arm64: kernel: fix architected PMU registers unconditional access

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commit f436b2ac90 upstream.

The Performance Monitors extension is an optional feature of the
AArch64 architecture, therefore, in order to access Performance
Monitors registers safely, the kernel should detect the architected
PMU unit presence through the ID_AA64DFR0_EL1 register PMUVer field
before accessing them.

This patch implements a guard by reading the ID_AA64DFR0_EL1 register
PMUVer field to detect the architected PMU presence and prevent accessing
PMU system registers if the Performance Monitors extension is not
implemented in the core.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: 60792ad349 ("arm64: kernel: enforce pmuserenr_el0 initialization and restore")
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Lorenzo Pieralisi 2016-01-13 14:50:03 +00:00 • committed by Greg Kroah-Hartman

parent f50c2907a9

commit 9497f702ab

3 changed files with 19 additions and 2 deletions

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5

arch/arm64/kernel/head.S

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12

arch/arm64/mm/proc-macros.S

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arch/arm64/mm/proc.S

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