From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227QxFvf9ikdGKRtT/tp0JTWuLnzMT2vuqxVCWeWrg5316ftvWn/XNJisPt2zlrgqtvioBRx ARC-Seal: i=1; a=rsa-sha256; t=1518709285; cv=none; d=google.com; s=arc-20160816; b=sJxwrE1rJNdub9mQ/lVp8toxrYYF/y+ExKZiS0HkxZc9GOUAy1reuB4KDbM1h4GkA8 oDtm8ojRFtrTuBJVIc4wVGazGTukDGv4PKpvpyViAolhcojVl3j0i/AgRPoPu0o9QicE 5If6qQgSJY79dUEaXz3LCo9R3C7XB+1oxU3RiEOmUgvpeV/5rRONqTvohYT9CxfA7VJ/ PS9NpAlwVpEVrOZnzpjdXDNcmRoAentHCKj4xBkDA0l3DpbN9K49ZXc97+QfEH3PK3dB 60dxkOsjZS9COX34bPLuogHyFJdbB4kFaCTONXidYj/zvbEh/hZ1W8p8wVNrl1qGM0Zp QfMA== 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=RUPGn9dJTKuY0WdlLNGthuB2Bml3Y4vmmdZFj5V0hiM=; b=EhB+aS0xBNsEGbwBW/mpMjpNe6VQ+95RpaBFFD/epP21i4inCfH7a3KqsqAmzpuNIs /MaAo9jjyh0qn8kOMkV+Nf9+m73DqEpvYLcYQZyoSermGxtJhbzZdkwSswjlgGG40IqW XDjNL1/ja4GL4iekNPNS/Aktq7aXruHNG5XiWjOHT/yzxxdFhWHlHRdXFaMtA5yVFBeA lJNHFmcC3I0FjeqwWJFrE8H5rvLBE4x3FDzQRfbQzJST6z9IYgk7ifwfDvpr3lBE2ucH 3kvmT7XqFJY8pQkIeSR173uRzSaWDLX+ZryvyMJw7IYWivzowZvTgTJcFj9Ye7/ibVBv WRzw== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 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 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Will Deacon , Marc Zyngier , Catalin Marinas Subject: [PATCH 4.15 064/202] [Variant 2/Spectre-v2] arm64: Move BP hardening to check_and_switch_context Date: Thu, 15 Feb 2018 16:16:04 +0100 Message-Id: <20180215151716.771905035@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180215151712.768794354@linuxfoundation.org> References: <20180215151712.768794354@linuxfoundation.org> User-Agent: quilt/0.65 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?1592481559754840687?= X-GMAIL-MSGID: =?utf-8?q?1592482108392274903?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marc Zyngier Commit a8e4c0a919ae upstream. We call arm64_apply_bp_hardening() from post_ttbr_update_workaround, which has the unexpected consequence of being triggered on every exception return to userspace when ARM64_SW_TTBR0_PAN is selected, even if no context switch actually occured. This is a bit suboptimal, and it would be more logical to only invalidate the branch predictor when we actually switch to a different mm. In order to solve this, move the call to arm64_apply_bp_hardening() into check_and_switch_context(), where we're guaranteed to pick a different mm context. Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- arch/arm64/mm/context.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -231,6 +231,9 @@ void check_and_switch_context(struct mm_ raw_spin_unlock_irqrestore(&cpu_asid_lock, flags); switch_mm_fastpath: + + arm64_apply_bp_hardening(); + /* * Defer TTBR0_EL1 setting for user threads to uaccess_enable() when * emulating PAN. @@ -246,8 +249,6 @@ asmlinkage void post_ttbr_update_workaro "ic iallu; dsb nsh; isb", ARM64_WORKAROUND_CAVIUM_27456, CONFIG_CAVIUM_ERRATUM_27456)); - - arm64_apply_bp_hardening(); } static int asids_init(void)