[PATCH 2/8] Add version and timestamp to oops header

[Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>]

Introduce version and timestamp information in the oops header.
oops_log_info (oops header) holds version (to distinguish between old
and new format oops header), length of the oops text
(compressed or uncompressed) and timestamp.

Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
---
 arch/powerpc/platforms/pseries/nvram.c |   57 +++++++++++++++++++++-----------
 1 file changed, 38 insertions(+), 19 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c
index e54a8b7..742735a 100644
--- a/arch/powerpc/platforms/pseries/nvram.c
+++ b/arch/powerpc/platforms/pseries/nvram.c
@@ -29,6 +29,13 @@
 /* Max bytes to read/write in one go */
 #define NVRW_CNT 0x20
 
+/*
+ * Set oops header version to distingush between old and new format header.
+ * lnx,oops-log partition max size is 4000, header version > 4000 will
+ * help in identifying new header.
+ */
+#define OOPS_HDR_VERSION 5000
+
 static unsigned int nvram_size;
 static int nvram_fetch, nvram_store;
 static char nvram_buf[NVRW_CNT];	/* assume this is in the first 4GB */
@@ -67,6 +74,12 @@ static const char *pseries_nvram_os_partitions[] = {
 	NULL
 };
 
+struct oops_log_info {
+	u16 version;
+	u16 report_length;
+	u64 timestamp;
+} __attribute__((packed));
+
 static void oops_to_nvram(struct kmsg_dumper *dumper,
 			  enum kmsg_dump_reason reason);
 
@@ -83,28 +96,28 @@ static unsigned long last_unread_rtas_event;	/* timestamp */
 
  * big_oops_buf[] holds the uncompressed text we're capturing.
  *
- * oops_buf[] holds the compressed text, preceded by a prefix.
- * The prefix is just a u16 holding the length of the compressed* text.
- * (*Or uncompressed, if compression fails.)  oops_buf[] gets written
- * to NVRAM.
+ * oops_buf[] holds the compressed text, preceded by a oops header.
+ * oops header has u16 holding the version of oops header (to differentiate
+ * between old and new format header) followed by u16 holding the length of
+ * the compressed* text (*Or uncompressed, if compression fails.) and u64
+ * holding the timestamp. oops_buf[] gets written to NVRAM.
  *
- * oops_len points to the prefix.  oops_data points to the compressed text.
+ * oops_log_info points to the header. oops_data points to the compressed text.
  *
  * +- oops_buf
- * |		+- oops_data
- * v		v
- * +------------+-----------------------------------------------+
- * | length	| text                                          |
- * | (2 bytes)	| (oops_data_sz bytes)                          |
- * +------------+-----------------------------------------------+
+ * |                                   +- oops_data
+ * v                                   v
+ * +-----------+-----------+-----------+------------------------+
+ * | version   | length    | timestamp | text                   |
+ * | (2 bytes) | (2 bytes) | (8 bytes) | (oops_data_sz bytes)   |
+ * +-----------+-----------+-----------+------------------------+
  * ^
- * +- oops_len
+ * +- oops_log_info
  *
  * We preallocate these buffers during init to avoid kmalloc during oops/panic.
  */
 static size_t big_oops_buf_sz;
 static char *big_oops_buf, *oops_buf;
-static u16 *oops_len;
 static char *oops_data;
 static size_t oops_data_sz;
 
@@ -425,9 +438,8 @@ static void __init nvram_init_oops_partition(int rtas_partition_exists)
 						oops_log_partition.name);
 		return;
 	}
-	oops_len = (u16*) oops_buf;
-	oops_data = oops_buf + sizeof(u16);
-	oops_data_sz = oops_log_partition.size - sizeof(u16);
+	oops_data = oops_buf + sizeof(struct oops_log_info);
+	oops_data_sz = oops_log_partition.size - sizeof(struct oops_log_info);
 
 	/*
 	 * Figure compression (preceded by elimination of each line's <n>
@@ -555,6 +567,7 @@ error:
 /* Compress the text from big_oops_buf into oops_buf. */
 static int zip_oops(size_t text_len)
 {
+	struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
 	int zipped_len = nvram_compress(big_oops_buf, oops_data, text_len,
 								oops_data_sz);
 	if (zipped_len < 0) {
@@ -562,7 +575,9 @@ static int zip_oops(size_t text_len)
 		pr_err("nvram: logging uncompressed oops/panic report\n");
 		return -1;
 	}
-	*oops_len = (u16) zipped_len;
+	oops_hdr->version = OOPS_HDR_VERSION;
+	oops_hdr->report_length = (u16) zipped_len;
+	oops_hdr->timestamp = get_seconds();
 	return 0;
 }
 
@@ -576,6 +591,7 @@ static int zip_oops(size_t text_len)
 static void oops_to_nvram(struct kmsg_dumper *dumper,
 			  enum kmsg_dump_reason reason)
 {
+	struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
 	static unsigned int oops_count = 0;
 	static bool panicking = false;
 	static DEFINE_SPINLOCK(lock);
@@ -622,11 +638,14 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
 		kmsg_dump_get_buffer(dumper, false,
 				     oops_data, oops_data_sz, &text_len);
 		err_type = ERR_TYPE_KERNEL_PANIC;
-		*oops_len = (u16) text_len;
+		oops_hdr->version = OOPS_HDR_VERSION;
+		oops_hdr->report_length = (u16) text_len;
+		oops_hdr->timestamp = get_seconds();
 	}
 
 	(void) nvram_write_os_partition(&oops_log_partition, oops_buf,
-		(int) (sizeof(*oops_len) + *oops_len), err_type, ++oops_count);
+		(int) (sizeof(*oops_hdr) + oops_hdr->report_length), err_type,
+		++oops_count);
 
 	spin_unlock_irqrestore(&lock, flags);
 }