[PATCH] kdump: Access dump file in elf format (/proc/vmcore)
From: "Vivek Goyal" <vgoyal@in.ibm.com>
o Support for /proc/vmcore interface. This interface exports elf core image
either in ELF32 or ELF64 format, depending on the format in which elf headers
have been stored by crashed kernel.
o Added support for CONFIG_VMCORE config option.
o Removed the dependency on /proc/kcore.
From: "Eric W. Biederman" <ebiederm@xmission.com>
This patch has been refactored to more closely match the prevailing style in
the affected files. And to clearly indicate the dependency between
/proc/kcore and proc/vmcore.c
From: Hariprasad Nellitheertha <hari@in.ibm.com>
This patch contains the code that provides an ELF format interface to the
previous kernel's memory post kexec reboot.
Signed off by Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/Kconfig b/fs/Kconfig
index 8157f2e..0621779 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -734,6 +734,12 @@
bool "/proc/kcore support" if !ARM
depends on PROC_FS && MMU
+config PROC_VMCORE
+ bool "/proc/vmcore support (EXPERIMENTAL)"
+ depends on PROC_FS && EMBEDDED && EXPERIMENTAL && CRASH_DUMP
+ help
+ Exports the dump image of crashed kernel in ELF format.
+
config SYSFS
bool "sysfs file system support" if EMBEDDED
default y
diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index 738b9b6..7431d7b 100644
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -11,4 +11,5 @@
kmsg.o proc_tty.o proc_misc.o
proc-$(CONFIG_PROC_KCORE) += kcore.o
+proc-$(CONFIG_PROC_VMCORE) += vmcore.o
proc-$(CONFIG_PROC_DEVICETREE) += proc_devtree.o
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 94b570a..a345355 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -44,6 +44,7 @@
#include <linux/jiffies.h>
#include <linux/sysrq.h>
#include <linux/vmalloc.h>
+#include <linux/crash_dump.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/io.h>
@@ -618,6 +619,11 @@
(size_t)high_memory - PAGE_OFFSET + PAGE_SIZE;
}
#endif
+#ifdef CONFIG_PROC_VMCORE
+ proc_vmcore = create_proc_entry("vmcore", S_IRUSR, NULL);
+ if (proc_vmcore)
+ proc_vmcore->proc_fops = &proc_vmcore_operations;
+#endif
#ifdef CONFIG_MAGIC_SYSRQ
entry = create_proc_entry("sysrq-trigger", S_IWUSR, NULL);
if (entry)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
new file mode 100644
index 0000000..8ad4678
--- /dev/null
+++ b/fs/proc/vmcore.c
@@ -0,0 +1,451 @@
+/*
+ * 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/config.h>
+#include <linux/mm.h>
+#include <linux/proc_fs.h>
+#include <linux/user.h>
+#include <linux/a.out.h>
+#include <linux/elf.h>
+#include <linux/elfcore.h>
+#include <linux/proc_fs.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;
+
+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,
+ loff_t *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);
+ if (pfn > saved_max_pfn)
+ return -EINVAL;
+
+ 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, nr_bytes;
+ u64 start;
+ 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 int open_vmcore(struct inode *inode, struct file *filp)
+{
+ return 0;
+}
+
+struct file_operations proc_vmcore_operations = {
+ .read = read_vmcore,
+ .open = open_vmcore,
+};
+
+static struct vmcore* __init get_new_element(void)
+{
+ struct vmcore *p;
+
+ p = kmalloc(sizeof(*p), GFP_KERNEL);
+ if (p)
+ memset(p, 0, sizeof(*p));
+ return p;
+}
+
+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;
+}
+
+/* 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;
+}
+
+/* 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;
+}
+
+/* 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;
+ }
+}
+
+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) ||
+ !elf_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_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 {
+ 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 (!(elfcorehdr_addr < ELFCORE_ADDR_MAX))
+ return rc;
+ rc = parse_crash_elf_headers();
+ if (rc) {
+ printk(KERN_WARNING "Kdump: vmcore not initialized\n");
+ return rc;
+ }
+
+ /* Initialize /proc/vmcore size if proc is already up. */
+ if (proc_vmcore)
+ proc_vmcore->size = vmcore_size;
+ return 0;
+}
+module_init(vmcore_init)
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 3f25fd1..534d750 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -7,8 +7,12 @@
#include <linux/device.h>
#include <linux/proc_fs.h>
+#define ELFCORE_ADDR_MAX (-1ULL)
extern unsigned long long elfcorehdr_addr;
extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
unsigned long, int);
+extern struct file_operations proc_vmcore_operations;
+extern struct proc_dir_entry *proc_vmcore;
+
#endif /* CONFIG_CRASH_DUMP */
#endif /* LINUX_CRASHDUMP_H */
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 59e5052..0563581 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -74,6 +74,13 @@
size_t size;
};
+struct vmcore {
+ struct list_head list;
+ unsigned long long paddr;
+ unsigned long size;
+ loff_t offset;
+};
+
#ifdef CONFIG_PROC_FS
extern struct proc_dir_entry proc_root;
diff --git a/kernel/crash_dump.c b/kernel/crash_dump.c
index 10b966c..459ba49 100644
--- a/kernel/crash_dump.c
+++ b/kernel/crash_dump.c
@@ -16,7 +16,7 @@
#include <asm/uaccess.h>
/* Stores the physical address of elf header of crash image. */
-unsigned long long elfcorehdr_addr;
+unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
/*
* Copy a page from "oldmem". For this page, there is no pte mapped