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=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 8D027C433B4 for ; Fri, 23 Apr 2021 07:10:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57C7B613F6 for ; Fri, 23 Apr 2021 07:10:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241068AbhDWHLF (ORCPT ); Fri, 23 Apr 2021 03:11:05 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:44080 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240744AbhDWHLD (ORCPT ); Fri, 23 Apr 2021 03:11:03 -0400 Date: Fri, 23 Apr 2021 07:10:25 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1619161826; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xI1Pd5v0WAfXx+BahMGzaQK3b5hSGu2vsXJZGgN8dmQ=; b=ezKLFQsjK/NGSmi3kSobotOWbfRGqkY7S4gFT9T6pE8n0qZIar0kG79wtaYuRFfIEXEY12 BmIHBYbqOC+SFKop6G43gIouBASUalh02OtZ+g98CE9/4CRRgmttXCS3UCsp2UYMyNAM/C Jq4sv6Pty4Xmcl6ZMWY8vzreFkAfewBlSgabGNYqqaEclxrbqt8OOyOkaykiWNNKHM85Id Cx8DFBaRuKJDm+p0QDWb9HEE1lz46Q13HCNNVvmD/AZj1kYHo6DUAR9BevdvfaTemWjIXj j6N0fnEMEI+ZekNnQyQBwfo+iz0/NxDSxpLLgQOErTlE+VAfzLQG+i0gtzP0vA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1619161826; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xI1Pd5v0WAfXx+BahMGzaQK3b5hSGu2vsXJZGgN8dmQ=; b=xxPoY886fGoALeoeRXMyQywDj9pAFYSHzAjYRbP5RqGzHijd1Wco0UHOM/4yEwiy0yK2wD 6SSy8ixZ/5v0UmDw== From: "tip-bot2 for Marco Elver" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/core] signal, perf: Fix siginfo_t by avoiding u64 on 32-bit architectures Cc: Marek Szyprowski , Jon Hunter , Marco Elver , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210422191823.79012-1-elver@google.com> References: <20210422191823.79012-1-elver@google.com> MIME-Version: 1.0 Message-ID: <161916182563.29796.7643401185171422433.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the perf/core branch of tip: Commit-ID: 3ddb3fd8cdb0a6c11b7c8d91ba42d84c4ea3cc43 Gitweb: https://git.kernel.org/tip/3ddb3fd8cdb0a6c11b7c8d91ba42d84c4ea3cc43 Author: Marco Elver AuthorDate: Thu, 22 Apr 2021 21:18:22 +02:00 Committer: Peter Zijlstra CommitterDate: Fri, 23 Apr 2021 09:03:16 +02:00 signal, perf: Fix siginfo_t by avoiding u64 on 32-bit architectures The alignment of a structure is that of its largest member. On architectures like 32-bit Arm (but not e.g. 32-bit x86) 64-bit integers will require 64-bit alignment and not its natural word size. This means that there is no portable way to add 64-bit integers to siginfo_t on 32-bit architectures without breaking the ABI, because siginfo_t does not yet (and therefore likely never will) contain 64-bit fields on 32-bit architectures. Adding a 64-bit integer could change the alignment of the union after the 3 initial int si_signo, si_errno, si_code, thus introducing 4 bytes of padding shifting the entire union, which would break the ABI. One alternative would be to use the __packed attribute, however, it is non-standard C. Given siginfo_t has definitions outside the Linux kernel in various standard libraries that can be compiled with any number of different compilers (not just those we rely on), using non-standard attributes on siginfo_t should be avoided to ensure portability. In the case of the si_perf field, word size is sufficient since there is no exact requirement on size, given the data it contains is user-defined via perf_event_attr::sig_data. On 32-bit architectures, any excess bits of perf_event_attr::sig_data will therefore be truncated when copying into si_perf. Since si_perf is intended to disambiguate events (e.g. encoding relevant information if there are more events of the same type), 32 bits should provide enough entropy to do so on 32-bit architectures. For 64-bit architectures, no change is intended. Fixes: fb6cc127e0b6 ("signal: Introduce TRAP_PERF si_code and si_perf to siginfo") Reported-by: Marek Szyprowski Reported-by: Jon Hunter Signed-off-by: Marco Elver Signed-off-by: Peter Zijlstra (Intel) Tested-by: Marek Szyprowski Tested-by: Jon Hunter Link: https://lkml.kernel.org/r/20210422191823.79012-1-elver@google.com --- include/linux/compat.h | 2 +- include/uapi/asm-generic/siginfo.h | 2 +- tools/testing/selftests/perf_events/sigtrap_threads.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index c8821d9..f0d2dd3 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -237,7 +237,7 @@ typedef struct compat_siginfo { u32 _pkey; } _addr_pkey; /* used when si_code=TRAP_PERF */ - compat_u64 _perf; + compat_ulong_t _perf; }; } _sigfault; diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h index d0bb912..03d6f6d 100644 --- a/include/uapi/asm-generic/siginfo.h +++ b/include/uapi/asm-generic/siginfo.h @@ -92,7 +92,7 @@ union __sifields { __u32 _pkey; } _addr_pkey; /* used when si_code=TRAP_PERF */ - __u64 _perf; + unsigned long _perf; }; } _sigfault; diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c index 9c0fd44..78ddf5e 100644 --- a/tools/testing/selftests/perf_events/sigtrap_threads.c +++ b/tools/testing/selftests/perf_events/sigtrap_threads.c @@ -44,7 +44,7 @@ static struct { } ctx; /* Unique value to check si_perf is correctly set from perf_event_attr::sig_data. */ -#define TEST_SIG_DATA(addr) (~(uint64_t)(addr)) +#define TEST_SIG_DATA(addr) (~(unsigned long)(addr)) static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr) {