On 11/24/2017 07:27 PM, Andy Lutomirski wrote: >>> + cpu_entry_area_begin = (void >>> *)(__fix_to_virt(FIX_CPU_ENTRY_AREA_BOTTOM)); >>> + cpu_entry_area_end = (void *)(__fix_to_virt(FIX_CPU_ENTRY_AREA_TOP) + >>> PAGE_SIZE); >>> + >>> kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END), >>> - (void *)KASAN_SHADOW_END); >>> + kasan_mem_to_shadow(cpu_entry_area_begin)); >>> + >>> + kasan_populate_shadow((unsigned >>> long)kasan_mem_to_shadow(cpu_entry_area_begin), >>> + (unsigned >>> long)kasan_mem_to_shadow(cpu_entry_area_end), >>> + 0); >>> + >>> + kasan_populate_zero_shadow(kasan_mem_to_shadow(cpu_entry_area_end), >> >> Seems we need to round_up kasan_mem_to_shadow(cpu_entry_area_end) to the >> next page >> (or alternatively - round_up(cpu_entry_area_end, >> KASAN_SHADOW_SCALE_SIZE*PAGE_SIZE)). >> Otherwise, kasan_populate_zero_shadow() will overpopulate the last shadow >> page of cpu_entry area with kasan_zero_page. >> >> We don't necessarily need to >> round_down(kasan_mem_to_shadow(cpu_entry_area_begin), PAGE_SIZE) because >> kasan_populate_zero_shadow() will not populate the last 'incomplete' page >> and kasan_populate_shadow() >> does round_down() internally, which is exactly what we want here. But it >> might be better to round_down() >> explicitly anyway, to avoid relying on such subtle implementation details. > > Any chance you could send a fixup patch or a replacement patch? You > obviously understand this code *way* better than I do. > > Or you could do my table-based approach and fix it permanently... :) >
Perhaps I'll look at table-based approach later. I've send you a fixed patch for now, to not slow you down.
