Re: [PATCH v5 19/26] powerpc/book3s64/kuap: Move KUAP related function outside radix
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2020-07-06 12:41:34
"Aneesh Kumar K.V" [off-list ref] writes:
The next set of patches adds support for kuap with hash translation.
That's no longer true of this series.
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c index 0d72c0246052..e93b65a0e6e7 100644 --- a/arch/powerpc/mm/book3s64/pkeys.c +++ b/arch/powerpc/mm/book3s64/pkeys.c@@ -199,6 +200,24 @@ void __init pkey_early_init_devtree(void) return; } +#ifdef CONFIG_PPC_KUAP +void __init setup_kuap(bool disabled) +{ + if (disabled || !early_radix_enabled()) + return; + + if (smp_processor_id() == boot_cpuid) { + pr_info("Activating Kernel Userspace Access Prevention\n"); + cur_cpu_spec->mmu_features |= MMU_FTR_RADIX_KUAP; + } + + /* Make sure userspace can't change the AMR */ + mtspr(SPRN_UAMOR, 0); + mtspr(SPRN_AMR, AMR_KUAP_BLOCKED); + isync(); +} +#endif
This makes this code depend on CONFIG_PPC_MEM_KEYS=y, which it didn't used to. That risks breaking people's existing .configs, if they have PPC_MEM_KEYS=n they will now lose KUAP. And I'm not convinced the two features should be tied together, at least at the user-visible Kconfig level. cheers