CONFIG_ARM64_ERRATUM_2038923: Cortex-A510: 2038923: workaround TRBE corruption with enable

General informations

The Linux kernel configuration item CONFIG_ARM64_ERRATUM_2038923:

• prompt: Cortex-A510: 2038923: workaround TRBE corruption with enable
• type: bool
• depends on: CONFIG_CORESIGHT_TRBE
• defined in arch/arm64/Kconfig
• found in Linux kernels: 5.17–5.19, 6.0–6.12, 6.13-rc+HEAD

Help text

This option adds the workaround for ARM Cortex-A510 erratum 2038923.

Affected Cortex-A510 core might cause an inconsistent view on whether trace is prohibited within the CPU. As a result, the trace buffer or trace buffer state might be corrupted. This happens after TRBE buffer has been enabled by setting TRBLIMITR_EL1.E, followed by just a single context synchronization event before execution changes from a context, in which trace is prohibited to one where it isn't, or vice versa. In these mentioned conditions, the view of whether trace is prohibited is inconsistent between parts of the CPU, and the trace buffer or the trace buffer state might be corrupted.

Work around this in the driver by preventing an inconsistent view of whether the trace is prohibited or not based on TRBLIMITR_EL1.E by immediately following a change to TRBLIMITR_EL1.E with at least one ISB instruction before an ERET, or two ISB instructions if no ERET is to take place.

If unsure, say Y.

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The data is retrived from:

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• Linux Kernel Driver DataBase (LKDDb)

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