elog: Eliminate the second in memory copy of the event log.

The event log driver keeps two copies of the event log in memory, one to
take the place of the historically memory mapped image of flash which is now
read and written manually, and one originally intended to be an in memory
cache of flash. Since both are now just copies in memory, there's no value in
having them both and keeping them in sync.

Built and booted on Link. Ran mosys eventlog list. Added 2000 events to
the log and ran mosys eventlog list again. Cleared the log by echoing a 1 into
/sys/firmware/gsmi/clear_eventlog and ran mosys eventlog list again.

Change-Id: Ibed62a10c78884849726aa15ec795ab2914afc35
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/49306
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
Reviewed-on: http://review.coreboot.org/4241
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

2 files changed, 55 insertions, 162 deletions

diff --git a/src/drivers/elog/elog.c b/src/drivers/elog/elog.c
index ab255d8d55..439ccc363c 100644
--- a/src/drivers/elog/elog.c
+++ b/src/drivers/elog/elog.c
@@ -60,12 +60,6 @@
 static int elog_initialized;
 static struct spi_flash *elog_spi;
 static struct elog_descriptor elog_flash_area;
-static struct elog_descriptor elog_mem_area;
-
-static inline struct elog_descriptor* elog_get_mem(void)
-{
-	return &elog_mem_area;
-}
 
 static inline struct elog_descriptor* elog_get_flash(void)
 {
@@ -262,29 +256,26 @@ static int elog_is_event_valid(struct elog_descriptor *elog, u32 offset)
 }
 
 /*
- * Write 'size' bytes of data provided in 'buffer' into flash
- * device at offset 'offset'. This will not erase the flash and
- * it assumes the flash area is erased appropriately.
+ * Write 'size' bytes of data pointed to by 'address' in the flash backing
+ * store into flash. This will not erase the flash and it assumes the flash
+ * area has been erased appropriately.
  */
-static void elog_flash_write(u8 *address, u8 *buffer, u32 size)
+static void elog_flash_write(u8 *address, u32 size)
 {
 	struct elog_descriptor *flash = elog_get_flash();
 	u32 offset;
 
-	if (!address || !buffer || !size || !elog_spi)
+	if (!address || !size || !elog_spi)
 		return;
 
 	offset = flash->flash_base;
 	offset += address - (u8*)flash->backing_store;
 
-	elog_debug("elog_flash_write(address=0x%p offset=0x%08x buffer=0x%p "
-		   "size=%u)\n", address, offset, buffer, size);
+	elog_debug("elog_flash_write(address=0x%p offset=0x%08x size=%u)\n",
+		   address, offset, size);
 
 	/* Write the data to flash */
-	elog_spi->write(elog_spi, offset, size, buffer);
-
-	/* Update the copy in memory */
-	memcpy(address, buffer, size);
+	elog_spi->write(elog_spi, offset, size, address);
 }
 
 /*
@@ -389,13 +380,10 @@ static void elog_validate_and_fill(struct elog_descriptor *elog)
  * Initialize a new ELOG descriptor
  */
 static void elog_init_descriptor(struct elog_descriptor *elog,
-				 elog_descriptor_type type,
 				 u8 *buffer, u32 size)
 {
-	elog_debug("elog_init_descriptor(type=%u buffer=0x%p size=%u)\n",
-		   type, buffer, size);
+	elog_debug("elog_init_descriptor(buffer=0x%p size=%u)\n", buffer, size);
 
-	elog->type = type;
 	elog->area_state = ELOG_AREA_UNDEFINED;
 	elog->header_state = ELOG_HEADER_INVALID;
 	elog->event_buffer_state = ELOG_EVENT_BUFFER_OK;
@@ -403,8 +391,7 @@ static void elog_init_descriptor(struct elog_descriptor *elog,
 	elog->total_size = size;
 
 	/* Fill memory buffer by reading from SPI */
-	if (type == ELOG_DESCRIPTOR_FLASH)
-		elog_spi->read(elog_spi, elog->flash_base, size, buffer);
+	elog_spi->read(elog_spi, elog->flash_base, size, buffer);
 
 	/* Data starts immediately after header */
 	elog->data = &buffer[sizeof(struct elog_header)];
@@ -424,8 +411,7 @@ static void elog_init_descriptor(struct elog_descriptor *elog,
 static void elog_reinit_descriptor(struct elog_descriptor *elog)
 {
 	elog_debug("elog_reinit_descriptor()\n");
-	elog_init_descriptor(elog, elog->type, elog->backing_store,
-			     elog->total_size);
+	elog_init_descriptor(elog, elog->backing_store, elog->total_size);
 }
 
 /*
@@ -450,17 +436,7 @@ static int elog_setup_descriptors(u32 flash_base, u32 area_size)
 		return -1;
 	}
 	elog_get_flash()->flash_base = flash_base;
-	elog_init_descriptor(elog_get_flash(), ELOG_DESCRIPTOR_FLASH,
-			     area, area_size);
-
-	/* Initialize the memory area to look like a cleared flash area */
-	area = malloc(area_size);
-	if (!area) {
-		printk(BIOS_ERR, "ELOG: Unable to allocate mem area\n");
-		return -1;
-	}
-	memset(area, ELOG_TYPE_EOL, area_size);
-	elog_init_descriptor(elog_get_mem(), ELOG_DESCRIPTOR_MEMORY,area, area_size);
+	elog_init_descriptor(elog_get_flash(), area, area_size);
 
 	return 0;
 }
@@ -476,8 +452,7 @@ static void elog_flash_erase_area(void)
 	elog_reinit_descriptor(elog);
 }
 
-static void elog_prepare_empty(struct elog_descriptor *elog,
-			       u8 *data, u32 data_size)
+static void elog_prepare_empty(struct elog_descriptor *elog)
 {
 	struct elog_header *header;
 
@@ -493,84 +468,31 @@ static void elog_prepare_empty(struct elog_descriptor *elog,
 	header->header_size = sizeof(struct elog_header);
 	header->reserved[0] = ELOG_TYPE_EOL;
 	header->reserved[1] = ELOG_TYPE_EOL;
-	elog_flash_write(elog->backing_store, (u8*)header,
-			 header->header_size);
-
-	/* Write out the data */
-	if (data)
-		elog_flash_write(elog->data, data, data_size);
+	elog_flash_write(elog->backing_store, header->header_size);
 
 	elog_reinit_descriptor(elog);
-
-	/* Clear the log if corrupt */
-	if (!elog_is_area_valid(elog))
-		elog_flash_erase_area();
 }
 
 static int elog_sync_flash_to_mem(void)
 {
-	struct elog_descriptor *mem = elog_get_mem();
 	struct elog_descriptor *flash = elog_get_flash();
 
 	elog_debug("elog_sync_flash_to_mem()\n");
 
 	/* Fill with empty pattern first */
-	memset(mem->backing_store, ELOG_TYPE_EOL, mem->total_size);
+	memset(flash->backing_store, ELOG_TYPE_EOL, flash->total_size);
 
 	/* Read the header from SPI to memory */
 	elog_spi->read(elog_spi, flash->flash_base,
-		       sizeof(struct elog_header), mem->backing_store);
+		       sizeof(struct elog_header), flash->backing_store);
 
 	/* Read the valid flash contents from SPI to memory */
 	elog_spi->read(elog_spi, flash->flash_base + sizeof(struct elog_header),
-		       flash->next_event_offset, mem->data);
-
-	elog_reinit_descriptor(mem);
-
-	return elog_is_area_valid(mem) ? 0 : -1;
-}
-
-static int elog_sync_mem_to_flash(void)
-{
-	struct elog_descriptor *mem = elog_get_mem();
-	struct elog_descriptor *flash = elog_get_flash();
-	u8 *src, *dest;
-	u32 size;
-
-	elog_debug("elog_sync_mem_to_flash()\n");
-
-	/*
-	 * In the case of a BIOS flash the active area will be cleared.
-	 * One can catch this case and log the proper shutdown event by
-	 * checking if the active flash elog is empty.  Note that if the
-	 * header size changes we will have corrupted the flash area.
-	 * However that will be corrected on the next boot.
-	 */
-	if (elog_is_area_clear(flash)) {
-		elog_prepare_empty(flash,
-				   (u8*)elog_get_last_event_base(mem),
-				   mem->last_event_size);
-		elog_sync_flash_to_mem();
-		return 0;
-	}
-
-	/* Calculate the destination and source bases */
-	dest = (u8*)elog_get_next_event_base(flash);
-	src = (u8*)elog_get_event_base(mem, flash->next_event_offset);
-
-	/* Calculate how much data to sync */
-	size = mem->next_event_offset - flash->next_event_offset;
-
-	/* Write the log data */
-	elog_flash_write(dest, src, size);
+		       flash->next_event_offset, flash->data);
 
-	/* Update descriptor */
-	flash->event_count = mem->event_count;
-	flash->next_event_offset = mem->next_event_offset;
-	flash->last_event_offset = mem->last_event_offset;
-	flash->last_event_size = mem->last_event_size;
+	elog_reinit_descriptor(flash);
 
-	return 0;
+	return elog_is_area_valid(flash) ? 0 : -1;
 }
 
 /*
@@ -589,26 +511,20 @@ static int elog_flash_area_bootstrap(void)
 
 	case ELOG_AREA_EMPTY:
 		/* Write a new header with no data */
-		elog_prepare_empty(elog, NULL, 0);
+		elog_prepare_empty(elog);
 		break;
 
 	case ELOG_AREA_HAS_CONTENT:
 		break;
 	}
 
-	if (elog->header_state == ELOG_HEADER_INVALID) {
-		/* If the header is invalid no events can be salvaged
-		 * so erase the entire area. */
-		printk(BIOS_ERR, "ELOG: flash area header invalid\n");
-		elog_flash_erase_area();
-		elog_prepare_empty(elog, NULL, 0);
-	}
-
-	if (elog->event_buffer_state == ELOG_EVENT_BUFFER_CORRUPTED) {
-		/* Wipe the source flash area */
+	if (elog->header_state == ELOG_HEADER_INVALID ||
+		elog->event_buffer_state == ELOG_EVENT_BUFFER_CORRUPTED) {
+		/* If the header is invalid or the events are corrupted,
+		 * no events can be salvaged so erase the entire area. */
+		printk(BIOS_ERR, "ELOG: flash area invalid\n");
 		elog_flash_erase_area();
-		elog_prepare_empty(elog, elog_get_mem()->data,
-				   elog_get_mem()->next_event_offset);
+		elog_prepare_empty(elog);
 	}
 
 	return 0;
@@ -620,7 +536,6 @@ static int elog_flash_area_bootstrap(void)
  */
 static int elog_shrink(void)
 {
-	struct elog_descriptor *mem = elog_get_mem();
 	struct elog_descriptor *flash = elog_get_flash();
 	struct event_header *event;
 	u16 discard_count = 0;
@@ -629,7 +544,7 @@ static int elog_shrink(void)
 
 	elog_debug("elog_shrink()\n");
 
-	if (mem->next_event_offset < CONFIG_ELOG_SHRINK_SIZE)
+	if (flash->next_event_offset < CONFIG_ELOG_SHRINK_SIZE)
 		return 0;
 
 	while (1) {
@@ -637,7 +552,7 @@ static int elog_shrink(void)
 		if (offset > CONFIG_ELOG_SHRINK_SIZE)
 			break;
 
-		event = elog_get_event_base(mem, offset);
+		event = elog_get_event_base(flash, offset);
 
 		/* Reached the end of the area */
 		if (!event || event->type == ELOG_TYPE_EOL)
@@ -647,23 +562,21 @@ static int elog_shrink(void)
 		discard_count++;
 	}
 
-	new_size = mem->next_event_offset - offset;
-	memmove(&mem->data[0], &mem->data[offset], new_size);
-	memset(&mem->data[new_size], ELOG_TYPE_EOL, mem->data_size - new_size);
-	elog_reinit_descriptor(mem);
+	new_size = flash->next_event_offset - offset;
+	memmove(&flash->data[0], &flash->data[offset], new_size);
+	memset(&flash->data[new_size], ELOG_TYPE_EOL,
+	       flash->data_size - new_size);
 
 	elog_flash_erase(flash->backing_store, flash->total_size);
+	elog_flash_write(flash->backing_store, flash->total_size);
+	elog_reinit_descriptor(flash);
 
 	/* Ensure the area was successfully erased */
-	if (mem->next_event_offset >= CONFIG_ELOG_FULL_THRESHOLD) {
+	if (flash->next_event_offset >= CONFIG_ELOG_FULL_THRESHOLD) {
 		printk(BIOS_ERR, "ELOG: Flash area was not erased!\n");
 		return -1;
 	}
 
-	elog_flash_write(flash->backing_store, mem->backing_store,
-			 mem->total_size);
-	elog_reinit_descriptor(flash);
-
 	/* Add clear event */
 	elog_add_event_word(ELOG_TYPE_LOG_CLEAR, offset);
 
@@ -746,7 +659,7 @@ int elog_clear(void)
 	elog_flash_erase_area();
 
 	/* Prepare new empty area */
-	elog_prepare_empty(flash, NULL, 0);
+	elog_prepare_empty(flash);
 
 	/* Update memory area from flash */
 	if (elog_sync_flash_to_mem() < 0)
@@ -816,8 +729,7 @@ int elog_init(void)
 
 	elog_initialized = 1;
 
-	printk(BIOS_INFO, "ELOG: MEM @0x%p FLASH @0x%p [SPI 0x%08x]\n",
-	       elog_get_mem()->backing_store,
+	printk(BIOS_INFO, "ELOG: FLASH @0x%p [SPI 0x%08x]\n",
 	       elog_get_flash()->backing_store, elog_get_flash()->flash_base);
 
 	printk(BIOS_INFO, "ELOG: areas are %d bytes, full threshold %d,"
@@ -830,7 +742,7 @@ int elog_init(void)
 				    elog_get_flash()->total_size);
 
 	/* Shrink the log if we are getting too full */
-	if (elog_get_mem()->next_event_offset >= CONFIG_ELOG_FULL_THRESHOLD)
+	if (elog_get_flash()->next_event_offset >= CONFIG_ELOG_FULL_THRESHOLD)
 		if (elog_shrink() < 0)
 			return -1;
 
@@ -873,37 +785,37 @@ static void elog_fill_timestamp(struct event_header *event)
 }
 
 /*
- * Add an event to the memory area
+ * Add an event to the log
  */
-static int elog_add_event_mem(u8 event_type, void *data, u8 data_size)
+void elog_add_event_raw(u8 event_type, void *data, u8 data_size)
 {
 	struct event_header *event;
-	struct elog_descriptor *mem = elog_get_mem();
+	struct elog_descriptor *flash = elog_get_flash();
 	u8 event_size;
 
-	elog_debug("elog_add_event_mem(type=%X)\n", event_type);
+	elog_debug("elog_add_event_raw(type=%X)\n", event_type);
 
 	/* Make sure ELOG structures are initialized */
 	if (elog_init() < 0)
-		return -1;
+		return;
 
 	/* Header + Data + Checksum */
 	event_size = sizeof(*event) + data_size + 1;
 	if (event_size > MAX_EVENT_SIZE) {
 		printk(BIOS_ERR, "ELOG: Event(%X) data size too "
 		       "big (%d)\n", event_type, event_size);
-		return -1;
+		return;
 	}
 
 	/* Make sure event data can fit */
-	if ((mem->next_event_offset + event_size) >= mem->data_size) {
+	if ((flash->next_event_offset + event_size) >= flash->data_size) {
 		printk(BIOS_ERR, "ELOG: Event(%X) does not fit\n",
 		       event_type);
-		return -1;
+		return;
 	}
 
 	/* Fill out event data */
-	event = elog_get_next_event_base(mem);
+	event = elog_get_next_event_base(flash);
 	event->type = event_type;
 	event->length = event_size;
 	elog_fill_timestamp(event);
@@ -916,31 +828,19 @@ static int elog_add_event_mem(u8 event_type, void *data, u8 data_size)
 	elog_update_checksum(event, -(elog_checksum_event(event)));
 
 	/* Update memory descriptor parameters */
-	mem->event_count++;
-	mem->last_event_offset = mem->next_event_offset;
-	mem->last_event_size = event_size;
-	mem->next_event_offset += event_size;
-
-	printk(BIOS_INFO, "ELOG: Event(%X) added with size %d\n",
-	       event_type, event_size);
-	return 0;
-}
+	flash->event_count++;
 
-void elog_add_event_raw(u8 event_type, void *data, u8 data_size)
-{
-	elog_debug("elog_add_event_raw(type=%X)\n", event_type);
+	elog_flash_write((void *)event, event_size);
 
-	/* Add event to the memory area */
-	if (elog_add_event_mem(event_type, data, data_size) < 0) {
-		printk(BIOS_ERR, "Unable to add event to memory area\n");
-		return;
-	}
+	flash->last_event_offset = flash->next_event_offset;
+	flash->last_event_size = event_size;
+	flash->next_event_offset += event_size;
 
-	/* Sync the memory buffer to flash */
-	elog_sync_mem_to_flash();
+	printk(BIOS_INFO, "ELOG: Event(%X) added with size %d\n",
+	       event_type, event_size);
 
 	/* Shrink the log if we are getting too full */
-	if (elog_get_mem()->next_event_offset >= CONFIG_ELOG_FULL_THRESHOLD)
+	if (flash->next_event_offset >= CONFIG_ELOG_FULL_THRESHOLD)
 		elog_shrink();
 }
 
diff --git a/src/drivers/elog/elog_internal.h b/src/drivers/elog/elog_internal.h
index 67026af383..799e7e2311 100644
--- a/src/drivers/elog/elog_internal.h
+++ b/src/drivers/elog/elog_internal.h
@@ -47,12 +47,6 @@ struct event_header {
 /* SMBIOS Type 15 related constants */
 #define ELOG_HEADER_TYPE_OEM		0x88
 
-typedef enum elog_descriptor_type {
-	ELOG_DESCRIPTOR_UNKNOWN,
-	ELOG_DESCRIPTOR_MEMORY,
-	ELOG_DESCRIPTOR_FLASH,
-} elog_descriptor_type;
-
 typedef enum elog_area_state {
 	ELOG_AREA_UNDEFINED,		/* Initial boot strap state */
 	ELOG_AREA_EMPTY,		/* Entire area is empty */
@@ -73,7 +67,6 @@ typedef enum elog_event_buffer_state {
  * Internal handler for event log buffers
  */
 struct elog_descriptor {
-	elog_descriptor_type	type;
 	elog_area_state		area_state;
 	elog_header_state	header_state;
 	elog_event_buffer_state	event_buffer_state;