On 8/29/19 10:20 AM, Philippe Mathieu-Daudé wrote:
>> + /* Avoid trapping reads of pages with a write breakpoint. */
>> + match = (prot & PAGE_READ ? BP_MEM_READ : 0)
>> + | (prot & PAGE_WRITE ? BP_MEM_WRITE : 0);
>
> Isn't it cheaper to do here:
>
> if (!match) {
> return iotlb;
> }
>
> or
>
> if (match) {
Note that PROT_NONE pages never reach here; they always trap in tlb_fill.
The only way we can get match == 0 here is for the case of an execute-only
page. Which is possible, but extremely unlikely. Almost all targets merge the
text and rodata sections, which means that virtually all executable pages are
also readable.
(Although I must say that in this age of ROP-gadgets, leaving the rodata
section executable is probably a mistake, and tools should be updated to *not*
merge them. That's still not necessarily execute-only for the text section,
but I don't see anything in principal that would prevent it.)
r~
