add circuitpython code

1 files changed, 1086 insertions, 0 deletions

diff --git a/circuitpython/tools/mpy_ld.py b/circuitpython/tools/mpy_ld.py
new file mode 100755
index 0000000..54df98e
--- /dev/null
+++ b/circuitpython/tools/mpy_ld.py
@@ -0,0 +1,1086 @@
+#!/usr/bin/env python3
+#
+# This file is part of the MicroPython project, http://micropython.org/
+#
+# The MIT License (MIT)
+#
+# Copyright (c) 2019 Damien P. George
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+"""
+Link .o files to .mpy
+"""
+
+import sys, os, struct, re
+from elftools.elf import elffile
+
+sys.path.append(os.path.dirname(__file__) + "/../py")
+import makeqstrdata as qstrutil
+
+# MicroPython constants
+MPY_VERSION = 5
+MP_NATIVE_ARCH_X86 = 1
+MP_NATIVE_ARCH_X64 = 2
+MP_NATIVE_ARCH_ARMV7M = 5
+MP_NATIVE_ARCH_ARMV7EMSP = 7
+MP_NATIVE_ARCH_ARMV7EMDP = 8
+MP_NATIVE_ARCH_XTENSA = 9
+MP_NATIVE_ARCH_XTENSAWIN = 10
+MP_CODE_BYTECODE = 2
+MP_CODE_NATIVE_VIPER = 4
+MP_SCOPE_FLAG_VIPERRELOC = 0x20
+MP_SCOPE_FLAG_VIPERRODATA = 0x40
+MP_SCOPE_FLAG_VIPERBSS = 0x80
+MICROPY_PY_BUILTINS_STR_UNICODE = 2
+MP_SMALL_INT_BITS = 31
+QSTR_WINDOW_SIZE = 32
+
+# ELF constants
+R_386_32 = 1
+R_X86_64_64 = 1
+R_XTENSA_32 = 1
+R_386_PC32 = 2
+R_X86_64_PC32 = 2
+R_ARM_ABS32 = 2
+R_386_GOT32 = 3
+R_ARM_REL32 = 3
+R_386_PLT32 = 4
+R_X86_64_PLT32 = 4
+R_XTENSA_PLT = 6
+R_386_GOTOFF = 9
+R_386_GOTPC = 10
+R_ARM_THM_CALL = 10
+R_XTENSA_DIFF32 = 19
+R_XTENSA_SLOT0_OP = 20
+R_ARM_BASE_PREL = 25  # aka R_ARM_GOTPC
+R_ARM_GOT_BREL = 26  # aka R_ARM_GOT32
+R_ARM_THM_JUMP24 = 30
+R_X86_64_GOTPCREL = 9
+R_X86_64_REX_GOTPCRELX = 42
+R_386_GOT32X = 43
+
+################################################################################
+# Architecture configuration
+
+
+def asm_jump_x86(entry):
+    return struct.pack("<BI", 0xE9, entry - 5)
+
+
+def asm_jump_arm(entry):
+    b_off = entry - 4
+    if b_off >> 11 == 0 or b_off >> 11 == -1:
+        # Signed value fits in 12 bits
+        b0 = 0xE000 | (b_off >> 1 & 0x07FF)
+        b1 = 0
+    else:
+        # Use large jump
+        b0 = 0xF000 | (b_off >> 12 & 0x07FF)
+        b1 = 0xB800 | (b_off >> 1 & 0x7FF)
+    return struct.pack("<HH", b0, b1)
+
+
+def asm_jump_xtensa(entry):
+    jump_offset = entry - 4
+    jump_op = jump_offset << 6 | 6
+    return struct.pack("<BH", jump_op & 0xFF, jump_op >> 8)
+
+
+class ArchData:
+    def __init__(self, name, mpy_feature, qstr_entry_size, word_size, arch_got, asm_jump):
+        self.name = name
+        self.mpy_feature = mpy_feature
+        self.qstr_entry_size = qstr_entry_size
+        self.word_size = word_size
+        self.arch_got = arch_got
+        self.asm_jump = asm_jump
+        self.separate_rodata = name == "EM_XTENSA" and qstr_entry_size == 4
+
+
+ARCH_DATA = {
+    "x86": ArchData(
+        "EM_386",
+        MP_NATIVE_ARCH_X86 << 2 | MICROPY_PY_BUILTINS_STR_UNICODE,
+        2,
+        4,
+        (R_386_PC32, R_386_GOT32, R_386_GOT32X),
+        asm_jump_x86,
+    ),
+    "x64": ArchData(
+        "EM_X86_64",
+        MP_NATIVE_ARCH_X64 << 2 | MICROPY_PY_BUILTINS_STR_UNICODE,
+        2,
+        8,
+        (R_X86_64_GOTPCREL, R_X86_64_REX_GOTPCRELX),
+        asm_jump_x86,
+    ),
+    "armv7m": ArchData(
+        "EM_ARM",
+        MP_NATIVE_ARCH_ARMV7M << 2 | MICROPY_PY_BUILTINS_STR_UNICODE,
+        2,
+        4,
+        (R_ARM_GOT_BREL,),
+        asm_jump_arm,
+    ),
+    "armv7emsp": ArchData(
+        "EM_ARM",
+        MP_NATIVE_ARCH_ARMV7EMSP << 2 | MICROPY_PY_BUILTINS_STR_UNICODE,
+        2,
+        4,
+        (R_ARM_GOT_BREL,),
+        asm_jump_arm,
+    ),
+    "armv7emdp": ArchData(
+        "EM_ARM",
+        MP_NATIVE_ARCH_ARMV7EMDP << 2 | MICROPY_PY_BUILTINS_STR_UNICODE,
+        2,
+        4,
+        (R_ARM_GOT_BREL,),
+        asm_jump_arm,
+    ),
+    "xtensa": ArchData(
+        "EM_XTENSA",
+        MP_NATIVE_ARCH_XTENSA << 2 | MICROPY_PY_BUILTINS_STR_UNICODE,
+        2,
+        4,
+        (R_XTENSA_32, R_XTENSA_PLT),
+        asm_jump_xtensa,
+    ),
+    "xtensawin": ArchData(
+        "EM_XTENSA",
+        MP_NATIVE_ARCH_XTENSAWIN << 2 | MICROPY_PY_BUILTINS_STR_UNICODE,
+        4,
+        4,
+        (R_XTENSA_32, R_XTENSA_PLT),
+        asm_jump_xtensa,
+    ),
+}
+
+################################################################################
+# Helper functions
+
+
+def align_to(value, align):
+    return (value + align - 1) & ~(align - 1)
+
+
+def unpack_u24le(data, offset):
+    return data[offset] | data[offset + 1] << 8 | data[offset + 2] << 16
+
+
+def pack_u24le(data, offset, value):
+    data[offset] = value & 0xFF
+    data[offset + 1] = value >> 8 & 0xFF
+    data[offset + 2] = value >> 16 & 0xFF
+
+
+def xxd(text):
+    for i in range(0, len(text), 16):
+        print("{:08x}:".format(i), end="")
+        for j in range(4):
+            off = i + j * 4
+            if off < len(text):
+                d = int.from_bytes(text[off : off + 4], "little")
+                print(" {:08x}".format(d), end="")
+        print()
+
+
+# Smaller numbers are enabled first
+LOG_LEVEL_1 = 1
+LOG_LEVEL_2 = 2
+LOG_LEVEL_3 = 3
+log_level = LOG_LEVEL_1
+
+
+def log(level, msg):
+    if level <= log_level:
+        print(msg)
+
+
+################################################################################
+# Qstr extraction
+
+
+def extract_qstrs(source_files):
+    def read_qstrs(f):
+        with open(f) as f:
+            vals = set()
+            objs = set()
+            for line in f:
+                while line:
+                    m = re.search(r"MP_OBJ_NEW_QSTR\((MP_QSTR_[A-Za-z0-9_]*)\)", line)
+                    if m:
+                        objs.add(m.group(1))
+                    else:
+                        m = re.search(r"MP_QSTR_[A-Za-z0-9_]*", line)
+                        if m:
+                            vals.add(m.group())
+                    if m:
+                        s = m.span()
+                        line = line[: s[0]] + line[s[1] :]
+                    else:
+                        line = ""
+            return vals, objs
+
+    static_qstrs = ["MP_QSTR_" + qstrutil.qstr_escape(q) for q in qstrutil.static_qstr_list]
+
+    qstr_vals = set()
+    qstr_objs = set()
+    for f in source_files:
+        vals, objs = read_qstrs(f)
+        qstr_vals.update(vals)
+        qstr_objs.update(objs)
+    qstr_vals.difference_update(static_qstrs)
+
+    return static_qstrs, qstr_vals, qstr_objs
+
+
+################################################################################
+# Linker
+
+
+class LinkError(Exception):
+    pass
+
+
+class Section:
+    def __init__(self, name, data, alignment, filename=None):
+        self.filename = filename
+        self.name = name
+        self.data = data
+        self.alignment = alignment
+        self.addr = 0
+        self.reloc = []
+
+    @staticmethod
+    def from_elfsec(elfsec, filename):
+        assert elfsec.header.sh_addr == 0
+        return Section(elfsec.name, elfsec.data(), elfsec.data_alignment, filename)
+
+
+class GOTEntry:
+    def __init__(self, name, sym, link_addr=0):
+        self.name = name
+        self.sym = sym
+        self.offset = None
+        self.link_addr = link_addr
+
+    def isexternal(self):
+        return self.sec_name.startswith(".external")
+
+    def istext(self):
+        return self.sec_name.startswith(".text")
+
+    def isrodata(self):
+        return self.sec_name.startswith((".rodata", ".data.rel.ro"))
+
+    def isbss(self):
+        return self.sec_name.startswith(".bss")
+
+
+class LiteralEntry:
+    def __init__(self, value, offset):
+        self.value = value
+        self.offset = offset
+
+
+class LinkEnv:
+    def __init__(self, arch):
+        self.arch = ARCH_DATA[arch]
+        self.sections = []  # list of sections in order of output
+        self.literal_sections = []  # list of literal sections (xtensa only)
+        self.known_syms = {}  # dict of symbols that are defined
+        self.unresolved_syms = []  # list of unresolved symbols
+        self.mpy_relocs = []  # list of relocations needed in the output .mpy file
+
+    def check_arch(self, arch_name):
+        if arch_name != self.arch.name:
+            raise LinkError("incompatible arch")
+
+    def print_sections(self):
+        log(LOG_LEVEL_2, "sections:")
+        for sec in self.sections:
+            log(LOG_LEVEL_2, "  {:08x} {} size={}".format(sec.addr, sec.name, len(sec.data)))
+
+    def find_addr(self, name):
+        if name in self.known_syms:
+            s = self.known_syms[name]
+            return s.section.addr + s["st_value"]
+        raise LinkError("unknown symbol: {}".format(name))
+
+
+def build_got_generic(env):
+    env.got_entries = {}
+    for sec in env.sections:
+        for r in sec.reloc:
+            s = r.sym
+            if not (
+                s.entry["st_info"]["bind"] == "STB_GLOBAL"
+                and r["r_info_type"] in env.arch.arch_got
+            ):
+                continue
+            s_type = s.entry["st_info"]["type"]
+            assert s_type in ("STT_NOTYPE", "STT_FUNC", "STT_OBJECT"), s_type
+            assert s.name
+            if s.name in env.got_entries:
+                continue
+            env.got_entries[s.name] = GOTEntry(s.name, s)
+
+
+def build_got_xtensa(env):
+    env.got_entries = {}
+    env.lit_entries = {}
+    env.xt_literals = {}
+
+    # Extract the values from the literal table
+    for sec in env.literal_sections:
+        assert len(sec.data) % env.arch.word_size == 0
+
+        # Look through literal relocations to find any global pointers that should be GOT entries
+        for r in sec.reloc:
+            s = r.sym
+            s_type = s.entry["st_info"]["type"]
+            assert s_type in ("STT_NOTYPE", "STT_FUNC", "STT_OBJECT", "STT_SECTION"), s_type
+            assert r["r_info_type"] in env.arch.arch_got
+            assert r["r_offset"] % env.arch.word_size == 0
+            # This entry is a global pointer
+            existing = struct.unpack_from("<I", sec.data, r["r_offset"])[0]
+            if s_type == "STT_SECTION":
+                assert r["r_addend"] == 0
+                name = "{}+0x{:x}".format(s.section.name, existing)
+            else:
+                assert existing == 0
+                name = s.name
+                if r["r_addend"] != 0:
+                    name = "{}+0x{:x}".format(name, r["r_addend"])
+            idx = "{}+0x{:x}".format(sec.filename, r["r_offset"])
+            env.xt_literals[idx] = name
+            if name in env.got_entries:
+                # Deduplicate GOT entries
+                continue
+            env.got_entries[name] = GOTEntry(name, s, existing)
+
+        # Go through all literal entries finding those that aren't global pointers so must be actual literals
+        for i in range(0, len(sec.data), env.arch.word_size):
+            idx = "{}+0x{:x}".format(sec.filename, i)
+            if idx not in env.xt_literals:
+                # This entry is an actual literal
+                value = struct.unpack_from("<I", sec.data, i)[0]
+                env.xt_literals[idx] = value
+                if value in env.lit_entries:
+                    # Deduplicate literals
+                    continue
+                env.lit_entries[value] = LiteralEntry(
+                    value, len(env.lit_entries) * env.arch.word_size
+                )
+
+
+def populate_got(env):
+    # Compute GOT destination addresses
+    for got_entry in env.got_entries.values():
+        sym = got_entry.sym
+        if hasattr(sym, "resolved"):
+            sym = sym.resolved
+        sec = sym.section
+        addr = sym["st_value"]
+        got_entry.sec_name = sec.name
+        got_entry.link_addr += sec.addr + addr
+
+    # Get sorted GOT, sorted by external, text, rodata, bss so relocations can be combined
+    got_list = sorted(
+        env.got_entries.values(),
+        key=lambda g: g.isexternal() + 2 * g.istext() + 3 * g.isrodata() + 4 * g.isbss(),
+    )
+
+    # Layout and populate the GOT
+    offset = 0
+    for got_entry in got_list:
+        got_entry.offset = offset
+        offset += env.arch.word_size
+        o = env.got_section.addr + got_entry.offset
+        env.full_text[o : o + env.arch.word_size] = got_entry.link_addr.to_bytes(
+            env.arch.word_size, "little"
+        )
+
+    # Create a relocation for each GOT entry
+    for got_entry in got_list:
+        if got_entry.name == "mp_fun_table":
+            dest = "mp_fun_table"
+        elif got_entry.name.startswith("mp_fun_table+0x"):
+            dest = int(got_entry.name.split("+")[1], 16) // env.arch.word_size
+        elif got_entry.sec_name.startswith(".text"):
+            dest = ".text"
+        elif got_entry.sec_name.startswith(".rodata"):
+            dest = ".rodata"
+        elif got_entry.sec_name.startswith(".data.rel.ro"):
+            dest = ".data.rel.ro"
+        elif got_entry.sec_name.startswith(".bss"):
+            dest = ".bss"
+        else:
+            assert 0, (got_entry.name, got_entry.sec_name)
+        env.mpy_relocs.append((".text", env.got_section.addr + got_entry.offset, dest))
+
+    # Print out the final GOT
+    log(LOG_LEVEL_2, "GOT: {:08x}".format(env.got_section.addr))
+    for g in got_list:
+        log(
+            LOG_LEVEL_2,
+            "  {:08x} {} -> {}+{:08x}".format(g.offset, g.name, g.sec_name, g.link_addr),
+        )
+
+
+def populate_lit(env):
+    log(LOG_LEVEL_2, "LIT: {:08x}".format(env.lit_section.addr))
+    for lit_entry in env.lit_entries.values():
+        value = lit_entry.value
+        log(LOG_LEVEL_2, "  {:08x} = {:08x}".format(lit_entry.offset, value))
+        o = env.lit_section.addr + lit_entry.offset
+        env.full_text[o : o + env.arch.word_size] = value.to_bytes(env.arch.word_size, "little")
+
+
+def do_relocation_text(env, text_addr, r):
+    # Extract relevant info about symbol that's being relocated
+    s = r.sym
+    s_bind = s.entry["st_info"]["bind"]
+    s_shndx = s.entry["st_shndx"]
+    s_type = s.entry["st_info"]["type"]
+    r_offset = r["r_offset"] + text_addr
+    r_info_type = r["r_info_type"]
+    try:
+        # only for RELA sections
+        r_addend = r["r_addend"]
+    except KeyError:
+        r_addend = 0
+
+    # Default relocation type and name for logging
+    reloc_type = "le32"
+    log_name = None
+
+    if (
+        env.arch.name == "EM_386"
+        and r_info_type in (R_386_PC32, R_386_PLT32)
+        or env.arch.name == "EM_X86_64"
+        and r_info_type in (R_X86_64_PC32, R_X86_64_PLT32)
+        or env.arch.name == "EM_ARM"
+        and r_info_type in (R_ARM_REL32, R_ARM_THM_CALL, R_ARM_THM_JUMP24)
+        or s_bind == "STB_LOCAL"
+        and env.arch.name == "EM_XTENSA"
+        and r_info_type == R_XTENSA_32  # not GOT
+    ):
+        # Standard relocation to fixed location within text/rodata
+        if hasattr(s, "resolved"):
+            s = s.resolved
+
+        sec = s.section
+
+        if env.arch.separate_rodata and sec.name.startswith(".rodata"):
+            raise LinkError("fixed relocation to rodata with rodata referenced via GOT")
+
+        if sec.name.startswith(".bss"):
+            raise LinkError(
+                "{}: fixed relocation to bss (bss variables can't be static)".format(s.filename)
+            )
+
+        if sec.name.startswith(".external"):
+            raise LinkError(
+                "{}: fixed relocation to external symbol: {}".format(s.filename, s.name)
+            )
+
+        addr = sec.addr + s["st_value"]
+        reloc = addr - r_offset + r_addend
+
+        if r_info_type in (R_ARM_THM_CALL, R_ARM_THM_JUMP24):
+            # Both relocations have the same bit pattern to rewrite:
+            #   R_ARM_THM_CALL: bl
+            #   R_ARM_THM_JUMP24: b.w
+            reloc_type = "thumb_b"
+
+    elif (
+        env.arch.name == "EM_386"
+        and r_info_type == R_386_GOTPC
+        or env.arch.name == "EM_ARM"
+        and r_info_type == R_ARM_BASE_PREL
+    ):
+        # Relocation to GOT address itself
+        assert s.name == "_GLOBAL_OFFSET_TABLE_"
+        addr = env.got_section.addr
+        reloc = addr - r_offset + r_addend
+
+    elif (
+        env.arch.name == "EM_386"
+        and r_info_type in (R_386_GOT32, R_386_GOT32X)
+        or env.arch.name == "EM_ARM"
+        and r_info_type == R_ARM_GOT_BREL
+    ):
+        # Relcation pointing to GOT
+        reloc = addr = env.got_entries[s.name].offset
+
+    elif env.arch.name == "EM_X86_64" and r_info_type in (
+        R_X86_64_GOTPCREL,
+        R_X86_64_REX_GOTPCRELX,
+    ):
+        # Relcation pointing to GOT
+        got_entry = env.got_entries[s.name]
+        addr = env.got_section.addr + got_entry.offset
+        reloc = addr - r_offset + r_addend
+
+    elif env.arch.name == "EM_386" and r_info_type == R_386_GOTOFF:
+        # Relocation relative to GOT
+        addr = s.section.addr + s["st_value"]
+        reloc = addr - env.got_section.addr + r_addend
+
+    elif env.arch.name == "EM_XTENSA" and r_info_type == R_XTENSA_SLOT0_OP:
+        # Relocation pointing to GOT, xtensa specific
+        sec = s.section
+        if sec.name.startswith(".text"):
+            # it looks like R_XTENSA_SLOT0_OP into .text is already correctly relocated
+            return
+        assert sec.name.startswith(".literal"), sec.name
+        lit_idx = "{}+0x{:x}".format(sec.filename, r_addend)
+        lit_ptr = env.xt_literals[lit_idx]
+        if isinstance(lit_ptr, str):
+            addr = env.got_section.addr + env.got_entries[lit_ptr].offset
+            log_name = "GOT {}".format(lit_ptr)
+        else:
+            addr = env.lit_section.addr + env.lit_entries[lit_ptr].offset
+            log_name = "LIT"
+        reloc = addr - r_offset
+        reloc_type = "xtensa_l32r"
+
+    elif env.arch.name == "EM_XTENSA" and r_info_type == R_XTENSA_DIFF32:
+        if s.section.name.startswith(".text"):
+            # it looks like R_XTENSA_DIFF32 into .text is already correctly relocated
+            return
+        assert 0
+
+    else:
+        # Unknown/unsupported relocation
+        assert 0, r_info_type
+
+    # Write relocation
+    if reloc_type == "le32":
+        (existing,) = struct.unpack_from("<I", env.full_text, r_offset)
+        struct.pack_into("<I", env.full_text, r_offset, (existing + reloc) & 0xFFFFFFFF)
+    elif reloc_type == "thumb_b":
+        b_h, b_l = struct.unpack_from("<HH", env.full_text, r_offset)
+        existing = (b_h & 0x7FF) << 12 | (b_l & 0x7FF) << 1
+        if existing >= 0x400000:  # 2's complement
+            existing -= 0x800000
+        new = existing + reloc
+        b_h = (b_h & 0xF800) | (new >> 12) & 0x7FF
+        b_l = (b_l & 0xF800) | (new >> 1) & 0x7FF
+        struct.pack_into("<HH", env.full_text, r_offset, b_h, b_l)
+    elif reloc_type == "xtensa_l32r":
+        l32r = unpack_u24le(env.full_text, r_offset)
+        assert l32r & 0xF == 1  # RI16 encoded l32r
+        l32r_imm16 = l32r >> 8
+        l32r_imm16 = (l32r_imm16 + reloc >> 2) & 0xFFFF
+        l32r = l32r & 0xFF | l32r_imm16 << 8
+        pack_u24le(env.full_text, r_offset, l32r)
+    else:
+        assert 0, reloc_type
+
+    # Log information about relocation
+    if log_name is None:
+        if s_type == "STT_SECTION":
+            log_name = s.section.name
+        else:
+            log_name = s.name
+    log(LOG_LEVEL_3, "  {:08x} {} -> {:08x}".format(r_offset, log_name, addr))
+
+
+def do_relocation_data(env, text_addr, r):
+    s = r.sym
+    s_type = s.entry["st_info"]["type"]
+    r_offset = r["r_offset"] + text_addr
+    r_info_type = r["r_info_type"]
+    try:
+        # only for RELA sections
+        r_addend = r["r_addend"]
+    except KeyError:
+        r_addend = 0
+
+    if (
+        env.arch.name == "EM_386"
+        and r_info_type == R_386_32
+        or env.arch.name == "EM_X86_64"
+        and r_info_type == R_X86_64_64
+        or env.arch.name == "EM_ARM"
+        and r_info_type == R_ARM_ABS32
+        or env.arch.name == "EM_XTENSA"
+        and r_info_type == R_XTENSA_32
+    ):
+        # Relocation in data.rel.ro to internal/external symbol
+        if env.arch.word_size == 4:
+            struct_type = "<I"
+        elif env.arch.word_size == 8:
+            struct_type = "<Q"
+        sec = s.section
+        assert r_offset % env.arch.word_size == 0
+        addr = sec.addr + s["st_value"] + r_addend
+        if s_type == "STT_SECTION":
+            log_name = sec.name
+        else:
+            log_name = s.name
+        log(LOG_LEVEL_3, "  {:08x} -> {} {:08x}".format(r_offset, log_name, addr))
+        if env.arch.separate_rodata:
+            data = env.full_rodata
+        else:
+            data = env.full_text
+        (existing,) = struct.unpack_from(struct_type, data, r_offset)
+        if sec.name.startswith((".text", ".rodata", ".data.rel.ro", ".bss")):
+            struct.pack_into(struct_type, data, r_offset, existing + addr)
+            kind = sec.name
+        elif sec.name == ".external.mp_fun_table":
+            assert addr == 0
+            kind = s.mp_fun_table_offset
+        else:
+            assert 0, sec.name
+        if env.arch.separate_rodata:
+            base = ".rodata"
+        else:
+            base = ".text"
+        env.mpy_relocs.append((base, r_offset, kind))
+
+    else:
+        # Unknown/unsupported relocation
+        assert 0, r_info_type
+
+
+def load_object_file(env, felf):
+    with open(felf, "rb") as f:
+        elf = elffile.ELFFile(f)
+        env.check_arch(elf["e_machine"])
+
+        # Get symbol table
+        symtab = list(elf.get_section_by_name(".symtab").iter_symbols())
+
+        # Load needed sections from ELF file
+        sections_shndx = {}  # maps elf shndx to Section object
+        for idx, s in enumerate(elf.iter_sections()):
+            if s.header.sh_type in ("SHT_PROGBITS", "SHT_NOBITS"):
+                if s.data_size == 0:
+                    # Ignore empty sections
+                    pass
+                elif s.name.startswith((".literal", ".text", ".rodata", ".data.rel.ro", ".bss")):
+                    sec = Section.from_elfsec(s, felf)
+                    sections_shndx[idx] = sec
+                    if s.name.startswith(".literal"):
+                        env.literal_sections.append(sec)
+                    else:
+                        env.sections.append(sec)
+                elif s.name.startswith(".data"):
+                    raise LinkError("{}: {} non-empty".format(felf, s.name))
+                else:
+                    # Ignore section
+                    pass
+            elif s.header.sh_type in ("SHT_REL", "SHT_RELA"):
+                shndx = s.header.sh_info
+                if shndx in sections_shndx:
+                    sec = sections_shndx[shndx]
+                    sec.reloc_name = s.name
+                    sec.reloc = list(s.iter_relocations())
+                    for r in sec.reloc:
+                        r.sym = symtab[r["r_info_sym"]]
+
+        # Link symbols to their sections, and update known and unresolved symbols
+        for sym in symtab:
+            sym.filename = felf
+            shndx = sym.entry["st_shndx"]
+            if shndx in sections_shndx:
+                # Symbol with associated section
+                sym.section = sections_shndx[shndx]
+                if sym["st_info"]["bind"] == "STB_GLOBAL":
+                    # Defined global symbol
+                    if sym.name in env.known_syms and not sym.name.startswith(
+                        "__x86.get_pc_thunk."
+                    ):
+                        raise LinkError("duplicate symbol: {}".format(sym.name))
+                    env.known_syms[sym.name] = sym
+            elif sym.entry["st_shndx"] == "SHN_UNDEF" and sym["st_info"]["bind"] == "STB_GLOBAL":
+                # Undefined global symbol, needs resolving
+                env.unresolved_syms.append(sym)
+
+
+def link_objects(env, native_qstr_vals_len, native_qstr_objs_len):
+    # Build GOT information
+    if env.arch.name == "EM_XTENSA":
+        build_got_xtensa(env)
+    else:
+        build_got_generic(env)
+
+    # Creat GOT section
+    got_size = len(env.got_entries) * env.arch.word_size
+    env.got_section = Section("GOT", bytearray(got_size), env.arch.word_size)
+    if env.arch.name == "EM_XTENSA":
+        env.sections.insert(0, env.got_section)
+    else:
+        env.sections.append(env.got_section)
+
+    # Create optional literal section
+    if env.arch.name == "EM_XTENSA":
+        lit_size = len(env.lit_entries) * env.arch.word_size
+        env.lit_section = Section("LIT", bytearray(lit_size), env.arch.word_size)
+        env.sections.insert(1, env.lit_section)
+
+    # Create section to contain mp_native_qstr_val_table
+    env.qstr_val_section = Section(
+        ".text.QSTR_VAL",
+        bytearray(native_qstr_vals_len * env.arch.qstr_entry_size),
+        env.arch.qstr_entry_size,
+    )
+    env.sections.append(env.qstr_val_section)
+
+    # Create section to contain mp_native_qstr_obj_table
+    env.qstr_obj_section = Section(
+        ".text.QSTR_OBJ", bytearray(native_qstr_objs_len * env.arch.word_size), env.arch.word_size
+    )
+    env.sections.append(env.qstr_obj_section)
+
+    # Resolve unknown symbols
+    mp_fun_table_sec = Section(".external.mp_fun_table", b"", 0)
+    fun_table = {
+        key: 68 + idx
+        for idx, key in enumerate(
+            [
+                "mp_type_type",
+                "mp_type_str",
+                "mp_type_list",
+                "mp_type_dict",
+                "mp_type_fun_builtin_0",
+                "mp_type_fun_builtin_1",
+                "mp_type_fun_builtin_2",
+                "mp_type_fun_builtin_3",
+                "mp_type_fun_builtin_var",
+                "mp_stream_read_obj",
+                "mp_stream_readinto_obj",
+                "mp_stream_unbuffered_readline_obj",
+                "mp_stream_write_obj",
+            ]
+        )
+    }
+    for sym in env.unresolved_syms:
+        assert sym["st_value"] == 0
+        if sym.name == "_GLOBAL_OFFSET_TABLE_":
+            pass
+        elif sym.name == "mp_fun_table":
+            sym.section = Section(".external", b"", 0)
+        elif sym.name == "mp_native_qstr_val_table":
+            sym.section = env.qstr_val_section
+        elif sym.name == "mp_native_qstr_obj_table":
+            sym.section = env.qstr_obj_section
+        elif sym.name in env.known_syms:
+            sym.resolved = env.known_syms[sym.name]
+        else:
+            if sym.name in fun_table:
+                sym.section = mp_fun_table_sec
+                sym.mp_fun_table_offset = fun_table[sym.name]
+            else:
+                raise LinkError("{}: undefined symbol: {}".format(sym.filename, sym.name))
+
+    # Align sections, assign their addresses, and create full_text
+    env.full_text = bytearray(env.arch.asm_jump(8))  # dummy, to be filled in later
+    env.full_rodata = bytearray(0)
+    env.full_bss = bytearray(0)
+    for sec in env.sections:
+        if env.arch.separate_rodata and sec.name.startswith((".rodata", ".data.rel.ro")):
+            data = env.full_rodata
+        elif sec.name.startswith(".bss"):
+            data = env.full_bss
+        else:
+            data = env.full_text
+        sec.addr = align_to(len(data), sec.alignment)
+        data.extend(b"\x00" * (sec.addr - len(data)))
+        data.extend(sec.data)
+
+    env.print_sections()
+
+    populate_got(env)
+    if env.arch.name == "EM_XTENSA":
+        populate_lit(env)
+
+    # Fill in relocations
+    for sec in env.sections:
+        if not sec.reloc:
+            continue
+        log(
+            LOG_LEVEL_3,
+            "{}: {} relocations via {}:".format(sec.filename, sec.name, sec.reloc_name),
+        )
+        for r in sec.reloc:
+            if sec.name.startswith((".text", ".rodata")):
+                do_relocation_text(env, sec.addr, r)
+            elif sec.name.startswith(".data.rel.ro"):
+                do_relocation_data(env, sec.addr, r)
+            else:
+                assert 0, sec.name
+
+
+################################################################################
+# .mpy output
+
+
+class MPYOutput:
+    def open(self, fname):
+        self.f = open(fname, "wb")
+        self.prev_base = -1
+        self.prev_offset = -1
+
+    def close(self):
+        self.f.close()
+
+    def write_bytes(self, buf):
+        self.f.write(buf)
+
+    def write_uint(self, val):
+        b = bytearray()
+        b.insert(0, val & 0x7F)
+        val >>= 7
+        while val:
+            b.insert(0, 0x80 | (val & 0x7F))
+            val >>= 7
+        self.write_bytes(b)
+
+    def write_qstr(self, s):
+        if s in qstrutil.static_qstr_list:
+            self.write_bytes(bytes([0, qstrutil.static_qstr_list.index(s) + 1]))
+        else:
+            s = bytes(s, "ascii")
+            self.write_uint(len(s) << 1)
+            self.write_bytes(s)
+
+    def write_reloc(self, base, offset, dest, n):
+        need_offset = not (base == self.prev_base and offset == self.prev_offset + 1)
+        self.prev_offset = offset + n - 1
+        if dest <= 2:
+            dest = (dest << 1) | (n > 1)
+        else:
+            assert 6 <= dest <= 127
+            assert n == 1
+        dest = dest << 1 | need_offset
+        assert 0 <= dest <= 0xFE, dest
+        self.write_bytes(bytes([dest]))
+        if need_offset:
+            if base == ".text":
+                base = 0
+            elif base == ".rodata":
+                base = 1
+            self.write_uint(offset << 1 | base)
+        if n > 1:
+            self.write_uint(n)
+
+
+def build_mpy(env, entry_offset, fmpy, native_qstr_vals, native_qstr_objs):
+    # Write jump instruction to start of text
+    jump = env.arch.asm_jump(entry_offset)
+    env.full_text[: len(jump)] = jump
+
+    log(LOG_LEVEL_1, "arch:         {}".format(env.arch.name))
+    log(LOG_LEVEL_1, "text size:    {}".format(len(env.full_text)))
+    if len(env.full_rodata):
+        log(LOG_LEVEL_1, "rodata size:  {}".format(len(env.full_rodata)))
+    log(LOG_LEVEL_1, "bss size:     {}".format(len(env.full_bss)))
+    log(LOG_LEVEL_1, "GOT entries:  {}".format(len(env.got_entries)))
+
+    # xxd(env.full_text)
+
+    out = MPYOutput()
+    out.open(fmpy)
+
+    # MPY: header
+    out.write_bytes(
+        bytearray(
+            [
+                ord("C"),
+                MPY_VERSION,
+                env.arch.mpy_feature,
+                MP_SMALL_INT_BITS,
+                QSTR_WINDOW_SIZE,
+            ]
+        )
+    )
+
+    # MPY: kind/len
+    out.write_uint(len(env.full_text) << 2 | (MP_CODE_NATIVE_VIPER - MP_CODE_BYTECODE))
+
+    # MPY: machine code
+    out.write_bytes(env.full_text)
+
+    # MPY: n_qstr_link (assumes little endian)
+    out.write_uint(len(native_qstr_vals) + len(native_qstr_objs))
+    for q in range(len(native_qstr_vals)):
+        off = env.qstr_val_section.addr + q * env.arch.qstr_entry_size
+        out.write_uint(off << 2)
+        out.write_qstr(native_qstr_vals[q])
+    for q in range(len(native_qstr_objs)):
+        off = env.qstr_obj_section.addr + q * env.arch.word_size
+        out.write_uint(off << 2 | 3)
+        out.write_qstr(native_qstr_objs[q])
+
+    # MPY: scope_flags
+    scope_flags = MP_SCOPE_FLAG_VIPERRELOC
+    if len(env.full_rodata):
+        scope_flags |= MP_SCOPE_FLAG_VIPERRODATA
+    if len(env.full_bss):
+        scope_flags |= MP_SCOPE_FLAG_VIPERBSS
+    out.write_uint(scope_flags)
+
+    # MPY: n_obj
+    out.write_uint(0)
+
+    # MPY: n_raw_code
+    out.write_uint(0)
+
+    # MPY: rodata and/or bss
+    if len(env.full_rodata):
+        rodata_const_table_idx = 1
+        out.write_uint(len(env.full_rodata))
+        out.write_bytes(env.full_rodata)
+    if len(env.full_bss):
+        bss_const_table_idx = bool(env.full_rodata) + 1
+        out.write_uint(len(env.full_bss))
+
+    # MPY: relocation information
+    prev_kind = None
+    for base, addr, kind in env.mpy_relocs:
+        if isinstance(kind, str) and kind.startswith(".text"):
+            kind = 0
+        elif kind in (".rodata", ".data.rel.ro"):
+            if env.arch.separate_rodata:
+                kind = rodata_const_table_idx
+            else:
+                kind = 0
+        elif isinstance(kind, str) and kind.startswith(".bss"):
+            kind = bss_const_table_idx
+        elif kind == "mp_fun_table":
+            kind = 6
+        else:
+            kind = 7 + kind
+        assert addr % env.arch.word_size == 0, addr
+        offset = addr // env.arch.word_size
+        if kind == prev_kind and base == prev_base and offset == prev_offset + 1:
+            prev_n += 1
+            prev_offset += 1
+        else:
+            if prev_kind is not None:
+                out.write_reloc(prev_base, prev_offset - prev_n + 1, prev_kind, prev_n)
+            prev_kind = kind
+            prev_base = base
+            prev_offset = offset
+            prev_n = 1
+    if prev_kind is not None:
+        out.write_reloc(prev_base, prev_offset - prev_n + 1, prev_kind, prev_n)
+
+    # MPY: sentinel for end of relocations
+    out.write_bytes(b"\xff")
+
+    out.close()
+
+
+################################################################################
+# main
+
+
+def do_preprocess(args):
+    if args.output is None:
+        assert args.files[0].endswith(".c")
+        args.output = args.files[0][:-1] + "config.h"
+    static_qstrs, qstr_vals, qstr_objs = extract_qstrs(args.files)
+    with open(args.output, "w") as f:
+        print(
+            "#include <stdint.h>\n"
+            "typedef uintptr_t mp_uint_t;\n"
+            "typedef intptr_t mp_int_t;\n"
+            "typedef uintptr_t mp_off_t;",
+            file=f,
+        )
+        for i, q in enumerate(static_qstrs):
+            print("#define %s (%u)" % (q, i + 1), file=f)
+        for i, q in enumerate(sorted(qstr_vals)):
+            print("#define %s (mp_native_qstr_val_table[%d])" % (q, i), file=f)
+        for i, q in enumerate(sorted(qstr_objs)):
+            print(
+                "#define MP_OBJ_NEW_QSTR_%s ((mp_obj_t)mp_native_qstr_obj_table[%d])" % (q, i),
+                file=f,
+            )
+        if args.arch == "xtensawin":
+            qstr_type = "uint32_t"  # esp32 can only read 32-bit values from IRAM
+        else:
+            qstr_type = "uint16_t"
+        print("extern const {} mp_native_qstr_val_table[];".format(qstr_type), file=f)
+        print("extern const mp_uint_t mp_native_qstr_obj_table[];", file=f)
+
+
+def do_link(args):
+    if args.output is None:
+        assert args.files[0].endswith(".o")
+        args.output = args.files[0][:-1] + "mpy"
+    native_qstr_vals = []
+    native_qstr_objs = []
+    if args.qstrs is not None:
+        with open(args.qstrs) as f:
+            for l in f:
+                m = re.match(r"#define MP_QSTR_([A-Za-z0-9_]*) \(mp_native_", l)
+                if m:
+                    native_qstr_vals.append(m.group(1))
+                else:
+                    m = re.match(r"#define MP_OBJ_NEW_QSTR_MP_QSTR_([A-Za-z0-9_]*)", l)
+                    if m:
+                        native_qstr_objs.append(m.group(1))
+    log(LOG_LEVEL_2, "qstr vals: " + ", ".join(native_qstr_vals))
+    log(LOG_LEVEL_2, "qstr objs: " + ", ".join(native_qstr_objs))
+    env = LinkEnv(args.arch)
+    try:
+        for file in args.files:
+            load_object_file(env, file)
+        link_objects(env, len(native_qstr_vals), len(native_qstr_objs))
+        build_mpy(env, env.find_addr("mpy_init"), args.output, native_qstr_vals, native_qstr_objs)
+    except LinkError as er:
+        print("LinkError:", er.args[0])
+        sys.exit(1)
+
+
+def main():
+    import argparse
+
+    cmd_parser = argparse.ArgumentParser(description="Run scripts on the pyboard.")
+    cmd_parser.add_argument(
+        "--verbose", "-v", action="count", default=1, help="increase verbosity"
+    )
+    cmd_parser.add_argument("--arch", default="x64", help="architecture")
+    cmd_parser.add_argument("--preprocess", action="store_true", help="preprocess source files")
+    cmd_parser.add_argument("--qstrs", default=None, help="file defining additional qstrs")
+    cmd_parser.add_argument(
+        "--output", "-o", default=None, help="output .mpy file (default to input with .o->.mpy)"
+    )
+    cmd_parser.add_argument("files", nargs="+", help="input files")
+    args = cmd_parser.parse_args()
+
+    global log_level
+    log_level = args.verbose
+
+    if args.preprocess:
+        do_preprocess(args)
+    else:
+        do_link(args)
+
+
+if __name__ == "__main__":
+    main()