Messages in this thread |  | | Date | Sat, 19 Oct 2013 18:36:27 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v2 03/13] uprobes: allow arch access to xol slot |
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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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