* Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx> wrote:
> +{
> + unsigned long vdso_end, vdso_start;
> +
> + if (!mm->context.vdso_base)
> + return;
> + vdso_start = mm->context.vdso_base;
> +
> +#ifdef CONFIG_PPC64
> + /* Calling is_32bit_task() implies that we are dealing with the
> + * current process memory. If there is a call path where mm is not
> + * owned by the current task, then we'll have need to store the
> + * vDSO size in the mm->context.
> + */
> + BUG_ON(current->mm != mm);
> + if (is_32bit_task())
> + vdso_end = vdso_start + (vdso32_pages << PAGE_SHIFT);
> + else
> + vdso_end = vdso_start + (vdso64_pages << PAGE_SHIFT);
> +#else
> + vdso_end = vdso_start + (vdso32_pages << PAGE_SHIFT);
> +#endif
> + vdso_end += (1<<PAGE_SHIFT); /* data page */
> +
> + /* Check if the vDSO is in the range of the remapped area */
> + if ((vdso_start <= old_start && old_start < vdso_end) ||
> + (vdso_start < old_end && old_end <= vdso_end) ||
> + (old_start <= vdso_start && vdso_start < old_end)) {
> + /* Update vdso_base if the vDSO is entirely moved. */
> + if (old_start == vdso_start && old_end == vdso_end &&
> + (old_end - old_start) == (new_end - new_start))
> + mm->context.vdso_base = new_start;
> + else
> + mm->context.vdso_base = 0;
> + }
> +}
Oh my, that really looks awfully complex, as you predicted, and right
in every mremap() call.
I'm fine with your original, imperfect, KISS approach. Sorry about
this detour ...
Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
Thanks,
Ingo
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