On 8/1/22 18:44, Sean Christopherson wrote:
> On Sun, Jul 31, 2022, Michal Luczaj wrote:
>> +{
>> + exceptions = 0;
>> + handle_exception(UD_VECTOR, illegal_lea_handler);
>
> No need to use a custom handler (ignore any patterns in emulator.c that suggest
> it's "mandatory", emulator is one of the oldest test). ASM_TRY() can handle all
> of this without any globals.
> ...
> static void test_illegal_lea(void)
> {
> unsigned int vector;
>
> asm volatile (ASM_TRY("1f")
> KVM_FEP ".byte 0x8d; .byte 0xc0\n\t"
> "1:"
> : : : "memory", "eax");
>
> vector = exception_vector();
> report(vector == UD_VECTOR,
> "Wanted #UD on LEA with /reg, got vector = %d", vector);
> }
I must be missing something important. There is
`handle_exception(UD_VECTOR, 0)` early in `main()` which simply undoes
`handle_exception(6, check_exception_table)` set by `setup_idt()`. If
there's no more exception table walk for #UD, `ASM_TRY` alone can't
possibly work, am I corrent?
If so, am I supposed to restore the `check_exception_table()` handler? Or
maybe using `test_for_exception()` would be more elegant:
static void illegal_lea(void *unused)
{
asm volatile(KVM_FEP ".byte 0x8d, 0xc0" : : : "memory", "eax");
}
static void test_illegal_lea(void)
{
bool fault;
fault = test_for_exception(UD_VECTOR, &illegal_lea, NULL);
report(fault, "Wanted #UD on LEA with /reg");
}
Thanks for hints,
Michal
