Merge tag 'pstore-v4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull pstore updates from Kees Cook:
 "Improvements and refactorings:

   - Improve compression handling

   - Refactor argument handling during initialization

   - Avoid needless locking for saner EFI backend handling

   - Add more kern-doc and improve debugging output"

* tag 'pstore-v4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  pstore/ram: Avoid NULL deref in ftrace merging failure path
  pstore: Convert buf_lock to semaphore
  pstore: Fix bool initialization/comparison
  pstore/ram: Do not treat empty buffers as valid
  pstore/ram: Simplify ramoops_get_next_prz() arguments
  pstore: Map PSTORE_TYPE_* to strings
  pstore: Replace open-coded << with BIT()
  pstore: Improve and update some comments and status output
  pstore/ram: Add kern-doc for struct persistent_ram_zone
  pstore/ram: Report backend assignments with finer granularity
  pstore/ram: Standardize module name in ramoops
  pstore: Avoid duplicate call of persistent_ram_zap()
  pstore: Remove needless lock during console writes
  pstore: Do not use crash buffer for decompression

2 files changed, 69 insertions, 15 deletions

diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 30fcec375a3a..b146181e8709 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -26,27 +26,38 @@
 #include <linux/errno.h>
 #include <linux/kmsg_dump.h>
 #include <linux/mutex.h>
-#include <linux/spinlock.h>
+#include <linux/semaphore.h>
 #include <linux/time.h>
 #include <linux/types.h>
 
 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
@@ -85,10 +96,10 @@ struct pstore_record {
 /**
  * struct pstore_info - backend pstore driver structure
  *
- * @owner:	module which is repsonsible for this backend driver
+ * @owner:	module which is responsible for this backend driver
  * @name:	name of the backend driver
  *
- * @buf_lock:	spinlock to serialize access to @buf
+ * @buf_lock:	semaphore to serialize access to @buf
  * @buf:	preallocated crash dump buffer
  * @bufsize:	size of @buf available for crash dump bytes (must match
  *		smallest number of bytes available for writing to a
@@ -173,7 +184,7 @@ struct pstore_info {
 	struct module	*owner;
 	char		*name;
 
-	spinlock_t	buf_lock;
+	struct semaphore buf_lock;
 	char		*buf;
 	size_t		bufsize;
 
@@ -192,14 +203,13 @@ struct pstore_info {
 };
 
 /* Supported frontends */
-#define PSTORE_FLAGS_DMESG	(1 << 0)
-#define PSTORE_FLAGS_CONSOLE	(1 << 1)
-#define PSTORE_FLAGS_FTRACE	(1 << 2)
-#define PSTORE_FLAGS_PMSG	(1 << 3)
+#define PSTORE_FLAGS_DMESG	BIT(0)
+#define PSTORE_FLAGS_CONSOLE	BIT(1)
+#define PSTORE_FLAGS_FTRACE	BIT(2)
+#define PSTORE_FLAGS_PMSG	BIT(3)
 
 extern int pstore_register(struct pstore_info *);
 extern void pstore_unregister(struct pstore_info *);
-extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason);
 
 struct pstore_ftrace_record {
 	unsigned long ip;
diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index 602d64725222..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>
 
 /*
@@ -30,6 +31,11 @@
  * PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required.
  */
 #define PRZ_FLAG_NO_LOCK	BIT(0)
+/*
+ * If a PRZ should only have a single-boot lifetime, this marks it as
+ * getting wiped after its contents get copied out after boot.
+ */
+#define PRZ_FLAG_ZAP_OLD	BIT(1)
 
 struct persistent_ram_buffer;
 struct rs_control;
@@ -42,17 +48,55 @@ struct persistent_ram_ecc_info {
 	uint16_t *par;
 };
 
+/**
+ * struct persistent_ram_zone - Details of a persistent RAM zone (PRZ)
+ *                              used as a pstore backend
+ *
+ * @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:
+ *	locks access to @buffer "size" bytes and "start" offset
+ * @buffer:
+ *	pointer to actual RAM area managed by this PRZ
+ * @buffer_size:
+ *	bytes in @buffer->data (not including any trailing ECC bytes)
+ *
+ * @par_buffer:
+ *	pointer into @buffer->data containing ECC bytes for @buffer->data
+ * @par_header:
+ *	pointer into @buffer->data containing ECC bytes for @buffer header
+ *	(i.e. all fields up to @data)
+ * @rs_decoder:
+ *	RSLIB instance for doing ECC calculations
+ * @corrected_bytes:
+ *	ECC corrected bytes accounting since boot
+ * @bad_blocks:
+ *	ECC uncorrectable bytes accounting since boot
+ * @ecc_info:
+ *	ECC configuration details
+ *
+ * @old_log:
+ *	saved copy of @buffer->data prior to most recent wipe
+ * @old_log_size:
+ *	bytes contained in @old_log
+ *
+ */
 struct persistent_ram_zone {
 	phys_addr_t paddr;
 	size_t size;
 	void *vaddr;
 	char *label;
-	struct persistent_ram_buffer *buffer;
-	size_t buffer_size;
+	enum pstore_type_id type;
 	u32 flags;
+
 	raw_spinlock_t buffer_lock;
+	struct persistent_ram_buffer *buffer;
+	size_t buffer_size;
 
-	/* ECC correction */
 	char *par_buffer;
 	char *par_header;
 	struct rs_control *rs_decoder;