From d946114dfe6b02c5d8b1c1617704478f112ce23f Mon Sep 17 00:00:00 2001
From: lazymio <mio@lazym.io>
Date: Fri, 25 Feb 2022 22:44:42 +0100
Subject: [PATCH] Set EFLAGS correctly on startup

---
 qemu/target/i386/unicorn.c |  2 +-
 tests/unit/test_x86.c      | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/qemu/target/i386/unicorn.c b/qemu/target/i386/unicorn.c
index ded937fe..b846cd69 100644
--- a/qemu/target/i386/unicorn.c
+++ b/qemu/target/i386/unicorn.c
@@ -80,7 +80,7 @@ void x86_reg_reset(struct uc_struct *uc)
     memset(&env->idt, 0, sizeof(env->idt));
 
     env->eip = 0;
-    env->eflags = 0;
+    cpu_load_eflags(env, 0, -1);
     env->cc_op = CC_OP_EFLAGS;
 
     env->fpstt = 0; /* top of stack index */
diff --git a/tests/unit/test_x86.c b/tests/unit/test_x86.c
index 6bec3554..4c786d5a 100644
--- a/tests/unit/test_x86.c
+++ b/tests/unit/test_x86.c
@@ -932,6 +932,26 @@ static void test_x86_64_nested_emu_start_error()
     OK(uc_close(uc));
 }
 
+static void test_x86_eflags_reserved_bit()
+{
+    uc_engine *uc;
+    uint32_t r_eflags;
+
+    OK(uc_open(UC_ARCH_X86, UC_MODE_32, &uc));
+
+    OK(uc_reg_read(uc, UC_X86_REG_EFLAGS, &r_eflags));
+
+    TEST_CHECK((r_eflags & 2) != 0);
+
+    OK(uc_reg_write(uc, UC_X86_REG_EFLAGS, &r_eflags));
+
+    OK(uc_reg_read(uc, UC_X86_REG_EFLAGS, &r_eflags));
+
+    TEST_CHECK((r_eflags & 2) != 0);
+
+    OK(uc_close(uc));
+}
+
 TEST_LIST = {
     {"test_x86_in", test_x86_in},
     {"test_x86_out", test_x86_out},
@@ -962,4 +982,5 @@ TEST_LIST = {
     {"test_x86_nested_emu_start", test_x86_nested_emu_start},
     {"test_x86_nested_emu_stop", test_x86_nested_emu_stop},
     {"test_x86_64_nested_emu_start_error", test_x86_64_nested_emu_start_error},
+    {"test_x86_eflags_reserved_bit", test_x86_eflags_reserved_bit},
     {NULL, NULL}};