armv7: Place reset vector + CBFS header + bootblock dynamically

This replaces hard-coded bootblock offsets using the new scheme.
The assembler will place the initial branch instruction after BL1,
skip 2 aligned chunks, and place the remaining bootblock code after.

It will also leave an anchor string, currently 0xdeadbeef which
cbfstool will find. Once found, cbfstool will place the master CBFS
header at the next aligned offset.

Here is how it looks:

             0x0000 |--------------|
                    |     BL1      |
             0x2000 |--------------|
                    |    branch    |
    0x2000 + align  |--------------|
                    |  CBFS header |
0x2000 + align * 2  |--------------|
                    |   bootblock  |
                    |--------------|

TODO: The option for alignment passed into cbfstool has always been
64. Can we set it to 16 instead?

Change-Id: Icbe817cbd8a37f11990aaf060aab77d2dc113cb1
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2148
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

3 files changed, 28 insertions, 20 deletions

diff --git a/src/arch/armv7/Makefile.inc b/src/arch/armv7/Makefile.inc
index a4f57f34c1..cc306335cd 100644
--- a/src/arch/armv7/Makefile.inc
+++ b/src/arch/armv7/Makefile.inc
@@ -48,8 +48,7 @@ prebuilt-files = $(foreach file,$(cbfs-files), $(call extract_nth,1,$(file)))
 
 $(obj)/coreboot.pre1: $(objcbfs)/bootblock.bin $$(prebuilt-files) $(CBFSTOOL)
 	$(CBFSTOOL) $@.tmp create -m armv7 -s $(CONFIG_COREBOOT_ROMSIZE_KB)K \
-		-B $(objcbfs)/bootblock.bin -a 64 \
-		-o $$(( $(CONFIG_ROM_SIZE) - $(CONFIG_CBFS_SIZE) ))
+		-B $(objcbfs)/bootblock.bin -a 64
 	$(prebuild-files) true
 	mv $@.tmp $@
 else
diff --git a/src/arch/armv7/bootblock.inc b/src/arch/armv7/bootblock.inc
index 90850d62dd..e1b8b19341 100644
--- a/src/arch/armv7/bootblock.inc
+++ b/src/arch/armv7/bootblock.inc
@@ -43,11 +43,11 @@ _start: b	reset
 	.balignl 16,0xdeadbeef
 
 _cbfs_master_header:
-	/* The CBFS master header is inserted here by cbfstool
-	 * when coreboot.rom is being created. Hence, we leave
-	 * some space for it.
+	/* The CBFS master header is inserted by cbfstool at the first
+	 * aligned offset after the above anchor string is found.
+	 * Hence, we leave some space for it.
 	 */
-	.skip 64
+	.skip 128			@ Assumes 64-byte alignment
 
 reset:
 	/*
diff --git a/util/cbfstool/common.c b/util/cbfstool/common.c
index 195cda13c6..5413958447 100644
--- a/util/cbfstool/common.c
+++ b/util/cbfstool/common.c
@@ -565,23 +565,32 @@ int create_cbfs_image(const char *romfile, uint32_t _romsize,
 		/* Set up physical/virtual mapping */
 		offset = romarea;
 
-		// should be aligned to align
-		uint32_t *arm_vec = (uint32_t *)(romarea + offs);
-		master_header = (struct cbfs_header *)(romarea + offs + 0x20);
-		loadfile(bootblock, &bootblocksize, romarea + offs + 0x20 +
-				sizeof(struct cbfs_header), SEEK_SET);
-
 		/*
-		 * Encoding for this branch instruction is:
-		 * 31:28 - condition (0xe for always/unconditional)
-		 * 27:24 - Branch (0xa, encoding A1)
-		 * 23: 0 - sign-extended offset (in multiples of 4)
+		 * The initial jump instruction and bootblock will be placed
+		 * before and after the master header, respectively. The
+		 * bootblock image must contain a blank, aligned region large
+		 * enough for the master header to fit.
 		 *
-		 * When executing the branch, the PC will read as the address
-		 * of current instruction + 8.
+		 * An anchor string must be left such that when cbfstool is run
+		 * we can find it and insert the master header at the next
+		 * aligned boundary.
 		 */
-		uint32_t imm = ((0x20 + sizeof(struct cbfs_header)) - 8) / 4;
-		arm_vec[0] = imm | (0xa << 24) | (0xe << 28);
+		loadfile(bootblock, &bootblocksize, romarea + offs, SEEK_SET);
+
+		unsigned char *p = romarea + offs;
+		while (1) {
+			/* FIXME: assumes little endian... */
+			if (*(uint32_t *)p == 0xdeadbeef)
+				break;
+			if (p >= (romarea + _romsize)) {
+				fprintf(stderr, "E: Could not determine CBFS "
+					"header location.\n", bootblock);
+				return 1;
+			}
+			p += (sizeof(unsigned int));
+		}
+		unsigned int u = ALIGN((unsigned int)(p - romarea), align);
+		master_header = (struct cbfs_header *)(romarea + u);
 
 		master_header->magic = ntohl(CBFS_HEADER_MAGIC);
 		master_header->version = ntohl(CBFS_HEADER_VERSION);