Re: [Xen-devel] [makedumpfile] extract vmcoreinfo from /proc/vmcore for Xen

["Ken'ichi Ohmichi" <oomichi@xxxxxxxxxxxxxxxxx>]

Hi,

Itsuro ODA wrote:
> > I'd like to support the "extract vmcoreinfo from /proc/vmcore"
> > function for the Xen extraction too.
> >
> > I think a way of supporting this as follows:
> > 
> > * The hypervisor makes its vmcoreinfo at the initialize.
> > * add a new hypervisor call to get the hypervisor's vmcoreinfo.
> >   The hypercall would be a subcommand of the kexec hypercall.
> > * dom-0 exposes the hypervisor's vmcoreinfo via 
> >   /sys/hypervisor/vmcoreinfo
> > * kexec-tool looks /sys/hypervisor/vmcoreinfo and makes an elf-note
> >   according it

That sounds good.

BTW, the testing tree of kexec-tools has not contain the patch for
vmcoreinfo yet. I think the tree is mainline now, and I hope the
patch is merged into the tree  ;-) 


Thanks
Ken'ichi Ohmichi 

Signed-off-by: Dan Aloni <da-x@xxxxxxxxxxxxx>
Signed-off-by: Ken'ichi Ohmichi <oomichi@xxxxxxxxxxxxxxxxx>

---
diff -rpuN a/kexec/crashdump-elf.c b/kexec/crashdump-elf.c
--- a/kexec/crashdump-elf.c     2007-03-30 13:34:36.000000000 +0900
+++ b/kexec/crashdump-elf.c     2007-09-07 22:58:18.000000000 +0900
@@ -36,6 +36,8 @@ int FUNC(struct kexec_info *info,
        char *bufp;
        long int nr_cpus = 0;
        uint64_t notes_addr, notes_len;
+       uint64_t vmcoreinfo_addr, vmcoreinfo_len;
+       int has_vmcoreinfo = 0;
        int (*get_note_info)(int cpu, uint64_t *addr, uint64_t *len);
 
        if (xen_present())
@@ -47,7 +49,11 @@ int FUNC(struct kexec_info *info,
                return -1;
        }
 
-       sz = sizeof(EHDR) + nr_cpus * sizeof(PHDR) + ranges * sizeof(PHDR);
+       if (get_kernel_vmcoreinfo(&vmcoreinfo_addr, &vmcoreinfo_len) == 0) {
+               has_vmcoreinfo = 1;
+       }
+
+       sz = sizeof(EHDR) + (nr_cpus + has_vmcoreinfo) * sizeof(PHDR) + ranges 
* sizeof(PHDR);
 
        /*
         * Certain architectures such as x86_64 and ia64 require a separate
@@ -148,6 +154,21 @@ int FUNC(struct kexec_info *info,
                dfprintf_phdr(stdout, "Elf header", phdr);
        }
 
+       if (has_vmcoreinfo) {
+               phdr = (PHDR *) bufp;
+               bufp += sizeof(PHDR);
+               phdr->p_type    = PT_NOTE;
+               phdr->p_flags   = 0;
+               phdr->p_offset  = phdr->p_paddr = vmcoreinfo_addr;
+               phdr->p_vaddr   = 0;
+               phdr->p_filesz  = phdr->p_memsz = vmcoreinfo_len;
+               /* Do we need any alignment of segments? */
+               phdr->p_align   = 0;
+
+               (elf->e_phnum)++;
+               dfprintf_phdr(stdout, "vmcoreinfo header", phdr);
+       }
+
        /* Setup an PT_LOAD type program header for the region where
         * Kernel is mapped if info->kern_size is non-zero.
         */
diff -rpuN a/kexec/crashdump.c b/kexec/crashdump.c
--- a/kexec/crashdump.c 2007-03-30 13:34:36.000000000 +0900
+++ b/kexec/crashdump.c 2007-09-07 23:03:55.000000000 +0900
@@ -108,3 +108,32 @@ int get_crash_notes_per_cpu(int cpu, uin
 
        return 0;
 }
+
+/* Returns the physical address of start of crash notes buffer for a kernel. */
+int get_kernel_vmcoreinfo(uint64_t *addr, uint64_t *len)
+{
+       char kdump_info[PATH_MAX];
+       char line[MAX_LINE];
+       int count;
+       FILE *fp;
+       unsigned long long temp, temp2;
+
+       *addr = 0;
+       *len = 0;
+
+       sprintf(kdump_info, "/sys/kernel/vmcoreinfo");
+       fp = fopen(kdump_info, "r");
+       if (!fp)
+               return 0;
+
+       if (!fgets(line, sizeof(line), fp))
+               die("Cannot parse %s: %s\n", kdump_info, strerror(errno));
+       count = sscanf(line, "%Lx %Lx", &temp, &temp2);
+       if (count != 2)
+               die("Cannot parse %s: %s\n", kdump_info, strerror(errno));
+
+       *addr = (uint64_t) temp;
+       *len = (uint64_t) temp2;
+
+       return 0;
+}
diff -rpuN a/kexec/crashdump.h b/kexec/crashdump.h
--- a/kexec/crashdump.h 2007-03-30 13:34:36.000000000 +0900
+++ b/kexec/crashdump.h 2007-09-07 22:58:18.000000000 +0900
@@ -2,6 +2,7 @@
 #define CRASHDUMP_H
 
 extern int get_crash_notes_per_cpu(int cpu, uint64_t *addr, uint64_t *len);
+extern int get_kernel_vmcoreinfo(uint64_t *addr, uint64_t *len);
 
 /* Need to find a better way to determine per cpu notes section size. */
 #define MAX_NOTE_BYTES         1024
_


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