pstore: Populate pstore record->time field

The current time will be initially available in the record->time field
for all pstore_read() and pstore_write() calls. Backends can either
update the field during read(), or use the field during write() instead
of fetching time themselves.
Signed-off-by: Kees Cook <keescook@chromium.org>

drivers/firmware/efi/efi-pstore.c

@@ -244,9 +244,6 @@ static int efi_pstore_write(struct pstore_record *record)
 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 	int i, ret = 0;
 
-	record->time.tv_sec = get_seconds();
-	record->time.tv_nsec = 0;
-
 	record->id = generic_id(record->time.tv_sec, record->part,
 				record->count);
 

fs/pstore/platform.c

@@ -480,6 +480,12 @@ void pstore_record_init(struct pstore_record *record,
 	memset(record, 0, sizeof(*record));
 
 	record->psi = psinfo;
+
+	/* Report zeroed timestamp if called before timekeeping has resumed. */
+	if (__getnstimeofday(&record->time)) {
+		record->time.tv_sec = 0;
+		record->time.tv_nsec = 0;
+	}
 }
 
 /*

fs/pstore/ram.c

@@ -27,7 +27,6 @@
 #include <linux/module.h>
 #include <linux/version.h>
 #include <linux/pstore.h>
-#include <linux/time.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/platform_device.h>
@@ -356,20 +355,15 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record)
 }
 
 static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
-				     bool compressed)
+				     struct pstore_record *record)
 {
 	char *hdr;
-	struct timespec timestamp;
 	size_t len;
 
-	/* Report zeroed timestamp if called before timekeeping has resumed. */
-	if (__getnstimeofday(&timestamp)) {
-		timestamp.tv_sec = 0;
-		timestamp.tv_nsec = 0;
-	}
 	hdr = kasprintf(GFP_ATOMIC, RAMOOPS_KERNMSG_HDR "%lu.%lu-%c\n",
-		(long)timestamp.tv_sec, (long)(timestamp.tv_nsec / 1000),
-		compressed ? 'C' : 'D');
+		record->time.tv_sec,
+		record->time.tv_nsec / 1000,
+		record->compressed ? 'C' : 'D');
 	WARN_ON_ONCE(!hdr);
 	len = hdr ? strlen(hdr) : 0;
 	persistent_ram_write(prz, hdr, len);
@@ -440,7 +434,7 @@ static int notrace ramoops_pstore_write(struct pstore_record *record)
 	prz = cxt->dprzs[cxt->dump_write_cnt];
 
 	/* Build header and append record contents. */
-	hlen = ramoops_write_kmsg_hdr(prz, record->compressed);
+	hlen = ramoops_write_kmsg_hdr(prz, record);
 	size = record->size;
 	if (size + hlen > prz->buffer_size)
 		size = prz->buffer_size - hlen;

include/linux/pstore.h

@@ -138,7 +138,10 @@ struct pstore_record {
  *		memory allocation may be broken during an Oops. Regardless,
  *		@buf must be proccesed or copied before returning. The
  *		backend is also expected to write @id with something that
- 8		can help identify this record to a future @erase callback.
+ *		can help identify this record to a future @erase callback.
+ *		The @time field will be prepopulated with the current time,
+ *		when available. The @size field will have the size of data
+ *		in @buf.
  *
  *	Returns 0 on success, and non-zero on error.
  *