Commit d418b19f authored by Sourabh Jain's avatar Sourabh Jain Committed by Michael Ellerman
Browse files

powerpc/fadump: Reorganize /sys/kernel/fadump_* sysfs files 



As the number of FADump sysfs files increases it is hard to manage all
of them inside /sys/kernel directory. It's better to have all the
FADump related sysfs files in a dedicated directory
/sys/kernel/fadump. But in order to maintain backward compatibility a
symlink has been added for every sysfs that has moved to new location.

As the FADump sysfs files are now part of a dedicated directory there
is no need to prefix their name with fadump_, hence sysfs file names
are also updated. For example fadump_enabled sysfs file is now
referred as enabled.

Also consolidate ABI documentation for all the FADump sysfs files in a
single file Documentation/ABI/testing/sysfs-kernel-fadump.

Signed-off-by: default avatarSourabh Jain <sourabhjain@linux.ibm.com>
Tested-by: default avatarMichal Suchanek <msuchanek@suse.de>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191211160910.21656-4-sourabhjain@linux.ibm.com
parent 9255782f

Documentation/ABI/testing/sysfs-kernel-fadump

0 → 100644
+33 −0
Original line number Diff line number Diff line 
What:		/sys/kernel/fadump/*

Date:		Dec 2019

Contact:	linuxppc-dev@lists.ozlabs.org

Description:

		The /sys/kernel/fadump/* is a collection of FADump sysfs

		file provide information about the configuration status

		of Firmware Assisted Dump (FADump).



What:		/sys/kernel/fadump/enabled

Date:		Dec 2019

Contact:	linuxppc-dev@lists.ozlabs.org

Description:	read only

		Primarily used to identify whether the FADump is enabled in

		the kernel or not.

User:		Kdump service



What:		/sys/kernel/fadump/registered

Date:		Dec 2019

Contact:	linuxppc-dev@lists.ozlabs.org

Description:	read/write

		Helps to control the dump collect feature from userspace.

		Setting 1 to this file enables the system to collect the

		dump and 0 to disable it.

User:		Kdump service



What:		/sys/kernel/fadump/release_mem

Date:		Dec 2019

Contact:	linuxppc-dev@lists.ozlabs.org

Description:	write only

		This is a special sysfs file and only available when

		the system is booted to capture the vmcore using FADump.

		It is used to release the memory reserved by FADump to

		save the crash dump.

arch/powerpc/kernel/fadump.c

+85 −34
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ static struct fw_dump fw_dump; 


static void __init fadump_reserve_crash_area(u64 base);



struct kobject *fadump_kobj;



#ifndef CONFIG_PRESERVE_FA_DUMP

static DEFINE_MUTEX(fadump_mutex);

struct fadump_mrange_info crash_mrange_info = { "crash", NULL, 0, 0, 0 };
@@ -1323,7 +1325,7 @@ static void fadump_invalidate_release_mem(void) 
	fw_dump.ops->fadump_init_mem_struct(&fw_dump);

}



static ssize_t fadump_release_memory_store(struct kobject *kobj,

static ssize_t release_mem_store(struct kobject *kobj,

				 struct kobj_attribute *attr,

				 const char *buf, size_t count)

{
@@ -1350,21 +1352,31 @@ static ssize_t fadump_release_memory_store(struct kobject *kobj, 
	return count;

}



static ssize_t fadump_enabled_show(struct kobject *kobj,

/* Release the reserved memory and disable the FADump */

static void unregister_fadump(void)

{

	fadump_cleanup();

	fadump_release_memory(fw_dump.reserve_dump_area_start,

			      fw_dump.reserve_dump_area_size);

	fw_dump.fadump_enabled = 0;

	kobject_put(fadump_kobj);

}



static ssize_t enabled_show(struct kobject *kobj,

			    struct kobj_attribute *attr,

			    char *buf)

{

	return sprintf(buf, "%d\n", fw_dump.fadump_enabled);

}



static ssize_t fadump_register_show(struct kobject *kobj,

static ssize_t registered_show(struct kobject *kobj,

			       struct kobj_attribute *attr,

			       char *buf)

{

	return sprintf(buf, "%d\n", fw_dump.dump_registered);

}



static ssize_t fadump_register_store(struct kobject *kobj,

static ssize_t registered_store(struct kobject *kobj,

				struct kobj_attribute *attr,

				const char *buf, size_t count)

{
@@ -1418,15 +1430,17 @@ static int fadump_region_show(struct seq_file *m, void *private) 
	return 0;

}



static struct kobj_attribute fadump_release_attr = __ATTR(fadump_release_mem,

						0200, NULL,

						fadump_release_memory_store);

static struct kobj_attribute fadump_attr = __ATTR(fadump_enabled,

						0444, fadump_enabled_show,

						NULL);

static struct kobj_attribute fadump_register_attr = __ATTR(fadump_registered,

						0644, fadump_register_show,

						fadump_register_store);

static struct kobj_attribute release_attr = __ATTR_WO(release_mem);

static struct kobj_attribute enable_attr = __ATTR_RO(enabled);

static struct kobj_attribute register_attr = __ATTR_RW(registered);



static struct attribute *fadump_attrs[] = {

	&enable_attr.attr,

	&register_attr.attr,

	NULL,

};



ATTRIBUTE_GROUPS(fadump);



DEFINE_SHOW_ATTRIBUTE(fadump_region);
@@ -1435,16 +1449,11 @@ static void fadump_init_files(void) 
	struct dentry *debugfs_file;

	int rc = 0;



	rc = sysfs_create_file(kernel_kobj, &fadump_attr.attr);

	if (rc)

		printk(KERN_ERR "fadump: unable to create sysfs file"

			" fadump_enabled (%d)\n", rc);



	rc = sysfs_create_file(kernel_kobj, &fadump_register_attr.attr);

	if (rc)

		printk(KERN_ERR "fadump: unable to create sysfs file"

			" fadump_registered (%d)\n", rc);



	fadump_kobj = kobject_create_and_add("fadump", kernel_kobj);

	if (!fadump_kobj) {

		pr_err("failed to create fadump kobject\n");

		return;

	}

	debugfs_file = debugfs_create_file("fadump_region", 0444,

					powerpc_debugfs_root, NULL,

					&fadump_region_fops);
@@ -1453,10 +1462,52 @@ static void fadump_init_files(void) 
				" fadump_region\n");



	if (fw_dump.dump_active) {

		rc = sysfs_create_file(kernel_kobj, &fadump_release_attr.attr);

		rc = sysfs_create_file(fadump_kobj, &release_attr.attr);

		if (rc)

			pr_err("unable to create release_mem sysfs file (%d)\n",

			       rc);

	}



	rc = sysfs_create_groups(fadump_kobj, fadump_groups);

	if (rc) {

		pr_err("sysfs group creation failed (%d), unregistering FADump",

		       rc);

		unregister_fadump();

		return;

	}



	/*

	 * The FADump sysfs are moved from kernel_kobj to fadump_kobj need to

	 * create symlink at old location to maintain backward compatibility.

	 *

	 *      - fadump_enabled -> fadump/enabled

	 *      - fadump_registered -> fadump/registered

	 *      - fadump_release_mem -> fadump/release_mem

	 */

	rc = compat_only_sysfs_link_entry_to_kobj(kernel_kobj, fadump_kobj,

						  "enabled", "fadump_enabled");

	if (rc) {

		pr_err("unable to create fadump_enabled symlink (%d)", rc);

		return;

	}



	rc = compat_only_sysfs_link_entry_to_kobj(kernel_kobj, fadump_kobj,

						  "registered",

						  "fadump_registered");

	if (rc) {

		pr_err("unable to create fadump_registered symlink (%d)", rc);

		sysfs_remove_link(kernel_kobj, "fadump_enabled");

		return;

	}



	if (fw_dump.dump_active) {

		rc = compat_only_sysfs_link_entry_to_kobj(kernel_kobj,

							  fadump_kobj,

							  "release_mem",

							  "fadump_release_mem");

		if (rc)

			printk(KERN_ERR "fadump: unable to create sysfs file"

				" fadump_release_mem (%d)\n", rc);

			pr_err("unable to create fadump_release_mem symlink (%d)",

			       rc);

	}

	return;

}

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