Add vmcoreinfo

This patch set frees the restriction that makedumpfile users should install a
vmlinux file (including the debugging information) into each system.

makedumpfile command is the dump filtering feature for kdump.  It creates a
small dumpfile by filtering unnecessary pages for the analysis.  To
distinguish unnecessary pages, it needs a vmlinux file including the debugging
information.  These days, the debugging package becomes a huge file, and it is
hard to install it into each system.

To solve the problem, kdump developers discussed it at lkml and kexec-ml.  As
the result, we reached the conclusion that necessary information for dump
filtering (called "vmcoreinfo") should be embedded into the first kernel file
and it should be accessed through /proc/vmcore during the second kernel.
(http://www.uwsg.iu.edu/hypermail/linux/kernel/0707.0/1806.html)

Dan Aloni created the patch set for the above implementation.
(http://www.uwsg.iu.edu/hypermail/linux/kernel/0707.1/1053.html)

And I updated it for multi architectures and memory models.
(http://lists.infradead.org/pipermail/kexec/2007-August/000479.html)

Signed-off-by: Dan Aloni <da-x@monatomic.org>
Signed-off-by: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 120 insertions, 0 deletions

diff --git a/kernel/kexec.c b/kernel/kexec.c
index d8de12e943cf..67828befbfc3 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -21,16 +21,26 @@
 #include <linux/hardirq.h>
 #include <linux/elf.h>
 #include <linux/elfcore.h>
+#include <linux/utsrelease.h>
+#include <linux/utsname.h>
+#include <linux/numa.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/system.h>
 #include <asm/semaphore.h>
+#include <asm/sections.h>
 
 /* Per cpu memory for storing cpu states in case of system crash. */
 note_buf_t* crash_notes;
 
+/* vmcoreinfo stuff */
+unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
+u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
+unsigned int vmcoreinfo_size = 0;
+unsigned int vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
+
 /* Location of the reserved area for the crash kernel */
 struct resource crashk_res = {
         .name  = "Crash kernel",
@@ -1060,6 +1070,7 @@ void crash_kexec(struct pt_regs *regs)
                 if (kexec_crash_image) {
                         struct pt_regs fixed_regs;
                         crash_setup_regs(&fixed_regs, regs);
+                        crash_save_vmcoreinfo();
                         machine_crash_shutdown(&fixed_regs);
                         machine_kexec(kexec_crash_image);
                 }
@@ -1134,3 +1145,102 @@ static int __init crash_notes_memory_init(void)
         return 0;
 }
 module_init(crash_notes_memory_init)
+
+void crash_save_vmcoreinfo(void)
+{
+        u32 *buf;
+
+        if (!vmcoreinfo_size)
+                return;
+
+        vmcoreinfo_append_str("CRASHTIME=%d", xtime.tv_sec);
+
+        buf = (u32 *)vmcoreinfo_note;
+
+        buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data,
+                              vmcoreinfo_size);
+
+        final_note(buf);
+}
+
+void vmcoreinfo_append_str(const char *fmt, ...)
+{
+        va_list args;
+        char buf[0x50];
+        int r;
+
+        va_start(args, fmt);
+        r = vsnprintf(buf, sizeof(buf), fmt, args);
+        va_end(args);
+
+        if (r + vmcoreinfo_size > vmcoreinfo_max_size)
+                r = vmcoreinfo_max_size - vmcoreinfo_size;
+
+        memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);
+
+        vmcoreinfo_size += r;
+}
+
+/*
+ * provide an empty default implementation here -- architecture
+ * code may override this
+ */
+void __attribute__ ((weak)) arch_crash_save_vmcoreinfo(void)
+{}
+
+unsigned long __attribute__ ((weak)) paddr_vmcoreinfo_note(void)
+{
+        return __pa((unsigned long)(char *)&vmcoreinfo_note);
+}
+
+static int __init crash_save_vmcoreinfo_init(void)
+{
+        vmcoreinfo_append_str("OSRELEASE=%s\n", UTS_RELEASE);
+        vmcoreinfo_append_str("PAGESIZE=%d\n", PAGE_SIZE);
+
+        SYMBOL(init_uts_ns);
+        SYMBOL(node_online_map);
+        SYMBOL(swapper_pg_dir);
+        SYMBOL(_stext);
+
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+        SYMBOL(mem_map);
+        SYMBOL(contig_page_data);
+#endif
+#ifdef CONFIG_SPARSEMEM
+        SYMBOL(mem_section);
+        LENGTH(mem_section, NR_SECTION_ROOTS);
+        SIZE(mem_section);
+        OFFSET(mem_section, section_mem_map);
+#endif
+        SIZE(page);
+        SIZE(pglist_data);
+        SIZE(zone);
+        SIZE(free_area);
+        SIZE(list_head);
+        OFFSET(page, flags);
+        OFFSET(page, _count);
+        OFFSET(page, mapping);
+        OFFSET(page, lru);
+        OFFSET(pglist_data, node_zones);
+        OFFSET(pglist_data, nr_zones);
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
+        OFFSET(pglist_data, node_mem_map);
+#endif
+        OFFSET(pglist_data, node_start_pfn);
+        OFFSET(pglist_data, node_spanned_pages);
+        OFFSET(pglist_data, node_id);
+        OFFSET(zone, free_area);
+        OFFSET(zone, vm_stat);
+        OFFSET(zone, spanned_pages);
+        OFFSET(free_area, free_list);
+        OFFSET(list_head, next);
+        OFFSET(list_head, prev);
+        LENGTH(zone.free_area, MAX_ORDER);
+
+        arch_crash_save_vmcoreinfo();
+
+        return 0;
+}
+
+module_init(crash_save_vmcoreinfo_init)
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 6046939d0804..38b38f957ef0 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -61,6 +61,15 @@ static ssize_t kexec_crash_loaded_show(struct kset *kset, char *page)
         return sprintf(page, "%d\n", !!kexec_crash_image);
 }
 KERNEL_ATTR_RO(kexec_crash_loaded);
+
+static ssize_t vmcoreinfo_show(struct kset *kset, char *page)
+{
+        return sprintf(page, "%lx %x\n",
+                       paddr_vmcoreinfo_note(),
+                       vmcoreinfo_max_size);
+}
+KERNEL_ATTR_RO(vmcoreinfo);
+
 #endif /* CONFIG_KEXEC */
 
 /*
@@ -96,6 +105,7 @@ static struct attribute * kernel_attrs[] = {
 #ifdef CONFIG_KEXEC
         &kexec_loaded_attr.attr,
         &kexec_crash_loaded_attr.attr,
+        &vmcoreinfo_attr.attr,
 #endif
         NULL
 };