/* * fs/proc/vmcore.c Interface for accessing the crash * dump from the system's previous life. * Heavily borrowed from fs/proc/kcore.c * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) * Copyright (C) IBM Corporation, 2004. All rights reserved * */ #include <linux/mm.h> #include <linux/proc_fs.h> #include <linux/user.h> #include <linux/elf.h> #include <linux/elfcore.h> #include <linux/slab.h> #include <linux/highmem.h> #include <linux/bootmem.h> #include <linux/init.h> #include <linux/crash_dump.h> #include <linux/list.h> #include <asm/uaccess.h> #include <asm/io.h> /* List representing chunks of contiguous memory areas and their offsets in * vmcore file. */ static LIST_HEAD(vmcore_list); /* Stores the pointer to the buffer containing kernel elf core headers. */ static char *elfcorebuf; static size_t elfcorebuf_sz; /* Total size of vmcore file. */ static u64 vmcore_size; static struct proc_dir_entry *proc_vmcore = NULL; /* Reads a page from the oldmem device from given offset. */ static ssize_t read_from_oldmem(char *buf, size_t count, u64 *ppos, int userbuf) { unsigned long pfn, offset; size_t nr_bytes; ssize_t read = 0, tmp; if (!count) return 0; offset = (unsigned long)(*ppos % PAGE_SIZE); pfn = (unsigned long)(*ppos / PAGE_SIZE); do { if (count > (PAGE_SIZE - offset)) nr_bytes = PAGE_SIZE - offset; else nr_bytes = count; tmp = copy_oldmem_page(pfn, buf, nr_bytes, offset, userbuf); if (tmp < 0) return tmp; *ppos += nr_bytes; count -= nr_bytes; buf += nr_bytes; read += nr_bytes; ++pfn; offset = 0; } while (count); return read; } /* Maps vmcore file offset to respective physical address in memroy. */ static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list, struct vmcore **m_ptr) { struct vmcore *m; u64 paddr; list_for_each_entry(m, vc_list, list) { u64 start, end; start = m->offset; end = m->offset + m->size - 1; if (offset >= start && offset <= end) { paddr = m->paddr + offset - start; *m_ptr = m; return paddr; } } *m_ptr = NULL; return 0; } /* Read from the ELF header and then the crash dump. On error, negative value is * returned otherwise number of bytes read are returned. */ static ssize_t read_vmcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) { ssize_t acc = 0, tmp; size_t tsz; u64 start, nr_bytes; struct vmcore *curr_m = NULL; if (buflen == 0 || *fpos >= vmcore_size) return 0; /* trim buflen to not go beyond EOF */ if (buflen > vmcore_size - *fpos) buflen = vmcore_size - *fpos; /* Read ELF core header */ if (*fpos < elfcorebuf_sz) { tsz = elfcorebuf_sz - *fpos; if (buflen < tsz) tsz = buflen; if (copy_to_user(buffer, elfcorebuf + *fpos, tsz)) return -EFAULT; buflen -= tsz; *fpos += tsz; buffer += tsz; acc += tsz; /* leave now if filled buffer already */ if (buflen == 0) return acc; } start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m); if (!curr_m) return -EINVAL; if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; /* Calculate left bytes in current memory segment. */ nr_bytes = (curr_m->size - (start - curr_m->paddr)); if (tsz > nr_bytes) tsz = nr_bytes; while (buflen) { tmp = read_from_oldmem(buffer, tsz, &start, 1); if (tmp < 0) return tmp; buflen -= tsz; *fpos += tsz; buffer += tsz; acc += tsz; if (start >= (curr_m->paddr + curr_m->size)) { if (curr_m->list.next == &vmcore_list) return acc; /*EOF*/ curr_m = list_entry(curr_m->list.next, struct vmcore, list); start = curr_m->paddr; } if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; /* Calculate left bytes in current memory segment. */ nr_bytes = (curr_m->size - (start - curr_m->paddr)); if (tsz > nr_bytes) tsz = nr_bytes; } return acc; } static const struct file_operations proc_vmcore_operations = { .read = read_vmcore, .llseek = default_llseek, }; static struct vmcore* __init get_new_element(void) { return kzalloc(sizeof(struct vmcore), GFP_KERNEL); } static u64 __init get_vmcore_size_elf64(char *elfptr) { int i; u64 size; Elf64_Ehdr *ehdr_ptr; Elf64_Phdr *phdr_ptr; ehdr_ptr = (Elf64_Ehdr *)elfptr; phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr)); for (i = 0; i < ehdr_ptr->e_phnum; i++) { size += phdr_ptr->p_memsz; phdr_ptr++; } return size; } static u64 __init get_vmcore_size_elf32(char *elfptr) { int i; u64 size; Elf32_Ehdr *ehdr_ptr; Elf32_Phdr *phdr_ptr; ehdr_ptr = (Elf32_Ehdr *)elfptr; phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr)); for (i = 0; i < ehdr_ptr->e_phnum; i++) { size += phdr_ptr->p_memsz; phdr_ptr++; } return size; } /* Merges all the PT_NOTE headers into one. */ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, struct list_head *vc_list) { int i, nr_ptnote=0, rc=0; char *tmp; Elf64_Ehdr *ehdr_ptr; Elf64_Phdr phdr, *phdr_ptr; Elf64_Nhdr *nhdr_ptr; u64 phdr_sz = 0, note_off; ehdr_ptr = (Elf64_Ehdr *)elfptr; phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) { int j; void *notes_section; struct vmcore *new; u64 offset, max_sz, sz, real_sz = 0; if (phdr_ptr->p_type != PT_NOTE) continue; nr_ptnote++; max_sz = phdr_ptr->p_memsz; offset = phdr_ptr->p_offset; notes_section = kmalloc(max_sz, GFP_KERNEL); if (!notes_section) return -ENOMEM; rc = read_from_oldmem(notes_section, max_sz, &offset, 0); if (rc < 0) { kfree(notes_section); return rc; } nhdr_ptr = notes_section; for (j = 0; j < max_sz; j += sz) { if (nhdr_ptr->n_namesz == 0) break; sz = sizeof(Elf64_Nhdr) + ((nhdr_ptr->n_namesz + 3) & ~3) + ((nhdr_ptr->n_descsz + 3) & ~3); real_sz += sz; nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz); } /* Add this contiguous chunk of notes section to vmcore list.*/ new = get_new_element(); if (!new) { kfree(notes_section); return -ENOMEM; } new->paddr = phdr_ptr->p_offset; new->size = real_sz; list_add_tail(&new->list, vc_list); phdr_sz += real_sz; kfree(notes_section); } /* Prepare merged PT_NOTE program header. */ phdr.p_type = PT_NOTE; phdr.p_flags = 0; note_off = sizeof(Elf64_Ehdr) + (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr); phdr.p_offset = note_off; phdr.p_vaddr = phdr.p_paddr = 0; phdr.p_filesz = phdr.p_memsz = phdr_sz; phdr.p_align = 0; /* Add merged PT_NOTE program header*/ tmp = elfptr + sizeof(Elf64_Ehdr); memcpy(tmp, &phdr, sizeof(phdr)); tmp += sizeof(phdr); /* Remove unwanted PT_NOTE program headers. */ i = (nr_ptnote - 1) * sizeof(Elf64_Phdr); *elfsz = *elfsz - i; memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr))); /* Modify e_phnum to reflect merged headers. */ ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1; return 0; } /* Merges all the PT_NOTE headers into one. */ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, struct list_head *vc_list) { int i, nr_ptnote=0, rc=0; char *tmp; Elf32_Ehdr *ehdr_ptr; Elf32_Phdr phdr, *phdr_ptr; Elf32_Nhdr *nhdr_ptr; u64 phdr_sz = 0, note_off; ehdr_ptr = (Elf32_Ehdr *)elfptr; phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) { int j; void *notes_section; struct vmcore *new; u64 offset, max_sz, sz, real_sz = 0; if (phdr_ptr->p_type != PT_NOTE) continue; nr_ptnote++; max_sz = phdr_ptr->p_memsz; offset = phdr_ptr->p_offset; notes_section = kmalloc(max_sz, GFP_KERNEL); if (!notes_section) return -ENOMEM; rc = read_from_oldmem(notes_section, max_sz, &offset, 0); if (rc < 0) { kfree(notes_section); return rc; } nhdr_ptr = notes_section; for (j = 0; j < max_sz; j += sz) { if (nhdr_ptr->n_namesz == 0) break; sz = sizeof(Elf32_Nhdr) + ((nhdr_ptr->n_namesz + 3) & ~3) + ((nhdr_ptr->n_descsz + 3) & ~3); real_sz += sz; nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz); } /* Add this contiguous chunk of notes section to vmcore list.*/ new = get_new_element(); if (!new) { kfree(notes_section); return -ENOMEM; } new->paddr = phdr_ptr->p_offset; new->size = real_sz; list_add_tail(&new->list, vc_list); phdr_sz += real_sz; kfree(notes_section); } /* Prepare merged PT_NOTE program header. */ phdr.p_type = PT_NOTE; phdr.p_flags = 0; note_off = sizeof(Elf32_Ehdr) + (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr); phdr.p_offset = note_off; phdr.p_vaddr = phdr.p_paddr = 0; phdr.p_filesz = phdr.p_memsz = phdr_sz; phdr.p_align = 0; /* Add merged PT_NOTE program header*/ tmp = elfptr + sizeof(Elf32_Ehdr); memcpy(tmp, &phdr, sizeof(phdr)); tmp += sizeof(phdr); /* Remove unwanted PT_NOTE program headers. */ i = (nr_ptnote - 1) * sizeof(Elf32_Phdr); *elfsz = *elfsz - i; memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr))); /* Modify e_phnum to reflect merged headers. */ ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1; return 0; } /* Add memory chunks represented by program headers to vmcore list. Also update * the new offset fields of exported program headers. */ static int __init process_ptload_program_headers_elf64(char *elfptr, size_t elfsz, struct list_head *vc_list) { int i; Elf64_Ehdr *ehdr_ptr; Elf64_Phdr *phdr_ptr; loff_t vmcore_off; struct vmcore *new; ehdr_ptr = (Elf64_Ehdr *)elfptr; phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */ /* First program header is PT_NOTE header. */ vmcore_off = sizeof(Elf64_Ehdr) + (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) + phdr_ptr->p_memsz; /* Note sections */ for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) { if (phdr_ptr->p_type != PT_LOAD) continue; /* Add this contiguous chunk of memory to vmcore list.*/ new = get_new_element(); if (!new) return -ENOMEM; new->paddr = phdr_ptr->p_offset; new->size = phdr_ptr->p_memsz; list_add_tail(&new->list, vc_list); /* Update the program header offset. */ phdr_ptr->p_offset = vmcore_off; vmcore_off = vmcore_off + phdr_ptr->p_memsz; } return 0; } static int __init process_ptload_program_headers_elf32(char *elfptr, size_t elfsz, struct list_head *vc_list) { int i; Elf32_Ehdr *ehdr_ptr; Elf32_Phdr *phdr_ptr; loff_t vmcore_off; struct vmcore *new; ehdr_ptr = (Elf32_Ehdr *)elfptr; phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */ /* First program header is PT_NOTE header. */ vmcore_off = sizeof(Elf32_Ehdr) + (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) + phdr_ptr->p_memsz; /* Note sections */ for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) { if (phdr_ptr->p_type != PT_LOAD) continue; /* Add this contiguous chunk of memory to vmcore list.*/ new = get_new_element(); if (!new) return -ENOMEM; new->paddr = phdr_ptr->p_offset; new->size = phdr_ptr->p_memsz; list_add_tail(&new->list, vc_list); /* Update the program header offset */ phdr_ptr->p_offset = vmcore_off; vmcore_off = vmcore_off + phdr_ptr->p_memsz; } return 0; } /* Sets offset fields of vmcore elements. */ static void __init set_vmcore_list_offsets_elf64(char *elfptr, struct list_head *vc_list) { loff_t vmcore_off; Elf64_Ehdr *ehdr_ptr; struct vmcore *m; ehdr_ptr = (Elf64_Ehdr *)elfptr; /* Skip Elf header and program headers. */ vmcore_off = sizeof(Elf64_Ehdr) + (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr); list_for_each_entry(m, vc_list, list) { m->offset = vmcore_off; vmcore_off += m->size; } } /* Sets offset fields of vmcore elements. */ static void __init set_vmcore_list_offsets_elf32(char *elfptr, struct list_head *vc_list) { loff_t vmcore_off; Elf32_Ehdr *ehdr_ptr; struct vmcore *m; ehdr_ptr = (Elf32_Ehdr *)elfptr; /* Skip Elf header and program headers. */ vmcore_off = sizeof(Elf32_Ehdr) + (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr); list_for_each_entry(m, vc_list, list) { m->offset = vmcore_off; vmcore_off += m->size; } } static int __init parse_crash_elf64_headers(void) { int rc=0; Elf64_Ehdr ehdr; u64 addr; addr = elfcorehdr_addr; /* Read Elf header */ rc = read_from_oldmem((char*)&ehdr, sizeof(Elf64_Ehdr), &addr, 0); if (rc < 0) return rc; /* Do some basic Verification. */ if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 || (ehdr.e_type != ET_CORE) || !vmcore_elf64_check_arch(&ehdr) || ehdr.e_ident[EI_CLASS] != ELFCLASS64 || ehdr.e_ident[EI_VERSION] != EV_CURRENT || ehdr.e_version != EV_CURRENT || ehdr.e_ehsize != sizeof(Elf64_Ehdr) || ehdr.e_phentsize != sizeof(Elf64_Phdr) || ehdr.e_phnum == 0) { printk(KERN_WARNING "Warning: Core image elf header is not" "sane\n"); return -EINVAL; } /* Read in all elf headers. */ elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr); elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL); if (!elfcorebuf) return -ENOMEM; addr = elfcorehdr_addr; rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0); if (rc < 0) { kfree(elfcorebuf); return rc; } /* Merge all PT_NOTE headers into one. */ rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list); if (rc) { kfree(elfcorebuf); return rc; } rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz, &vmcore_list); if (rc) { kfree(elfcorebuf); return rc; } set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list); return 0; } static int __init parse_crash_elf32_headers(void) { int rc=0; Elf32_Ehdr ehdr; u64 addr; addr = elfcorehdr_addr; /* Read Elf header */ rc = read_from_oldmem((char*)&ehdr, sizeof(Elf32_Ehdr), &addr, 0); if (rc < 0) return rc; /* Do some basic Verification. */ if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 || (ehdr.e_type != ET_CORE) || !elf_check_arch(&ehdr) || ehdr.e_ident[EI_CLASS] != ELFCLASS32|| ehdr.e_ident[EI_VERSION] != EV_CURRENT || ehdr.e_version != EV_CURRENT || ehdr.e_ehsize != sizeof(Elf32_Ehdr) || ehdr.e_phentsize != sizeof(Elf32_Phdr) || ehdr.e_phnum == 0) { printk(KERN_WARNING "Warning: Core image elf header is not" "sane\n"); return -EINVAL; } /* Read in all elf headers. */ elfcorebuf_sz = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr); elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL); if (!elfcorebuf) return -ENOMEM; addr = elfcorehdr_addr; rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0); if (rc < 0) { kfree(elfcorebuf); return rc; } /* Merge all PT_NOTE headers into one. */ rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list); if (rc) { kfree(elfcorebuf); return rc; } rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz, &vmcore_list); if (rc) { kfree(elfcorebuf); return rc; } set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list); return 0; } static int __init parse_crash_elf_headers(void) { unsigned char e_ident[EI_NIDENT]; u64 addr; int rc=0; addr = elfcorehdr_addr; rc = read_from_oldmem(e_ident, EI_NIDENT, &addr, 0); if (rc < 0) return rc; if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) { printk(KERN_WARNING "Warning: Core image elf header" " not found\n"); return -EINVAL; } if (e_ident[EI_CLASS] == ELFCLASS64) { rc = parse_crash_elf64_headers(); if (rc) return rc; /* Determine vmcore size. */ vmcore_size = get_vmcore_size_elf64(elfcorebuf); } else if (e_ident[EI_CLASS] == ELFCLASS32) { rc = parse_crash_elf32_headers(); if (rc) return rc; /* Determine vmcore size. */ vmcore_size = get_vmcore_size_elf32(elfcorebuf); } else { printk(KERN_WARNING "Warning: Core image elf header is not" " sane\n"); return -EINVAL; } return 0; } /* Init function for vmcore module. */ static int __init vmcore_init(void) { int rc = 0; /* If elfcorehdr= has been passed in cmdline, then capture the dump.*/ if (!(is_vmcore_usable())) return rc; rc = parse_crash_elf_headers(); if (rc) { printk(KERN_WARNING "Kdump: vmcore not initialized\n"); return rc; } proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations); if (proc_vmcore) proc_vmcore->size = vmcore_size; return 0; } module_init(vmcore_init)