From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754911AbcJKUks (ORCPT ); Tue, 11 Oct 2016 16:40:48 -0400 Received: from mout.kundenserver.de ([212.227.17.24]:54629 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753113AbcJKUkq (ORCPT ); Tue, 11 Oct 2016 16:40:46 -0400 From: Arnd Bergmann To: Josh Poimboeuf Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Denys Vlasenko Subject: Re: [PATCH] [RFC] x86: avoid -mtune=atom for objtool warnings Date: Tue, 11 Oct 2016 22:38:42 +0200 Message-ID: <2252957.Vm1BYSSRqP@wuerfel> User-Agent: KMail/5.1.3 (Linux/4.4.0-34-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: <20161011155146.icyl3zewdvmms2h2@treble> References: <20161010125709.1870563-1-arnd@arndb.de> <20161011150541.opini6gbolmnpzy5@treble> <20161011155146.icyl3zewdvmms2h2@treble> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:SlHXDR5127XVQuFQPvfb1fhmKoXoOLHSnN15UllM4ivrnqW9nQ6 lfIJ361GBRWWxDI5XZuy15k7lkMu0BXVejI7vuFfBl+42yk9sGGv8erMrKZtIzkTGDQNPSN bBSviOHMojGOuIZn5SuVwRmwU9jj4FM+e1W81Iewkzg0YSIe+ljMwc3mTxMvjd1rayBeFIg krEVCwclhNVRqxeA+Ss9w== X-UI-Out-Filterresults: notjunk:1;V01:K0:DeOW1TOA/gw=:9+MTmYTA8joGLfPgOr/nSg G9d1hLMnB8YCiduuX6gVhRADc3owOsaOrmglBI1Q+d4TvHc4xCyteUIBPz/CMcoKzGqe0vgDX oYfcyyIIUQHoFoqanOkhSpkyNfLB84jjyfsXN50mqlq/bHjf0+yyEt9bqKmTcT24nbCWHNHJ2 3OMszNHpj86uHKUY5Id8QEh4QVAiHLEkkN6Y4TYiitKzWvFWmqQ3fmS5i6OhJVUi8C3eeb2Gv pqmOsmBBjAVbNZ+TxfCXp1E3X6u7cxlp68NQ3Hgkz1jD0vjZAut4+B9qMFyGge3W4oTbu/pwZ OfcMYM5F/bzQm66/uBwXFMjlQi1TWYHShGn7frYztdyUQ+jaDvZ+pyOTYMPda2FCGLklF3Z4U Q6Vl7va2h3qrbZjat00o1G1cho/nmGpSJu6U/PhVmEpIdQx0epF3y2A0pyq0gLQiqB2pvDFeR TnmfKr0gM+zMqgDUTPIHFbPq1ec0pRoew8FymCBFCFFUOQmyAs4fJ484otRif3bwqFpHcysLJ iNNMqMqmB87ybmjWulP+SZwW8P6M6BoTchwuyA0BiJhxYHg9LYq0zhDlq/FHX3YKXECYLQOiY fviBIiR9CdF9nYJTMlIcDwYuOBx/qo0w8ClaS6WrDmotLZABtCaCoSvdKLzs3ewOArfttWw+9 D5BZ5JPJnos1MyFVMnyyACBb9j/UELtA3qv2IS+baStEXU565zOgt+/rXxSLPpxoHW3zXYc6r 7WZwOHauB7dTlD74 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, October 11, 2016 10:51:46 AM CEST Josh Poimboeuf wrote: > > 3) 0xFC244C03-config: > drivers/scsi/fnic/fnic_main.o: warning: objtool: fnic_log_q_error() falls through to next function fnic_handle_link_event() > drivers/scsi/snic/snic_res.o: warning: objtool: .text: unexpected end of section > > These look like another bad gcc bug which is truncating functions: Same bug for both of them? > > 0000000000000940 : > 940: 55 push %rbp > 941: 48 89 e5 mov %rsp,%rbp > 944: 53 push %rbx > 945: 48 89 fb mov %rdi,%rbx > 948: e8 00 00 00 00 callq 94d > 949: R_X86_64_PC32 __sanitizer_cov_trace_pc-0x4 > 94d: 8b 83 58 02 00 00 mov 0x258(%rbx),%eax > 953: 85 c0 test %eax,%eax > 955: 75 08 jne 95f > 957: e8 00 00 00 00 callq 95c > 958: R_X86_64_PC32 __sanitizer_cov_trace_pc-0x4 > 95c: 5b pop %rbx > 95d: 5d pop %rbp > 95e: c3 retq > 95f: e8 00 00 00 00 callq 964 > 960: R_X86_64_PC32 __sanitizer_cov_trace_pc-0x4 > 964: 48 8b 83 10 1c 00 00 mov 0x1c10(%rbx),%rax > 96b: 48 8d 78 50 lea 0x50(%rax),%rdi > 96f: e8 00 00 00 00 callq 974 > 970: R_X86_64_PC32 ioread32-0x4 > 974: 83 bb 58 02 00 00 01 cmpl $0x1,0x258(%rbx) > 97b: 76 da jbe 957 > 97d: e8 00 00 00 00 callq 982 > 97e: R_X86_64_PC32 __sanitizer_cov_trace_pc-0x4 > > [end of file] > > Notice how it just falls off the end of the function. We had a similar > bug before: > > https://lkml.kernel.org/r/20160413033649.7r3msnmo3trtq47z@treble I remember that nightmare :( > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646 > > I'm not sure yet if this is the same gcc bug or a different one. Maybe > it's related to the new GCC_PLUGIN_SANCOV? I've reduced one of the test cases to this now: /* gcc-6 -O2 -fno-strict-aliasing -fno-reorder-blocks -fno-omit-frame-pointer -Wno-pointer-sign -fsanitize-coverage=trace-pc -Wall -Werror -c snic_res.c -o snic_res.o */ typedef int spinlock_t; extern unsigned int ioread32(void *); struct vnic_wq_ctrl { unsigned int error_status; }; struct vnic_wq { struct vnic_wq_ctrl *ctrl; } mempool_t; struct snic { unsigned int wq_count; __attribute__ ((__aligned__)) struct vnic_wq wq[1]; spinlock_t wq_lock[1]; }; unsigned int snic_log_q_error_err_status; void snic_log_q_error(struct snic *snic) { unsigned int i; for (i = 0; i < snic->wq_count; i++) snic_log_q_error_err_status = ioread32(&snic->wq[i].ctrl->error_status); } which gets compiled into 0000000000000000 : 0: 55 push %rbp 1: 48 89 e5 mov %rsp,%rbp 4: 53 push %rbx 5: 48 89 fb mov %rdi,%rbx 8: 48 83 ec 08 sub $0x8,%rsp c: e8 00 00 00 00 callq 11 d: R_X86_64_PC32 __sanitizer_cov_trace_pc-0x4 11: 8b 03 mov (%rbx),%eax 13: 85 c0 test %eax,%eax 15: 75 11 jne 28 17: 48 83 c4 08 add $0x8,%rsp 1b: 5b pop %rbx 1c: 5d pop %rbp 1d: e9 00 00 00 00 jmpq 22 1e: R_X86_64_PC32 __sanitizer_cov_trace_pc-0x4 22: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1) 28: e8 00 00 00 00 callq 2d 29: R_X86_64_PC32 __sanitizer_cov_trace_pc-0x4 2d: 48 8b 7b 10 mov 0x10(%rbx),%rdi 31: e8 00 00 00 00 callq 36 32: R_X86_64_PC32 ioread32-0x4 36: 89 05 00 00 00 00 mov %eax,0x0(%rip) # 3c 38: R_X86_64_PC32 snic_log_q_error_err_status-0x4 3c: 83 3b 01 cmpl $0x1,(%rbx) 3f: 76 d6 jbe 17 41: e8 00 00 00 00 callq 46 42: R_X86_64_PC32 __sanitizer_cov_trace_pc-0x4 Arnd