From mboxrd@z Thu Jan 1 00:00:00 1970 From: mlangsdo@redhat.com (Mark Langsdorf) Date: Thu, 31 May 2018 12:08:32 -0500 Subject: [PATCH v2 2/2] arm64: cpufeature: always log KPTI setting on boot In-Reply-To: <20180531170832.14263-1-mlangsdo@redhat.com> References: <20180531170832.14263-1-mlangsdo@redhat.com> Message-ID: <20180531170832.14263-3-mlangsdo@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Always log KPTI setting at boot time, whether or not KPTI was forced by a kernel parameter. Signed-off-by: Mark Langsdorf --- arch/arm64/kernel/cpufeature.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 7c5d8712..2bfbbe4 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -860,6 +860,7 @@ static bool has_cache_dic(const struct arm64_cpu_capabilities *entry, #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ +static bool __pti_enabled; static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, int scope) @@ -884,21 +885,26 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, /* Forced? */ if (__kpti_forced) { + __pti_enabled = __kpti_forced > 0; pr_info_once("kernel page table isolation forced %s by %s\n", - __kpti_forced > 0 ? "ON" : "OFF", str); - return __kpti_forced > 0; - } - - /* Useful for KASLR robustness */ - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) - return true; + __pti_enabled ? "ON" : "OFF", str); + } else { + str = "default"; + /* Useful for KASLR robustness */ + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) + __pti_enabled = true; + /* Don't force KPTI for CPUs that are not vulnerable */ + else if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) + __pti_enabled = false; + /* Defer to CPU feature registers */ + else + __pti_enabled = !has_cpuid_feature(entry, scope); - /* Don't force KPTI for CPUs that are not vulnerable */ - if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) - return false; + pr_info_once("kernel page table isolation %s by %s\n", + __pti_enabled ? "ON" : "OFF", str); + } - /* Defer to CPU feature registers */ - return !has_cpuid_feature(entry, scope); + return __pti_enabled; } static void -- 2.9.5