From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from szxga03-in.huawei.com ([119.145.14.66]:27116 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751705AbcBBDxj (ORCPT ); Mon, 1 Feb 2016 22:53:39 -0500 From: Hanjun Guo To: , CC: Subject: >From 3ebb85898a0542dcccaa3ab6e7b559ed6a4ff50f Mon Sep 17 00:00:00 2001 Date: Tue, 2 Feb 2016 11:49:53 +0800 Message-ID: <1454384995-10592-2-git-send-email-guohanjun@huawei.com> In-Reply-To: <1454384995-10592-1-git-send-email-guohanjun@huawei.com> References: <1454384995-10592-1-git-send-email-guohanjun@huawei.com> MIME-Version: 1.0 Content-Type: text/plain Sender: stable-owner@vger.kernel.org List-ID: commit 04d7e098f541769721d7511d56aea4b976fd29fd upstream. If a syscall is entered without TIF_SYSCALL_TRACE set, then it goes on the fast path. It's then possible to have TIF_SYSCALL_TRACE added in the middle of the syscall, but ret_fast_syscall doesn't check this flag again. This causes a ptrace syscall-exit-stop to be missed. For instance, from a PTRACE_EVENT_FORK reported during do_fork, the tracer might resume with PTRACE_SYSCALL, setting TIF_SYSCALL_TRACE. Now the completion of the fork should have a syscall-exit-stop. Russell King fixed this on arm by re-checking _TIF_SYSCALL_WORK in the fast exit path. Do the same on arm64. Reviewed-by: Will Deacon Cc: Russell King Signed-off-by: Josh Stone Signed-off-by: Catalin Marinas Signed-off-by: Hanjun Guo --- arch/arm64/kernel/entry.S | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index bddd04d..6657a09 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -609,11 +609,16 @@ ENDPROC(cpu_switch_to) */ ret_fast_syscall: disable_irq // disable interrupts - ldr x1, [tsk, #TI_FLAGS] + ldr x1, [tsk, #TI_FLAGS] // re-check for syscall tracing + and x2, x1, #_TIF_SYSCALL_WORK + cbnz x2, ret_fast_syscall_trace and x2, x1, #_TIF_WORK_MASK cbnz x2, fast_work_pending enable_step_tsk x1, x2 kernel_exit 0, ret = 1 +ret_fast_syscall_trace: + enable_irq // enable interrupts + b __sys_trace_return /* * Ok, we need to do extra processing, enter the slow path. -- 1.9.1