def _call_mem_eq(i, **kwargs):
if (not isinstance(i.src_vars[1], _mem.ConstVar)
or not issubclass(i.src_vars[1].var_type, ctypes.Array)):
raise TranslationError(
i.starts_line, 'first arg to mem_eq must be const ctypes.Array')
ret = []
# stack=None because we shouldn't need to allocate anything
ret.extend(_lea(i, i.src_vars[2], bi.Reg.R2, stack=None))
false, done = _make_tmp_label(), _make_tmp_label()
for off, v in enumerate(i.src_vars[1].val.value):
ret.extend([
bi.Mov(bi.Mem(bi.Reg.R2, off, bi.Size.Byte), bi.Reg.R1),
bi.JumpIfNotEqual(bi.Imm(v), bi.Reg.R1, false)
])
# If we made it here, it's a match
ret.extend(_mov(bi.Imm(1), i.dst_vars[0]))
ret.append(bi.Jump(done))
# if we jumped here, it's not a match
ret.append(bi.Label(false))
ret.extend(_mov(bi.Imm(0), i.dst_vars[0]))
ret.append(bi.Label(done))
return ret
def _call_packet_copy(i, **kwargs):
# If you're thinking 'wow, this function looks complicated,' just go
# take a look at kernel/bpf/verifier.c:find_good_pkt_pointers to see
# the hoops that we're jumping through here.
ret = []
fn, skb, dst_ptr, offset, num_bytes = i.src_vars
# TODO: also support ptr to context?
if not isinstance(skb, _mem.ArgVar):
raise TranslationError(
i.starts_line,
'First argument to packet_copy must be SkBuffContext argument')
elif not isinstance(num_bytes, _mem.ConstVar):
raise TranslationError(
i.starts_line,
'Num bytes must not be dynamically defined for packet_copy')
skb_data_mem = bi.Mem(_get_var_reg(skb), skb.var_type.data.offset,
bi.Size.Word)
skb_data_end_mem = bi.Mem(_get_var_reg(skb), skb.var_type.data_end.offset,
bi.Size.Word)
out_of_bounds = _make_tmp_label()
# ret = _mov(dst_ptr, bi.Reg.R1)
dst_ptr = _convert_var(dst_ptr)
# %r2 = skb->data
ret.append(bi.Mov(skb_data_mem, bi.Reg.R2))
# %r2 += offset
if isinstance(offset, _mem.ConstVar):
off_val = offset.val
if hasattr(off_val, 'value'):
off_val = off_val.value
if off_val != 0:
ret.append(bi.Add(bi.Imm(off_val), bi.Reg.R2))
else:
ret.extend(_mov(offset, bi.Reg.R3))
ret.append(bi.Add(bi.Reg.R3, bi.Reg.R2))
# %r3 = %r2
ret.append(bi.Mov(bi.Reg.R2, bi.Reg.R3))
# %r2 += num_bytes
ret.append(bi.Add(bi.Imm(num_bytes.val), bi.Reg.R2))
# %r4 = skb->data_end
ret.append(bi.Mov(skb_data_end_mem, bi.Reg.R4))
# if skb->data + offset + num_bytes > skb->data_end: goto out_of_bounds
ret.append(bi.JumpIfGreaterThan(bi.Reg.R4, bi.Reg.R2, out_of_bounds))
ret.extend(_memcpy_packet(i, dst_ptr, bi.Reg.R3, num_bytes.val))
ret.append(bi.Label(out_of_bounds))
return ret
def _binary_subscr_map(i, **kwargs):
m, k, dv = i.src_vars[0], i.src_vars[1], i.dst_vars[0]
if not isinstance(m, _mem.ConstVar):
raise TranslationError(i.starts_line,
'Cannot subscript dynamically select map')
found, done = _make_tmp_label(), _make_tmp_label()
ret = []
ret.extend(_mov(bi.MapFdImm(m.val.fd), bi.Reg.R1))
ret.extend(_lea(i, k, bi.Reg.R2, **kwargs))
ret.extend([
bi.Call(bi.Imm(funcs.map_lookup_elem.num)),
])
if _is_ptr(dv.var_type):
sz = _get_cdata_size(dv.var_type)
ret.extend(_mov(bi.Reg.R0, dv))
else:
ret.extend([
bi.JumpIfNotEqual(bi.Imm(0), bi.Reg.R0, found),
])
# Move default value
dr = _get_var_reg(dv)
ret.extend(_mov_const(dv.var_type, m.val.DEFAULT_VALUE, dr, dv.offset))
ret.extend([
bi.Jump(done),
bi.Label(found),
])
# Primitives by value, others by reference
if issubclass(dv.var_type, _ctypes._SimpleCData):
sz = _get_cdata_size(dv.var_type)
ret.extend(_mov(bi.Mem(bi.Reg.R0, 0, sz), dv))
else:
ret.extend(_mov(bi.Reg.R0, dv))
ret.append(bi.Label(done))
return ret
def _compare_op(i, **kwargs):
lhs, rhs = i.src_vars
op = i.argval
if op == '<':
lhs, rhs = rhs, lhs
op = '>'
elif op == '<=':
lhs, rhs = rhs, lhs
op = '>='
jmp_type = {
'>': bi.JumpIfGreaterThan,
'>=': bi.JumpIfGreaterOrEqual,
'==': bi.JumpIfEqual,
'!=': bi.JumpIfNotEqual,
}[op]
true, done = _make_tmp_label(), _make_tmp_label()
return (_mov(lhs, bi.Reg.R1) + _mov(rhs, bi.Reg.R2) +
[jmp_type(bi.Reg.R1, bi.Reg.R2, true)] +
_mov(bi.Imm(0), i.dst_vars[0]) + [bi.Jump(done)] +
[bi.Label(true)] + _mov(bi.Imm(1), i.dst_vars[0]) +
[bi.Label(done)])
def _label(i):
return [bi.Label('label_{}'.format(i.offset))]