CVE-2026-80623: coresight: ete: Always save state on power down
In the Linux kernel, the following vulnerability has been resolved:
coresight: ete: Always save state on power down
System register ETMs and ETE are unlikely to be preserved on CPU power down. The ETE DT binding also never documented "arm,coresight-loses-context-with-cpu" so nobody would have legitimately been able to use that binding to fix it and ACPI has no such binding at all.
Fix it by hard coding the setting for sysreg ETMs (ETE is always sysreg) or ACPI boots. Use a local variable when setting up savestate so that it's immune to concurrent probing when devices have different configurations which is an issue with modifying the global.
This fixes the following error when using Coresight with ACPI on the FVP which supports CPU PM:
coresight ete0: External agent took claim tag WARNING: drivers/hwtracing/coresight/coresight-core.c:248 at coresightdisclaimdeviceunlocked+0xe0/0xe8, CPU#0: perf/117
Affected Software
Event History
Frequently Asked Questions
Which systems are most likely to encounter this issue?
Systems using Linux CoreSight system-register ETMs, including ETE, are affected when CPUs can power down. The description specifically identifies CoreSight running with ACPI on an FVP that supports CPU power management.
Does this depend on a device-tree setting being configured?
No. The ETE device-tree binding never documented the arm,coresight-loses-context-with-cpu property, so it could not legitimately be used to address the issue; ACPI provides no equivalent binding. The fix hard-codes state saving for system-register ETMs and for ACPI boots.
How might the issue appear on an affected system?
The reported symptom is an "External agent took claim tag" warning from coresight_disclaim_device_unlocked while using CoreSight with ACPI and CPU power management. The warning was observed for an ETE device on FVP.