From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753487AbeBTRix (ORCPT ); Tue, 20 Feb 2018 12:38:53 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44240 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753359AbeBTRiE (ORCPT ); Tue, 20 Feb 2018 12:38:04 -0500 From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Steven Rostedt , Ingo Molnar , Thomas Gleixner , Linus Torvalds , Peter Zijlstra , Jason Baron , Borislav Petkov Subject: [PATCH v4 2/3] jump_label: Warn on failed jump_label patch Date: Tue, 20 Feb 2018 11:37:52 -0600 Message-Id: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When the jump label code encounters an address which isn't recognized by kernel_text_address(), it just silently fails. This can be dangerous because jump labels are used in a variety of places, and are generally expected to work. Convert the silent failure to a warning. This won't warn about attempted writes to tracepoints in __init code after initmem has been freed, as those are already guarded by the entry->code check. Signed-off-by: Josh Poimboeuf --- kernel/jump_label.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/kernel/jump_label.c b/kernel/jump_label.c index b71776576a66..b2f0b479191b 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -367,12 +367,15 @@ static void __jump_label_update(struct static_key *key, { for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { /* - * entry->code set to 0 invalidates module init text sections - * kernel_text_address() verifies we are not in core kernel - * init code, see jump_label_invalidate_module_init(). + * An entry->code of 0 indicates an entry which has been + * disabled because it was in an init text area. */ - if (entry->code && kernel_text_address(entry->code)) - arch_jump_label_transform(entry, jump_label_type(entry)); + if (entry->code) { + if (kernel_text_address(entry->code)) + arch_jump_label_transform(entry, jump_label_type(entry)); + else + WARN_ONCE(1, "can't patch jump_label at %pS", (void *)entry->code); + } } } -- 2.14.3