From 181ed5cccd7222b8725b25c1879448e67e3ec4c3 Mon Sep 17 00:00:00 2001
From: Lephenixnoir <sebastien.michelland@protonmail.com>
Date: Wed, 5 Jun 2024 10:49:48 +0200
Subject: [PATCH] fxsdk: add ELF patch mechanism for HH2 to specify filename
 for stage-2

---
 fxsdk/cmake/GenerateHH2Bin.cmake    |  4 +-
 fxsdk/scripts/large_obj.py          |  3 +-
 fxsdk/scripts/patch_hh2_filename.py | 90 +++++++++++++++++++++++++++++
 3 files changed, 94 insertions(+), 3 deletions(-)
 create mode 100755 fxsdk/scripts/patch_hh2_filename.py

diff --git a/fxsdk/cmake/GenerateHH2Bin.cmake b/fxsdk/cmake/GenerateHH2Bin.cmake
index ae77af5..e5095e3 100644
--- a/fxsdk/cmake/GenerateHH2Bin.cmake
+++ b/fxsdk/cmake/GenerateHH2Bin.cmake
@@ -29,8 +29,8 @@ function(generate_hh2_bin)
 
   add_custom_command(
     TARGET "${HH2_TARGET}" POST_BUILD
+    COMMAND fxsdk script patch_hh2_filename.py ${HH2_TARGET} ${HH2_OUTPUT}
     COMMAND ${OBJCOPY} -O binary -R .bss -R .gint_bss ${HH2_TARGET} ${HH2_OUTPUT}
     WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
-    COMMAND_EXPAND_LISTS
-  )
+    COMMAND_EXPAND_LISTS)
 endfunction()
diff --git a/fxsdk/scripts/large_obj.py b/fxsdk/scripts/large_obj.py
index 1b6cca4..0b03d17 100755
--- a/fxsdk/scripts/large_obj.py
+++ b/fxsdk/scripts/large_obj.py
@@ -8,7 +8,8 @@ import elftools.elf.elffile
 
 if len(sys.argv) != 2 or "-h" in sys.argv or "--help" in sys.argv:
     print(f"usage: {sys.argv[0]} <FOLDER>", file=sys.stderr)
-    print("Prints sections of *.o/*.obj files in the folder, sorted by size")
+    print("Prints sections of *.o/*.obj files in the folder, sorted by size",
+        file=sys.stderr)
     sys.exit(1)
 
 files  = glob.glob(sys.argv[1] + "/**/*.o", recursive=True)
diff --git a/fxsdk/scripts/patch_hh2_filename.py b/fxsdk/scripts/patch_hh2_filename.py
new file mode 100755
index 0000000..c334517
--- /dev/null
+++ b/fxsdk/scripts/patch_hh2_filename.py
@@ -0,0 +1,90 @@
+#! /usr/bin/env python
+
+import subprocess
+import struct
+import sys
+import os
+import re
+
+eprint = lambda *args, **kwargs: print(*args, **kwargs, file=sys.stderr)
+def error(*args, **kwargs):
+    eprint("error:", *args, **kwargs)
+    sys.exit(1)
+
+if len(sys.argv) != 3:
+    eprint(f"usage: {sys.argv[0]} <ELF> <BIN>")
+    eprint("Patches filenames into HH2-targeted ELF files for stage-2 load")
+    sys.exit(1)
+
+# Check that the filename fits
+path = sys.argv[1]
+name = os.path.basename(sys.argv[2])
+encoded_name = bytes(name, "utf-8")
+if len(encoded_name) > 31:
+    error(f"output filename {name} is too long (max. 31 bytes)")
+
+# Run a command and return its stdout
+def cmd(command):
+    rc = subprocess.run(command, stdout=subprocess.PIPE, check=True)
+    return rc.stdout.decode("utf-8")
+
+# Get the list of addresses at which a symbol called "name" is defined
+def getsym(path, name):
+    # All syms as a list of (address, type, name)
+    syms = [l.split(" ") for l in cmd(["sh-elf-nm", path]).splitlines()]
+    return [int(t[0], 16) for t in syms if t[2] == name]
+
+# Get the section info for the section that contains address "addr"
+def getsection(path, addr):
+    RE_SECTION = re.compile(
+        r'^\s*\[\s*\d+\]\s*([\w._]+)\s+([A-Z]+)\s+([0-9a-fA-F]+)\s+([0-9a-fA-F]+)\s+([0-9a-fA-F]+)')
+    lines = cmd(["sh-elf-readelf", "-S", path]).splitlines()
+
+    # Parse sections from the output of readelf
+    sections = []
+    for l in lines:
+        m = RE_SECTION.match(l)
+        if m is None:
+            continue
+        sections.append((m[1], m[2], int(m[3], 16), int(m[4], 16), int(m[5], 16)))
+
+    # Find sections that contain the given address
+    matches = []
+    for name, kind, start, off, size in sections:
+        if kind == "PROGBITS" and start <= addr < start + size:
+            matches.append((name, off + (addr - start)))
+
+    return matches
+
+# Get the address of symbol .stage2_filename
+s = getsym(path, ".stage2_filename")
+if len(s) == 0:
+    error(f"no symbol .stage2_filename, is this built for fx-CP?")
+if len(s) > 1:
+    error(f"multiple ({len(s)}) symbols named .stage2_filename, what?")
+filename_address = s[0]
+
+s = getsection(path, filename_address)
+if len(s) == 0:
+    error(f".stage2_filename is not in any section?")
+if len(s) > 1:
+    error(f"overlapping sections ({', '.join(e[0] for e in s)}), excuse me?")
+if s[0][0] != ".hh2":
+    error("how is .stage2_filename not in the .hh2 section?")
+name_offset = s[0][1]
+
+# Load file contents
+with open(path, "rb+") as fp:
+    fp.seek(name_offset)
+    name_placeholder = struct.unpack(">8i", fp.read(32))
+    if name_placeholder != tuple(range(1, 8+1)):
+        error("name placeholder is wrong, check binary format and ELF parsing")
+
+    # Pad to 32 bytes
+    encoded_name += bytes(32 - len(encoded_name))
+    assert len(encoded_name) == 32
+
+    fp.seek(name_offset)
+    fp.write(encoded_name)
+
+sys.exit(0)