From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FA52C54FCB for ; Thu, 23 Apr 2020 23:07:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EB93520784 for ; Thu, 23 Apr 2020 23:07:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728864AbgDWXHZ (ORCPT ); Thu, 23 Apr 2020 19:07:25 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50262 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728572AbgDWXGw (ORCPT ); Thu, 23 Apr 2020 19:06:52 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1jRkva-0004m9-QA; Fri, 24 Apr 2020 00:06:43 +0100 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1jRkvY-00E6xo-0t; Fri, 24 Apr 2020 00:06:40 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Russell King" , "Steven Rostedt (VMware)" , "Greg Kroah-Hartman" , "Alex Sverdlin" Date: Fri, 24 Apr 2020 00:07:06 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 199/245] ARM: 8950/1: ftrace/recordmcount: filter relocation types In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.83-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alex Sverdlin commit 927d780ee371d7e121cea4fc7812f6ef2cea461c upstream. Scenario 1, ARMv7 ================= If code in arch/arm/kernel/ftrace.c would operate on mcount() pointer the following may be generated: 00000230 : 230: b5f8 push {r3, r4, r5, r6, r7, lr} 232: b500 push {lr} 234: f7ff fffe bl 0 <__gnu_mcount_nc> 234: R_ARM_THM_CALL __gnu_mcount_nc 238: f240 0600 movw r6, #0 238: R_ARM_THM_MOVW_ABS_NC __gnu_mcount_nc 23c: f8d0 1180 ldr.w r1, [r0, #384] ; 0x180 FTRACE currently is not able to deal with it: WARNING: CPU: 0 PID: 0 at .../kernel/trace/ftrace.c:1979 ftrace_bug+0x1ad/0x230() ... CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.116-... #1 ... [] (unwind_backtrace) from [] (show_stack+0x11/0x14) [] (show_stack) from [] (dump_stack+0x81/0xa8) [] (dump_stack) from [] (warn_slowpath_common+0x69/0x90) [] (warn_slowpath_common) from [] (warn_slowpath_null+0x17/0x1c) [] (warn_slowpath_null) from [] (ftrace_bug+0x1ad/0x230) [] (ftrace_bug) from [] (ftrace_process_locs+0x27d/0x444) [] (ftrace_process_locs) from [] (ftrace_init+0x91/0xe8) [] (ftrace_init) from [] (start_kernel+0x34b/0x358) [] (start_kernel) from [<00308095>] (0x308095) ---[ end trace cb88537fdc8fa200 ]--- ftrace failed to modify [] prealloc_fixed_plts+0x8/0x60 actual: 44:f2:e1:36 ftrace record flags: 0 (0) expected tramp: c03143e9 Scenario 2, ARMv4T ================== ftrace: allocating 14435 entries in 43 pages ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2029 ftrace_bug+0x204/0x310 CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.5 #1 Hardware name: Cirrus Logic EDB9302 Evaluation Board [] (unwind_backtrace) from [] (show_stack+0x20/0x2c) [] (show_stack) from [] (dump_stack+0x20/0x30) [] (dump_stack) from [] (__warn+0xdc/0x104) [] (__warn) from [] (warn_slowpath_null+0x4c/0x5c) [] (warn_slowpath_null) from [] (ftrace_bug+0x204/0x310) [] (ftrace_bug) from [] (ftrace_init+0x3b4/0x4d4) [] (ftrace_init) from [] (start_kernel+0x20c/0x410) [] (start_kernel) from [<00000000>] ( (null)) ---[ end trace 0506a2f5dae6b341 ]--- ftrace failed to modify [] perf_trace_sys_exit+0x5c/0xe8 actual: 1e:ff:2f:e1 Initializing ftrace call sites ftrace record flags: 0 (0) expected tramp: c000fb24 The analysis for this problem has been already performed previously, refer to the link below. Fix the above problems by allowing only selected reloc types in __mcount_loc. The list itself comes from the legacy recordmcount.pl script. Link: https://lore.kernel.org/lkml/56961010.6000806@pengutronix.de/ Fixes: ed60453fa8f8 ("ARM: 6511/1: ftrace: add ARM support for C version of recordmcount") Signed-off-by: Alexander Sverdlin Acked-by: Steven Rostedt (VMware) Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- scripts/recordmcount.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) --- a/scripts/recordmcount.c +++ b/scripts/recordmcount.c @@ -52,6 +52,10 @@ #define R_AARCH64_ABS64 257 #endif +#define R_ARM_PC24 1 +#define R_ARM_THM_CALL 10 +#define R_ARM_CALL 28 + static int fd_map; /* File descriptor for file being modified. */ static int mmap_failed; /* Boolean flag. */ static char gpfx; /* prefix for global symbol name (sometimes '_') */ @@ -355,6 +359,18 @@ is_mcounted_section_name(char const *con #define RECORD_MCOUNT_64 #include "recordmcount.h" +static int arm_is_fake_mcount(Elf32_Rel const *rp) +{ + switch (ELF32_R_TYPE(w(rp->r_info))) { + case R_ARM_THM_CALL: + case R_ARM_CALL: + case R_ARM_PC24: + return 0; + } + + return 1; +} + /* 64-bit EM_MIPS has weird ELF64_Rela.r_info. * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40] @@ -443,6 +459,7 @@ do_file(char const *const fname) break; case EM_ARM: reltype = R_ARM_ABS32; altmcount = "__gnu_mcount_nc"; + is_fake_mcount32 = arm_is_fake_mcount; break; case EM_AARCH64: reltype = R_AARCH64_ABS64; gpfx = '_'; break;