[PATCH v6 0/6] reorganize and add FADump sysfs files

[PATCH v6 0/6] reorganize and add FADump sysfs files

[Sourabh Jain]

Currently, FADump sysfs files are present inside /sys/kernel directory.
But as the number of FADump sysfs file increases it is not a good idea to
push all of them in /sys/kernel directory. It is better to have separate
directory to keep all the FADump sysfs files.

Patch series reorganizes the FADump sysfs files and avail all the existing
FADump sysfs files present inside /sys/kernel into a new directory
/sys/kernel/fadump. The backward compatibility is maintained by adding a
symlink for every sysfs file that has moved to new location. Also a new
FADump sys interface is added to get the amount of memory reserved by FADump
for saving the crash dump.

Changelog:
v1 -> v5:
  - https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-December/201642.html

v5 -> v6
  - Unregister FADump if fadump group creation fails.
  - Remove fadump_enabled symlink if fadump_registered symlink
    creation fails.
  - Removed CREATE_SYMLINK macro.

Sourabh Jain (6):
  Documentation/ABI: add ABI documentation for /sys/kernel/fadump_*
  sysfs: wrap __compat_only_sysfs_link_entry_to_kobj function to change
    the symlink name
  powerpc/fadump: reorganize /sys/kernel/fadump_* sysfs files
  powerpc/powernv: move core and fadump_release_opalcore under new
    kobject
  Documentation/ABI: mark /sys/kernel/fadump_* sysfs files deprecated
  powerpc/fadump: sysfs for fadump memory reservation

 .../ABI/obsolete/sysfs-kernel-fadump_enabled  |   9 ++
 .../obsolete/sysfs-kernel-fadump_registered   |  10 ++
 .../obsolete/sysfs-kernel-fadump_release_mem  |  10 ++
 .../sysfs-kernel-fadump_release_opalcore      |   9 ++
 Documentation/ABI/testing/sysfs-kernel-fadump |  40 ++++++
 .../powerpc/firmware-assisted-dump.rst        |  28 +++-
 arch/powerpc/kernel/fadump.c                  | 127 +++++++++++++-----
 arch/powerpc/platforms/powernv/opal-core.c    |  55 +++++---
 fs/sysfs/group.c                              |  28 +++-
 include/linux/sysfs.h                         |  12 ++
 10 files changed, 270 insertions(+), 58 deletions(-)
 create mode 100644 Documentation/ABI/obsolete/sysfs-kernel-fadump_enabled
 create mode 100644 Documentation/ABI/obsolete/sysfs-kernel-fadump_registered
 create mode 100644 Documentation/ABI/obsolete/sysfs-kernel-fadump_release_mem
 create mode 100644 Documentation/ABI/removed/sysfs-kernel-fadump_release_opalcore
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump

-- 
2.17.2

[PATCH v6 1/6] Documentation/ABI: add ABI documentation for /sys/kernel/fadump_*

[Sourabh Jain]

Add missing ABI documentation for existing FADump sysfs files.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 Documentation/ABI/testing/sysfs-kernel-fadump_enabled     | 7 +++++++
 Documentation/ABI/testing/sysfs-kernel-fadump_registered  | 8 ++++++++
 Documentation/ABI/testing/sysfs-kernel-fadump_release_mem | 8 ++++++++
 .../ABI/testing/sysfs-kernel-fadump_release_opalcore      | 7 +++++++
 4 files changed, 30 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump_enabled
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump_registered
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump_release_mem
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_enabled b/Documentation/ABI/testing/sysfs-kernel-fadump_enabled
new file mode 100644
index 000000000000..f73632b1c006
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump_enabled
@@ -0,0 +1,7 @@
+What:		/sys/kernel/fadump_enabled
+Date:		Feb 2012
+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
diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_registered b/Documentation/ABI/testing/sysfs-kernel-fadump_registered
new file mode 100644
index 000000000000..dcf925e53f0f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump_registered
@@ -0,0 +1,8 @@
+What:		/sys/kernel/fadump_registered
+Date:		Feb 2012
+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
diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_release_mem b/Documentation/ABI/testing/sysfs-kernel-fadump_release_mem
new file mode 100644
index 000000000000..9c20d64ab48d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump_release_mem
@@ -0,0 +1,8 @@
+What:		/sys/kernel/fadump_release_mem
+Date:		Feb 2012
+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.
diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore b/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
new file mode 100644
index 000000000000..53313c1d4e7a
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
@@ -0,0 +1,7 @@
+What:		/sys/kernel/fadump_release_opalcore
+Date:		Sep 2019
+Contact:	linuxppc-dev@lists.ozlabs.org
+Description:	write only
+		The sysfs file is available when the system is booted to
+		collect the dump on OPAL based machine. It used to release
+		the memory used to collect the opalcore.
-- 
2.17.2

Re: [PATCH v6 1/6] Documentation/ABI: add ABI documentation for /sys/kernel/fadump_*

[Hari Bathini]

On 11/12/19 9:39 PM, Sourabh Jain wrote:
> Add missing ABI documentation for existing FADump sysfs files.
> 
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>

The patch series adds a new sysfs attribute that provides the amount of memory
reserved for FADump. It also streamlines FADump specific sysfs interfaces.
Thanks for looking into this.

For the series...

Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>

> ---
>  Documentation/ABI/testing/sysfs-kernel-fadump_enabled     | 7 +++++++
>  Documentation/ABI/testing/sysfs-kernel-fadump_registered  | 8 ++++++++
>  Documentation/ABI/testing/sysfs-kernel-fadump_release_mem | 8 ++++++++
>  .../ABI/testing/sysfs-kernel-fadump_release_opalcore      | 7 +++++++
>  4 files changed, 30 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump_enabled
>  create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump_registered
>  create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump_release_mem
>  create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
> 
> diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_enabled b/Documentation/ABI/testing/sysfs-kernel-fadump_enabled
> new file mode 100644
> index 000000000000..f73632b1c006
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-kernel-fadump_enabled
> @@ -0,0 +1,7 @@
> +What:		/sys/kernel/fadump_enabled
> +Date:		Feb 2012
> +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
> diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_registered b/Documentation/ABI/testing/sysfs-kernel-fadump_registered
> new file mode 100644
> index 000000000000..dcf925e53f0f
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-kernel-fadump_registered
> @@ -0,0 +1,8 @@
> +What:		/sys/kernel/fadump_registered
> +Date:		Feb 2012
> +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
> diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_release_mem b/Documentation/ABI/testing/sysfs-kernel-fadump_release_mem
> new file mode 100644
> index 000000000000..9c20d64ab48d
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-kernel-fadump_release_mem
> @@ -0,0 +1,8 @@
> +What:		/sys/kernel/fadump_release_mem
> +Date:		Feb 2012
> +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.
> diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore b/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
> new file mode 100644
> index 000000000000..53313c1d4e7a
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
> @@ -0,0 +1,7 @@
> +What:		/sys/kernel/fadump_release_opalcore
> +Date:		Sep 2019
> +Contact:	linuxppc-dev@lists.ozlabs.org
> +Description:	write only
> +		The sysfs file is available when the system is booted to
> +		collect the dump on OPAL based machine. It used to release
> +		the memory used to collect the opalcore.
> 

-- 
- Hari

Re: [PATCH v6 1/6] Documentation/ABI: add ABI documentation for /sys/kernel/fadump_*

[Michael Ellerman]

On Wed, 2019-12-11 at 16:09:05 UTC, Sourabh Jain wrote:
> Add missing ABI documentation for existing FADump sysfs files.
> 
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/f52153ab383f04a45c38d8a7f55a4249477b20df

cheers

[PATCH v6 2/6] sysfs: wrap __compat_only_sysfs_link_entry_to_kobj function to change the symlink name

[Sourabh Jain]

The __compat_only_sysfs_link_entry_to_kobj function creates a symlink to a
kobject but doesn't provide an option to change the symlink file name.

This patch adds a wrapper function compat_only_sysfs_link_entry_to_kobj
that extends the __compat_only_sysfs_link_entry_to_kobj functionality
which allows function caller to customize the symlink name.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 fs/sysfs/group.c      | 28 +++++++++++++++++++++++++---
 include/linux/sysfs.h | 12 ++++++++++++
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index d41c21fef138..0993645f0b59 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -424,6 +424,25 @@ EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
 int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
 				      struct kobject *target_kobj,
 				      const char *target_name)
+{
+	return compat_only_sysfs_link_entry_to_kobj(kobj, target_kobj,
+						target_name, NULL);
+}
+EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
+
+/**
+ * compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
+ * to a group or an attribute
+ * @kobj:		The kobject containing the group.
+ * @target_kobj:	The target kobject.
+ * @target_name:	The name of the target group or attribute.
+ * @symlink_name:	The name of the symlink file (target_name will be
+ *			considered if symlink_name is NULL).
+ */
+int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
+					 struct kobject *target_kobj,
+					 const char *target_name,
+					 const char *symlink_name)
 {
 	struct kernfs_node *target;
 	struct kernfs_node *entry;
@@ -448,12 +467,15 @@ int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
 		return -ENOENT;
 	}
 
-	link = kernfs_create_link(kobj->sd, target_name, entry);
+	if (!symlink_name)
+		symlink_name = target_name;
+
+	link = kernfs_create_link(kobj->sd, symlink_name, entry);
 	if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
-		sysfs_warn_dup(kobj->sd, target_name);
+		sysfs_warn_dup(kobj->sd, symlink_name);
 
 	kernfs_put(entry);
 	kernfs_put(target);
 	return PTR_ERR_OR_ZERO(link);
 }
-EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
+EXPORT_SYMBOL_GPL(compat_only_sysfs_link_entry_to_kobj);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 5420817ed317..15b195a4529d 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -300,6 +300,10 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
 				      struct kobject *target_kobj,
 				      const char *target_name);
+int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
+					 struct kobject *target_kobj,
+					 const char *target_name,
+					 const char *symlink_name);
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
 
@@ -508,6 +512,14 @@ static inline int __compat_only_sysfs_link_entry_to_kobj(
 	return 0;
 }
 
+static int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
+						struct kobject *target_kobj,
+						const char *target_name,
+						const char *symlink_name)
+{
+	return 0;
+}
+
 static inline void sysfs_notify(struct kobject *kobj, const char *dir,
 				const char *attr)
 {
-- 
2.17.2

Re: [PATCH v6 2/6] sysfs: wrap __compat_only_sysfs_link_entry_to_kobj function to change the symlink name

[Michael Ellerman]

Sourabh Jain <sourabhjain@linux.ibm.com> writes:
> The __compat_only_sysfs_link_entry_to_kobj function creates a symlink to a
> kobject but doesn't provide an option to change the symlink file name.
>
> This patch adds a wrapper function compat_only_sysfs_link_entry_to_kobj
> that extends the __compat_only_sysfs_link_entry_to_kobj functionality
> which allows function caller to customize the symlink name.
>
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
> ---
>  fs/sysfs/group.c      | 28 +++++++++++++++++++++++++---
>  include/linux/sysfs.h | 12 ++++++++++++
>  2 files changed, 37 insertions(+), 3 deletions(-)

I'll assume no one has any objections to this and merge it via the
powerpc tree with the rest of the series.

cheers

> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index d41c21fef138..0993645f0b59 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -424,6 +424,25 @@ EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
>  int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
>  				      struct kobject *target_kobj,
>  				      const char *target_name)
> +{
> +	return compat_only_sysfs_link_entry_to_kobj(kobj, target_kobj,
> +						target_name, NULL);
> +}
> +EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
> +
> +/**
> + * compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
> + * to a group or an attribute
> + * @kobj:		The kobject containing the group.
> + * @target_kobj:	The target kobject.
> + * @target_name:	The name of the target group or attribute.
> + * @symlink_name:	The name of the symlink file (target_name will be
> + *			considered if symlink_name is NULL).
> + */
> +int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
> +					 struct kobject *target_kobj,
> +					 const char *target_name,
> +					 const char *symlink_name)
>  {
>  	struct kernfs_node *target;
>  	struct kernfs_node *entry;
> @@ -448,12 +467,15 @@ int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
>  		return -ENOENT;
>  	}
>  
> -	link = kernfs_create_link(kobj->sd, target_name, entry);
> +	if (!symlink_name)
> +		symlink_name = target_name;
> +
> +	link = kernfs_create_link(kobj->sd, symlink_name, entry);
>  	if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
> -		sysfs_warn_dup(kobj->sd, target_name);
> +		sysfs_warn_dup(kobj->sd, symlink_name);
>  
>  	kernfs_put(entry);
>  	kernfs_put(target);
>  	return PTR_ERR_OR_ZERO(link);
>  }
> -EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
> +EXPORT_SYMBOL_GPL(compat_only_sysfs_link_entry_to_kobj);
> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
> index 5420817ed317..15b195a4529d 100644
> --- a/include/linux/sysfs.h
> +++ b/include/linux/sysfs.h
> @@ -300,6 +300,10 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
>  int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
>  				      struct kobject *target_kobj,
>  				      const char *target_name);
> +int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
> +					 struct kobject *target_kobj,
> +					 const char *target_name,
> +					 const char *symlink_name);
>  
>  void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
>  
> @@ -508,6 +512,14 @@ static inline int __compat_only_sysfs_link_entry_to_kobj(
>  	return 0;
>  }
>  
> +static int compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
> +						struct kobject *target_kobj,
> +						const char *target_name,
> +						const char *symlink_name)
> +{
> +	return 0;
> +}
> +
>  static inline void sysfs_notify(struct kobject *kobj, const char *dir,
>  				const char *attr)
>  {
> -- 
> 2.17.2

[PATCH v6 3/6] powerpc/fadump: reorganize /sys/kernel/fadump_* sysfs files

[Sourabh Jain]

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: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 Documentation/ABI/testing/sysfs-kernel-fadump |  33 +++++
 arch/powerpc/kernel/fadump.c                  | 118 +++++++++++++-----
 2 files changed, 117 insertions(+), 34 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump b/Documentation/ABI/testing/sysfs-kernel-fadump
new file mode 100644
index 000000000000..5d988b919e81
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump
@@ -0,0 +1,33 @@
+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.
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index ed59855430b9..23f15bfea512 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -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 };
@@ -1323,9 +1325,9 @@ 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,
-					struct kobj_attribute *attr,
-					const char *buf, size_t count)
+static ssize_t release_mem_store(struct kobject *kobj,
+				 struct kobj_attribute *attr,
+				 const char *buf, size_t count)
 {
 	int input = -1;
 
@@ -1350,23 +1352,33 @@ static ssize_t fadump_release_memory_store(struct kobject *kobj,
 	return count;
 }
 
-static ssize_t fadump_enabled_show(struct kobject *kobj,
-					struct kobj_attribute *attr,
-					char *buf)
+/* 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,
-					struct kobj_attribute *attr,
-					char *buf)
+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,
-					struct kobj_attribute *attr,
-					const char *buf, size_t count)
+static ssize_t registered_store(struct kobject *kobj,
+				struct kobj_attribute *attr,
+				const char *buf, size_t count)
 {
 	int ret = 0;
 	int input = -1;
@@ -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 +1462,51 @@ 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;
 }
-- 
2.17.2

Re: [PATCH v6 3/6] powerpc/fadump: reorganize /sys/kernel/fadump_* sysfs files

[Michal Suchánek]

On Wed, Dec 11, 2019 at 09:39:07PM +0530, Sourabh Jain wrote:
> 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.

Patched this series into my test kernel and the sysfs sfiles look OK.

Tested-by: Michal Suchanek <msuchanek@suse.de>

Thanks

Michal

[PATCH v6 4/6] powerpc/powernv: move core and fadump_release_opalcore under new kobject

[Sourabh Jain]

The /sys/firmware/opal/core and /sys/kernel/fadump_release_opalcore sysfs
files are used to export and release the OPAL memory on PowerNV platform.
let's organize them into a new kobject under /sys/firmware/opal/mpipl/
directory.

A symlink is added to maintain the backward compatibility for
/sys/firmware/opal/core sysfs file.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 .../sysfs-kernel-fadump_release_opalcore      |  2 +
 .../powerpc/firmware-assisted-dump.rst        | 15 +++--
 arch/powerpc/platforms/powernv/opal-core.c    | 55 ++++++++++++++-----
 3 files changed, 51 insertions(+), 21 deletions(-)
 rename Documentation/ABI/{testing => removed}/sysfs-kernel-fadump_release_opalcore (82%)

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore b/Documentation/ABI/removed/sysfs-kernel-fadump_release_opalcore
similarity index 82%
rename from Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
rename to Documentation/ABI/removed/sysfs-kernel-fadump_release_opalcore
index 53313c1d4e7a..a8d46cd0f4e6 100644
--- a/Documentation/ABI/testing/sysfs-kernel-fadump_release_opalcore
+++ b/Documentation/ABI/removed/sysfs-kernel-fadump_release_opalcore
@@ -1,3 +1,5 @@
+This ABI is moved to /sys/firmware/opal/mpipl/release_core.
+
 What:		/sys/kernel/fadump_release_opalcore
 Date:		Sep 2019
 Contact:	linuxppc-dev@lists.ozlabs.org
diff --git a/Documentation/powerpc/firmware-assisted-dump.rst b/Documentation/powerpc/firmware-assisted-dump.rst
index 0455a78486d5..345a3405206e 100644
--- a/Documentation/powerpc/firmware-assisted-dump.rst
+++ b/Documentation/powerpc/firmware-assisted-dump.rst
@@ -112,13 +112,13 @@ to ensure that crash data is preserved to process later.
 
 -- On OPAL based machines (PowerNV), if the kernel is build with
    CONFIG_OPAL_CORE=y, OPAL memory at the time of crash is also
-   exported as /sys/firmware/opal/core file. This procfs file is
+   exported as /sys/firmware/opal/mpipl/core file. This procfs file is
    helpful in debugging OPAL crashes with GDB. The kernel memory
    used for exporting this procfs file can be released by echo'ing
-   '1' to /sys/kernel/fadump_release_opalcore node.
+   '1' to /sys/firmware/opal/mpipl/release_core node.
 
    e.g.
-     # echo 1 > /sys/kernel/fadump_release_opalcore
+     # echo 1 > /sys/firmware/opal/mpipl/release_core
 
 Implementation details:
 -----------------------
@@ -283,14 +283,17 @@ Here is the list of files under kernel sysfs:
     enhanced to use this interface to release the memory reserved for
     dump and continue without 2nd reboot.
 
- /sys/kernel/fadump_release_opalcore
+Note: /sys/kernel/fadump_release_opalcore sysfs has moved to
+      /sys/firmware/opal/mpipl/release_core
+
+ /sys/firmware/opal/mpipl/release_core
 
     This file is available only on OPAL based machines when FADump is
     active during capture kernel. This is used to release the memory
-    used by the kernel to export /sys/firmware/opal/core file. To
+    used by the kernel to export /sys/firmware/opal/mpipl/core file. To
     release this memory, echo '1' to it:
 
-    echo 1  > /sys/kernel/fadump_release_opalcore
+    echo 1  > /sys/firmware/opal/mpipl/release_core
 
 Here is the list of files under powerpc debugfs:
 (Assuming debugfs is mounted on /sys/kernel/debug directory.)
diff --git a/arch/powerpc/platforms/powernv/opal-core.c b/arch/powerpc/platforms/powernv/opal-core.c
index ed895d82c048..6dba3b62269f 100644
--- a/arch/powerpc/platforms/powernv/opal-core.c
+++ b/arch/powerpc/platforms/powernv/opal-core.c
@@ -71,6 +71,7 @@ static LIST_HEAD(opalcore_list);
 static struct opalcore_config *oc_conf;
 static const struct opal_mpipl_fadump *opalc_metadata;
 static const struct opal_mpipl_fadump *opalc_cpu_metadata;
+struct kobject *mpipl_kobj;
 
 /*
  * Set crashing CPU's signal to SIGUSR1. if the kernel is triggered
@@ -428,7 +429,7 @@ static void opalcore_cleanup(void)
 		return;
 
 	/* Remove OPAL core sysfs file */
-	sysfs_remove_bin_file(opal_kobj, &opal_core_attr);
+	sysfs_remove_bin_file(mpipl_kobj, &opal_core_attr);
 	oc_conf->ptload_phdr = NULL;
 	oc_conf->ptload_cnt = 0;
 
@@ -563,9 +564,9 @@ static void __init opalcore_config_init(void)
 	of_node_put(np);
 }
 
-static ssize_t fadump_release_opalcore_store(struct kobject *kobj,
-					     struct kobj_attribute *attr,
-					     const char *buf, size_t count)
+static ssize_t release_core_store(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  const char *buf, size_t count)
 {
 	int input = -1;
 
@@ -589,9 +590,23 @@ static ssize_t fadump_release_opalcore_store(struct kobject *kobj,
 	return count;
 }
 
-static struct kobj_attribute opalcore_rel_attr = __ATTR(fadump_release_opalcore,
-						0200, NULL,
-						fadump_release_opalcore_store);
+static struct kobj_attribute opalcore_rel_attr = __ATTR_WO(release_core);
+
+static struct attribute *mpipl_attr[] = {
+	&opalcore_rel_attr.attr,
+	NULL,
+};
+
+static struct bin_attribute *mpipl_bin_attr[] = {
+	&opal_core_attr,
+	NULL,
+
+};
+
+static struct attribute_group mpipl_group = {
+	.attrs = mpipl_attr,
+	.bin_attrs =  mpipl_bin_attr,
+};
 
 static int __init opalcore_init(void)
 {
@@ -609,7 +624,7 @@ static int __init opalcore_init(void)
 	 * then capture the dump.
 	 */
 	if (!(is_opalcore_usable())) {
-		pr_err("Failed to export /sys/firmware/opal/core\n");
+		pr_err("Failed to export /sys/firmware/opal/mpipl/core\n");
 		opalcore_cleanup();
 		return rc;
 	}
@@ -617,18 +632,28 @@ static int __init opalcore_init(void)
 	/* Set OPAL core file size */
 	opal_core_attr.size = oc_conf->opalcore_size;
 
+	mpipl_kobj = kobject_create_and_add("mpipl", opal_kobj);
+	if (!mpipl_kobj) {
+		pr_err("unable to create mpipl kobject\n");
+		return -ENOMEM;
+	}
+
 	/* Export OPAL core sysfs file */
-	rc = sysfs_create_bin_file(opal_kobj, &opal_core_attr);
-	if (rc != 0) {
-		pr_err("Failed to export /sys/firmware/opal/core\n");
+	rc = sysfs_create_group(mpipl_kobj, &mpipl_group);
+	if (rc) {
+		pr_err("mpipl sysfs group creation failed (%d)", rc);
 		opalcore_cleanup();
 		return rc;
 	}
-
-	rc = sysfs_create_file(kernel_kobj, &opalcore_rel_attr.attr);
+	/* The /sys/firmware/opal/core is moved to /sys/firmware/opal/mpipl/
+	 * directory, need to create symlink at old location to maintain
+	 * backward compatibility.
+	 */
+	rc = compat_only_sysfs_link_entry_to_kobj(opal_kobj, mpipl_kobj,
+						  "core", NULL);
 	if (rc) {
-		pr_warn("unable to create sysfs file fadump_release_opalcore (%d)\n",
-			rc);
+		pr_err("unable to create core symlink (%d)\n", rc);
+		return rc;
 	}
 
 	return 0;
-- 
2.17.2

[PATCH v6 5/6] Documentation/ABI: mark /sys/kernel/fadump_* sysfs files deprecated

[Sourabh Jain]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=y, Size: 3604 bytes --]

Add a deprecation note in FADump sysfs ABI documentation files and move
them from ABI/testing to ABI/obsolete directory.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 .../ABI/{testing => obsolete}/sysfs-kernel-fadump_enabled | 2 ++
 .../{testing => obsolete}/sysfs-kernel-fadump_registered  | 2 ++
 .../{testing => obsolete}/sysfs-kernel-fadump_release_mem | 2 ++
 Documentation/powerpc/firmware-assisted-dump.rst          | 8 ++++++++
 4 files changed, 14 insertions(+)
 rename Documentation/ABI/{testing => obsolete}/sysfs-kernel-fadump_enabled (73%)
 rename Documentation/ABI/{testing => obsolete}/sysfs-kernel-fadump_registered (77%)
 rename Documentation/ABI/{testing => obsolete}/sysfs-kernel-fadump_release_mem (78%)

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_enabled b/Documentation/ABI/obsolete/sysfs-kernel-fadump_enabled
similarity index 73%
rename from Documentation/ABI/testing/sysfs-kernel-fadump_enabled
rename to Documentation/ABI/obsolete/sysfs-kernel-fadump_enabled
index f73632b1c006..e9c2de8b3688 100644
--- a/Documentation/ABI/testing/sysfs-kernel-fadump_enabled
+++ b/Documentation/ABI/obsolete/sysfs-kernel-fadump_enabled
@@ -1,3 +1,5 @@
+This ABI is renamed and moved to a new location /sys/kernel/fadump/enabled.
+
 What:		/sys/kernel/fadump_enabled
 Date:		Feb 2012
 Contact:	linuxppc-dev@lists.ozlabs.org
diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_registered b/Documentation/ABI/obsolete/sysfs-kernel-fadump_registered
similarity index 77%
rename from Documentation/ABI/testing/sysfs-kernel-fadump_registered
rename to Documentation/ABI/obsolete/sysfs-kernel-fadump_registered
index dcf925e53f0f..0360be39c98e 100644
--- a/Documentation/ABI/testing/sysfs-kernel-fadump_registered
+++ b/Documentation/ABI/obsolete/sysfs-kernel-fadump_registered
@@ -1,3 +1,5 @@
+This ABI is renamed and moved to a new location /sys/kernel/fadump/registered.¬
+
 What:		/sys/kernel/fadump_registered
 Date:		Feb 2012
 Contact:	linuxppc-dev@lists.ozlabs.org
diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump_release_mem b/Documentation/ABI/obsolete/sysfs-kernel-fadump_release_mem
similarity index 78%
rename from Documentation/ABI/testing/sysfs-kernel-fadump_release_mem
rename to Documentation/ABI/obsolete/sysfs-kernel-fadump_release_mem
index 9c20d64ab48d..6ce0b129ab12 100644
--- a/Documentation/ABI/testing/sysfs-kernel-fadump_release_mem
+++ b/Documentation/ABI/obsolete/sysfs-kernel-fadump_release_mem
@@ -1,3 +1,5 @@
+This ABI is renamed and moved to a new location /sys/kernel/fadump/release_mem.¬
+
 What:		/sys/kernel/fadump_release_mem
 Date:		Feb 2012
 Contact:	linuxppc-dev@lists.ozlabs.org
diff --git a/Documentation/powerpc/firmware-assisted-dump.rst b/Documentation/powerpc/firmware-assisted-dump.rst
index 345a3405206e..365c10209ef3 100644
--- a/Documentation/powerpc/firmware-assisted-dump.rst
+++ b/Documentation/powerpc/firmware-assisted-dump.rst
@@ -295,6 +295,14 @@ Note: /sys/kernel/fadump_release_opalcore sysfs has moved to
 
     echo 1  > /sys/firmware/opal/mpipl/release_core
 
+Note: The following FADump sysfs files are deprecated.
+
+    Deprecated                           Alternative
+    --------------------------------------------------------------------
+    /sys/kernel/fadump_enabled           /sys/kernel/fadump/enabled
+    /sys/kernel/fadump_registered        /sys/kernel/fadump/registered
+    /sys/kernel/fadump_release_mem       /sys/kernel/fadump/release_mem
+
 Here is the list of files under powerpc debugfs:
 (Assuming debugfs is mounted on /sys/kernel/debug directory.)
 
-- 
2.17.2

[PATCH v6 6/6] powerpc/fadump: sysfs for fadump memory reservation

[Sourabh Jain]

Add a sys interface to allow querying the memory reserved by FADump for
saving the crash dump.

Also added Documentation/ABI for the new sysfs file.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 Documentation/ABI/testing/sysfs-kernel-fadump    | 7 +++++++
 Documentation/powerpc/firmware-assisted-dump.rst | 5 +++++
 arch/powerpc/kernel/fadump.c                     | 9 +++++++++
 3 files changed, 21 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump b/Documentation/ABI/testing/sysfs-kernel-fadump
index 5d988b919e81..8f7a64a81783 100644
--- a/Documentation/ABI/testing/sysfs-kernel-fadump
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump
@@ -31,3 +31,10 @@ Description:	write only
 		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.
+
+What:		/sys/kernel/fadump/mem_reserved
+Date:		Dec 2019
+Contact:	linuxppc-dev@lists.ozlabs.org
+Description:	read only
+		Provide information about the amount of memory reserved by
+		FADump to save the crash dump in bytes.
diff --git a/Documentation/powerpc/firmware-assisted-dump.rst b/Documentation/powerpc/firmware-assisted-dump.rst
index 365c10209ef3..04993eaf3113 100644
--- a/Documentation/powerpc/firmware-assisted-dump.rst
+++ b/Documentation/powerpc/firmware-assisted-dump.rst
@@ -268,6 +268,11 @@ Here is the list of files under kernel sysfs:
     be handled and vmcore will not be captured. This interface can be
     easily integrated with kdump service start/stop.
 
+ /sys/kernel/fadump/mem_reserved
+
+   This is used to display the memory reserved by FADump for saving the
+   crash dump.
+
  /sys/kernel/fadump_release_mem
     This file is available only when FADump is active during
     second kernel. This is used to release the reserved memory
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 23f15bfea512..1c9b23c5b296 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1369,6 +1369,13 @@ static ssize_t enabled_show(struct kobject *kobj,
 	return sprintf(buf, "%d\n", fw_dump.fadump_enabled);
 }
 
+static ssize_t mem_reserved_show(struct kobject *kobj,
+				 struct kobj_attribute *attr,
+				 char *buf)
+{
+	return sprintf(buf, "%ld\n", fw_dump.reserve_dump_area_size);
+}
+
 static ssize_t registered_show(struct kobject *kobj,
 			       struct kobj_attribute *attr,
 			       char *buf)
@@ -1433,10 +1440,12 @@ static int fadump_region_show(struct seq_file *m, void *private)
 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 kobj_attribute mem_reserved_attr = __ATTR_RO(mem_reserved);
 
 static struct attribute *fadump_attrs[] = {
 	&enable_attr.attr,
 	&register_attr.attr,
+	&mem_reserved_attr.attr,
 	NULL,
 };
 
-- 
2.17.2