Re: [tip:x86/asm] x86/mm/64: Enable vmapped stacks (CONFIG_HAVE_ARCH_VMAP_STACK=y)

[Matt Fleming]

On Fri, 21 Oct, at 05:18:30PM, Andy Lutomirski wrote:
> 
> This is asking for trouble if any of the variable length parameters
> are on the stack.  How about adding a "size_t size" parameter and
> doing:
> 
> if (!va) {
>   return 0;
> } else if (virt_addr_valid(va)) {
>   return virt_to_phys(va);
> } else {
>   /* A fully aligned variable on the stack is guaranteed not to cross
> a page boundary. */
>   WARN_ON(!IS_ALIGNED((uintptr_t)va, size) || size > PAGE_SIZE);
>   return slow_virt_to_phys(va);
> }

Ah, good catch. Something like this?

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