Qemu does not generate a double fault (DBF) on x86, if a general protection
fault could not be delivered. Instead it hangs in a loop.
The patch fix this bug by checking whether we are already in a GPF exception.
Bernhard Kauer
Index: helper.c
===================================================================
RCS file: /sources/qemu/qemu/target-i386/helper.c,v
retrieving revision 1.74
diff -u -r1.74 helper.c
--- helper.c 1 Feb 2007 22:12:19 -0000 1.74
+++ helper.c 27 Mar 2007 11:33:34 -0000
@@ -592,6 +592,16 @@
sp += 4;\
}
+void
+raise_gpf(int intno, int is_int, int is_hw, int error)
+{
+ if (!is_int && !is_hw && intno == EXCP0D_GPF)
+ raise_exception_err(EXCP08_DBLE, 0);
+ else
+ raise_exception_err(EXCP0D_GPF, error >= 0 ? error : intno *
TARGET_LONG_SIZE + 2);
+}
+
+
/* protected mode interrupt */
static void do_interrupt_protected(int intno, int is_int, int error_code,
unsigned int next_eip, int is_hw)
@@ -624,7 +634,7 @@
dt = &env->idt;
if (intno * 8 + 7 > dt->limit)
- raise_exception_err(EXCP0D_GPF, intno * 8 + 2);
+ raise_gpf(intno, is_int, is_hw, -1);
ptr = dt->base + intno * 8;
e1 = ldl_kernel(ptr);
e2 = ldl_kernel(ptr + 4);
@@ -661,29 +671,30 @@
case 15: /* 386 trap gate */
break;
default:
- raise_exception_err(EXCP0D_GPF, intno * 8 + 2);
+ raise_gpf(intno, is_int, is_hw, -1);
break;
}
dpl = (e2 >> DESC_DPL_SHIFT) & 3;
cpl = env->hflags & HF_CPL_MASK;
/* check privledge if software int */
if (is_int && dpl < cpl)
- raise_exception_err(EXCP0D_GPF, intno * 8 + 2);
+ raise_gpf(intno, is_int, is_hw, -1);
+
/* check valid bit */
if (!(e2 & DESC_P_MASK))
raise_exception_err(EXCP0B_NOSEG, intno * 8 + 2);
selector = e1 >> 16;
offset = (e2 & 0xffff0000) | (e1 & 0x0000ffff);
if ((selector & 0xfffc) == 0)
- raise_exception_err(EXCP0D_GPF, 0);
+ raise_gpf(intno, is_int, is_hw, 0);
if (load_segment(&e1, &e2, selector) != 0)
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
if (!(e2 & DESC_S_MASK) || !(e2 & (DESC_CS_MASK)))
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
dpl = (e2 >> DESC_DPL_SHIFT) & 3;
if (dpl > cpl)
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
if (!(e2 & DESC_P_MASK))
raise_exception_err(EXCP0B_NOSEG, selector & 0xfffc);
if (!(e2 & DESC_C_MASK) && dpl < cpl) {
@@ -710,14 +721,14 @@
} else if ((e2 & DESC_C_MASK) || dpl == cpl) {
/* to same priviledge */
if (env->eflags & VM_MASK)
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
new_stack = 0;
sp_mask = get_sp_mask(env->segs[R_SS].flags);
ssp = env->segs[R_SS].base;
esp = ESP;
dpl = cpl;
} else {
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
new_stack = 0; /* avoid warning */
sp_mask = 0; /* avoid warning */
ssp = 0; /* avoid warning */
@@ -860,7 +871,7 @@
dt = &env->idt;
if (intno * 16 + 15 > dt->limit)
- raise_exception_err(EXCP0D_GPF, intno * 16 + 2);
+ raise_gpf(intno, is_int, is_hw, -1);
ptr = dt->base + intno * 16;
e1 = ldl_kernel(ptr);
e2 = ldl_kernel(ptr + 4);
@@ -872,14 +883,13 @@
case 15: /* 386 trap gate */
break;
default:
- raise_exception_err(EXCP0D_GPF, intno * 16 + 2);
- break;
+ raise_gpf(intno, is_int, is_hw, -1);
}
dpl = (e2 >> DESC_DPL_SHIFT) & 3;
cpl = env->hflags & HF_CPL_MASK;
/* check privledge if software int */
if (is_int && dpl < cpl)
- raise_exception_err(EXCP0D_GPF, intno * 16 + 2);
+ raise_gpf(intno, is_int, is_hw, -1);
/* check valid bit */
if (!(e2 & DESC_P_MASK))
raise_exception_err(EXCP0B_NOSEG, intno * 16 + 2);
@@ -887,19 +897,19 @@
offset = ((target_ulong)e3 << 32) | (e2 & 0xffff0000) | (e1 & 0x0000ffff);
ist = e2 & 7;
if ((selector & 0xfffc) == 0)
- raise_exception_err(EXCP0D_GPF, 0);
+ raise_gpf(intno, is_int, is_hw, 0);
if (load_segment(&e1, &e2, selector) != 0)
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
if (!(e2 & DESC_S_MASK) || !(e2 & (DESC_CS_MASK)))
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
dpl = (e2 >> DESC_DPL_SHIFT) & 3;
if (dpl > cpl)
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
if (!(e2 & DESC_P_MASK))
raise_exception_err(EXCP0B_NOSEG, selector & 0xfffc);
if (!(e2 & DESC_L_MASK) || (e2 & DESC_B_MASK))
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
if ((!(e2 & DESC_C_MASK) && dpl < cpl) || ist != 0) {
/* to inner priviledge */
if (ist != 0)
@@ -912,7 +922,7 @@
} else if ((e2 & DESC_C_MASK) || dpl == cpl) {
/* to same priviledge */
if (env->eflags & VM_MASK)
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
new_stack = 0;
if (ist != 0)
esp = get_rsp_from_tss(ist + 3);
@@ -921,7 +931,7 @@
esp &= ~0xfLL; /* align stack */
dpl = cpl;
} else {
- raise_exception_err(EXCP0D_GPF, selector & 0xfffc);
+ raise_gpf(intno, is_int, is_hw, selector & 0xfffc);
new_stack = 0; /* avoid warning */
esp = 0; /* avoid warning */
}
@@ -1089,7 +1099,12 @@
/* real mode (simpler !) */
dt = &env->idt;
if (intno * 4 + 3 > dt->limit)
- raise_exception_err(EXCP0D_GPF, intno * 8 + 2);
+ {
+ if (!is_int && intno == EXCP0D_GPF)
+ raise_exception_err(EXCP08_DBLE, 0);
+ else
+ raise_exception_err(EXCP0D_GPF, intno * 4 + 2);
+ }
ptr = dt->base + intno * 4;
offset = lduw_kernel(ptr);
selector = lduw_kernel(ptr + 2);
