OpenCloudOS-Kernel/Documentation/arm64/silicon-errata.rst

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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 |
+================+=================+=================+=============================+
clocksource/drivers/arch_timer: Workaround for Allwinner A64 timer instability The Allwinner A64 SoC is known[1] to have an unstable architectural timer, which manifests itself most obviously in the time jumping forward a multiple of 95 years[2][3]. This coincides with 2^56 cycles at a timer frequency of 24 MHz, implying that the time went slightly backward (and this was interpreted by the kernel as it jumping forward and wrapping around past the epoch). Investigation revealed instability in the low bits of CNTVCT at the point a high bit rolls over. This leads to power-of-two cycle forward and backward jumps. (Testing shows that forward jumps are about twice as likely as backward jumps.) Since the counter value returns to normal after an indeterminate read, each "jump" really consists of both a forward and backward jump from the software perspective. Unless the kernel is trapping CNTVCT reads, a userspace program is able to read the register in a loop faster than it changes. A test program running on all 4 CPU cores that reported jumps larger than 100 ms was run for 13.6 hours and reported the following: Count | Event -------+--------------------------- 9940 | jumped backward 699ms 268 | jumped backward 1398ms 1 | jumped backward 2097ms 16020 | jumped forward 175ms 6443 | jumped forward 699ms 2976 | jumped forward 1398ms 9 | jumped forward 356516ms 9 | jumped forward 357215ms 4 | jumped forward 714430ms 1 | jumped forward 3578440ms This works out to a jump larger than 100 ms about every 5.5 seconds on each CPU core. The largest jump (almost an hour!) was the following sequence of reads: 0x0000007fffffffff → 0x00000093feffffff → 0x0000008000000000 Note that the middle bits don't necessarily all read as all zeroes or all ones during the anomalous behavior; however the low 10 bits checked by the function in this patch have never been observed with any other value. Also note that smaller jumps are much more common, with backward jumps of 2048 (2^11) cycles observed over 400 times per second on each core. (Of course, this is partially explained by lower bits rolling over more frequently.) Any one of these could have caused the 95 year time skip. Similar anomalies were observed while reading CNTPCT (after patching the kernel to allow reads from userspace). However, the CNTPCT jumps are much less frequent, and only small jumps were observed. The same program as before (except now reading CNTPCT) observed after 72 hours: Count | Event -------+--------------------------- 17 | jumped backward 699ms 52 | jumped forward 175ms 2831 | jumped forward 699ms 5 | jumped forward 1398ms Further investigation showed that the instability in CNTPCT/CNTVCT also affected the respective timer's TVAL register. The following values were observed immediately after writing CNVT_TVAL to 0x10000000: CNTVCT | CNTV_TVAL | CNTV_CVAL | CNTV_TVAL Error --------------------+------------+--------------------+----------------- 0x000000d4a2d8bfff | 0x10003fff | 0x000000d4b2d8bfff | +0x00004000 0x000000d4a2d94000 | 0x0fffffff | 0x000000d4b2d97fff | -0x00004000 0x000000d4a2d97fff | 0x10003fff | 0x000000d4b2d97fff | +0x00004000 0x000000d4a2d9c000 | 0x0fffffff | 0x000000d4b2d9ffff | -0x00004000 The pattern of errors in CNTV_TVAL seemed to depend on exactly which value was written to it. For example, after writing 0x10101010: CNTVCT | CNTV_TVAL | CNTV_CVAL | CNTV_TVAL Error --------------------+------------+--------------------+----------------- 0x000001ac3effffff | 0x1110100f | 0x000001ac4f10100f | +0x1000000 0x000001ac40000000 | 0x1010100f | 0x000001ac5110100f | -0x1000000 0x000001ac58ffffff | 0x1110100f | 0x000001ac6910100f | +0x1000000 0x000001ac66000000 | 0x1010100f | 0x000001ac7710100f | -0x1000000 0x000001ac6affffff | 0x1110100f | 0x000001ac7b10100f | +0x1000000 0x000001ac6e000000 | 0x1010100f | 0x000001ac7f10100f | -0x1000000 I was also twice able to reproduce the issue covered by Allwinner's workaround[4], that writing to TVAL sometimes fails, and both CVAL and TVAL are left with entirely bogus values. One was the following values: CNTVCT | CNTV_TVAL | CNTV_CVAL --------------------+------------+-------------------------------------- 0x000000d4a2d6014c | 0x8fbd5721 | 0x000000d132935fff (615s in the past) Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> ======================================================================== Because the CPU can read the CNTPCT/CNTVCT registers faster than they change, performing two reads of the register and comparing the high bits (like other workarounds) is not a workable solution. And because the timer can jump both forward and backward, no pair of reads can distinguish a good value from a bad one. The only way to guarantee a good value from consecutive reads would be to read _three_ times, and take the middle value only if the three values are 1) each unique and 2) increasing. This takes at minimum 3 counter cycles (125 ns), or more if an anomaly is detected. However, since there is a distinct pattern to the bad values, we can optimize the common case (1022/1024 of the time) to a single read by simply ignoring values that match the error pattern. This still takes no more than 3 cycles in the worst case, and requires much less code. As an additional safety check, we still limit the loop iteration to the number of max-frequency (1.2 GHz) CPU cycles in three 24 MHz counter periods. For the TVAL registers, the simple solution is to not use them. Instead, read or write the CVAL and calculate the TVAL value in software. Although the manufacturer is aware of at least part of the erratum[4], there is no official name for it. For now, use the kernel-internal name "UNKNOWN1". [1]: https://github.com/armbian/build/commit/a08cd6fe7ae9 [2]: https://forum.armbian.com/topic/3458-a64-datetime-clock-issue/ [3]: https://irclog.whitequark.org/linux-sunxi/2018-01-26 [4]: https://github.com/Allwinner-Homlet/H6-BSP4.9-linux/blob/master/drivers/clocksource/arm_arch_timer.c#L272 Acked-by: Maxime Ripard <maxime.ripard@bootlin.com> Tested-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Samuel Holland <samuel@sholland.org> Cc: stable@vger.kernel.org Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2019-01-13 10:17:18 +08:00
| Allwinner | A64/R18 | UNKNOWN1 | SUN50I_ERRATUM_UNKNOWN1 |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| 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-A57 | #1319537 | ARM64_ERRATUM_1319367 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A72 | #853709 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A72 | #1319367 | ARM64_ERRATUM_1319367 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A73 | #858921 | ARM64_ERRATUM_858921 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A55 | #1024718 | ARM64_ERRATUM_1024718 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1188873,1418040| ARM64_ERRATUM_1418040 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1165522 | ARM64_ERRATUM_1165522 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1286807 | ARM64_ERRATUM_1286807 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1463225 | ARM64_ERRATUM_1463225 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A55 | #1530923 | ARM64_ERRATUM_1530923 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1349291 | N/A |
ARM: * support for chained PMU counters in guests * improved SError handling * handle Neoverse N1 erratum #1349291 * allow side-channel mitigation status to be migrated * standardise most AArch64 system register accesses to msr_s/mrs_s * fix host MPIDR corruption on 32bit * selftests ckleanups x86: * PMU event {white,black}listing * ability for the guest to disable host-side interrupt polling * fixes for enlightened VMCS (Hyper-V pv nested virtualization), * new hypercall to yield to IPI target * support for passing cstate MSRs through to the guest * lots of cleanups and optimizations Generic: * Some txt->rST conversions for the documentation -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQEcBAABAgAGBQJdJzdIAAoJEL/70l94x66DQDoH/i83/8kX4I8AWDlushPru4ts Q4lCE5VAPha+o4pLb1dtfFL3gTmSbsB1N++JSlqK3JOo6LphIOy6b0wBjQBbAa6U 3CT1dJaHJoScLLj09vyBlvClGUH2ZKEQTWOiquCCf7JfPofxwPUA6vJ7TYsdkckx zR3ygbADWmnfS7hFfiqN3JzuYh9eoooGNWSU+Giq6VF41SiL3IqhBGZhWS0zE9c2 2c5lpqqdeHmAYNBqsyzNiDRKp7+zLFSmZ7Z5/0L755L8KYwR6F5beTnmBMHvb4lA PWH/SWOC8EYR+PEowfrH+TxKZwp0gMn1kcAKjilHk0uCRwG1IzuHAr2jlNxICCk= =t/Oq -----END PGP SIGNATURE----- Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm Pull KVM updates from Paolo Bonzini: "ARM: - support for chained PMU counters in guests - improved SError handling - handle Neoverse N1 erratum #1349291 - allow side-channel mitigation status to be migrated - standardise most AArch64 system register accesses to msr_s/mrs_s - fix host MPIDR corruption on 32bit - selftests ckleanups x86: - PMU event {white,black}listing - ability for the guest to disable host-side interrupt polling - fixes for enlightened VMCS (Hyper-V pv nested virtualization), - new hypercall to yield to IPI target - support for passing cstate MSRs through to the guest - lots of cleanups and optimizations Generic: - Some txt->rST conversions for the documentation" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (128 commits) Documentation: virtual: Add toctree hooks Documentation: kvm: Convert cpuid.txt to .rst Documentation: virtual: Convert paravirt_ops.txt to .rst KVM: x86: Unconditionally enable irqs in guest context KVM: x86: PMU Event Filter kvm: x86: Fix -Wmissing-prototypes warnings KVM: Properly check if "page" is valid in kvm_vcpu_unmap KVM: arm/arm64: Initialise host's MPIDRs by reading the actual register KVM: LAPIC: Retry tune per-vCPU timer_advance_ns if adaptive tuning goes insane kvm: LAPIC: write down valid APIC registers KVM: arm64: Migrate _elx sysreg accessors to msr_s/mrs_s KVM: doc: Add API documentation on the KVM_REG_ARM_WORKAROUNDS register KVM: arm/arm64: Add save/restore support for firmware workaround state arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests KVM: arm/arm64: Support chained PMU counters KVM: arm/arm64: Remove pmc->bitmask KVM: arm/arm64: Re-create event when setting counter value KVM: arm/arm64: Extract duplicated code to own function KVM: arm/arm64: Rename kvm_pmu_{enable/disable}_counter functions KVM: LAPIC: ARBPRI is a reserved register for x2APIC ...
2019-07-13 06:35:14 +08:00
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1542419 | ARM64_ERRATUM_1542419 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | MMU-500 | #841119,826419 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Broadcom | Brahma-B53 | N/A | ARM64_ERRATUM_845719 |
+----------------+-----------------+-----------------+-----------------------------+
| Broadcom | Brahma-B53 | N/A | ARM64_ERRATUM_843419 |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX ITS | #22375,24313 | CAVIUM_ERRATUM_22375 |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX ITS | #23144 | CAVIUM_ERRATUM_23144 |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX GICv3 | #23154 | CAVIUM_ERRATUM_23154 |
+----------------+-----------------+-----------------+-----------------------------+
irqchip/gic-v3: Workaround Cavium erratum 38539 when reading GICD_TYPER2 Despite the architecture spec requiring that reserved registers in the GIC distributor memory map are RES0 (and thus are not allowed to generate an exception), the Cavium ThunderX (aka TX1) SoC explodes as such: [ 0.000000] GICv3: GIC: Using split EOI/Deactivate mode [ 0.000000] GICv3: 128 SPIs implemented [ 0.000000] GICv3: 0 Extended SPIs implemented [ 0.000000] Internal error: synchronous external abort: 96000210 [#1] SMP [ 0.000000] Modules linked in: [ 0.000000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc4-00035-g3cf6a3d5725f #7956 [ 0.000000] Hardware name: cavium,thunder-88xx (DT) [ 0.000000] pstate: 60000085 (nZCv daIf -PAN -UAO) [ 0.000000] pc : __raw_readl+0x0/0x8 [ 0.000000] lr : gic_init_bases+0x110/0x560 [ 0.000000] sp : ffff800011243d90 [ 0.000000] x29: ffff800011243d90 x28: 0000000000000000 [ 0.000000] x27: 0000000000000018 x26: 0000000000000002 [ 0.000000] x25: ffff8000116f0000 x24: ffff000fbe6a2c80 [ 0.000000] x23: 0000000000000000 x22: ffff010fdc322b68 [ 0.000000] x21: ffff800010a7a208 x20: 00000000009b0404 [ 0.000000] x19: ffff80001124dad0 x18: 0000000000000010 [ 0.000000] x17: 000000004d8d492b x16: 00000000f67eb9af [ 0.000000] x15: ffffffffffffffff x14: ffff800011249908 [ 0.000000] x13: ffff800091243ae7 x12: ffff800011243af4 [ 0.000000] x11: ffff80001126e000 x10: ffff800011243a70 [ 0.000000] x9 : 00000000ffffffd0 x8 : ffff80001069c828 [ 0.000000] x7 : 0000000000000059 x6 : ffff8000113fb4d1 [ 0.000000] x5 : 0000000000000001 x4 : 0000000000000000 [ 0.000000] x3 : 0000000000000000 x2 : 0000000000000000 [ 0.000000] x1 : 0000000000000000 x0 : ffff8000116f000c [ 0.000000] Call trace: [ 0.000000] __raw_readl+0x0/0x8 [ 0.000000] gic_of_init+0x188/0x224 [ 0.000000] of_irq_init+0x200/0x3cc [ 0.000000] irqchip_init+0x1c/0x40 [ 0.000000] init_IRQ+0x160/0x1d0 [ 0.000000] start_kernel+0x2ec/0x4b8 [ 0.000000] Code: a8c47bfd d65f03c0 d538d080 d65f03c0 (b9400000) when reading the GICv4.1 GICD_TYPER2 register, which is unexpected... Work around it by adding a new quirk for the following variants: ThunderX: CN88xx OCTEON TX: CN83xx, CN81xx OCTEON TX2: CN93xx, CN96xx, CN98xx, CNF95xx* and use this flag to avoid accessing GICD_TYPER2. Note that all reserved registers (including redistributors and ITS) are impacted by this erratum, but that only GICD_TYPER2 has to be worked around so far. Signed-off-by: Marc Zyngier <maz@kernel.org> Tested-by: Robert Richter <rrichter@marvell.com> Tested-by: Mark Salter <msalter@redhat.com> Tested-by: Tim Harvey <tharvey@gateworks.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Robert Richter <rrichter@marvell.com> Link: https://lore.kernel.org/r/20191027144234.8395-11-maz@kernel.org Link: https://lore.kernel.org/r/20200311115649.26060-1-maz@kernel.org
2020-03-11 19:56:49 +08:00
| Cavium | ThunderX GICv3 | #38539 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| 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 |
+----------------+-----------------+-----------------+-----------------------------+
| Cavium | ThunderX2 Core | #219 | CAVIUM_TX2_ERRATUM_219 |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| 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 | Hip0{6,7} | #161010803 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| Hisilicon | Hip07 | #161600802 | HISILICON_ERRATUM_161600802 |
+----------------+-----------------+-----------------+-----------------------------+
| Hisilicon | Hip08 SMMU PMCG | #162001800 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Qualcomm Tech. | Kryo/Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 |
+----------------+-----------------+-----------------+-----------------------------+
| Qualcomm Tech. | Kryo/Falkor v1 | E1009 | QCOM_FALKOR_ERRATUM_1009 |
+----------------+-----------------+-----------------+-----------------------------+
| Qualcomm Tech. | QDF2400 ITS | E0065 | QCOM_QDF2400_ERRATUM_0065 |
+----------------+-----------------+-----------------+-----------------------------+
arm64: Add software workaround for Falkor erratum 1041 The ARM architecture defines the memory locations that are permitted to be accessed as the result of a speculative instruction fetch from an exception level for which all stages of translation are disabled. Specifically, the core is permitted to speculatively fetch from the 4KB region containing the current program counter 4K and next 4K. When translation is changed from enabled to disabled for the running exception level (SCTLR_ELn[M] changed from a value of 1 to 0), the Falkor core may errantly speculatively access memory locations outside of the 4KB region permitted by the architecture. The errant memory access may lead to one of the following unexpected behaviors. 1) A System Error Interrupt (SEI) being raised by the Falkor core due to the errant memory access attempting to access a region of memory that is protected by a slave-side memory protection unit. 2) Unpredictable device behavior due to a speculative read from device memory. This behavior may only occur if the instruction cache is disabled prior to or coincident with translation being changed from enabled to disabled. The conditions leading to this erratum will not occur when either of the following occur: 1) A higher exception level disables translation of a lower exception level (e.g. EL2 changing SCTLR_EL1[M] from a value of 1 to 0). 2) An exception level disabling its stage-1 translation if its stage-2 translation is enabled (e.g. EL1 changing SCTLR_EL1[M] from a value of 1 to 0 when HCR_EL2[VM] has a value of 1). To avoid the errant behavior, software must execute an ISB immediately prior to executing the MSR that will change SCTLR_ELn[M] from 1 to 0. Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-12-12 06:42:32 +08:00
| Qualcomm Tech. | Falkor v{1,2} | E1041 | QCOM_FALKOR_ERRATUM_1041 |
+----------------+-----------------+-----------------+-----------------------------+
+----------------+-----------------+-----------------+-----------------------------+
| Fujitsu | A64FX | E#010001 | FUJITSU_ERRATUM_010001 |
+----------------+-----------------+-----------------+-----------------------------+