[PATCH v4 6/6] powerpc/fadump: sysfs for fadump memory reservation

Sourabh Jain
2019-12-06T12:25:10Z

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 | 15 +++++++++++++++
3 files changed, 27 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 41a3cda81791..b2af51b7c750 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1357,6 +1357,13 @@ static ssize_t fadump_enabled_show(struct kobject *kobj,
return sprintf(buf, "%d\n", fw_dump.fadump_enabled);
}

+static ssize_t fadump_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 fadump_register_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
@@ -1430,6 +1437,10 @@ static struct kobj_attribute enable_attr = __ATTR(enabled,
static struct kobj_attribute register_attr = __ATTR(registered,
0644, fadump_register_show,
fadump_register_store);
+static struct kobj_attribute mem_reserved_attr = __ATTR(mem_reserved,
+ 0444, fadump_mem_reserved_show,
+ NULL);
+

DEFINE_SHOW_ATTRIBUTE(fadump_region);

@@ -1464,6 +1475,10 @@ static void fadump_init_files(void)
pr_err("unable to create release_mem sysfs file (%d)\n",
rc);
}
+ rc = sysfs_create_file(fadump_kobj, &mem_reserved_attr.attr);
+ if (rc)
+ pr_err("unable to create mem_reserved sysfs file (%d)\n",
+ rc);

/* The FADump sysfs are moved from kernel_kobj to fadump_kobj need to
* create symlink at old location to maintain backward compatibility.
--
2.17.2