forked from Minki/linux
arm64: kernel: enforce pmuserenr_el0 initialization and restore
The pmuserenr_el0 register value is architecturally UNKNOWN on reset. Current kernel code resets that register value iff the core pmu device is correctly probed in the kernel. On platforms with missing DT pmu nodes (or disabled perf events in the kernel), the pmu is not probed, therefore the pmuserenr_el0 register is not reset in the kernel, which means that its value retains the reset value that is architecturally UNKNOWN (system may run with eg pmuserenr_el0 == 0x1, which means that PMU counters access is available at EL0, which must be disallowed). This patch adds code that resets pmuserenr_el0 on cold boot and restores it on core resume from shutdown, so that the pmuserenr_el0 setup is always enforced in the kernel. Cc: <stable@vger.kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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@ -705,9 +705,6 @@ static void armv8pmu_reset(void *info)
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/* Initialize & Reset PMNC: C and P bits. */
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armv8pmu_pmcr_write(ARMV8_PMCR_P | ARMV8_PMCR_C);
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/* Disable access from userspace. */
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asm volatile("msr pmuserenr_el0, %0" :: "r" (0));
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}
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static int armv8_pmuv3_map_event(struct perf_event *event)
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@ -117,6 +117,7 @@ ENTRY(cpu_do_resume)
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*/
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ubfx x11, x11, #1, #1
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msr oslar_el1, x11
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msr pmuserenr_el0, xzr // Disable PMU access from EL0
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mov x0, x12
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dsb nsh // Make sure local tlb invalidation completed
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isb
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@ -155,6 +156,7 @@ ENTRY(__cpu_setup)
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msr cpacr_el1, x0 // Enable FP/ASIMD
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mov x0, #1 << 12 // Reset mdscr_el1 and disable
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msr mdscr_el1, x0 // access to the DCC from EL0
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msr pmuserenr_el0, xzr // Disable PMU access from EL0
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/*
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* Memory region attributes for LPAE:
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*
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