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kexec: move vmcoreinfo out of the kernel's .bss section
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. Link: http://lkml.kernel.org/r/1493281021-20737-1-git-send-email-xlpang@redhat.com Signed-off-by: Xunlei Pang <xlpang@redhat.com> Tested-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Reviewed-by: Juergen Gross <jgross@suse.com> Suggested-by: Eric Biederman <ebiederm@xmission.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Young <dyoung@redhat.com> Cc: Hari Bathini <hbathini@linux.vnet.ibm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -163,8 +163,3 @@ void arch_crash_save_vmcoreinfo(void)
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#endif
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}
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phys_addr_t paddr_vmcoreinfo_note(void)
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{
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return ia64_tpa((unsigned long)(char *)&vmcoreinfo_note);
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}
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@ -246,6 +246,7 @@ void arch_crash_save_vmcoreinfo(void)
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VMCOREINFO_SYMBOL(lowcore_ptr);
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VMCOREINFO_SYMBOL(high_memory);
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VMCOREINFO_LENGTH(lowcore_ptr, NR_CPUS);
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mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note());
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}
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void machine_shutdown(void)
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@ -496,11 +496,6 @@ static void __init setup_memory_end(void)
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pr_notice("The maximum memory size is %luMB\n", memory_end >> 20);
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}
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static void __init setup_vmcoreinfo(void)
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{
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mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note());
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}
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#ifdef CONFIG_CRASH_DUMP
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/*
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@ -939,7 +934,6 @@ void __init setup_arch(char **cmdline_p)
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#endif
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setup_resources();
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setup_vmcoreinfo();
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setup_lowcore();
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smp_fill_possible_mask();
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cpu_detect_mhz_feature();
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@ -457,7 +457,7 @@ static int prepare_elf64_headers(struct crash_elf_data *ced,
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bufp += sizeof(Elf64_Phdr);
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phdr->p_type = PT_NOTE;
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phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
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phdr->p_filesz = phdr->p_memsz = sizeof(vmcoreinfo_note);
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phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
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(ehdr->e_phnum)++;
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#ifdef CONFIG_X86_64
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@ -2693,8 +2693,8 @@ EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
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phys_addr_t paddr_vmcoreinfo_note(void)
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{
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if (xen_pv_domain())
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return virt_to_machine(&vmcoreinfo_note).maddr;
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return virt_to_machine(vmcoreinfo_note).maddr;
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else
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return __pa_symbol(&vmcoreinfo_note);
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return __pa(vmcoreinfo_note);
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}
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#endif /* CONFIG_KEXEC_CORE */
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@ -19,7 +19,7 @@
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CRASH_CORE_NOTE_NAME_BYTES + \
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CRASH_CORE_NOTE_DESC_BYTES)
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#define VMCOREINFO_BYTES (4096)
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#define VMCOREINFO_BYTES PAGE_SIZE
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#define VMCOREINFO_NOTE_NAME "VMCOREINFO"
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#define VMCOREINFO_NOTE_NAME_BYTES ALIGN(sizeof(VMCOREINFO_NOTE_NAME), 4)
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#define VMCOREINFO_NOTE_SIZE ((CRASH_CORE_NOTE_HEAD_BYTES * 2) + \
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@ -56,7 +56,7 @@ phys_addr_t paddr_vmcoreinfo_note(void);
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#define VMCOREINFO_CONFIG(name) \
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vmcoreinfo_append_str("CONFIG_%s=y\n", #name)
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extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
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extern u32 *vmcoreinfo_note;
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extern size_t vmcoreinfo_size;
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extern size_t vmcoreinfo_max_size;
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@ -14,10 +14,10 @@
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#include <asm/sections.h>
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/* vmcoreinfo stuff */
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static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
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u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
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static unsigned char *vmcoreinfo_data;
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size_t vmcoreinfo_size;
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size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
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size_t vmcoreinfo_max_size = VMCOREINFO_BYTES;
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u32 *vmcoreinfo_note;
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/*
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* parsing the "crashkernel" commandline
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@ -326,6 +326,9 @@ static void update_vmcoreinfo_note(void)
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void crash_save_vmcoreinfo(void)
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{
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if (!vmcoreinfo_note)
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return;
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vmcoreinfo_append_str("CRASHTIME=%ld\n", get_seconds());
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update_vmcoreinfo_note();
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}
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@ -356,11 +359,26 @@ void __weak arch_crash_save_vmcoreinfo(void)
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phys_addr_t __weak paddr_vmcoreinfo_note(void)
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{
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return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note);
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return __pa(vmcoreinfo_note);
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}
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static int __init crash_save_vmcoreinfo_init(void)
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{
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vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL);
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if (!vmcoreinfo_data) {
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pr_warn("Memory allocation for vmcoreinfo_data failed\n");
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return -ENOMEM;
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}
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vmcoreinfo_note = alloc_pages_exact(VMCOREINFO_NOTE_SIZE,
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GFP_KERNEL | __GFP_ZERO);
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if (!vmcoreinfo_note) {
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free_page((unsigned long)vmcoreinfo_data);
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vmcoreinfo_data = NULL;
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pr_warn("Memory allocation for vmcoreinfo_note failed\n");
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return -ENOMEM;
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}
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VMCOREINFO_OSRELEASE(init_uts_ns.name.release);
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VMCOREINFO_PAGESIZE(PAGE_SIZE);
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@ -134,7 +134,7 @@ static ssize_t vmcoreinfo_show(struct kobject *kobj,
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{
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phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
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return sprintf(buf, "%pa %x\n", &vmcore_base,
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(unsigned int)sizeof(vmcoreinfo_note));
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(unsigned int)VMCOREINFO_NOTE_SIZE);
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}
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KERNEL_ATTR_RO(vmcoreinfo);
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