From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx4+lkxiF731Z3Ooxgr+sfAAlKYpuL4KnJFlAO0MOS0jEcHGO20HVd4/HRvkhKpIf07sVRird ARC-Seal: i=1; a=rsa-sha256; t=1523021840; cv=none; d=google.com; s=arc-20160816; b=Z3k1AqByBA69r2uEY0R3vsdLjh0K569EZ1BUMzjbhjrOLylOOo5Tgg0hZ2gzFoECIQ megCiWXrEzok32KgpYLHBBXS9yvswyKd7al1BVVVlEcVHvWwGxn1Ovyl77o8zzm61mwn +ewtGCzSU3t7yTQFfxAji905F6tCrRreeeeHYcM+nhVZqIO3i2sBSpYDGKYluaHvs4Z+ 0izYhmUa7AHgTtPiZsYI1fCLW0xiYVZAxonb6S+iy/zjm45z8PqZp+jqjWQmVxvjbRzA ZIvOCi+5gbnNXR18t+Q0TBYaJiuWQ3VUHRrDJkKMXVphfQdZjqzi34MmH1GNEV1FTLNn CqIg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=Iv5JXZgaKLP4eXy/ibrUlmhvLP5vVkLc7t0dwtokLUI=; b=BsPGiJNov1PGsCX8ohAOR2mYavZxWo9kDw9NgnYv81XQgFz9pCCQkToLNLnhGQj0RV 4VhgNYf8i2IZ/+QQcntDTkOznV5TgCH0aumz6RXE1b3HwE0HQBW1k2lkxMsXZ8Gqg2TG 17IOCKBKs8MO3d0cfBIqCBBfgA4KsPgH1OfPndhZyqBzwdFDVkI8x4AwZ74k/Bi3s2eD xQEzKfrBuZhqPoUOvM12GUUpQiZGGY7vFKFo6sLGNaRvOOAo0PcnZpTewGkCpuOSucF+ l63v4a6MNemC+6PY0Iu+k0FYhwWcpIuZs9JLHfYm+gLsNawPa2mLu7SYHlRT9qTuVepy E3uQ== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Will Deacon , Jayachandran C , Catalin Marinas , Greg Hackmann , Alex Shi , Mark Rutland Subject: [PATCH 4.9 071/102] arm64: Turn on KPTI only on CPUs that need it Date: Fri, 6 Apr 2018 15:23:52 +0200 Message-Id: <20180406084341.470027340@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180406084331.507038179@linuxfoundation.org> References: <20180406084331.507038179@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1597004149116145630?= X-GMAIL-MSGID: =?utf-8?q?1597004149116145630?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jayachandran C commit 0ba2e29c7fc1 upstream. Whitelist Broadcom Vulcan/Cavium ThunderX2 processors in unmap_kernel_at_el0(). These CPUs are not vulnerable to CVE-2017-5754 and do not need KPTI when KASLR is off. Acked-by: Will Deacon Signed-off-by: Jayachandran C Signed-off-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Alex Shi [v4.9 backport] Signed-off-by: Mark Rutland [v4.9 backport] Tested-by: Will Deacon Tested-by: Greg Hackmann Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/cpufeature.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -766,6 +766,13 @@ static bool unmap_kernel_at_el0(const st if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) return true; + /* Don't force KPTI for CPUs that are not vulnerable */ + switch (read_cpuid_id() & MIDR_CPU_MODEL_MASK) { + case MIDR_CAVIUM_THUNDERX2: + case MIDR_BRCM_VULCAN: + return false; + } + /* Defer to CPU feature registers */ return !cpuid_feature_extract_unsigned_field(pfr0, ID_AA64PFR0_CSV3_SHIFT);