On Thu, Aug 13, 2020 at 12:01 PM Kevin Brodsky <kevin.brod...@arm.com> wrote: > > On 12/08/2020 20:06, Evgenii Stepanov wrote: > > On Wed, Aug 12, 2020 at 11:03 AM Andrey Konovalov <andreyk...@google.com> > wrote: >> >> On Wed, Aug 12, 2020 at 7:52 PM Richard Henderson >> <richard.hender...@linaro.org> wrote: >> > >> > On 8/12/20 10:38 AM, Andrey Konovalov wrote: >> > > On Wed, Aug 12, 2020 at 7:19 PM Richard Henderson >> > > <richard.hender...@linaro.org> wrote: >> > >> >> > >> As reported by Andrey, I was missing the complete ISS info for >> > >> the Data Abort raised upon a synchronous tag check fail. >> > >> >> > >> The following should fix that. All the twisty little rules for >> > >> the ISS.ISV bit are already handled by merge_syn_data_abort. >> > >> Probably the most important bit that was missing was ISS.WnR, >> > >> as that is independent of ISS.ISV. >> > >> >> > >> Andrey, will you please test? >> > > >> > > Looks like WnR is now being set properly, but SAS is still always 0. >> > >> > Are you looking at ESR_EL1? >> > >> > On page D13-2992 of revision F.a: >> > >> > # ISV is 0 for all faults reported in ESR_EL1 or ESR_EL3. >> > >> > which means that ISS[23:14] are RES0, which includes SAS. >> >> +more Arm and Google people >> >> Is this known? Do we not get access size when MTE fault happens? > > > It sounds like this applies to all data abort exceptions, no matter MTE or > not. > > > Correct. For data aborts in general, the extra syndrome information in > ISS[23:14] is only provided at EL2, in order to help hypervisors emulate > simple loads/stores (that access device memory) by looking at ESR_EL2 without > having to decode the trapped instruction.
OK, got it. The WnR bit works properly though, so Tested-by: Andrey Konovalov <andreyk...@google.com> for the series. > Did you have any particular use-case in mind for SAS being set even in > ESR_EL1? Yes, we could use that to extract the size of the access that caused the fault to print more informative KASAN reports. We usually have a header like: BUG: KASAN: slab-out-of-bounds in usb_destroy_configuration+0x636/0x6d0 Read of size 8 at addr ffff8881c7e3c758 by task kworker/1:7/3434
