From patchwork Wed Jul 25 23:59:20 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Omar Sandoval X-Patchwork-Id: 10544943 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4CCD9139A for ; Wed, 25 Jul 2018 23:59:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3C1112A9C4 for ; Wed, 25 Jul 2018 23:59:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3044F2A9D4; Wed, 25 Jul 2018 23:59:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A26C62A9C4 for ; Wed, 25 Jul 2018 23:59:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728744AbeGZBNx (ORCPT ); Wed, 25 Jul 2018 21:13:53 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:40432 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728618AbeGZBNm (ORCPT ); Wed, 25 Jul 2018 21:13:42 -0400 Received: by mail-pf1-f196.google.com with SMTP id e13-v6so2198929pff.7 for ; Wed, 25 Jul 2018 16:59:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=DoMV7TytVt090kzod3DGVHCSv6oSSVhrF14RLi5zS0Q=; b=P1sFx1vYYkdRIyMcY55Bpnb8HMNJbzetxAaR2/WZKLYWP8zUgBAYpknQJjCy6U3UmG zfBPSnj+b00gUNwZCj8jblaxSQJnVYtzwvnGFGGCUFhZugPD3nBYHrq3FWvMjZU+d2T/ y9lgD5ZwxKxJhiV7Aa+eqpW33hQUlQudAnbl3MrdyZZrygje1nnKdWlU6gV4XbZsbZZp +FeSUribSeZR1xuVVDBsZcjzo5uGYiJrSGnViB/lPoaCPfkZy7YbomYUlomYPIe6yPU6 JPi49nff3u3tLmjbRGdTcVICL+cNu8JhJLKl1mPIaRpFoPARjU/dNj9qChCud2GnQIcB 1cZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=DoMV7TytVt090kzod3DGVHCSv6oSSVhrF14RLi5zS0Q=; b=o6ugl71NAfnnx9TJXyJgVjEU/jD06qXb7bT+jS1LyTyODll4z/HURHluRj6cMRQ29W QDSetO/UO9M62VVNyucZpXuBfgVij1orK490Srf0NpSy+cWJfov7mCl0EJLT5jN6DDNQ RAkt106iSd49A/vguiq899WdyNkwXdK9WFZ/ZgssJpbnXFKq46MwcPmVpR4iNDfosTwy RKmcHsWCvHHW9C7NrAWu/UeM1MdFUSYf/c4JKj0/2Dy/bT80IQFxCevIq0G+yNBRMgKF oN8q10Z8DZhmNBhHeKSOIfu1Fe/zA40EQYK1k2LiBMS3nRkr28fbMFhRMAcAhktvmbDi BtTQ== X-Gm-Message-State: AOUpUlEqqEo75ppWxfsht9mpLgiIJJM/7E+ejYsgsGt5aiLsOKEUAP/R XTYbYGXkhG06RvxhVqPtipLzNQ== X-Google-Smtp-Source: AAOMgpfqieXQ3k61Cm6pNbhqli4zjNhTk0lz9CFxEOhw8G7HXU7zAV1gg64GhvzMPuX+G7LIiyvv4g== X-Received: by 2002:a63:524e:: with SMTP id s14-v6mr22814746pgl.35.1532563177747; Wed, 25 Jul 2018 16:59:37 -0700 (PDT) Received: from vader.thefacebook.com ([2620:10d:c090:180::1:8d38]) by smtp.gmail.com with ESMTPSA id 65-v6sm23188753pfq.81.2018.07.25.16.59.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 25 Jul 2018 16:59:37 -0700 (PDT) From: Omar Sandoval To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton Cc: Alexey Dobriyan , Eric Biederman , James Morse , Bhupesh Sharma , kernel-team@fb.com Subject: [PATCH v4 9/9] proc/kcore: add vmcoreinfo note to /proc/kcore Date: Wed, 25 Jul 2018 16:59:20 -0700 Message-Id: X-Mailer: git-send-email 2.18.0 In-Reply-To: References: Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Omar Sandoval The vmcoreinfo information is useful for runtime debugging tools, not just for crash dumps. A lot of this information can be determined by other means, but this is much more convenient, and it only adds a page at most to the file. Signed-off-by: Omar Sandoval --- fs/proc/Kconfig | 1 + fs/proc/kcore.c | 18 ++++++++++++++++-- include/linux/crash_core.h | 2 ++ kernel/crash_core.c | 4 ++-- 4 files changed, 21 insertions(+), 4 deletions(-) diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig index 0eaeb41453f5..817c02b13b1d 100644 --- a/fs/proc/Kconfig +++ b/fs/proc/Kconfig @@ -31,6 +31,7 @@ config PROC_FS config PROC_KCORE bool "/proc/kcore support" if !ARM depends on PROC_FS && MMU + select CRASH_CORE help Provides a virtual ELF core file of the live kernel. This can be read with gdb and other ELF tools. No modifications can be diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 758c14e46a44..80464432dfe6 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -10,6 +10,7 @@ * Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar */ +#include #include #include #include @@ -81,10 +82,13 @@ static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len, } *phdrs_len = *nphdr * sizeof(struct elf_phdr); - *notes_len = (3 * (sizeof(struct elf_note) + ALIGN(sizeof(CORE_STR), 4)) + + *notes_len = (4 * sizeof(struct elf_note) + + 3 * ALIGN(sizeof(CORE_STR), 4) + + VMCOREINFO_NOTE_NAME_BYTES + ALIGN(sizeof(struct elf_prstatus), 4) + ALIGN(sizeof(struct elf_prpsinfo), 4) + - ALIGN(arch_task_struct_size, 4)); + ALIGN(arch_task_struct_size, 4) + + ALIGN(vmcoreinfo_size, 4)); *data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len + *notes_len); return *data_offset + size; @@ -406,6 +410,16 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) sizeof(prpsinfo)); append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current, arch_task_struct_size); + /* + * vmcoreinfo_size is mostly constant after init time, but it + * can be changed by crash_save_vmcoreinfo(). Racing here with a + * panic on another CPU before the machine goes down is insanely + * unlikely, but it's better to not leave potential buffer + * overflows lying around, regardless. + */ + append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0, + vmcoreinfo_data, + min(vmcoreinfo_size, notes_len - i)); tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index b511f6d24b42..525510a9f965 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -60,6 +60,8 @@ phys_addr_t paddr_vmcoreinfo_note(void); #define VMCOREINFO_CONFIG(name) \ vmcoreinfo_append_str("CONFIG_%s=y\n", #name) +extern unsigned char *vmcoreinfo_data; +extern size_t vmcoreinfo_size; extern u32 *vmcoreinfo_note; Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type, diff --git a/kernel/crash_core.c b/kernel/crash_core.c index e7b4025c7b24..a683bfb0530f 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -14,8 +14,8 @@ #include /* vmcoreinfo stuff */ -static unsigned char *vmcoreinfo_data; -static size_t vmcoreinfo_size; +unsigned char *vmcoreinfo_data; +size_t vmcoreinfo_size; u32 *vmcoreinfo_note; /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */