[PATCH] test: Add emulator test for iret instruction

[Mohammed Gamal <m.gamal005@gmail.com>]

This adds a unit test for real mode emulation of the iret instruction

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>

---
Changes from v1:
- Added test for 16-bit iret
- Added tests for returned eflags
---
 kvm/test/x86/realmode.c |   79 +++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 79 insertions(+), 0 deletions(-)

diff --git a/kvm/test/x86/realmode.c b/kvm/test/x86/realmode.c
index bd79348..74456c3 100644
--- a/kvm/test/x86/realmode.c
+++ b/kvm/test/x86/realmode.c
@@ -865,6 +865,84 @@ void test_pusha_popa()
 		print_serial("Pusha/Popa Test2: PASS\n");
 }
 
+void test_iret()
+{
+	struct regs inregs = { 0 }, outregs;
+
+	MK_INSN(iret32, "pushf\n\t"
+			"pushl %cs\n\t"
+			"call 1f\n\t" /* a near call will push eip onto the stack */
+			"jmp 2f\n\t"
+			"1: iret\n\t"
+			"2:\n\t"
+		     );
+
+	MK_INSN(iret16, "pushfw\n\t"
+			"pushw %cs\n\t"
+			"callw 1f\n\t"
+			"jmp 2f\n\t"
+			"1: iretw\n\t"
+			"2:\n\t");
+
+	MK_INSN(iret_flags32, "pushfl\n\t"
+			      "popl %eax\n\t"
+			      "andl $~0x2, %eax\n\t"
+			      "orl $0xffc08028, %eax\n\t"
+			      "pushl %eax\n\t"
+			      "pushl %cs\n\t"
+			      "call 1f\n\t"
+			      "jmp 2f\n\t"
+			      "1: iret\n\t"
+			      "2:\n\t");
+
+	MK_INSN(iret_flags16, "pushfw\n\t"
+			      "popw %ax\n\t"
+			      "and $~0x2, %ax\n\t"
+			      "or $0x8028, %ax\n\t" 
+			      "pushw %ax\n\t"
+			      "pushw %cs\n\t"
+			      "callw 1f\n\t"
+			      "jmp 2f\n\t"
+			      "1: iretw\n\t"
+			      "2:\n\t");
+
+	exec_in_big_real_mode(&inregs, &outregs,
+			      insn_iret32,
+			      insn_iret32_end - insn_iret32);
+
+	if (!regs_equal(&inregs, &outregs, 0))
+		print_serial("iret Test 1: FAIL\n");
+	else
+		print_serial("iret Test 1: PASS\n");
+
+	exec_in_big_real_mode(&inregs, &outregs,
+			      insn_iret16,
+			      insn_iret16_end - insn_iret16);
+
+	if (!regs_equal(&inregs, &outregs, 0))
+		print_serial("iret Test 2: FAIL\n");
+	else
+		print_serial("iret Test 2: PASS\n");
+
+	exec_in_big_real_mode(&inregs, &outregs,
+			      insn_iret_flags32,
+			      insn_iret_flags32_end - insn_iret_flags32);
+
+	if (!regs_equal(&inregs, &outregs, R_AX))
+		print_serial("iret Test 3: FAIL\n");
+	else
+		print_serial("iret Test 3: PASS\n");
+
+	exec_in_big_real_mode(&inregs, &outregs,
+			      insn_iret_flags16,
+			      insn_iret_flags16_end - insn_iret_flags16);
+
+	if (!regs_equal(&inregs, &outregs, R_AX))
+		print_serial("iret Test 4: FAIL\n");
+	else
+		print_serial("iret Test 4: PASS\n");
+}
+
 void realmode_start(void)
 {
 	test_null();
@@ -886,6 +964,7 @@ void realmode_start(void)
 	/* long jmp test uses call near so test it after testing call */
 	test_long_jmp();
 	test_xchg();
+	test_iret();
 
 	exit(0);
 }
-- 
1.7.0.4