sysfs_emit(buf, "%zd\n", size);
+}
+static ssize_t 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;
+}
+static struct kobj_attribute crash_size_attr = __ATTR_RW(crash_size);
+
+#ifdef CONFIG_CRASH_HOTPLUG
+static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ unsigned int sz = crash_get_elfcorehdr_size();
+
+ return sysfs_emit(buf, "%u\n", sz);
+}
+static struct kobj_attribute crash_elfcorehdr_size_attr = __ATTR_RO(crash_elfcorehdr_size);
+
+#endif /* CONFIG_CRASH_HOTPLUG */
+#endif /* CONFIG_CRASH_DUMP */
+
+static struct attribute *kexec_attrs[] = {
+ &loaded_attr.attr,
+#ifdef CONFIG_CRASH_DUMP
+ &crash_loaded_attr.attr,
+ &crash_size_attr.attr,
+#ifdef CONFIG_CRASH_HOTPLUG
+ &crash_elfcorehdr_size_attr.attr,
+#endif
+#endif
+ NULL
+};
+
+struct kexec_link_entry {
+ const char *target;
+ const char *name;
+};
+
+static struct kexec_link_entry kexec_links[] = {
+ { "loaded", "kexec_loaded" },
+#ifdef CONFIG_CRASH_DUMP
+ { "crash_loaded", "kexec_crash_loaded" },
+ { "crash_size", "kexec_crash_size" },
+#ifdef CONFIG_CRASH_HOTPLUG
+ { "crash_elfcorehdr_size", "crash_elfcorehdr_size" },
+#endif
+#endif
+
+};
+
+struct kobject *kexec_kobj;
+ATTRIBUTE_GROUPS(kexec);
+
+static int __init init_kexec_sysctl(void)
+{
+ int error;
+ int i;
+
+ kexec_kobj = kobject_create_and_add("kexec", kernel_kobj);
+ if (!kexec_kobj) {
+ pr_err("failed to create kexec kobject\n");
+ return -ENOMEM;
+ }
+
+ error = sysfs_create_groups(kexec_kobj, kexec_groups);
+ if (error)
+ goto kset_exit;
+
+ for (i = 0; i < ARRAY_SIZE(kexec_links); i++) {
+ error = compat_only_sysfs_link_entry_to_kobj(kernel_kobj, kexec_kobj,
+ kexec_links[i].target,
+ kexec_links[i].name);
+ if (error)
+ pr_err("Unable to create %s symlink (%d)", kexec_links[i].name, error);
+ }
+
+ return 0;
+
+kset_exit:
+ kobject_put(kexec_kobj);
+ return error;
+}
+
+subsys_initcall(init_kexec_sysctl);
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index eefb67d9883c..a9e6354d9e25 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -12,7 +12,7 @@
#include <linux/sysfs.h>
#include <linux/export.h>
#include <linux/init.h>
-#include <linux/kexec.h>
+#include <linux/vmcore_info.h>
#include <linux/profile.h>
#include <linux/stat.h>
#include <linux/sched.h>
@@ -119,50 +119,6 @@ static ssize_t profiling_store(struct kobject *kobj,
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 sysfs_emit(buf, "%d\n", !!kexec_image);
-}
-KERNEL_ATTR_RO(kexec_loaded);
-
-#ifdef CONFIG_CRASH_DUMP
-static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sysfs_emit(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)
-{
- ssize_t size = crash_get_memory_size();
-
- if (size < 0)
- return size;
-
- return sysfs_emit(buf, "%zd\n", 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_CRASH_DUMP*/
-#endif /* CONFIG_KEXEC_CORE */
-
#ifdef CONFIG_VMCORE_INFO
static ssize_t vmcoreinfo_show(struct kobject *kobj,
@@ -174,18 +130,6 @@ static ssize_t vmcoreinfo_show(struct kobject *kobj,
}
KERNEL_ATTR_RO(vmcoreinfo);
-#ifdef CONFIG_CRASH_HOTPLUG
-static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- unsigned int sz = crash_get_elfcorehdr_size();
-
- return sysfs_emit(buf, "%u\n", sz);
-}
-KERNEL_ATTR_RO(crash_elfcorehdr_size);
-
-#endif
-
#endif /* CONFIG_VMCORE_INFO */
/* whether file capabilities are enabled */
@@ -255,18 +199,8 @@ static struct attribute * kernel_attrs[] = {
#ifdef CONFIG_PROFILING
&profiling_attr.attr,
#endif
-#ifdef CONFIG_KEXEC_CORE
- &kexec_loaded_attr.attr,
-#ifdef CONFIG_CRASH_DUMP
- &kexec_crash_loaded_attr.attr,
- &kexec_crash_size_attr.attr,
-#endif
-#endif
#ifdef CONFIG_VMCORE_INFO
&vmcoreinfo_attr.attr,
-#ifdef CONFIG_CRASH_HOTPLUG
- &crash_elfcorehdr_size_attr.attr,
-#endif
#endif
#ifndef CONFIG_TINY_RCU
&rcu_expedited_attr.attr,
--
2.51.0
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