From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1173268AbdDXPSn (ORCPT ); Mon, 24 Apr 2017 11:18:43 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41054 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1173254AbdDXPSf (ORCPT ); Mon, 24 Apr 2017 11:18:35 -0400 Date: Mon, 24 Apr 2017 17:18:25 +0200 From: Michael Holzheu To: Xunlei Pang Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, akpm@linux-foundation.org, Eric Biederman , Dave Young , Baoquan He , Petr Tesarik , Hari Bathini , Juergen Gross Subject: Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section In-Reply-To: <1492688374-27903-1-git-send-email-xlpang@redhat.com> References: <1492688374-27903-1-git-send-email-xlpang@redhat.com> Organization: IBM X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.23; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17042415-0008-0000-0000-000004301779 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17042415-0009-0000-0000-00001D63C3E8 Message-Id: <20170424171825.2aafb644@TP-holzheu> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-24_12:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1704240262 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Thu, 20 Apr 2017 19:39:32 +0800 schrieb Xunlei Pang : > 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 > Cc: Michael Holzheu > Cc: Juergen Gross > Signed-off-by: Xunlei Pang Now s390 seems to work with the patches. I tested kdump and zfcpdump. Tested-by: Michael Holzheu > --- > v3->v4: > -Rebased on the latest linux-next > -Handle S390 vmcoreinfo_note properly > -Handle the newly-added xen/mmu_pv.c > > arch/ia64/kernel/machine_kexec.c | 5 ----- > arch/s390/kernel/machine_kexec.c | 1 + > arch/s390/kernel/setup.c | 6 ------ > arch/x86/kernel/crash.c | 2 +- > arch/x86/xen/mmu_pv.c | 4 ++-- > include/linux/crash_core.h | 2 +- > kernel/crash_core.c | 27 +++++++++++++++++++++++---- > kernel/ksysfs.c | 2 +- > 8 files changed, 29 insertions(+), 20 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/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c > index 49a6bd4..3d0b14a 100644 > --- a/arch/s390/kernel/machine_kexec.c > +++ b/arch/s390/kernel/machine_kexec.c > @@ -246,6 +246,7 @@ void arch_crash_save_vmcoreinfo(void) > VMCOREINFO_SYMBOL(lowcore_ptr); > VMCOREINFO_SYMBOL(high_memory); > VMCOREINFO_LENGTH(lowcore_ptr, NR_CPUS); > + mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note()); > } > > void machine_shutdown(void) > diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c > index 3ae756c..3d1d808 100644 > --- a/arch/s390/kernel/setup.c > +++ b/arch/s390/kernel/setup.c > @@ -496,11 +496,6 @@ static void __init setup_memory_end(void) > pr_notice("The maximum memory size is %luMB\n", memory_end >> 20); > } > > -static void __init setup_vmcoreinfo(void) > -{ > - mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note()); > -} > - > #ifdef CONFIG_CRASH_DUMP > > /* > @@ -939,7 +934,6 @@ void __init setup_arch(char **cmdline_p) > #endif > > setup_resources(); > - setup_vmcoreinfo(); > setup_lowcore(); > smp_fill_possible_mask(); > cpu_detect_mhz_feature(); > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > index 22217ec..44404e2 100644 > --- a/arch/x86/kernel/crash.c > +++ b/arch/x86/kernel/crash.c > @@ -457,7 +457,7 @@ 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/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c > index 9d9ae66..35543fa 100644 > --- a/arch/x86/xen/mmu_pv.c > +++ b/arch/x86/xen/mmu_pv.c > @@ -2723,8 +2723,8 @@ void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order) > phys_addr_t paddr_vmcoreinfo_note(void) > { > if (xen_pv_domain()) > - return virt_to_machine(&vmcoreinfo_note).maddr; > + return virt_to_machine(vmcoreinfo_note).maddr; > else > - return __pa_symbol(&vmcoreinfo_note); > + return __pa(vmcoreinfo_note); > } > #endif /* CONFIG_KEXEC_CORE */ > diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h > index eb71a70..ba283a2 100644 > --- a/include/linux/crash_core.h > +++ b/include/linux/crash_core.h > @@ -53,7 +53,7 @@ > #define VMCOREINFO_PHYS_BASE(value) \ > vmcoreinfo_append_str("PHYS_BASE=%lx\n", (unsigned long)value) > > -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/crash_core.c b/kernel/crash_core.c > index fcbd568..0321f04 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -14,10 +14,10 @@ > #include > > /* 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; > > /* > * parsing the "crashkernel" commandline > @@ -326,6 +326,9 @@ 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(); > } > @@ -356,11 +359,27 @@ void __weak arch_crash_save_vmcoreinfo(void) > > phys_addr_t __weak 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 23cd706..c40a4e5 100644 > --- a/kernel/ksysfs.c > +++ b/kernel/ksysfs.c > @@ -134,7 +134,7 @@ 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); >