From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx4/YcfGVvaou34LLnaHnCvjjTUcnil9UVCwxTwsxNBpuvOQBMnYIJO7VhMIf1locQeKITP3O ARC-Seal: i=1; a=rsa-sha256; t=1523021710; cv=none; d=google.com; s=arc-20160816; b=PZ0PLonyxHS6v+QP1CNCOwIHerEnlAcqDgZisXDgfNEi0+yV3YipAcKIbTYFpiWoFk vOueUYHvW6GKQhdolz0SgVnnDKnMwWDBY8GPJxAiuZLDzKPiDCmKvRXhG/V6oLg1/GPI Leu0/0ETiujQQ+942qTib5K0R26JWWheZ90XB5TMBiRPN4/pRIDBvJbABlHg1BAXCcaj Ol5h6AXyuWg1ob0+ZrAaOvK+j1/5PE9GAUr1Wr+DdFZrMPacSSVAv1b/jN5jIQTWl23t U2Ems8Qub6Na3tP/u8unLzh6h0KkvZgrwZD/hOdrwOAHUA9MmYPi+8dIOyVYkJv3YZcY z4zg== 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=j87reN/DDdwrUMLNSJqL/TMSwRsPa5woUJ1KVf9YRNI=; b=HobpgOyQ/8TzYu0SwFVDPiSR6yQKdmoRFbCP3A2FwECJQTaLEyHvnCwaiqZn7Biqxs bNObKokMncKrErCU6evjai5Jvlqh91pONq0FSyUOnZeGL6hZ4sN7PTU1YvGtepkiXN4V VdDNkq+pzVDlaNXmjOGEtSzZu4gF3YUWHJWAfDOZgvdhO0hDV1ljBvtTFETiFZp6IFHm coy8CPagsXyXtEuZsJ8NBztrWeDIPt7DeE63IhBfPjrk22VBoY99zek4iK1FBg2GevHk Ejs0UQYmzua8HCkT+8oiU4kOla9sh2bWLNTkXscFZv2b7LgwoiOErd46YeoK78TWfv8E yVLA== 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 , Mark Rutland , Laura Abbott , Shanker Donthineni , Will Deacon , Greg Hackmann , Alex Shi Subject: [PATCH 4.9 061/102] arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks Date: Fri, 6 Apr 2018 15:23:42 +0200 Message-Id: <20180406084340.132540841@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?1597004012545038833?= X-GMAIL-MSGID: =?utf-8?q?1597004012545038833?= 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: Will Deacon commit 18011eac28c7 upstream. When unmapping the kernel at EL0, we use tpidrro_el0 as a scratch register during exception entry from native tasks and subsequently zero it in the kernel_ventry macro. We can therefore avoid zeroing tpidrro_el0 in the context-switch path for native tasks using the entry trampoline. Reviewed-by: Mark Rutland Tested-by: Laura Abbott Tested-by: Shanker Donthineni 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/process.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -306,17 +306,17 @@ int copy_thread(unsigned long clone_flag static void tls_thread_switch(struct task_struct *next) { - unsigned long tpidr, tpidrro; + unsigned long tpidr; tpidr = read_sysreg(tpidr_el0); *task_user_tls(current) = tpidr; - tpidr = *task_user_tls(next); - tpidrro = is_compat_thread(task_thread_info(next)) ? - next->thread.tp_value : 0; + if (is_compat_thread(task_thread_info(next))) + write_sysreg(next->thread.tp_value, tpidrro_el0); + else if (!arm64_kernel_unmapped_at_el0()) + write_sysreg(0, tpidrro_el0); - write_sysreg(tpidr, tpidr_el0); - write_sysreg(tpidrro, tpidrro_el0); + write_sysreg(*task_user_tls(next), tpidr_el0); } /* Restore the UAO state depending on next's addr_limit */