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authorWeiXiong Liao <liaoweixiong@allwinnertech.com>2020-03-25 16:54:57 +0800
committerKees Cook <keescook@chromium.org>2020-05-30 10:34:03 -0700
commit17639f67c1d61aba3c05e7703f75cd468f9d484f (patch)
tree029d85bdaab1530b7b76d47e2033137864857afc /include/linux/pstore_blk.h
parentd26c3321fe18dc74517dc1f518d584aa33b0a851 (diff)
downloadlinux-17639f67c1d61aba3c05e7703f75cd468f9d484f.tar.bz2
pstore/blk: Introduce backend for block devices
pstore/blk is similar to pstore/ram, but uses a block device as the storage rather than persistent ram. The pstore/blk backend solves two common use-cases that used to preclude using pstore/ram: - not all devices have a battery that could be used to persist regular RAM across power failures. - most embedded intelligent equipment have no persistent ram, which increases costs, instead preferring cheaper solutions, like block devices. pstore/blk provides separate configurations for the end user and for the block drivers. User configuration determines how pstore/blk operates, such as record sizes, max kmsg dump reasons, etc. These can be set by Kconfig and/or module parameters, but module parameter have priority over Kconfig. Driver configuration covers all the details about the target block device, such as total size of the device and how to perform read/write operations. These are provided by block drivers, calling pstore_register_blkdev(), including an optional panic_write callback used to bypass regular IO APIs in an effort to avoid potentially destabilized kernel code during a panic. Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com> Link: https://lore.kernel.org/lkml/20200511233229.27745-3-keescook@chromium.org/ Co-developed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'include/linux/pstore_blk.h')
-rw-r--r--include/linux/pstore_blk.h51
1 files changed, 51 insertions, 0 deletions
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
new file mode 100644
index 000000000000..4501977b1336
--- /dev/null
+++ b/include/linux/pstore_blk.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __PSTORE_BLK_H_
+#define __PSTORE_BLK_H_
+
+#include <linux/types.h>
+#include <linux/pstore.h>
+#include <linux/pstore_zone.h>
+
+/**
+ * typedef pstore_blk_panic_write_op - panic write operation to block device
+ *
+ * @buf: the data to write
+ * @start_sect: start sector to block device
+ * @sects: sectors count on buf
+ *
+ * Return: On success, zero should be returned. Others mean error.
+ *
+ * Panic write to block device must be aligned to SECTOR_SIZE.
+ */
+typedef int (*pstore_blk_panic_write_op)(const char *buf, sector_t start_sect,
+ sector_t sects);
+
+/**
+ * struct pstore_blk_info - pstore/blk registration details
+ *
+ * @major: Which major device number to support with pstore/blk
+ * @flags: The supported PSTORE_FLAGS_* from linux/pstore.h.
+ * @panic_write:The write operation only used for the panic case.
+ * This can be NULL, but is recommended to avoid losing
+ * crash data if the kernel's IO path or work queues are
+ * broken during a panic.
+ * @devt: The dev_t that pstore/blk has attached to.
+ * @nr_sects: Number of sectors on @devt.
+ * @start_sect: Starting sector on @devt.
+ */
+struct pstore_blk_info {
+ unsigned int major;
+ unsigned int flags;
+ pstore_blk_panic_write_op panic_write;
+
+ /* Filled in by pstore/blk after registration. */
+ dev_t devt;
+ sector_t nr_sects;
+ sector_t start_sect;
+};
+
+int register_pstore_blk(struct pstore_blk_info *info);
+void unregister_pstore_blk(unsigned int major);
+
+#endif