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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 0289AC433B4 for ; Wed, 5 May 2021 14:11:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5F8E613BC for ; Wed, 5 May 2021 14:11:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233843AbhEEOM1 (ORCPT ); Wed, 5 May 2021 10:12:27 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:57674 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233831AbhEEOMY (ORCPT ); Wed, 5 May 2021 10:12:24 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out01.mta.xmission.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1leIFL-003DB2-5n; Wed, 05 May 2021 08:11:27 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=fess.int.ebiederm.org) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1leIFJ-00007y-Dn; Wed, 05 May 2021 08:11:26 -0600 From: "Eric W. Beiderman" To: Marco Elver Cc: Arnd Bergmann , Florian Weimer , "David S. Miller" , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Peter Collingbourne , Dmitry Vyukov , Alexander Potapenko , sparclinux , linux-arch , Linux Kernel Mailing List , Linux API , kasan-dev , "Eric W. Biederman" Date: Wed, 5 May 2021 09:10:54 -0500 Message-Id: <20210505141101.11519-5-ebiederm@xmission.com> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210505141101.11519-1-ebiederm@xmission.com> References: <20210505141101.11519-1-ebiederm@xmission.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-XM-SPF: eid=1leIFJ-00007y-Dn;;;mid=<20210505141101.11519-5-ebiederm@xmission.com>;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX193/sNNsEzFeClA7fw6ofCtHebW1VKeDf4= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH v3 05/12] siginfo: Move si_trapno inside the union inside _si_fault X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Eric W. Biederman" It turns out that linux uses si_trapno very sparingly, and as such it can be considered extra information for a very narrow selection of signals, rather than information that is present with every fault reported in siginfo. As such move si_trapno inside the union inside of _si_fault. This results in no change in placement, and makes it eaiser to extend _si_fault in the future as this reduces the number of special cases. In particular with si_trapno included in the union it is no longer a concern that the union must be pointer alligned on most architectures because the union followes immediately after si_addr which is a pointer. This change results in a difference in siginfo field placement on sparc and alpha for the fields si_addr_lsb, si_lower, si_upper, si_pkey, and si_perf. These architectures do not implement the signals that would use si_addr_lsb, si_lower, si_upper, si_pkey, and si_perf. Further these architecture have not yet implemented the userspace that would use si_perf. The point of this change is in fact to correct these placement issues before sparc or alpha grow userspace that cares. This change was discussed[1] and the agreement is that this change is currently safe. [1]: https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com Acked-by: Marco Elver v1: https://lkml.kernel.org/r/m1tunns7yf.fsf_-_@fess.ebiederm.org Signed-off-by: "Eric W. Biederman" --- arch/sparc/kernel/signal32.c | 10 +++++----- arch/sparc/kernel/signal_64.c | 10 +++++----- arch/x86/kernel/signal_compat.c | 3 +++ include/linux/compat.h | 5 ++--- include/uapi/asm-generic/siginfo.h | 7 ++----- kernel/signal.c | 1 + 6 files changed, 18 insertions(+), 18 deletions(-) diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c index 32b977f253e3..5573722e34ad 100644 --- a/arch/sparc/kernel/signal32.c +++ b/arch/sparc/kernel/signal32.c @@ -774,10 +774,10 @@ static_assert(offsetof(compat_siginfo_t, si_int) == 0x14); static_assert(offsetof(compat_siginfo_t, si_ptr) == 0x14); static_assert(offsetof(compat_siginfo_t, si_addr) == 0x0c); static_assert(offsetof(compat_siginfo_t, si_trapno) == 0x10); -static_assert(offsetof(compat_siginfo_t, si_addr_lsb) == 0x14); -static_assert(offsetof(compat_siginfo_t, si_lower) == 0x18); -static_assert(offsetof(compat_siginfo_t, si_upper) == 0x1c); -static_assert(offsetof(compat_siginfo_t, si_pkey) == 0x18); -static_assert(offsetof(compat_siginfo_t, si_perf) == 0x14); +static_assert(offsetof(compat_siginfo_t, si_addr_lsb) == 0x10); +static_assert(offsetof(compat_siginfo_t, si_lower) == 0x14); +static_assert(offsetof(compat_siginfo_t, si_upper) == 0x18); +static_assert(offsetof(compat_siginfo_t, si_pkey) == 0x14); +static_assert(offsetof(compat_siginfo_t, si_perf) == 0x10); static_assert(offsetof(compat_siginfo_t, si_band) == 0x0c); static_assert(offsetof(compat_siginfo_t, si_fd) == 0x10); diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c index e9dda9db156c..a69a78984c36 100644 --- a/arch/sparc/kernel/signal_64.c +++ b/arch/sparc/kernel/signal_64.c @@ -584,10 +584,10 @@ static_assert(offsetof(siginfo_t, si_int) == 0x18); static_assert(offsetof(siginfo_t, si_ptr) == 0x18); static_assert(offsetof(siginfo_t, si_addr) == 0x10); static_assert(offsetof(siginfo_t, si_trapno) == 0x18); -static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x20); -static_assert(offsetof(siginfo_t, si_lower) == 0x28); -static_assert(offsetof(siginfo_t, si_upper) == 0x30); -static_assert(offsetof(siginfo_t, si_pkey) == 0x28); -static_assert(offsetof(siginfo_t, si_perf) == 0x20); +static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x18); +static_assert(offsetof(siginfo_t, si_lower) == 0x20); +static_assert(offsetof(siginfo_t, si_upper) == 0x28); +static_assert(offsetof(siginfo_t, si_pkey) == 0x20); +static_assert(offsetof(siginfo_t, si_perf) == 0x18); static_assert(offsetof(siginfo_t, si_band) == 0x10); static_assert(offsetof(siginfo_t, si_fd) == 0x14); diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c index e735bc129331..c9601f092a1e 100644 --- a/arch/x86/kernel/signal_compat.c +++ b/arch/x86/kernel/signal_compat.c @@ -133,6 +133,9 @@ static inline void signal_compat_build_tests(void) BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10); BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C); + BUILD_BUG_ON(offsetof(siginfo_t, si_trapno) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_trapno) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18); BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10); diff --git a/include/linux/compat.h b/include/linux/compat.h index f0d2dd35d408..6af7bef15e94 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -214,12 +214,11 @@ typedef struct compat_siginfo { /* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */ struct { compat_uptr_t _addr; /* faulting insn/memory ref. */ -#ifdef __ARCH_SI_TRAPNO - int _trapno; /* TRAP # which caused the signal */ -#endif #define __COMPAT_ADDR_BND_PKEY_PAD (__alignof__(compat_uptr_t) < sizeof(short) ? \ sizeof(short) : __alignof__(compat_uptr_t)) union { + /* used on alpha and sparc */ + int _trapno; /* TRAP # which caused the signal */ /* * used when si_code=BUS_MCEERR_AR or * used when si_code=BUS_MCEERR_AO diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h index 91c80d0c10c5..3503282021aa 100644 --- a/include/uapi/asm-generic/siginfo.h +++ b/include/uapi/asm-generic/siginfo.h @@ -68,9 +68,6 @@ union __sifields { /* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */ struct { void __user *_addr; /* faulting insn/memory ref. */ -#ifdef __ARCH_SI_TRAPNO - int _trapno; /* TRAP # which caused the signal */ -#endif #ifdef __ia64__ int _imm; /* immediate value for "break" */ unsigned int _flags; /* see ia64 si_flags */ @@ -80,6 +77,8 @@ union __sifields { #define __ADDR_BND_PKEY_PAD (__alignof__(void *) < sizeof(short) ? \ sizeof(short) : __alignof__(void *)) union { + /* used on alpha and sparc */ + int _trapno; /* TRAP # which caused the signal */ /* * used when si_code=BUS_MCEERR_AR or * used when si_code=BUS_MCEERR_AO @@ -155,9 +154,7 @@ typedef struct siginfo { #define si_int _sifields._rt._sigval.sival_int #define si_ptr _sifields._rt._sigval.sival_ptr #define si_addr _sifields._sigfault._addr -#ifdef __ARCH_SI_TRAPNO #define si_trapno _sifields._sigfault._trapno -#endif #define si_addr_lsb _sifields._sigfault._addr_lsb #define si_lower _sifields._sigfault._addr_bnd._lower #define si_upper _sifields._sigfault._addr_bnd._upper diff --git a/kernel/signal.c b/kernel/signal.c index c3017aa8024a..65888aec65a0 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -4607,6 +4607,7 @@ static inline void siginfo_buildtime_checks(void) /* sigfault */ CHECK_OFFSET(si_addr); + CHECK_OFFSET(si_trapno); CHECK_OFFSET(si_addr_lsb); CHECK_OFFSET(si_lower); CHECK_OFFSET(si_upper); -- 2.30.1