alistair23-linux/Documentation/arm64/silicon-errata.txt
Linus Torvalds 0aebc6a440 arm64 updates for 4.16:
- Security mitigations:
   - variant 2: invalidating the branch predictor with a call to secure firmware
   - variant 3: implementing KPTI for arm64
 
 - 52-bit physical address support for arm64 (ARMv8.2)
 
 - arm64 support for RAS (firmware first only) and SDEI (software
   delegated exception interface; allows firmware to inject a RAS error
   into the OS)
 
 - Perf support for the ARM DynamIQ Shared Unit PMU
 
 - CPUID and HWCAP bits updated for new floating point multiplication
   instructions in ARMv8.4
 
 - Removing some virtual memory layout printks during boot
 
 - Fix initial page table creation to cope with larger than 32M kernel
   images when 16K pages are enabled
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Catalin Marinas:
 "The main theme of this pull request is security covering variants 2
  and 3 for arm64. I expect to send additional patches next week
  covering an improved firmware interface (requires firmware changes)
  for variant 2 and way for KPTI to be disabled on unaffected CPUs
  (Cavium's ThunderX doesn't work properly with KPTI enabled because of
  a hardware erratum).

  Summary:

   - Security mitigations:
      - variant 2: invalidate the branch predictor with a call to
        secure firmware
      - variant 3: implement KPTI for arm64

   - 52-bit physical address support for arm64 (ARMv8.2)

   - arm64 support for RAS (firmware first only) and SDEI (software
     delegated exception interface; allows firmware to inject a RAS
     error into the OS)

   - perf support for the ARM DynamIQ Shared Unit PMU

   - CPUID and HWCAP bits updated for new floating point multiplication
     instructions in ARMv8.4

   - remove some virtual memory layout printks during boot

   - fix initial page table creation to cope with larger than 32M kernel
     images when 16K pages are enabled"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (104 commits)
  arm64: Fix TTBR + PAN + 52-bit PA logic in cpu_do_switch_mm
  arm64: Turn on KPTI only on CPUs that need it
  arm64: Branch predictor hardening for Cavium ThunderX2
  arm64: Run enable method for errata work arounds on late CPUs
  arm64: Move BP hardening to check_and_switch_context
  arm64: mm: ignore memory above supported physical address size
  arm64: kpti: Fix the interaction between ASID switching and software PAN
  KVM: arm64: Emulate RAS error registers and set HCR_EL2's TERR & TEA
  KVM: arm64: Handle RAS SErrors from EL2 on guest exit
  KVM: arm64: Handle RAS SErrors from EL1 on guest exit
  KVM: arm64: Save ESR_EL2 on guest SError
  KVM: arm64: Save/Restore guest DISR_EL1
  KVM: arm64: Set an impdef ESR for Virtual-SError using VSESR_EL2.
  KVM: arm/arm64: mask/unmask daif around VHE guests
  arm64: kernel: Prepare for a DISR user
  arm64: Unconditionally enable IESB on exception entry/return for firmware-first
  arm64: kernel: Survive corrected RAS errors notified by SError
  arm64: cpufeature: Detect CPU RAS Extentions
  arm64: sysreg: Move to use definitions for all the SCTLR bits
  arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early
  ...
2018-01-30 13:57:43 -08:00

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Silicon Errata and Software Workarounds
=======================================
Author: Will Deacon <will.deacon@arm.com>
Date : 27 November 2015
It is an unfortunate fact of life that hardware is often produced with
so-called "errata", which can cause it to deviate from the architecture
under specific circumstances. For hardware produced by ARM, these
errata are broadly classified into the following categories:
Category A: A critical error without a viable workaround.
Category B: A significant or critical error with an acceptable
workaround.
Category C: A minor error that is not expected to occur under normal
operation.
For more information, consult one of the "Software Developers Errata
Notice" documents available on infocenter.arm.com (registration
required).
As far as Linux is concerned, Category B errata may require some special
treatment in the operating system. For example, avoiding a particular
sequence of code, or configuring the processor in a particular way. A
less common situation may require similar actions in order to declassify
a Category A erratum into a Category C erratum. These are collectively
known as "software workarounds" and are only required in the minority of
cases (e.g. those cases that both require a non-secure workaround *and*
can be triggered by Linux).
For software workarounds that may adversely impact systems unaffected by
the erratum in question, a Kconfig entry is added under "Kernel
Features" -> "ARM errata workarounds via the alternatives framework".
These are enabled by default and patched in at runtime when an affected
CPU is detected. For less-intrusive workarounds, a Kconfig option is not
available and the code is structured (preferably with a comment) in such
a way that the erratum will not be hit.
This approach can make it slightly onerous to determine exactly which
errata are worked around in an arbitrary kernel source tree, so this
file acts as a registry of software workarounds in the Linux Kernel and
will be updated when new workarounds are committed and backported to
stable kernels.
| Implementor | Component | Erratum ID | Kconfig |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A53 | #826319 | ARM64_ERRATUM_826319 |
| ARM | Cortex-A53 | #827319 | ARM64_ERRATUM_827319 |
| ARM | Cortex-A53 | #824069 | ARM64_ERRATUM_824069 |
| ARM | Cortex-A53 | #819472 | ARM64_ERRATUM_819472 |
| ARM | Cortex-A53 | #845719 | ARM64_ERRATUM_845719 |
| ARM | Cortex-A53 | #843419 | ARM64_ERRATUM_843419 |
| ARM | Cortex-A57 | #832075 | ARM64_ERRATUM_832075 |
| ARM | Cortex-A57 | #852523 | N/A |
| ARM | Cortex-A57 | #834220 | ARM64_ERRATUM_834220 |
| ARM | Cortex-A72 | #853709 | N/A |
| ARM | Cortex-A73 | #858921 | ARM64_ERRATUM_858921 |
| ARM | MMU-500 | #841119,#826419 | N/A |
| | | | |
| Cavium | ThunderX ITS | #22375, #24313 | CAVIUM_ERRATUM_22375 |
| Cavium | ThunderX ITS | #23144 | CAVIUM_ERRATUM_23144 |
| Cavium | ThunderX GICv3 | #23154 | CAVIUM_ERRATUM_23154 |
| Cavium | ThunderX Core | #27456 | CAVIUM_ERRATUM_27456 |
| Cavium | ThunderX Core | #30115 | CAVIUM_ERRATUM_30115 |
| Cavium | ThunderX SMMUv2 | #27704 | N/A |
| Cavium | ThunderX2 SMMUv3| #74 | N/A |
| Cavium | ThunderX2 SMMUv3| #126 | N/A |
| | | | |
| Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
| | | | |
| Hisilicon | Hip0{5,6,7} | #161010101 | HISILICON_ERRATUM_161010101 |
| Hisilicon | Hip0{6,7} | #161010701 | N/A |
| Hisilicon | Hip07 | #161600802 | HISILICON_ERRATUM_161600802 |
| | | | |
| Qualcomm Tech. | Kryo/Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 |
| Qualcomm Tech. | Falkor v1 | E1009 | QCOM_FALKOR_ERRATUM_1009 |
| Qualcomm Tech. | QDF2400 ITS | E0065 | QCOM_QDF2400_ERRATUM_0065 |
| Qualcomm Tech. | Falkor v{1,2} | E1041 | QCOM_FALKOR_ERRATUM_1041 |