115 lines
4.6 KiB
Bash
Executable File
115 lines
4.6 KiB
Bash
Executable File
#!/bin/sh
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# build-uboot-payload.sh — build the krane U-Boot payload for mmcblk0p1:
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#
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# 0x0000 64-byte arm64 Image header (code0 = b +0x40, image_size,
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# flags bit3, magic at 0x38 — booting.rst contract, verified
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# against depthcharge src/arch/arm/boot64.c)
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# 0x0040 uboot-wrapper.S (diagnostic: revive display + magenta fill +
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# blink train, then branch to U-Boot; branch imm26 patched)
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# 0x0040+ uboot.bin (u-boot-nodtb.bin + embedded control DTB),
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# contiguous — NO interior padding.
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#
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# U-Boot's PIE fixup requires runtime _start == link _start (mod 4K);
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# CONFIG_TEXT_BASE is chosen so link _start is 4K-aligned (with the
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# vectors/stub bytes preceding it), and the file is placed so the
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# runtime _start lands on a 4K boundary. Verified via u-boot.sym and
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# the ELF section table.
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#
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# then pack with mkdepthcharge (devkeys) and verify.
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set -e
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cd "$(dirname "$0")"
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UBOOT_BIN="${UBOOT_BIN:-/home/vhaudiquet/u-boot/u-boot.bin}"
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UBOOT_SYM="${UBOOT_SYM:-/home/vhaudiquet/u-boot/u-boot.sym}"
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DTB="${DTB:-krane-sku176.dtb}"
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WRAP_IMG=krane-uboot.bin
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OUT_PAYLOAD=krane-uboot-payload.bin
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# 1. assemble the diagnostic wrapper (raw binary, no relocations)
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aarch64-linux-gnu-gcc -c uboot-wrapper.S -o uboot-wrapper.o
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aarch64-linux-gnu-objcopy -O binary uboot-wrapper.o uboot-wrapper.bin
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WRAP_LEN=$(stat -c %s uboot-wrapper.bin)
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# 2. header + wrapper + u-boot, patch the wrapper's `b .` branch
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python3 - "$UBOOT_BIN" "$UBOOT_SYM" "$WRAP_IMG" "$WRAP_LEN" <<'EOF'
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import struct, subprocess, sys
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uboot_path, sym_path, out = sys.argv[1], sys.argv[2], sys.argv[3]
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wrap_len = int(sys.argv[4])
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uboot = open(uboot_path, 'rb').read()
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wrapper = open('uboot-wrapper.bin', 'rb').read()
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assert len(wrapper) == wrap_len
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# u-boot.bin starts at __image_copy_start (the lowest output VMA);
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# _start's file offset is its delta from that base. The PIE fixup in
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# start.S loads the link base from _TEXT_BASE and the run base from
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# adr _start, so _start MUST equal __image_copy_start (a 4-byte
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# linker fill sneaks in when CONFIG_TEXT_BASE is not 8-aligned —
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# start.o's .text input section is 8-aligned — and then every
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# relocated pointer is skewed by 4). Fail loudly instead.
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copy_vma = None
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start_vma = None
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for line in open(sym_path):
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parts = line.split()
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if len(parts) >= 2 and parts[-1] == '__image_copy_start':
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copy_vma = int(parts[0], 16)
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elif len(parts) >= 2 and parts[-1] == '_start':
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start_vma = int(parts[0], 16)
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if copy_vma is None or start_vma is None:
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raise SystemExit('symbols not found in u-boot.sym')
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assert start_vma == copy_vma, \
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("_start 0x%x != __image_copy_start 0x%x: CONFIG_TEXT_BASE is not "
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"8-aligned and a linker fill shifted _start" %
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(start_vma, copy_vma))
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assert start_vma % 0x1000 == 0, \
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"link _start 0x%x not 4K-aligned" % start_vma
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start_file_off = start_vma - copy_vma
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wrap_off = 0x40
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uboot_off = 0x1000
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while (uboot_off + start_file_off) % 0x1000:
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uboot_off += 0x1000
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pad = uboot_off - wrap_off - wrap_len
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assert pad >= 0
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total = uboot_off + len(uboot)
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assert (0x40000000 + uboot_off + start_file_off) % 0x1000 == 0
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hdr = bytearray(64)
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hdr[0:4] = struct.pack('<I', (0x40 >> 2) | 0x14000000) # code0: b +0x40
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struct.pack_into('<Q', hdr, 0x10, total) # image_size
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struct.pack_into('<Q', hdr, 0x18, 1 << 3) # flags: bit3
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hdr[0x38:0x3c] = b'ARM\x64' # magic
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# patch the wrapper's `b .` — searched, NOT assumed to be the last
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# instruction (v3 has the delay subroutine after it; patching blind
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# overwrites delay's `ret` and the first blink never returns).
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hits = [i for i in range(0, len(wrapper), 4)
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if struct.unpack_from('<I', wrapper, i)[0] == 0x14000000]
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assert len(hits) == 1, \
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"expected exactly one `b .` in wrapper, found %d" % len(hits)
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br_off = wrap_off + hits[0]
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imm = (uboot_off + start_file_off - br_off) // 4
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wrapper = bytearray(wrapper)
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wrapper[hits[0]:hits[0] + 4] = \
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struct.pack('<I', (imm & 0x03ffffff) | 0x14000000)
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with open(out, 'wb') as f:
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f.write(hdr)
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f.write(wrapper)
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f.write(bytes(pad))
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f.write(uboot)
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print("layout: header 64, wrapper %d (0x40..0x%x), uboot %d @0x%x, "
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"total %d, runtime _start 0x%x" %
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(wrap_len, uboot_off, len(uboot), uboot_off, total,
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0x40000000 + uboot_off + start_file_off))
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EOF
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# 3. pack + verify
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PYTHONPATH=/root/krane-fb-stub/src/depthcharge-tools python3 -m depthcharge_tools.mkdepthcharge \
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-A arm64 \
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-o "$OUT_PAYLOAD" \
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-n "krane u-boot framebuffer console" \
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-d "$WRAP_IMG" \
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-b "$DTB"
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echo "---- verify ----"
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futility vbutil_kernel --verify "$OUT_PAYLOAD"
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sha256sum "$OUT_PAYLOAD"
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