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b18: S7 exit router + dstub trap + docs

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SashegDev
2026-09-12 10:30:18 +00:00
parent 67539f7351
commit 049f98122b
6 changed files with 1097 additions and 50 deletions
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tools/sbl_uni.py
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#!/usr/bin/env python3
"""sbl_uni.py — быстрый harness SBL1 на Unicorn (без пересборки QEMU).
Карта RAM как в saimaa; ELF-сегменты; UARTDM/TF в stdout; MMIO->0.
Использование:
./tools/sbl_uni.py fw/img/patch/img0_b17.elf --thumb 0x802f63f [--regs r0=0x220000,...]
[--fill 0x085F0000:0x10000:0x08006831] [--poke 0xADDR=0xVAL] [--limit 1000000]
Печатает: выполнено инстр., последний PC, fault-адрес, UART.
"""
import struct
import sys
from unicorn import (Uc, UC_ARCH_ARM, UC_MODE_THUMB, UC_HOOK_MEM_UNMAPPED,
UC_HOOK_MEM_WRITE, UC_HOOK_CODE)
from unicorn.arm_const import (UC_ARM_REG_R0, UC_ARM_REG_R1, UC_ARM_REG_R2,
UC_ARM_REG_R3, UC_ARM_REG_R4, UC_ARM_REG_R5,
UC_ARM_REG_R6, UC_ARM_REG_R7, UC_ARM_REG_SP,
UC_ARM_REG_LR, UC_ARM_REG_PC,
UC_ARM_REG_CPSR)
_REGS = (UC_ARM_REG_R0, UC_ARM_REG_R1, UC_ARM_REG_R2, UC_ARM_REG_R3,
UC_ARM_REG_R4, UC_ARM_REG_R5, UC_ARM_REG_R6, UC_ARM_REG_R7)
RAMS = [
(0x00000000, 0x00001000), # zero page (QEMU-compat: [0] writes succeed)
(0x00200000, 0x00100000), # OCIMEM
(0x00400000, 0x07400000), # RPM range (heap-ish)
(0x08000000, 0x00600000), # DDRLOW
(0x08600000, 0x00010000), # IMEM
(0x80000000, 0x07C00000), # DDRHIGH_A
(0x87C00000, 0x00800000), # SMEM(+SBL BSS)
(0x078AF000, 0x00001000), # UARTDM page
(0x13000000, 0x00002000), # UEFI tables (already above, keep)
]
UART_TF = 0x078AF070
UART_SR = 0x078AF008
def load_elf(mu, path):
d = open(path, "rb").read()
assert d[:4] == b"\x7fELF"
entry = struct.unpack("<I", d[24:28])[0]
phoff = struct.unpack("<I", d[28:32])[0]
phnum = struct.unpack("<H", d[44:46])[0]
for k in range(phnum):
p = d[phoff + k * 32:phoff + (k + 1) * 32]
t, off, v, pa, fsz, msz, fl, al = struct.unpack("<IIIIIIII", p)
if t != 1:
continue
if fsz and v != 0x00220000: # QEMU parity: skip OCIMEM seg file-bytes
mu.mem_write(v, d[off:off + fsz])
for z in range(v + fsz, v + msz, 4):
mu.mem_write(z, b"\x00\x00\x00\x00")
return entry
def main():
path = sys.argv[1]
thumb = int(sys.argv[sys.argv.index("--thumb") + 1], 0)
mu = Uc(UC_ARCH_ARM, UC_MODE_THUMB)
for base, size in RAMS:
mu.mem_map(base, size)
uart_out = []
unmapped = {"n": 0, "first": []}
def hook_unmapped(mu, access, addr, size, value, data):
unmapped["n"] += 1
if len(unmapped["first"]) < 5:
unmapped["first"].append((hex(addr), size, access))
return False
mu.hook_add(UC_HOOK_MEM_UNMAPPED, hook_unmapped)
# SR reads return TX-ready
mu.mem_write(UART_SR, struct.pack("<I", 0xA0))
mu.mem_write(0x13000000, struct.pack("<II", 0x49535953, 0x54535953))
def hook_uw(mu, access, addr, size, value, data):
if addr == UART_TF:
uart_out.append(chr(value & 0xFF))
mu.hook_add(UC_HOOK_MEM_WRITE, hook_uw, begin=UART_TF, end=UART_TF)
entry = load_elf(mu, path)
for r in range(13):
mu.reg_write(UC_ARM_REG_R0 + r, 0)
if "--regs" in sys.argv:
for kv in sys.argv[sys.argv.index("--regs") + 1].split(","):
r, v = kv.split("=")
mu.reg_write(UC_ARM_REG_R0 + int(r[1:]), int(v, 0))
mu.reg_write(UC_ARM_REG_SP, 0x085FFF00)
from unicorn.arm_const import UC_ARM_REG_LR as _LR
mu.reg_write(_LR, 0x08006B8D) # QEMU parity: stale lr -> maze
mu.reg_write(UC_ARM_REG_CPSR, 0x13)
if "--fill" in sys.argv:
for spec in sys.argv[sys.argv.index("--fill") + 1].split(","):
a, sz, v = spec.split(":")
a, sz, v = int(a, 0), int(sz, 0), int(v, 0)
mu.mem_write(a, struct.pack("<I", v) * (sz // 4))
if "--poke" in sys.argv:
for spec in sys.argv[sys.argv.index("--poke") + 1].split(","):
a, v = spec.split("=")
mu.mem_write(int(a, 0), struct.pack("<I", int(v, 0)))
count = [0]
last = [0]
from collections import deque
hist = deque(maxlen=20000)
calls = [] if "--calltrace" in sys.argv else None
rets = [] if "--retrace" in sys.argv else None
qlog = [] if "--querylog" in sys.argv else None
_spmax = [0x085FFF00]
_splog = [] if "--spytrack" in sys.argv else None
elog = [] if "--entrylog" in sys.argv else None
_prev = [0]
_eranges = []
_inrng = []
if "--entrylog" in sys.argv:
for _spec in sys.argv[sys.argv.index("--entrylog") + 1].split(","):
_lo, _sz = _spec.split(":")
_lo, _sz = int(_lo, 0), int(_sz, 0)
_eranges.append((_lo, _lo + _sz))
_inrng.append(False)
from unicorn.arm_const import UC_ARM_REG_CPSR as _CPSR
def hook_code(mu, addr, size, data):
count[0] += 1
last[0] = addr
if _splog is not None:
try:
sp = mu.reg_read(UC_ARM_REG_SP)
except Exception:
sp = 0
if sp > _spmax[0] and len(_splog) < 40:
_spmax[0] = sp
_splog.append((count[0], addr, sp))
if _dirty[0]:
# deferred restore: MEM_WRITE hooks fire BEFORE the write lands,
# so in-hook restore gets overwritten by the instruction itself
_inww[0] = True
try:
for a, b in _dirty[1]:
mu.mem_write(a, stub_snap[a - STUB_LO:b - STUB_LO])
finally:
_inww[0] = False
_dirty[0] = False
del _dirty[1][:]
try:
thumb = (mu.reg_read(_CPSR) >> 5) & 1
except Exception:
thumb = 1
hist.append((addr, thumb))
if qlog is not None and addr in (0x8017EA4, 0x8017C60):
try:
vals = [mu.reg_read(_REGS[i]) for i in range(8)]
except Exception:
vals = []
qlog.append((addr, vals,
mu.reg_read(UC_ARM_REG_SP),
mu.reg_read(UC_ARM_REG_LR)))
if elog is not None:
for _i, (_elo, _ehi) in enumerate(_eranges):
inside = _elo <= addr < _ehi
if inside and not _inrng[_i]:
if len(elog) < 20000:
elog.append((count[0], _prev[0], addr))
_inrng[_i] = inside
_prev[0] = addr
if calls is not None and size in (2, 4):
try:
if size == 2:
h = struct.unpack("<H", mu.mem_read(addr & ~1, 2))[0]
is_blx = (h & 0xFF80) == 0x4780
rm = (h >> 3) & 7 if is_blx else -1
# bx Rm (jump, no link): 010001110 Rm:000
is_bx = (h & 0xFF80) == 0x4700
if is_bx:
bxrm = (h >> 3) & 15
try:
if bxrm < 8:
bxt = mu.reg_read(_REGS[bxrm])
elif bxrm == 14:
bxt = mu.reg_read(_LR)
else:
bxt = -1
except Exception:
bxt = -1
if len(calls) < 8000:
calls.append((addr, 100 + bxrm, bxt))
if rets is not None and 0x8017E00 <= addr < 0x8018000:
# pop {..,pc} (0xBD00+) or bx lr (0x4770)
if h == 0x4770 or (h & 0xFF00) == 0xBD00:
try:
rv = mu.reg_read(_REGS[0])
except Exception:
rv = -1
if len(rets) < 200:
rets.append((addr, rv))
else:
w = struct.unpack("<I", mu.mem_read(addr & ~3, 4))[0]
# ARM bx/blx Rm: cond(4) 0001001011111111111100x1 Rm(4)
is_blx = (w & 0x0FFFFFF0) in (0x012FFF10, 0x012FFF30)
rm = w & 15 if is_blx else -1
tgt = -1
if not is_blx and calls is not None:
# Thumb32 BL: h0=11110S+imm10, h1=1111x+J+imm11
h0 = w & 0xFFFF
h1 = (w >> 16) & 0xFFFF
if (h0 & 0xF800) == 0xF000 and (h1 & 0xE000) == 0xE000:
S = (h0 >> 10) & 1
J1 = (h1 >> 13) & 1
J2 = (h1 >> 11) & 1
I1 = 1 - (J1 ^ S)
I2 = 1 - (J2 ^ S)
off = (I1 << 23) | (I2 << 22) | ((h0 & 0x3FF) << 12) | ((h1 & 0x7FF) << 1)
if S:
off -= 0x1000000
if len(calls) < 8000:
calls.append((addr, 200, (addr + 4 + off) & 0xFFFFFFFF))
if rets is not None and 0x8017E00 <= addr < 0x8018000:
# pop.w {...,pc}: 0xE8BDxxxx with bit15 set
if (w & 0xFFFF8000) == 0xE8BD8000:
try:
rv = mu.reg_read(_REGS[0])
except Exception:
rv = -1
if len(rets) < 200:
rets.append((addr, rv))
if is_blx:
try:
tgt = mu.reg_read(_REGS[rm])
except Exception:
tgt = -1
if len(calls) < 4000:
calls.append((addr, rm, tgt))
except Exception:
return
mu.hook_add(UC_HOOK_CODE, hook_code)
# null-fetch redirect: branch-to-0 lands in maze (movs r0,#0; bx lr),
# immune to [0]-writes that clobber a static maze copy
from unicorn.arm_const import UC_ARM_REG_PC as _PC
_nulllog = []
def hook_null(mu, addr, size, data):
if len(_nulllog) < 10:
try:
r = [mu.reg_read(_REGS[i]) for i in range(4)]
lr = mu.reg_read(_LR)
sp = mu.reg_read(UC_ARM_REG_SP)
except Exception:
r, lr, sp = [], -1, -1
# walk back: find the branch source from hist
_nulllog.append((count[0], r, lr, sp))
mu.reg_write(_PC, STUB + 1)
mu.hook_add(UC_HOOK_CODE, hook_null, begin=0x0, end=0xFFF)
if "--watchcode" in sys.argv:
from unicorn.arm_const import UC_ARM_REG_PC as _PC2
wlog = []
def hook_ww(mu, access, addr, size, value, data):
if len(wlog) < 30:
try:
pc = mu.reg_read(_PC2)
except Exception:
pc = -1
wlog.append((pc, addr, size, value))
mu.hook_add(UC_HOOK_MEM_WRITE, hook_ww,
begin=0x8005800, end=0x8039254)
import atexit
def _dump():
print(f"code-writes: {len(wlog)}")
for pc, a, sz, v in wlog[:30]:
print(f" pc={pc:#x} [{a:#x}] sz={sz} val={v:#x}")
atexit.register(_dump)
# --- machine scaffold parity (saimaa.c values, verbatim) ---
def W32(a, v):
mu.mem_write(a, struct.pack("<I", v & 0xFFFFFFFF))
S, STUB, STUBV = 0x08006B80, 0x08006B8C, 0x08006B8D
W32(S, S + 8)
W32(S + 4, STUBV)
W32(S + 8, STUBV)
# maze blob (18B)
mu.mem_write(STUB, bytes([
0x00, 0x20, 0x4f, 0xea, 0x1e, 0x6c, 0xbc, 0xf1,
0x08, 0x0f, 0x00, 0xd1, 0x70, 0x47, 0x72, 0xb6,
0xfd, 0xe7]))
print("maze-rb:", bytes(mu.mem_read(STUB, 18)).hex())
for a in (0x087c29d18, 0x08050b28, 0x08070000):
W32(a, S)
# S6 stublet (14B @0x08006B9E)
mu.mem_write(0x08006B9E, bytes([
0xbd, 0xe8, 0xfc, 0x47, 0x43, 0xf6, 0xa5, 0x3e,
0xc0, 0xf6, 0x01, 0x0e, 0x70, 0x47]))
# banner stub (34B @0x08006BAC, prints r0 via UARTDM)
mu.mem_write(0x08006BAC, bytes([
0x10, 0xb5, 0x4f, 0xf2, 0x00, 0x03, 0xc0, 0xf2,
0x8a, 0x73, 0x21, 0x21, 0x19, 0x67, 0x10, 0xf8,
0x01, 0x1b, 0x09, 0xb1, 0x19, 0x67, 0xfa, 0xe7,
0x4f, 0xf2, 0x94, 0x6e, 0xc0, 0xf6, 0x02, 0x0e,
0x70, 0x47]))
# PBL stub (52B @0x080068C0)
mu.mem_write(0x080068C0, bytes([
0xf0, 0xb5, 0x46, 0xf6, 0x81, 0x3c, 0xc0, 0xf6,
0x00, 0x0c, 0xe0, 0x47, 0x40, 0xf2, 0x00, 0x00,
0xc0, 0xf2, 0x22, 0x00, 0x05, 0x46, 0x40, 0xf2,
0x00, 0x0a, 0xc0, 0xf6, 0x06, 0x0a, 0x41, 0xf2,
0x00, 0x0b, 0xc0, 0xf6, 0x06, 0x0b, 0x4f, 0xf2,
0x3f, 0x6e, 0xc0, 0xf6, 0x02, 0x0e, 0x70, 0x47,
0x00, 0x00, 0x00, 0x00]))
# S7 stublet (52B @0x08006C10, b18): delay-epilogue exit router.
# cmp r4,#0xff: iterate (r4<=0xff -> restart 0x8013ba5) or done
# (restore r4/r5/sl/fp, return to sbl_main 0x802f681).
mu.mem_write(0x08006C10, bytes.fromhex(
"ff2c13d940f20004c0f2220440f20005c0f2220540f2000a"
"c0f6060a41f2000bc0f6060bdff800f081f60208dff800f0"
"a53b0108"))
# stack zone fill (STUBV odd)
mu.mem_write(0x085F0000, struct.pack("<I", STUBV) * (0x10000 // 4))
# pop-site slots (sp values from traces)
for a, v in [(0x085FFF14, 0x802f65d), (0x085FFF1C, 0x802f665),
(0x085FFF44, 0x8013ba5), (0x085FFF5C, 0x802f681),
(0x085FFF74, 0x8016183)]:
W32(a, v)
W32(0x085FFF58, 0)
W32(0x085FFF34, 0)
W32(0x085FFF54, 0)
W32(0x085FFF6C, 0)
W32(0x08600944, 0) # IMEM poll magic
# minimal UEFI tables (ST/BS/RS/CO + ret0 stubs)
ST, BS, RS, CO, STUBS, LI, HEAP = (0x13000000, 0x13000100, 0x13000200,
0x13000300, 0x13000400, 0x13000500,
0x13001000)
for i in range(24):
mu.mem_write(STUBS + i * 8, bytes([0x00, 0x20, 0x70, 0x47,
0x00, 0x00, 0x00, 0x00]))
W32(BS + 24 + i * 4, STUBS + i * 8 + 1)
W32(BS, 0x56524553)
W32(ST, 0x49535953)
W32(ST + 4, 0x54535953)
W32(ST + 12, 0x00020000)
W32(ST + 16, 0x13000048)
W32(ST + 40, CO)
W32(ST + 44, CO)
W32(ST + 56, RS)
W32(ST + 60, BS)
W32(LI, 0x3130414d)
W32(HEAP - 4, HEAP)
# NOTE: no vendor string bytes (QEMU leaves zeros at 0x13000048)
# map UEFI table region (already in RAMS? add 0x13000000)
# --- end parity ---
# stub range is readonly on HW/QEMU: ignore SBL heap-clobber writes,
# keep maze/stublets intact (restore-on-write with reentrancy guard)
STUB_LO, STUB_HI = 0x080068C0, 0x08006C50 # +S7 + banner tail
stub_snap = bytes(mu.mem_read(STUB_LO, STUB_HI - STUB_LO))
_inww = [False]
_swn = [0]
_swlog = []
_dirty = [False, []]
print("stub-snap:", stub_snap[:24].hex())
print("stub-snap-maze:", stub_snap[0x2CC:0x2CC + 18].hex())
def hook_stubw(mu, access, addr, size, value, data):
if _inww[0]:
return
if addr + size <= STUB_LO or addr >= STUB_HI:
return
_swn[0] += 1
if len(_swlog) < 8:
try:
_pc = mu.reg_read(_PC)
except Exception:
_pc = -1
_swlog.append((_pc, addr, size))
# record for deferred restore (see hook_code); in-hook restore
# would be overwritten by the faulting instruction itself
a = max(addr, STUB_LO)
b = min(addr + size, STUB_HI)
if b > a and len(_dirty[1]) < 16:
_dirty[1].append((a, b))
_dirty[0] = True
#hook all DDRLOW, filter in python (catches writes starting below LO)
mu.hook_add(UC_HOOK_MEM_WRITE, hook_stubw,
begin=0x08000000, end=0x085FFFFF)
if "--watchmaze" in sys.argv:
from unicorn.arm_const import UC_ARM_REG_PC as _PC3
mzlog = []
def hook_mz(mu, access, addr, size, value, data):
if len(mzlog) < 40:
try:
pc = mu.reg_read(_PC3)
except Exception:
pc = -1
mzlog.append((pc, addr, size, value))
mu.hook_add(UC_HOOK_MEM_WRITE, hook_mz,
begin=0x08006B8C, end=0x08006B9D)
import atexit as _ax
def _dmz():
print(f"maze-writes: {len(mzlog)}")
for pc, a, sz, v in mzlog[:40]:
print(f" pc={pc:#x} [{a:#x}] sz={sz} val={v:#x}")
_ax.register(_dmz)
if "--watchlow" in sys.argv:
_spec = sys.argv[sys.argv.index("--watchlow") + 1].split(":")
_wlo, _whi = int(_spec[0], 0), int(_spec[0], 0) + int(_spec[1], 0)
from unicorn.arm_const import UC_ARM_REG_PC as _PC4
wlolog = []
def hook_wlo(mu, access, addr, size, value, data):
if len(wlolog) < 60:
try:
pc = mu.reg_read(_PC4)
except Exception:
pc = -1
wlolog.append((pc, addr, size, value))
mu.hook_add(UC_HOOK_MEM_WRITE, hook_wlo,
begin=0x08000000, end=0x085FFFFF)
import atexit as _ax2
def _dwlo():
inn = [(pc, a, sz, v) for pc, a, sz, v in wlolog
if not (a + sz <= _wlo or a >= _whi)]
print(f"low-writes-in-range: {len(inn)}")
for pc, a, sz, v in inn[:60]:
print(f" pc={pc:#x} [{a:#x}] sz={sz} val={v:#x}")
_ax2.register(_dwlo)
limit = 2000000
if "--limit" in sys.argv:
limit = int(sys.argv[sys.argv.index("--limit") + 1])
try:
mu.emu_start(thumb | 1, 0xFFFFFFFF, 0, limit)
except Exception as e:
print("EMU-EXC:", str(e)[:120])
print("insns:", count[0], "last-pc:", hex(last[0]))
print("unmapped:", unmapped["n"], unmapped["first"][:4])
print("regs:",
" ".join(f"r{i}={mu.reg_read(_REGS[i]):#x}" for i in range(8)),
f"sp={mu.reg_read(UC_ARM_REG_SP):#x}",
f"lr={mu.reg_read(UC_ARM_REG_LR):#x}",
f"pc={mu.reg_read(UC_ARM_REG_PC):#x}")
try:
from capstone import Cs, CS_ARCH_ARM, CS_MODE_THUMB, CS_MODE_ARM
md_t = Cs(CS_ARCH_ARM, CS_MODE_THUMB)
md_a = Cs(CS_ARCH_ARM, CS_MODE_ARM)
real = [(pc, th) for pc, th in hist
if not (0 <= (pc & ~1) < 0x1000)][-48:]
for pc, thumb in real:
try:
base = pc & ~1
code = mu.mem_read(base, 8 if thumb else 12)
md = md_t if thumb else md_a
for ins in md.disasm(code, base):
print(f" {base:#x}{'t' if thumb else 'a'}: {ins.mnemonic} {ins.op_str}")
break
except Exception:
print(f" {pc:#x}: <unreadable>")
except ImportError:
print("hist:", [hex(pc) for pc, _ in list(hist)[-12:]])
if elog is not None:
print(f"entries: {len(elog)}")
for n, prev, cur in elog[-30:]:
print(f" insn#{n} {prev:#x} -> {cur:#x}")
if _splog is not None:
print(f"sp-highs: {len(_splog)}")
for n, pc, sp in _splog:
print(f" insn#{n} {pc:#x} sp={sp:#x}")
if _nulllog:
print(f"null-entries: {len(_nulllog)}")
for n, r, lr, sp in _nulllog:
print(f" insn#{n} r0-r3={[hex(x) for x in r]} lr={lr:#x} sp={sp:#x}")
if qlog is not None:
print(f"querylog: {len(qlog)}")
for pc, r, sp, lr in qlog[:20]:
print(f" {pc:#x} r0-r7={[hex(x) for x in r]} sp={sp:#x} lr={lr:#x}")
if rets is not None:
print(f"rets-in-range: {len(rets)}")
for pc, rv in rets[-20:]:
print(f" ret {pc:#x} r0={rv:#x}" if rv >= 0 else f" ret {pc:#x} r0=?")
if calls is not None:
print(f"blx-calls: {len(calls)}")
bls = [(pc, tgt) for pc, rm, tgt in calls if rm == 200]
print(f"bl-immed: {len(bls)}")
for pc, tgt in bls[-30:]:
print(f" {pc:#x}: bl #{tgt:#x}")
for pc, rm, tgt in calls[-12:]:
if rm == 200:
continue
tag = f"bx r{rm - 100}" if rm >= 100 else f"blx r{rm}"
print(f" {pc:#x}: {tag} -> {tgt:#x}" if tgt >= 0 else f" {pc:#x}: {tag} -> ?")
if "--dumpmem" in sys.argv:
for spec in sys.argv[sys.argv.index("--dumpmem") + 1].split(","):
a, sz = spec.split(":")
a, sz = int(a, 0), int(sz, 0)
print(f"mem[{a:#x}+{sz:#x}]:")
print(bytes(mu.mem_read(a, sz)).hex())
print("UART:", "".join(uart_out)[:160])
print(f"stubguard-hits: {_swn[0]}")
for _pc, _a, _s in _swlog:
print(f" guarded pc={_pc:#x} [{_a:#x}] sz={_s}")
if __name__ == "__main__":
main()