x64: fix cmp rax, 0xffffffff_fff00fff

jjyg · Dec 3, 2013 · 96ee958 · 96ee958
1 parent 716a0ce
commit 96ee958
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Showing 3 changed files with 17 additions and 2 deletions.
diff --git a/metasm/cpu/ia32/opcodes.rb b/metasm/cpu/ia32/opcodes.rb
@@ -26,7 +26,7 @@ def init_cpu_constants
 		 :vexvxmm, :vexvymm, :vexvreg, :i4xmm, :i4ymm
 		].each { |a| @valid_args[a] = true }
 
-		[:strop, :stropz, :opsz, :argsz, :setip,
+		[:strop, :stropz, :opsz, :adsz, :argsz, :setip,
 		 :stopexec, :saveip, :unsigned_imm, :random, :needpfx,
 		 :xmmx, :modrmR, :modrmA, :mrmvex 
 		].each { |a| @valid_props[a] = true }

diff --git a/metasm/cpu/x86_64/encode.rb b/metasm/cpu/x86_64/encode.rb
@@ -258,7 +258,19 @@ def encode_instr_op(program, i, op)
 			when :mrm_imm; ed = ia.imm.encode("a#{op.props[:adsz] || 64}".to_sym, @endianness)
 			when :i8, :u8, :i16, :u16, :i32, :u32, :i64, :u64; ed = ia.encode(oa, @endianness)
 			when :i
-				type = (opsz == 64 ? op.props[:imm64] ? :a64 : :i32 : "#{op.props[:unsigned_imm] ? 'a' : 'i'}#{opsz}".to_sym)
+				type = if opsz == 64
+					if op.props[:imm64]
+						:a64
+					else
+						# handle 0xffffffff_ffffffff -> -1, which should fit in i32
+						ia = Expression[ia, :-, [(1<<64), :*, [[[ia, :>>, 63], :&, 1], :&, [ia, :>, 0]]]]
+						:i32
+					end
+				elsif op.props[:unsigned_imm]
+					"a#{opsz}".to_sym
+				else
+					"i#{opsz}".to_sym
+				end
 			       	ed = ia.encode(type, @endianness)
 			when :i4xmm, :i4ymm
 				ed = ia.val << 4	# u8

diff --git a/tests/x86_64.rb b/tests/x86_64.rb
@@ -26,6 +26,7 @@ def test_basic
 		assert_equal("\x48\xbb\xef\xcd\xab\x89\x67\x45\x23\x01", assemble("mov rbx, 0123456789abcdefh"))
 		assert_equal("\x8d\x05\x0c\0\0\0", assemble("lea eax, [rip+12]"))
 		assert_equal("\x8d\x04\x25\x0c\0\0\0", assemble("lea eax, [12]"))
+		assert_equal("\x48\x81\xE3\xFF\xF0\xFF\xFF", assemble("and rbx, 0xffffffff_fffff0ff"))
 	end
 
 	def test_err
@@ -35,6 +36,8 @@ def test_err
 		assert_raise(Metasm::ParseError) { assemble("add [bx]") }
 		assert_raise(Metasm::ParseError) { assemble("add [eip+4*eax]") }
 		assert_raise(Metasm::ParseError) { assemble("add ah, r8b") }
+		assert_raise(Metasm::EncodeError) { assemble("and rbx, 0x1_ffffffff_ffffffff") }
+		assert_raise(Metasm::EncodeError) { assemble("mov rbx, 011123456789abcdefh") }
 	end
 
 	def disassemble(bin, cpu=@@cpu)