Commit 2e6f549f authored Feb 21, 2018 by Kees Cook Committed by Will Deacon Mar 05, 2018

arm64: cpufeature: Relocate PAN emulation report



The PAN emulation notification was only happening for non-boot CPUs
if CPU capabilities had already been configured. This seems to be the
wrong place, as it's system-wide and isn't attached to capabilities,
so its reporting didn't normally happen. Instead, report it once from
the boot CPU.

Before (missing PAN emulation report):

 SMP: Total of 4 processors activated.
 CPU features: detected feature: 32-bit EL0 Support
 CPU features: detected feature: Kernel page table isolation (KPTI)
 CPU: All CPU(s) started at EL2

After:

 SMP: Total of 4 processors activated.
 CPU features: detected feature: 32-bit EL0 Support
 CPU features: detected feature: Kernel page table isolation (KPTI)
 CPU features: emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching
 CPU: All CPU(s) started at EL2

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent 6141ac1c

arch/arm64/kernel/cpufeature.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1335,9 +1335,6 @@ static void verify_local_cpu_capabilities(void)

		if (system_supports_sve())
		verify_sve_features();

		if (system_uses_ttbr0_pan())
		pr_info("Emulating Privileged Access Never (PAN) using TTBR0_EL1 switching\n");
		}

		void check_local_cpu_capabilities(void)
		@@ -1396,6 +1393,9 @@ void __init setup_cpu_features(void)
		if (system_supports_32bit_el0())
		setup_elf_hwcaps(compat_elf_hwcaps);

		if (system_uses_ttbr0_pan())
		pr_info("emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching\n");

		sve_setup();

		/* Advertise that we have computed the system capabilities */

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