From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from terminus.zytor.com ([198.137.202.136]:43333 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727649AbeIJRd6 (ORCPT ); Mon, 10 Sep 2018 13:33:58 -0400 Date: Mon, 10 Sep 2018 05:39:39 -0700 From: tip-bot for Yabin Cui Message-ID: Cc: torvalds@linux-foundation.org, hpa@zytor.com, stable@vger.kernel.org, yabinc@google.com, peterz@infradead.org, linux-kernel@vger.kernel.org, namhyung@kernel.org, tglx@linutronix.de, jolsa@redhat.com, alexander.shishkin@linux.intel.com, mingo@kernel.org, acme@kernel.org Reply-To: acme@kernel.org, mingo@kernel.org, namhyung@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, peterz@infradead.org, yabinc@google.com, stable@vger.kernel.org, hpa@zytor.com, torvalds@linux-foundation.org In-Reply-To: <20180823225935.27035-1-yabinc@google.com> References: <20180823225935.27035-1-yabinc@google.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf/core: Force USER_DS when recording user stack data MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: stable-owner@vger.kernel.org List-ID: Commit-ID: 02e184476eff848273826c1d6617bb37e5bcc7ad Gitweb: https://git.kernel.org/tip/02e184476eff848273826c1d6617bb37e5bcc7ad Author: Yabin Cui AuthorDate: Thu, 23 Aug 2018 15:59:35 -0700 Committer: Ingo Molnar CommitDate: Mon, 10 Sep 2018 14:01:46 +0200 perf/core: Force USER_DS when recording user stack data Perf can record user stack data in response to a synchronous request, such as a tracepoint firing. If this happens under set_fs(KERNEL_DS), then we end up reading user stack data using __copy_from_user_inatomic() under set_fs(KERNEL_DS). I think this conflicts with the intention of using set_fs(KERNEL_DS). And it is explicitly forbidden by hardware on ARM64 when both CONFIG_ARM64_UAO and CONFIG_ARM64_PAN are used. So fix this by forcing USER_DS when recording user stack data. Signed-off-by: Yabin Cui Acked-by: Peter Zijlstra (Intel) Cc: Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 88b0193d9418 ("perf/callchain: Force USER_DS when invoking perf_callchain_user()") Link: http://lkml.kernel.org/r/20180823225935.27035-1-yabinc@google.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index abaed4f8bb7f..c80549bf82c6 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5943,6 +5943,7 @@ perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size, unsigned long sp; unsigned int rem; u64 dyn_size; + mm_segment_t fs; /* * We dump: @@ -5960,7 +5961,10 @@ perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size, /* Data. */ sp = perf_user_stack_pointer(regs); + fs = get_fs(); + set_fs(USER_DS); rem = __output_copy_user(handle, (void *) sp, dump_size); + set_fs(fs); dyn_size = dump_size - rem; perf_output_skip(handle, rem);