Messages in this thread | | | Subject | Re: [PATCH v5 04/15] arm64: errata: Add detection for TRBE write to out-of-range | From | Suzuki K Poulose <> | Date | Tue, 19 Oct 2021 14:29:58 +0100 |
| |
On 18/10/2021 16:50, Mathieu Poirier wrote: > Good morning, > > On Thu, Oct 14, 2021 at 11:31:14PM +0100, Suzuki K Poulose wrote: >> Arm Neoverse-N2 and Cortex-A710 cores are affected by an erratum where the >> trbe, under some circumstances, might write upto 64bytes to an address after > > Checkpatch gives me a warning about this line... > >> the Limit as programmed by the TRBLIMITR_EL1.LIMIT. This might - >> >> - Corrupt a page in the ring buffer, which may corrupt trace from a >> previous session, consumed by userspace. >> - Hit the guard page at the end of the vmalloc area and raise a fault. >> >> To keep the handling simpler, we always leave the last page from the >> range, which TRBE is allowed to write. This can be achieved by ensuring >> that we always have more than a PAGE worth space in the range, while >> calculating the LIMIT for TRBE. And then the LIMIT pointer can be adjusted >> to leave the PAGE (TRBLIMITR.LIMIT -= PAGE_SIZE), out of the TRBE range >> while enabling it. This makes sure that the TRBE will only write to an area >> within its allowed limit (i.e, [head-head+size]) and we do not have to handle > > I'm pretty sure this line will also be flagged. >
Thanks for pointing them out. I have fixed it now.
Suzuki
| |