pstore: Map PSTORE_TYPE_* to strings

In later patches we will need to map types to names, so create a
constant table for that which can also be used in different parts of
old and new code. This saves the type in the PRZ which will be useful
in later patches.

Instead of having an explicit PSTORE_TYPE_UNKNOWN, just use ..._MAX.

This includes removing the now redundant filename templates which can use
a single format string. Also, there's no reason to limit the "is it still
compressed?" test to only PSTORE_TYPE_DMESG when building the pstorefs
filename. Records are zero-initialized, so a backend would need to have
explicitly set compressed=1.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

2 files changed, 17 insertions, 3 deletions

diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index f46e5df76b58..a9ec285d85d1 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -32,21 +32,32 @@
 
 struct module;
 
-/* pstore record types (see fs/pstore/inode.c for filename templates) */
+/*
+ * pstore record types (see fs/pstore/platform.c for pstore_type_names[])
+ * These values may be written to storage (see EFI vars backend), so
+ * they are kind of an ABI. Be careful changing the mappings.
+ */
 enum pstore_type_id {
+	/* Frontend storage types */
 	PSTORE_TYPE_DMESG	= 0,
 	PSTORE_TYPE_MCE		= 1,
 	PSTORE_TYPE_CONSOLE	= 2,
 	PSTORE_TYPE_FTRACE	= 3,
-	/* PPC64 partition types */
+
+	/* PPC64-specific partition types */
 	PSTORE_TYPE_PPC_RTAS	= 4,
 	PSTORE_TYPE_PPC_OF	= 5,
 	PSTORE_TYPE_PPC_COMMON	= 6,
 	PSTORE_TYPE_PMSG	= 7,
 	PSTORE_TYPE_PPC_OPAL	= 8,
-	PSTORE_TYPE_UNKNOWN	= 255
+
+	/* End of the list */
+	PSTORE_TYPE_MAX
 };
 
+const char *pstore_type_to_name(enum pstore_type_id type);
+enum pstore_type_id pstore_name_to_type(const char *name);
+
 struct pstore_info;
 /**
  * struct pstore_record - details of a pstore record entry
diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index 5d10ad51c1c4..337971c41980 100644
--- a/include/linux/pstore_ram.h
+++ b/include/linux/pstore_ram.h
@@ -22,6 +22,7 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
+#include <linux/pstore.h>
 #include <linux/types.h>
 
 /*
@@ -54,6 +55,7 @@ struct persistent_ram_ecc_info {
  * @paddr:	physical address of the mapped RAM area
  * @size:	size of mapping
  * @label:	unique name of this PRZ
+ * @type:	frontend type for this PRZ
  * @flags:	holds PRZ_FLAGS_* bits
  *
  * @buffer_lock:
@@ -88,6 +90,7 @@ struct persistent_ram_zone {
 	size_t size;
 	void *vaddr;
 	char *label;
+	enum pstore_type_id type;
 	u32 flags;
 
 	raw_spinlock_t buffer_lock;