Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752768AbdCTFs3 (ORCPT ); Mon, 20 Mar 2017 01:48:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42366 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751467AbdCTFs1 (ORCPT ); Mon, 20 Mar 2017 01:48:27 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 2536061D01 Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=xlpang@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 2536061D01 From: Xunlei Pang To: linux-kernel@vger.kernel.org, kexec@lists.infradead.org Cc: akpm@linux-foundation.org, Eric Biederman , Dave Young , Baoquan He , Petr Tesarik , Mahesh Salgaonkar , Xunlei Pang Subject: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section Date: Mon, 20 Mar 2017 13:50:31 +0800 Message-Id: <1489989033-1179-1-git-send-email-xlpang@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Mon, 20 Mar 2017 05:48:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4693 Lines: 138 As Eric said, "what we need to do is move the variable vmcoreinfo_note out of the kernel's .bss section. And modify the code to regenerate and keep this information in something like the control page. Definitely something like this needs a page all to itself, and ideally far away from any other kernel data structures. I clearly was not watching closely the data someone decided to keep this silly thing in the kernel's .bss section." This patch allocates extra pages for these vmcoreinfo_XXX variables, one advantage is that it enhances some safety of vmcoreinfo, because vmcoreinfo now is kept far away from other kernel data structures. Suggested-by: Eric Biederman Signed-off-by: Xunlei Pang --- arch/ia64/kernel/machine_kexec.c | 5 ----- arch/x86/kernel/crash.c | 2 +- include/linux/kexec.h | 2 +- kernel/kexec_core.c | 29 ++++++++++++++++++++++++----- kernel/ksysfs.c | 2 +- 5 files changed, 27 insertions(+), 13 deletions(-) diff --git a/arch/ia64/kernel/machine_kexec.c b/arch/ia64/kernel/machine_kexec.c index 599507b..c14815d 100644 --- a/arch/ia64/kernel/machine_kexec.c +++ b/arch/ia64/kernel/machine_kexec.c @@ -163,8 +163,3 @@ void arch_crash_save_vmcoreinfo(void) #endif } -phys_addr_t paddr_vmcoreinfo_note(void) -{ - return ia64_tpa((unsigned long)(char *)&vmcoreinfo_note); -} - diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 3741461..4d35fbb 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -456,7 +456,7 @@ static int prepare_elf64_headers(struct crash_elf_data *ced, bufp += sizeof(Elf64_Phdr); phdr->p_type = PT_NOTE; phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note(); - phdr->p_filesz = phdr->p_memsz = sizeof(vmcoreinfo_note); + phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE; (ehdr->e_phnum)++; #ifdef CONFIG_X86_64 diff --git a/include/linux/kexec.h b/include/linux/kexec.h index e98e546..f1c601b 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -317,7 +317,7 @@ extern void *kexec_purgatory_get_symbol_addr(struct kimage *image, extern struct resource crashk_low_res; typedef u32 note_buf_t[KEXEC_NOTE_BYTES/4]; extern note_buf_t __percpu *crash_notes; -extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4]; +extern u32 *vmcoreinfo_note; extern size_t vmcoreinfo_size; extern size_t vmcoreinfo_max_size; diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index bfe62d5..e3a4bda 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -52,10 +52,10 @@ note_buf_t __percpu *crash_notes; /* vmcoreinfo stuff */ -static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES]; -u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4]; +static unsigned char *vmcoreinfo_data; size_t vmcoreinfo_size; -size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data); +size_t vmcoreinfo_max_size = VMCOREINFO_BYTES; +u32 *vmcoreinfo_note; /* Flag to indicate we are going to kexec a new kernel */ bool kexec_in_progress = false; @@ -1369,6 +1369,9 @@ static void update_vmcoreinfo_note(void) void crash_save_vmcoreinfo(void) { + if (!vmcoreinfo_note) + return; + vmcoreinfo_append_str("CRASHTIME=%ld\n", get_seconds()); update_vmcoreinfo_note(); } @@ -1397,13 +1400,29 @@ void vmcoreinfo_append_str(const char *fmt, ...) void __weak arch_crash_save_vmcoreinfo(void) {} -phys_addr_t __weak paddr_vmcoreinfo_note(void) +phys_addr_t paddr_vmcoreinfo_note(void) { - return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note); + return __pa(vmcoreinfo_note); } static int __init crash_save_vmcoreinfo_init(void) { + /* One page should be enough for VMCOREINFO_BYTES under all archs */ + vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL); + if (!vmcoreinfo_data) { + pr_warn("Memory allocation for vmcoreinfo_data failed\n"); + return -ENOMEM; + } + + vmcoreinfo_note = alloc_pages_exact(VMCOREINFO_NOTE_SIZE, + GFP_KERNEL | __GFP_ZERO); + if (!vmcoreinfo_note) { + free_page((unsigned long)vmcoreinfo_data); + vmcoreinfo_data = NULL; + pr_warn("Memory allocation for vmcoreinfo_note failed\n"); + return -ENOMEM; + } + VMCOREINFO_OSRELEASE(init_uts_ns.name.release); VMCOREINFO_PAGESIZE(PAGE_SIZE); diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index ee1bc1b..9de6fcc 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -130,7 +130,7 @@ static ssize_t vmcoreinfo_show(struct kobject *kobj, { phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); return sprintf(buf, "%pa %x\n", &vmcore_base, - (unsigned int)sizeof(vmcoreinfo_note)); + (unsigned int)VMCOREINFO_NOTE_SIZE); } KERNEL_ATTR_RO(vmcoreinfo); -- 1.8.3.1