[PATCH v4 10/12] pstore/blk: Provide way to query pstore configuration

[Kees Cook <keescook@chromium.org>]

From: WeiXiong Liao <liaoweixiong@allwinnertech.com>

In order to configure itself, the MTD backend needs to be able to query
the current pstore configuration. Introduce pstore_blk_usr_info() for
this purpose.

Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Link: https://lore.kernel.org/r/1585126506-18635-10-git-send-email-liaoweixiong@allwinnertech.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/pstore/blk.c            | 37 ++++++++++++++++++++++++++++++-------
 include/linux/pstore_blk.h | 10 ++++++++++
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
index e33e58afd4cb..c6d99d5dcd7f 100644
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -86,6 +86,17 @@ static struct bdev_info {
 	sector_t start_sect;
 } g_bdev_info;
 
+#define check_size(name, alignsize) ({				\
+	long _##name_ = (name);					\
+	_##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024);	\
+	if (_##name_ & ((alignsize) - 1)) {			\
+		pr_info(#name " must align to %d\n",		\
+				(alignsize));			\
+		_##name_ = ALIGN(name, (alignsize));		\
+	}							\
+	_##name_;						\
+})
+
 /**
  * struct psblk_device - back-end pstore/blk driver structure.
  *
@@ -140,13 +151,11 @@ static int psblk_register_do(struct psblk_device *dev)
 	if (!dev->flags)
 		dev->flags = UINT_MAX;
 #define verify_size(name, alignsize, enable) {				\
-		long _##name_ = (enable) ? (name) : 0;			\
-		_##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024);	\
-		if (_##name_ & ((alignsize) - 1)) {			\
-			pr_info(#name " must align to %d\n",		\
-					(alignsize));			\
-			_##name_ = ALIGN(name, (alignsize));		\
-		}							\
+		long _##name_;						\
+		if (enable)						\
+			_##name_ = check_size(name, alignsize);		\
+		else							\
+			_##name_ = 0;					\
 		name = _##name_ / 1024;					\
 		pstore_zone_info->name = _##name_;				\
 	}
@@ -465,6 +474,20 @@ int psblk_blkdev_info(dev_t *devt, sector_t *nr_sects, sector_t *start_sect)
 }
 EXPORT_SYMBOL_GPL(psblk_blkdev_info);
 
+/* get information of pstore/blk */
+int pstore_blk_usr_info(struct pstore_blk_info *info)
+{
+	strncpy(info->device, blkdev, 80);
+	info->max_reason = max_reason;
+	info->kmsg_size = check_size(kmsg_size, 4096);
+	info->pmsg_size = check_size(pmsg_size, 4096);
+	info->ftrace_size = check_size(ftrace_size, 4096);
+	info->console_size = check_size(console_size, 4096);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pstore_blk_usr_info);
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>");
 MODULE_DESCRIPTION("pstore backend for block devices");
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index 828b0763d477..dd5213044e21 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -27,4 +27,14 @@ int  psblk_register_blkdev(unsigned int major, unsigned int flags,
 void psblk_unregister_blkdev(unsigned int major);
 int  psblk_blkdev_info(dev_t *devt, sector_t *nr_sects, sector_t *start_sect);
 
+struct pstore_blk_info {
+	char device[80];
+	enum kmsg_dump_reason max_reason;
+	unsigned long kmsg_size;
+	unsigned long pmsg_size;
+	unsigned long console_size;
+	unsigned long ftrace_size;
+};
+int pstore_blk_usr_info(struct pstore_blk_info *info);
+
 #endif
-- 
2.20.1