From 8d81b2a38ddfc4b03662d2359765648c8b4cc73c Mon Sep 17 00:00:00 2001 From: Suzuki K Poulose Date: Tue, 19 Oct 2021 17:31:42 +0100 Subject: arm64: errata: Add detection for TRBE write to out-of-range 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 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 address faults within the driver. Cc: Anshuman Khandual Cc: Mathieu Poirier Cc: Mike Leach Cc: Leo Yan Cc: Will Deacon Cc: Mark Rutland Reviewed-by: Anshuman Khandual Reviewed-by: Mathieu Poirier Acked-by: Catalin Marinas Signed-off-by: Suzuki K Poulose Link: https://lore.kernel.org/r/20211019163153.3692640-5-suzuki.poulose@arm.com Signed-off-by: Will Deacon --- Documentation/arm64/silicon-errata.rst | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'Documentation/arm64/silicon-errata.rst') diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index 569a92411dcd..5342e895fb60 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -96,6 +96,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-A710 | #2054223 | ARM64_ERRATUM_2054223 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-A710 | #2224489 | ARM64_ERRATUM_2224489 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1349291 | N/A | @@ -106,6 +108,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N2 | #2067961 | ARM64_ERRATUM_2067961 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Neoverse-N2 | #2253138 | ARM64_ERRATUM_2253138 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-500 | #841119,826419 | N/A | +----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ -- cgit