[PATCH 28/29] crashdump-elf-format-dump-file-access

From: Eric W. Biederman
Date: Wed Jan 19 2005 - 02:39:03 EST


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@xxxxxxxxxx>

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@xxxxxxxxxx>

Signed-off-by: Eric Biederman <ebiederm@xxxxxxxxxxxx>
---

fs/proc/Makefile | 3
fs/proc/kcore.c | 10 -
fs/proc/proc_misc.c | 8 +
fs/proc/vmcore.c | 239 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/crash_dump.h | 13 ++
5 files changed, 267 insertions(+), 6 deletions(-)

diff -uNr linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/fs/proc/Makefile linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/fs/proc/Makefile
--- linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/fs/proc/Makefile Fri Jan 14 04:28:46 2005
+++ linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/fs/proc/Makefile Tue Jan 18 23:16:57 2005
@@ -10,5 +10,6 @@
proc-y += inode.o root.o base.o generic.o array.o \
kmsg.o proc_tty.o proc_misc.o

-proc-$(CONFIG_PROC_KCORE) += kcore.o
+kcore-$(CONFIG_CRASH_DUMP) += vmcore.o
+proc-$(CONFIG_PROC_KCORE) += kcore.o $(kcore-y)
proc-$(CONFIG_PROC_DEVICETREE) += proc_devtree.o
diff -uNr linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/fs/proc/kcore.c linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/fs/proc/kcore.c
--- linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/fs/proc/kcore.c Fri Jan 14 04:32:26 2005
+++ linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/fs/proc/kcore.c Tue Jan 18 23:16:57 2005
@@ -97,7 +97,7 @@
/*
* determine size of ELF note
*/
-static int notesize(struct memelfnote *en)
+int notesize(struct memelfnote *en)
{
int sz;

@@ -112,7 +112,7 @@
/*
* store a note in the header buffer
*/
-static char *storenote(struct memelfnote *men, char *bufp)
+char *storenote(struct memelfnote *men, char *bufp)
{
struct elf_note en;

@@ -139,7 +139,7 @@
* store an ELF coredump header in the supplied buffer
* nphdr is the number of elf_phdr to insert
*/
-static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
+void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff, struct kcore_list *clist)
{
struct elf_prstatus prstatus; /* NT_PRSTATUS */
struct elf_prpsinfo prpsinfo; /* NT_PRPSINFO */
@@ -191,7 +191,7 @@
nhdr->p_align = 0;

/* setup ELF PT_LOAD program header for every area */
- for (m=kclist; m; m=m->next) {
+ for (m=clist; m; m=m->next) {
phdr = (struct elf_phdr *) bufp;
bufp += sizeof(struct elf_phdr);
offset += sizeof(struct elf_phdr);
@@ -287,7 +287,7 @@
return -ENOMEM;
}
memset(elf_buf, 0, elf_buflen);
- elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
+ elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen, kclist);
read_unlock(&kclist_lock);
if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
kfree(elf_buf);
diff -uNr linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/fs/proc/proc_misc.c linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/fs/proc/proc_misc.c
--- linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/fs/proc/proc_misc.c Fri Jan 14 04:28:46 2005
+++ linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/fs/proc/proc_misc.c Tue Jan 18 23:16:57 2005
@@ -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>
@@ -598,6 +599,13 @@
proc_root_kcore->size =
(size_t)high_memory - PAGE_OFFSET + PAGE_SIZE;
}
+# ifdef CONFIG_CRASH_DUMP
+ entry = create_proc_entry("vmcore", S_IRUSR, NULL);
+ if (entry) {
+ entry->proc_fops = &proc_vmcore_operations;
+ entry->size = (size_t)(saved_max_pfn << PAGE_SHIFT);
+ }
+# endif
#endif
#ifdef CONFIG_MAGIC_SYSRQ
entry = create_proc_entry("sysrq-trigger", S_IWUSR, NULL);
diff -uNr linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/fs/proc/vmcore.c linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/fs/proc/vmcore.c
--- linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/fs/proc/vmcore.c Wed Dec 31 17:00:00 1969
+++ linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/fs/proc/vmcore.c Tue Jan 18 23:16:57 2005
@@ -0,0 +1,239 @@
+/*
+ * 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@xxxxxxxxxx)
+ * 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/vmalloc.h>
+#include <linux/proc_fs.h>
+#include <linux/highmem.h>
+#include <linux/bootmem.h>
+#include <linux/init.h>
+#include <linux/crash_dump.h>
+#include <asm/uaccess.h>
+#include <asm/io.h>
+
+/* This is to re-use the kcore header creation code */
+static struct kcore_list vmcore_mem;
+
+static int open_vmcore(struct inode * inode, struct file * filp)
+{
+ return 0;
+}
+
+static ssize_t read_vmcore(struct file *,char __user *,size_t, loff_t *);
+
+#define BACKUP_START CRASH_BACKUP_BASE
+#define BACKUP_END CRASH_BACKUP_BASE + CRASH_BACKUP_SIZE
+#define REG_SIZE sizeof(elf_gregset_t)
+
+struct file_operations proc_vmcore_operations = {
+ .read = read_vmcore,
+ .open = open_vmcore,
+};
+
+struct proc_dir_entry *proc_vmcore;
+
+struct memelfnote
+{
+ const char *name;
+ int type;
+ unsigned int datasz;
+ void *data;
+};
+
+static size_t get_vmcore_size(int *nphdr, size_t *elf_buflen)
+{
+ size_t size;
+
+ /* We need 1 PT_LOAD segment headers
+ * In addition, we need one PT_NOTE header
+ */
+ *nphdr = 2;
+ size = (size_t)(saved_max_pfn << PAGE_SHIFT);
+
+ *elf_buflen = sizeof(struct elfhdr) +
+ (*nphdr + 2)*sizeof(struct elf_phdr) +
+ 3 * sizeof(struct memelfnote) +
+ sizeof(struct elf_prstatus) +
+ sizeof(struct elf_prpsinfo) +
+ sizeof(struct task_struct);
+ *elf_buflen = PAGE_ALIGN(*elf_buflen);
+ return size + *elf_buflen;
+}
+
+/*
+ * 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;
+ size_t read = 0;
+
+ pfn = (unsigned long)(*ppos / PAGE_SIZE);
+
+ if (pfn > saved_max_pfn) {
+ read = -EINVAL;
+ goto done;
+ }
+
+ count = (count > PAGE_SIZE) ? PAGE_SIZE : count;
+
+ if (copy_oldmem_page(pfn, buf, count, userbuf)) {
+ read = -EFAULT;
+ goto done;
+ }
+
+ *ppos += count;
+done:
+ return read;
+}
+
+/*
+ * store an ELF crash dump header in the supplied buffer
+ * nphdr is the number of elf_phdr to insert
+ */
+static void elf_vmcore_store_hdr(char *bufp, int nphdr, int dataoff)
+{
+ struct elf_prstatus prstatus; /* NT_PRSTATUS */
+ struct memelfnote notes[1];
+ char reg_buf[REG_SIZE];
+ loff_t reg_ppos;
+ char *buf = bufp;
+
+ vmcore_mem.addr = (unsigned long)__va(0);
+ vmcore_mem.size = saved_max_pfn << PAGE_SHIFT;
+ vmcore_mem.next = NULL;
+
+ /* Re-use the kcore code */
+ elf_kcore_store_hdr(bufp, nphdr, dataoff, &vmcore_mem);
+ buf += sizeof(struct elfhdr) + 2*sizeof(struct elf_phdr);
+
+ /* set up the process status */
+ notes[0].name = "CORE";
+ notes[0].type = NT_PRSTATUS;
+ notes[0].datasz = sizeof(struct elf_prstatus);
+ notes[0].data = &prstatus;
+
+ memset(&prstatus, 0, sizeof(struct elf_prstatus));
+
+ /* 1 - Get the registers from the reserved memory area */
+ reg_ppos = BACKUP_END + CRASH_RELOCATE_SIZE;
+ read_from_oldmem(reg_buf, REG_SIZE, &reg_ppos, 0);
+ elf_core_copy_regs(&prstatus.pr_reg, (struct pt_regs *)reg_buf);
+ buf = storenote(&notes[0], buf);
+}
+
+/*
+ * read from the ELF header and then the crash dump
+ */
+static ssize_t read_vmcore(
+struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
+{
+ ssize_t acc = 0;
+ size_t size, tsz;
+ size_t elf_buflen;
+ int nphdr;
+ unsigned long start;
+
+ tsz = get_vmcore_size(&nphdr, &elf_buflen);
+ proc_vmcore->size = size = tsz + elf_buflen;
+ if (buflen == 0 || *fpos >= size) {
+ goto done;
+ }
+
+ /* trim buflen to not go beyond EOF */
+ if (buflen > size - *fpos)
+ buflen = size - *fpos;
+
+ /* construct an ELF core header if we'll need some of it */
+ if (*fpos < elf_buflen) {
+ char * elf_buf;
+
+ tsz = elf_buflen - *fpos;
+ if (buflen < tsz)
+ tsz = buflen;
+ elf_buf = kmalloc(elf_buflen, GFP_ATOMIC);
+ if (!elf_buf) {
+ acc = -ENOMEM;
+ goto done;
+ }
+ memset(elf_buf, 0, elf_buflen);
+ elf_vmcore_store_hdr(elf_buf, nphdr, elf_buflen);
+ if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
+ kfree(elf_buf);
+ acc = -EFAULT;
+ goto done;
+ }
+ kfree(elf_buf);
+ buflen -= tsz;
+ *fpos += tsz;
+ buffer += tsz;
+ acc += tsz;
+
+ /* leave now if filled buffer already */
+ if (buflen == 0) {
+ goto done;
+ }
+ }
+
+ start = *fpos - elf_buflen;
+ if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
+ tsz = buflen;
+
+ while (buflen) {
+ unsigned long p;
+ loff_t pdup;
+
+ if ((start < 0) || (start >= size))
+ if (clear_user(buffer, tsz)) {
+ acc = -EFAULT;
+ goto done;
+ }
+
+ /* tsz contains actual len of dump to be read.
+ * buflen is the total len that was requested.
+ * This may contain part of ELF header. start
+ * is the fpos for the oldmem region
+ * If the file position corresponds to the second
+ * kernel's memory, we just return zeroes
+ */
+ p = start;
+ if ((p >= BACKUP_START) && (p < BACKUP_END)) {
+ if (clear_user(buffer, tsz)) {
+ acc = -EFAULT;
+ goto done;
+ }
+
+ goto read_done;
+ } else if (p < CRASH_RELOCATE_SIZE)
+ p += BACKUP_END;
+
+ pdup = p;
+ if (read_from_oldmem(buffer, tsz, &pdup, 1)) {
+ acc = -EINVAL;
+ goto done;
+ }
+
+read_done:
+ buflen -= tsz;
+ *fpos += tsz;
+ buffer += tsz;
+ acc += tsz;
+ start += tsz;
+ tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
+ }
+
+done:
+ return acc;
+}
diff -uNr linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/include/linux/crash_dump.h linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/include/linux/crash_dump.h
--- linux-2.6.11-rc1-mm1-nokexec-crashdump-routines-for-copying-dump-pages/include/linux/crash_dump.h Tue Jan 18 23:16:24 2005
+++ linux-2.6.11-rc1-mm1-nokexec-crashdump-elf-format-dump-file-access/include/linux/crash_dump.h Tue Jan 18 23:16:57 2005
@@ -1,10 +1,23 @@
#include <linux/kexec.h>
#include <linux/smp_lock.h>
#include <linux/device.h>
+#include <linux/proc_fs.h>
#ifdef CONFIG_CRASH_DUMP
#include <asm/crash_dump.h>
#endif

+extern unsigned long saved_max_pfn;
+extern struct memelfnote memelfnote;
+extern int notesize(struct memelfnote *);
+extern char *storenote(struct memelfnote *, char *);
+extern void elf_kcore_store_hdr(char *, int, int, struct kcore_list *);
+
#ifdef CONFIG_CRASH_DUMP
+extern struct file_operations proc_vmcore_operations;
+extern struct proc_dir_entry *proc_vmcore;
+
+extern ssize_t copy_oldmem_page(unsigned long, char *, size_t, int);
+extern void crash_create_proc_entry(void);
#else
+#define crash_create_proc_entry() do { } while(0)
#endif
-
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