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| author | Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> | 2016-01-13 14:50:03 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-01-25 11:09:06 +0000 |
| commit | f436b2ac90a095746beb6729b8ee8ed87c9eaede (patch) | |
| tree | a0b7c5945966d064ccdded655b690be7daf0bb75 /arch/arm64/kernel/head.S | |
| parent | 7b1af9795773d745c2a8c7d4ca5f2936e8b6adfb (diff) | |
| download | talos-obmc-linux-f436b2ac90a095746beb6729b8ee8ed87c9eaede.tar.gz talos-obmc-linux-f436b2ac90a095746beb6729b8ee8ed87c9eaede.zip | |
arm64: kernel: fix architected PMU registers unconditional access
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>
Cc: <stable@vger.kernel.org>
Fixes: 60792ad349f3 ("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>
Diffstat (limited to 'arch/arm64/kernel/head.S')
| -rw-r--r-- | arch/arm64/kernel/head.S | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index ffe9c2b6431b..917d98108b3f 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -514,9 +514,14 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems #endif /* EL2 debug */ + mrs x0, id_aa64dfr0_el1 // Check ID_AA64DFR0_EL1 PMUVer + sbfx x0, x0, #8, #4 + cmp x0, #1 + b.lt 4f // Skip if no PMU present mrs x0, pmcr_el0 // Disable debug access traps ubfx x0, x0, #11, #5 // to EL2 and allow access to msr mdcr_el2, x0 // all PMU counters from EL1 +4: /* Stage-2 translation */ msr vttbr_el2, xzr |
