On Wed, 1 Feb 2017, Dave Hansen wrote:
> FIXME: we also need to ensure that we check the current state of the
> larger address space opt-in. If we've opted in to larger address spaces
> we can not allow a small bounds directory to be used. Also, if we've
> not opted in, we can not allow the larger bounds directory to be used.
> This can be fixed once the in-kernel API for opting in/out is settled.
Ok.
> /* Register/unregister a process' MPX related resource */
> -#define MPX_ENABLE_MANAGEMENT() mpx_enable_management()
> +#define MPX_ENABLE_MANAGEMENT(bd_size) mpx_enable_management(bd_size)
> #define MPX_DISABLE_MANAGEMENT() mpx_disable_management()
Please add another tab before mpx_disable so both are aligned.
> -int mpx_enable_management(void)
> +int mpx_set_mm_bd_size(unsigned long bd_size)
static ?
> +{
> + struct mm_struct *mm = current->mm;
> +
> + switch ((unsigned long long)bd_size) {
> + case 0:
> + /* Legacy call to prctl(): */
> + mm->context.mpx_bd_shift = 0;
> + return 0;
> + case MPX_BD_SIZE_BYTES_32:
> + /* 32-bit, legacy-sized bounds directory: */
> + if (is_64bit_mm(mm))
> + return -EINVAL;
> + mm->context.mpx_bd_shift = 0;
> + return 0;
> + case MPX_BD_BASE_SIZE_BYTES_64:
> + /* 64-bit, legacy-sized bounds directory: */
> + if (!is_64bit_mm(mm)
> + // FIXME && ! opted-in to larger address space
Hmm. Confused. This is where we enable MPX and decode the requested address
space. How can an already opt in happen?
If that's a enable call for an already enabled thing, then we should catch
that at the call site, I think.
> + case MPX_BD_BASE_SIZE_BYTES_64 << MPX_LARGE_BOUNDS_DIR_SHIFT:
> + /*
> + * Non-legacy call, with larger directory.
> + * Note that there is no 32-bit equivalent for
> + * this case since its address space does not
> + * change sizes.
> + */
> + if (!is_64bit_mm(mm))
> + return -EINVAL;
> + /*
> + * Do not let this be enabled unles we are on
> + * 5-level hardware *and* have that feature
> + * enabled. FIXME: need runtime check
Runtime check? Isn't the feature bit enough?
Thanks,
tglx
