Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2996921AbdDZJvS (ORCPT ); Wed, 26 Apr 2017 05:51:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38556 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1956019AbdDZJug (ORCPT ); Wed, 26 Apr 2017 05:50:36 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 9793EC059735 Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=xpang@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 9793EC059735 Reply-To: xlpang@redhat.com Subject: Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section References: <1492688374-27903-1-git-send-email-xlpang@redhat.com> <20170426071916.GD5381@dhcp-128-65.nay.redhat.com> To: Dave Young , Xunlei Pang Cc: Juergen Gross , linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org, Baoquan He , kexec@lists.infradead.org, Petr Tesarik , linux-kernel@vger.kernel.org, Eric Biederman , Hari Bathini , akpm@linux-foundation.org, Michael Holzheu From: Xunlei Pang Message-ID: <59006DAB.8030908@redhat.com> Date: Wed, 26 Apr 2017 17:51:39 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20170426071916.GD5381@dhcp-128-65.nay.redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 26 Apr 2017 09:50:35 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8021 Lines: 229 On 04/26/2017 at 03:19 PM, Dave Young wrote: > Add ia64i list, and s390 list although Michael has tested it > > On 04/20/17 at 07:39pm, Xunlei Pang wrote: >> 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 >> --- >> 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 */ > Can we add a comment in the VMCOREINFO_BYTES header file about the one > page assumption? > > Or just define the VMCOREINFO_BYTES as PAGE_SIZE instead of 4096 Yes, I considered this before, but VMCOREINFO_BYTES is also used by VMCOREINFO_NOTE_SIZE definition which is exported to sysfs, also some platform has larger page size(64KB), so I didn't touch this 4096 value. I think I should use kmalloc() to allocate both of them, then move this comment to Patch3 kimage_crash_copy_vmcoreinfo(). Regards, Xunlei > >> + 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); >> >> -- >> 1.8.3.1 >> >> >> _______________________________________________ >> kexec mailing list >> kexec@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/kexec > Thanks > Dave > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec