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Subject[PATCH v13 2/4] pstore/blk: add blkoops for pstore_blk
Date
blkoops is a sample for pstore/blk. It can only record oops, excluding
panics as no read/write apis for panic registered. It support settings
on Kconfg/module parameters. It can record oops log even power failure
if "PSTORE_BLKOOPS_BLKDEV" on Kconfig or "blkdev" on module parameter
is valid. Otherwise, it can only record data to ram buffer, which will
be dropped when reboot.

Signed-off-by: liaoweixiong <liaoweixiong@allwinnertech.com>
---
MAINTAINERS | 2 +-
fs/pstore/Kconfig | 102 +++++++++++++++++++++++
fs/pstore/Makefile | 2 +
fs/pstore/blkoops.c | 198 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/pstore_blk.h | 14 +++-
5 files changed, 313 insertions(+), 5 deletions(-)
create mode 100644 fs/pstore/blkoops.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 51029a4..4e9242a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12318,7 +12318,7 @@ F: drivers/firmware/efi/efi-pstore.c
F: drivers/acpi/apei/erst.c
F: Documentation/admin-guide/ramoops.rst
F: Documentation/devicetree/bindings/reserved-memory/ramoops.txt
-K: \b(pstore|ramoops)
+K: \b(pstore|ramoops|blkoops)

PTP HARDWARE CLOCK SUPPORT
M: Richard Cochran <richardcochran@gmail.com>
diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index defcb75..2fba1c5 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -160,3 +160,105 @@ config PSTORE_BLK
help
This enables panic and oops message to be logged to a block dev
where it can be read back at some later point.
+
+config PSTORE_BLKOOPS
+ tristate "pstore block with oops logger"
+ depends on PSTORE_BLK
+ help
+ This is a sample for pstore block with oops logger.
+
+ It CANNOT record panic log as no read/write APIs for panic registered.
+
+ It CAN record oops log even power failure if
+ "PSTORE_BLKOOPS_BLKDEV" on Kconfig or "block-device" on dts or
+ "blkdev" on module parameter is valid.
+
+ Otherwise, it can only record data to ram buffer, which will be
+ dropped on reboot.
+
+ NOTE that, there are two ways to set parameters of blkoops and
+ prioritize according to configuration flexibility. That is
+ Kconfig < module parameters. It means that the value can
+ be overwritten by higher priority settings.
+ 1. Kconfig
+ It just sets a default value.
+ 2. module parameters
+ It is the first priority. Take care of that blkoops will take lower
+ priority settings if higher priority one do not set.
+
+config PSTORE_BLKOOPS_DMESG_SIZE
+ int "dmesg size in kbytes for blkoops"
+ depends on PSTORE_BLKOOPS
+ default 64
+ help
+ This just sets size of dmesg (dmesg_size) for pstore/blk. The value
+ must be a multiple of 4096.
+
+ NOTE that, there are two ways to set parameters of blkoops and
+ prioritize according to configuration flexibility. That is
+ Kconfig < module parameters. It means that the value can
+ be overwritten by higher priority settings.
+ 1. Kconfig
+ It just sets a default value.
+ 2. module parameters
+ It is the first priority. Take care of that blkoops will take lower
+ priority settings if higher priority one do not set.
+
+config PSTORE_BLKOOPS_TOTAL_SIZE
+ int "total size in kbytes for blkoops"
+ depends on PSTORE_BLKOOPS
+ default 0
+ help
+ The total size in kbytes pstore/blk can use. It must be less than or
+ equal to size of block device if @blkdev valid. If @total_size is zero
+ with @blkdev, @total_size will be set equal to size of @blkdev.
+ The value must be a multiple of 4096.
+
+ NOTE that, there are two ways to set parameters of blkoops and
+ prioritize according to configuration flexibility. That is
+ Kconfig < module parameters. It means that the value can
+ be overwritten by higher priority settings.
+ 1. Kconfig
+ It just sets a default value.
+ 2. module parameters
+ It is the first priority. Take care of that blkoops will take lower
+ priority settings if higher priority one do not set.
+
+config PSTORE_BLKOOPS_BLKDEV
+ string "block device for blkoops"
+ depends on PSTORE_BLKOOPS
+ default ""
+ help
+ This just sets block device (blkdev) for pstore/blk. Pstore/blk
+ will record data to this block device to avoid losing data due to
+ power failure. So, if it is not set, pstore/blk will drop all data
+ when on reboot.
+
+ It accept the following variants:
+ 1) <hex_major><hex_minor> device number in hexadecimal represents
+ itself no leading 0x, for example b302.
+ 2) /dev/<disk_name> represents the device number of disk
+ 3) /dev/<disk_name><decimal> represents the device number
+ of partition - device number of disk plus the partition number
+ 4) /dev/<disk_name>p<decimal> - same as the above, this form is
+ used when disk name of partitioned disk ends with a digit.
+ 5) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
+ unique id of a partition if the partition table provides it.
+ The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
+ partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
+ filled hex representation of the 32-bit "NT disk signature", and PP
+ is a zero-filled hex representation of the 1-based partition number.
+ 6) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation
+ to a partition with a known unique id.
+ 7) <major>:<minor> major and minor number of the device separated by
+ a colon.
+
+ NOTE that, there are two ways to set parameters of blkoops and
+ prioritize according to configuration flexibility. That is
+ Kconfig < module parameters. It means that the value can
+ be overwritten by higher priority settings.
+ 1. Kconfig
+ It just sets a default value.
+ 2. module parameters
+ It is the first priority. Take care of that blkoops will take lower
+ priority settings if higher priority one do not set.
diff --git a/fs/pstore/Makefile b/fs/pstore/Makefile
index 0ee2fc8..24b3d48 100644
--- a/fs/pstore/Makefile
+++ b/fs/pstore/Makefile
@@ -15,3 +15,5 @@ obj-$(CONFIG_PSTORE_RAM) += ramoops.o

obj-$(CONFIG_PSTORE_BLK) += pstore_blk.o
pstore_blk-y += blkzone.o
+
+obj-$(CONFIG_PSTORE_BLKOOPS) += blkoops.o
diff --git a/fs/pstore/blkoops.c b/fs/pstore/blkoops.c
new file mode 100644
index 0000000..22c0c84
--- /dev/null
+++ b/fs/pstore/blkoops.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * blkoops.c: Block device Oops logger
+ *
+ * Copyright (C) 2019 liaoweixiong <liaoweixiong@gallwinnertech.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+#define MODNAME "blkoops"
+#define pr_fmt(fmt) MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pstore_blk.h>
+
+static long dmesg_size = -1;
+module_param(dmesg_size, long, 0400);
+MODULE_PARM_DESC(dmesg_size, "demsg size in kbytes");
+
+static long total_size = -1;
+module_param(total_size, long, 0400);
+MODULE_PARM_DESC(total_size, "total size in kbytes");
+
+#define BLKDEV_INVALID "INVALID"
+static char blkdev[80] = {BLKDEV_INVALID};
+module_param_string(blkdev, blkdev, 80, 0400);
+MODULE_PARM_DESC(blkdev, "the block device for general read/write");
+
+struct blkz_info blkz_info = {
+ .owner = THIS_MODULE,
+ .name = "blkoops",
+ .dump_oops = true,
+};
+
+struct blkoops_info {
+ unsigned long dmesg_size;
+ unsigned long total_size;
+ const char *blkdev;
+};
+struct blkoops_info blkoops_info = {
+ .dmesg_size = CONFIG_PSTORE_BLKOOPS_DMESG_SIZE * 1024,
+ .total_size = CONFIG_PSTORE_BLKOOPS_TOTAL_SIZE * 1024,
+ .blkdev = CONFIG_PSTORE_BLKOOPS_BLKDEV,
+};
+
+static struct platform_device *dummy;
+DEFINE_SPINLOCK(modify_blkzinfo);
+
+/**
+ * Block driver use this function to add panic read/write apis to blkoops.
+ * By this, block driver can do the least work that just provides panic ops.
+ */
+int blkoops_add_panic_ops(blkz_read_op panic_read, blkz_write_op panic_write)
+{
+ struct blkz_info *info = &blkz_info;
+
+ spin_lock(&modify_blkzinfo);
+ if (info->panic_read || info->panic_write) {
+ spin_unlock(&modify_blkzinfo);
+ return -EBUSY;
+ }
+
+ info->panic_read = panic_read;
+ info->panic_write = panic_write;
+
+ spin_unlock(&modify_blkzinfo);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(blkoops_add_panic_ops);
+
+static int blkoops_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct blkoops_info *info = dev->platform_data;
+
+ if (info->blkdev[0] == '\0' || !strcmp(info->blkdev, BLKDEV_INVALID)) {
+ pr_info("no block device, use ram buffer only\n");
+ } else {
+ pr_debug("block device: %s\n", info->blkdev);
+ blkz_info.blkdev = info->blkdev;
+ }
+
+#define check_size(name, size) { \
+ if (info->name & (size - 1)) { \
+ pr_err(#name " must be a multiple of %d\n", \
+ (size)); \
+ return -EINVAL; \
+ } \
+ blkz_info.name = info->name; \
+ }
+
+ check_size(total_size, 4096);
+ check_size(dmesg_size, 4096);
+
+#undef check_size
+
+ /*
+ * Update the module parameter variables as well so they are visible
+ * through /sys/module/blkoops/parameters/
+ */
+ dmesg_size = blkz_info.dmesg_size;
+ total_size = blkz_info.total_size;
+ if (blkz_info.blkdev)
+ strncpy(blkdev, blkz_info.blkdev, 80 - 1);
+ else
+ blkdev[0] = '\0';
+ return blkz_register(&blkz_info);
+}
+
+static int blkoops_remove(struct platform_device *pdev)
+{
+ blkz_unregister(&blkz_info);
+ return 0;
+}
+
+static const struct of_device_id dt_match[] = {
+ { .compatible = MODNAME},
+ {}
+};
+
+static struct platform_driver blkoops_driver = {
+ .probe = blkoops_probe,
+ .remove = blkoops_remove,
+ .driver = {
+ .name = MODNAME,
+ .of_match_table = dt_match,
+ },
+};
+
+void blkoops_register_dummy(void)
+{
+ struct blkoops_info *info = &blkoops_info;
+
+ /*
+ * Prepare a dummy platform data structure to carry the module
+ * parameters or kconfig value.
+ */
+ if (total_size > 0 || strcmp(blkdev, BLKDEV_INVALID)) {
+ pr_info("using module parameters\n");
+ if (total_size >= 0)
+ info->total_size = (unsigned long)total_size * 1024;
+ if (strcmp(blkdev, BLKDEV_INVALID))
+ info->blkdev = (const char *)blkdev;
+ if (dmesg_size >= 0)
+ info->dmesg_size = (unsigned long)dmesg_size * 1024;
+ } else if (info->total_size > 0 || strlen(info->blkdev)) {
+ pr_info("using kconfig value\n");
+ } else {
+ return;
+ }
+
+ dummy = platform_device_register_data(NULL, MODNAME, -1, info,
+ sizeof(*info));
+ if (IS_ERR(dummy)) {
+ pr_err("could not create platform device: %ld\n",
+ PTR_ERR(dummy));
+ dummy = NULL;
+ }
+}
+
+static int __init blkoops_init(void)
+{
+ int ret;
+
+ blkoops_register_dummy();
+ ret = platform_driver_register(&blkoops_driver);
+ if (ret != 0) {
+ platform_device_unregister(dummy);
+ dummy = NULL;
+ }
+ return ret;
+}
+late_initcall(blkoops_init);
+
+static void __exit blkoops_exit(void)
+{
+ platform_driver_unregister(&blkoops_driver);
+ platform_device_unregister(dummy);
+ dummy = NULL;
+}
+module_exit(blkoops_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("liaoweixiong <liaoweixiong@allwinnertech.com>");
+MODULE_DESCRIPTION("Sample for Pstore BLK with Oops logger");
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index 4f239f0..2d2ff97 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -60,6 +60,8 @@
* @panic_write:
* the write operation only used for panic.
*/
+typedef ssize_t (*blkz_read_op)(char *, size_t, loff_t);
+typedef ssize_t (*blkz_write_op)(const char *, size_t, loff_t);
struct blkz_info {
struct module *owner;
const char *name;
@@ -68,13 +70,17 @@ struct blkz_info {
unsigned long total_size;
unsigned long dmesg_size;
int dump_oops;
- ssize_t (*read)(char *buf, size_t bytes, loff_t pos);
- ssize_t (*write)(const char *buf, size_t bytes, loff_t pos);
- ssize_t (*panic_read)(char *buf, size_t bytes, loff_t pos);
- ssize_t (*panic_write)(const char *buf, size_t bytes, loff_t pos);
+ blkz_read_op read;
+ blkz_write_op write;
+ blkz_read_op panic_read;
+ blkz_write_op panic_write;
};

extern int blkz_register(struct blkz_info *info);
extern void blkz_unregister(struct blkz_info *info);

+#if IS_ENABLED(CONFIG_PSTORE_BLKOOPS)
+extern int blkoops_add_panic_ops(blkz_read_op, blkz_write_op);
+#endif
+
#endif
--
1.9.1
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