cbfs: Add LZ4 in-place decompression support for pre-RAM stages

This patch ports the LZ4 decompression code that debuted in libpayload
last year to coreboot for use in CBFS stages (upgrading the base
algorithm to LZ4's dev branch to access the new in-place decompression
checks). This is especially useful for pre-RAM stages in constrained
SRAM-based systems, which previously could not be compressed due to
the size requirements of the LZMA scratchpad and bounce buffer. The
LZ4 algorithm offers a very lean decompressor function and in-place
decompression support to achieve roughly the same boot speed gains
(trading compression ratio for decompression time) with nearly no
memory overhead.

For now we only activate it for the stages that had previously not been
compressed at all on non-XIP (read: non-x86) boards. In the future we
may also consider replacing LZMA completely for certain boards, since
which algorithm wins out on boot speed depends on board-specific
parameters (architecture, processor speed, SPI transfer rate, etc.).

BRANCH=None
BUG=None
TEST=Built and booted Oak, Jerry, Nyan and Falco. Measured boot time on
Oak to be about ~20ms faster (cutting load times for affected stages
almost in half).

Change-Id: Iec256c0e6d585d1b69985461939884a54e3ab900
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/13638
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 41 insertions, 0 deletions

diff --git a/util/cbfstool/compress.c b/util/cbfstool/compress.c
index 51353317f4..a6a0df4dd1 100644
--- a/util/cbfstool/compress.c
+++ b/util/cbfstool/compress.c
@@ -20,7 +20,42 @@
 
 #include <string.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include "common.h"
+#include "lz4/lib/lz4frame.h"
+#include <commonlib/compression.h>
+
+static int lz4_compress(char *in, int in_len, char *out, int *out_len)
+{
+	LZ4F_preferences_t prefs = {
+		.compressionLevel = 20,
+		.frameInfo = {
+			.blockSizeID = max4MB,
+			.blockMode = blockIndependent,
+			.contentChecksumFlag = noContentChecksum,
+		},
+	};
+	size_t worst_size = LZ4F_compressFrameBound(in_len, &prefs);
+	void *bounce = malloc(worst_size);
+	if (!bounce)
+		return -1;
+	*out_len = LZ4F_compressFrame(bounce, worst_size, in, in_len, &prefs);
+	if (LZ4F_isError(*out_len) || *out_len >= in_len)
+		return -1;
+	memcpy(out, bounce, *out_len);
+	return 0;
+}
+
+static int lz4_decompress(char *in, int in_len, char *out, int out_len,
+			  size_t *actual_size)
+{
+	size_t result = ulz4fn(in, in_len, out, out_len);
+	if (result == 0)
+		return -1;
+	if (actual_size != NULL)
+		*actual_size = result;
+	return 0;
+}
 
 static int lzma_compress(char *in, int in_len, char *out, int *out_len)
 {
@@ -58,6 +93,9 @@ comp_func_ptr compression_function(enum comp_algo algo)
 	case CBFS_COMPRESS_LZMA:
 		compress = lzma_compress;
 		break;
+	case CBFS_COMPRESS_LZ4:
+		compress = lz4_compress;
+		break;
 	default:
 		ERROR("Unknown compression algorithm %d!\n", algo);
 		return NULL;
@@ -75,6 +113,9 @@ decomp_func_ptr decompression_function(enum comp_algo algo)
 	case CBFS_COMPRESS_LZMA:
 		decompress = lzma_decompress;
 		break;
+	case CBFS_COMPRESS_LZ4:
+		decompress = lz4_decompress;
+		break;
 	default:
 		ERROR("Unknown compression algorithm %d!\n", algo);
 		return NULL;