mirror of https://gitee.com/openkylin/linux.git
s390/kdump: Fix elfcorehdr size calculation
Before the memory for the elfcorehdr is allocated the required size is
estimated with
alloc_size = 0x1000 + get_cpu_cnt() * 0x4a0 +
mem_chunk_cnt * sizeof(Elf64_Phdr);
Where 0x4a0 is used as size for the ELF notes to store the register
contend. This size is 8 bytes too small. Usually this does not immediately
cause a problem because the page reserved for overhead (Elf_Ehdr,
vmcoreinfo, etc.) is pretty generous. So usually there is enough spare
memory to counter the mis-calculated per cpu size. However, with growing
overhead and/or a huge cpu count the allocated size gets too small for the
elfcorehdr. Ultimately a BUG_ON is triggered causing the crash kernel to
panic.
Fix this by properly calculating the required size instead of relying on
magic numbers.
Fixes: a62bc07392
("s390/kdump: add support for vector extension")
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
parent
5223c67167
commit
8cce437fbb
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@ -306,6 +306,15 @@ static void *kzalloc_panic(int len)
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return rc;
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}
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static const char *nt_name(Elf64_Word type)
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{
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const char *name = "LINUX";
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if (type == NT_PRPSINFO || type == NT_PRSTATUS || type == NT_PRFPREG)
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name = KEXEC_CORE_NOTE_NAME;
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return name;
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}
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/*
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* Initialize ELF note
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*/
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@ -332,11 +341,26 @@ static void *nt_init_name(void *buf, Elf64_Word type, void *desc, int d_len,
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static inline void *nt_init(void *buf, Elf64_Word type, void *desc, int d_len)
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{
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const char *note_name = "LINUX";
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return nt_init_name(buf, type, desc, d_len, nt_name(type));
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}
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if (type == NT_PRPSINFO || type == NT_PRSTATUS || type == NT_PRFPREG)
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note_name = KEXEC_CORE_NOTE_NAME;
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return nt_init_name(buf, type, desc, d_len, note_name);
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/*
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* Calculate the size of ELF note
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*/
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static size_t nt_size_name(int d_len, const char *name)
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{
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size_t size;
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size = sizeof(Elf64_Nhdr);
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size += roundup(strlen(name) + 1, 4);
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size += roundup(d_len, 4);
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return size;
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}
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static inline size_t nt_size(Elf64_Word type, int d_len)
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{
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return nt_size_name(d_len, nt_name(type));
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}
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/*
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@ -374,6 +398,29 @@ static void *fill_cpu_elf_notes(void *ptr, int cpu, struct save_area *sa)
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return ptr;
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}
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/*
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* Calculate size of ELF notes per cpu
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*/
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static size_t get_cpu_elf_notes_size(void)
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{
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struct save_area *sa = NULL;
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size_t size;
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size = nt_size(NT_PRSTATUS, sizeof(struct elf_prstatus));
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size += nt_size(NT_PRFPREG, sizeof(elf_fpregset_t));
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size += nt_size(NT_S390_TIMER, sizeof(sa->timer));
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size += nt_size(NT_S390_TODCMP, sizeof(sa->todcmp));
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size += nt_size(NT_S390_TODPREG, sizeof(sa->todpreg));
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size += nt_size(NT_S390_CTRS, sizeof(sa->ctrs));
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size += nt_size(NT_S390_PREFIX, sizeof(sa->prefix));
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if (MACHINE_HAS_VX) {
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size += nt_size(NT_S390_VXRS_HIGH, sizeof(sa->vxrs_high));
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size += nt_size(NT_S390_VXRS_LOW, sizeof(sa->vxrs_low));
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}
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return size;
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}
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/*
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* Initialize prpsinfo note (new kernel)
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*/
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@ -429,6 +476,30 @@ static void *nt_vmcoreinfo(void *ptr)
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return nt_init_name(ptr, 0, vmcoreinfo, size, "VMCOREINFO");
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}
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static size_t nt_vmcoreinfo_size(void)
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{
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const char *name = "VMCOREINFO";
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char nt_name[11];
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Elf64_Nhdr note;
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void *addr;
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if (copy_oldmem_kernel(&addr, &S390_lowcore.vmcore_info, sizeof(addr)))
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return 0;
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if (copy_oldmem_kernel(¬e, addr, sizeof(note)))
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return 0;
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memset(nt_name, 0, sizeof(nt_name));
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if (copy_oldmem_kernel(nt_name, addr + sizeof(note),
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sizeof(nt_name) - 1))
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return 0;
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if (strcmp(nt_name, name) != 0)
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return 0;
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return nt_size_name(note.n_descsz, name);
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}
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/*
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* Initialize final note (needed for /proc/vmcore code)
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*/
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@ -539,6 +610,27 @@ static void *notes_init(Elf64_Phdr *phdr, void *ptr, u64 notes_offset)
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return ptr;
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}
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static size_t get_elfcorehdr_size(int mem_chunk_cnt)
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{
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size_t size;
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size = sizeof(Elf64_Ehdr);
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/* PT_NOTES */
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size += sizeof(Elf64_Phdr);
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/* nt_prpsinfo */
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size += nt_size(NT_PRPSINFO, sizeof(struct elf_prpsinfo));
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/* regsets */
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size += get_cpu_cnt() * get_cpu_elf_notes_size();
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/* nt_vmcoreinfo */
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size += nt_vmcoreinfo_size();
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/* nt_final */
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size += sizeof(Elf64_Nhdr);
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/* PT_LOADS */
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size += mem_chunk_cnt * sizeof(Elf64_Phdr);
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return size;
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}
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/*
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* Create ELF core header (new kernel)
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*/
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@ -566,8 +658,8 @@ int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
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mem_chunk_cnt = get_mem_chunk_cnt();
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alloc_size = 0x1000 + get_cpu_cnt() * 0x4a0 +
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mem_chunk_cnt * sizeof(Elf64_Phdr);
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alloc_size = get_elfcorehdr_size(mem_chunk_cnt);
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hdr = kzalloc_panic(alloc_size);
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/* Init elf header */
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ptr = ehdr_init(hdr, mem_chunk_cnt);
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