diff options
| author | Marc Zyngier <marc.zyngier@arm.com> | 2018-01-29 11:59:56 +0000 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2018-03-01 16:11:11 +0800 |
| commit | d3597d8823bd2f2197b84ff4550e04f970a04802 (patch) | |
| tree | 6e88c3bcd88cc238e71744ba37545b82d80a5a20 | |
| parent | 6b308a42688999555d486348b6a38567a20c59de (diff) | |
arm64: Force KPTI to be disabled on Cavium ThunderX
commit 6dc52b15c4a4 upstream.
Cavium ThunderX's erratum 27456 results in a corruption of icache
entries that are loaded from memory that is mapped as non-global
(i.e. ASID-tagged).
As KPTI is based on memory being mapped non-global, let's prevent
it from kicking in if this erratum is detected.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
[will: Update comment]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Conflicts:
using old function read_system_reg/cpus_have_cap to replace
read_sanitised_ftr_reg/cpus_have_const_cap in
arch/arm64/kernel/cpufeature.c
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 0fba6105ebd0..760c851439b1 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -753,12 +753,23 @@ static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, int __unused) { + char const *str = "command line option"; u64 pfr0 = read_system_reg(SYS_ID_AA64PFR0_EL1); - /* Forced on command line? */ + /* + * For reasons that aren't entirely clear, enabling KPTI on Cavium + * ThunderX leads to apparent I-cache corruption of kernel text, which + * ends as well as you might imagine. Don't even try. + */ + if (cpus_have_cap(ARM64_WORKAROUND_CAVIUM_27456)) { + str = "ARM64_WORKAROUND_CAVIUM_27456"; + __kpti_forced = -1; + } + + /* Forced? */ if (__kpti_forced) { - pr_info_once("kernel page table isolation forced %s by command line option\n", - __kpti_forced > 0 ? "ON" : "OFF"); + pr_info_once("kernel page table isolation forced %s by %s\n", + __kpti_forced > 0 ? "ON" : "OFF", str); return __kpti_forced > 0; } |