On 10/15, David Long wrote:
>
> Allow arches to customize how the instruction is filled into the xol
> slot. ARM will use this to insert an undefined instruction after the
> real instruction in order to simulate a single step of the instruction
> without hardware support.
OK, but
> +void __weak arch_uprobe_xol_copy(struct arch_uprobe *auprobe, void *vaddr)
> +{
> + memcpy(vaddr, auprobe->insn, MAX_UINSN_BYTES);
> +}
> +
> /*
> * xol_get_insn_slot - allocate a slot for xol.
> * Returns the allocated slot address or 0.
> @@ -1246,6 +1251,7 @@ static unsigned long xol_get_insn_slot(struct uprobe
> *uprobe)
> {
> struct xol_area *area;
> unsigned long xol_vaddr;
> + void *kaddr;
>
> area = get_xol_area();
> if (!area)
> @@ -1256,7 +1262,9 @@ static unsigned long xol_get_insn_slot(struct uprobe
> *uprobe)
> return 0;
>
> /* Initialize the slot */
> - copy_to_page(area->page, xol_vaddr, uprobe->arch.insn, MAX_UINSN_BYTES);
> + kaddr = kmap_atomic(area->page);
> + arch_uprobe_xol_copy(&uprobe->arch, kaddr + (xol_vaddr & ~PAGE_MASK));
> + kunmap_atomic(kaddr);
This looks a bit strange and defeats the purpose of generic helper...
How about
void __weak arch_uprobe_xol_copy(...)
{
copy_to_page(...);
}
then just
- copy_to_page(...);
+ arch_uprobe_xol_copy(...);
?
Or, I am just curious, can't we have an empty "__weak arch_uprobe_xol_copy" if
we call it right after copy_to_page() ?
Oleg.
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