** Description changed:
[Impact]
- cntvct_el0 could be left untrapped if reset with the user access bit set
+ This bug captures a few issues with the ARM arch_timer driver:
+
+ 1) Some arm64 systems have hardware defects in their architected timer
+ implementations that require errata, which we workaround in the kernel.
+ However, it's possible that this workaround will not be applied if the
+ timer was reset w/ the user access bit set.
+
+ 2) The Juno board fails to initialize a timer at boot:
+
+ arch_timer: Unable to map frame @ 0x0000000000000000
+ arch_timer: Frame missing phys irq.
+ Failed to initialize '/timer@2a810000': -22
+
+ 3) Possible boot warning from arch_timer_mem_of_init():
+ 'Trying to vfree() nonexistent vm area'
+
+ 4) There's a theoretical problem where the first frame of a timer could
+ be used even though a better suited timer frame is available.
+
+ 5) An infinite recursion loop will occur when enabling the function
+ tracer in builds with CONFIG_PREEMPT_TRACER=y. Ubuntu does not enable
+ CONFIG_PREEMPT_TRACER, so this will only be a problem if that changes.
[Test Case]
+
[Regression Risk]
** Changed in: linux (Ubuntu)
Status: Incomplete => Confirmed
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https://bugs.launchpad.net/bugs/1713821
Title:
arm64 arch_timer fixes
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