pstore/blk: Provide way to query pstore configuration

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

Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Link: https://lore.kernel.org/lkml/20200511233229.27745-9-keescook@chromium.org/
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
index 67343d6..631bc27 100644 (file)
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -94,6 +94,17 @@ struct bdev_info {
        sector_t start_sect;
 };
 
+#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 pstore_device_info - back-end pstore/blk driver structure.
  *
@@ -149,13 +160,11 @@ static int psblk_register_do(struct pstore_device_info *dev)
                dev->flags = UINT_MAX;
 
 #define verify_size(name, alignsize, enabled) {                                \
-               long _##name_ = (enabled) ? (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 (enabled)                                            \
+                       _##name_ = check_size(name, alignsize);         \
+               else                                                    \
+                       _##name_ = 0;                                   \
                name = _##name_ / 1024;                                 \
                pstore_zone_info->name = _##name_;                      \
        }
@@ -453,6 +462,20 @@ void unregister_pstore_blk(unsigned int major)
 }
 EXPORT_SYMBOL_GPL(unregister_pstore_blk);
 
+/* get information of pstore/blk */
+int pstore_blk_get_config(struct pstore_blk_config *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_get_config);
+
 static void __exit pstore_blk_exit(void)
 {
        mutex_lock(&pstore_blk_lock);

diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index ccba8c0..0c40774 100644 (file)
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -49,4 +49,32 @@ struct pstore_blk_info {
 int  register_pstore_blk(struct pstore_blk_info *info);
 void unregister_pstore_blk(unsigned int major);
 
+/**
+ * struct pstore_blk_config - the pstore_blk backend configuration
+ *
+ * @device:            Name of the desired block device
+ * @max_reason:                Maximum kmsg dump reason to store to block device
+ * @kmsg_size:         Total size of for kmsg dumps
+ * @pmsg_size:         Total size of the pmsg storage area
+ * @console_size:      Total size of the console storage area
+ * @ftrace_size:       Total size for ftrace logging data (for all CPUs)
+ */
+struct pstore_blk_config {
+       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;
+};
+
+/**
+ * pstore_blk_get_config - get a copy of the pstore_blk backend configuration
+ *
+ * @info:      The sturct pstore_blk_config to be filled in
+ *
+ * Failure returns negative error code, and success returns 0.
+ */
+int pstore_blk_get_config(struct pstore_blk_config *info);
+
 #endif