s390/kdump: Make elfcorehdr size calculation ABI compliant

There are two ways to pass the vmcoreinfo to the crash kernel 1) via the
os_info mechanism and 2) via the lowcore->vmcore_info field. In the Linux
kernel only the second way is used. However, the first way is ABI for
stand-alone kdump. So other OSes use it to pass additional debug info. Make
the elfcorehdr size calculation aware of both possible ways.

Fixes: 8cce437fbb5c ("s390/kdump: Fix elfcorehdr size calculation")
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index c3620ba..4b2773e 100644 (file)
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -478,26 +478,20 @@ static void *nt_vmcoreinfo(void *ptr)
 
 static size_t nt_vmcoreinfo_size(void)
 {
-       const char *name = "VMCOREINFO";
-       char nt_name[11];
-       Elf64_Nhdr note;
-       void *addr;
-
-       if (copy_oldmem_kernel(&addr, &S390_lowcore.vmcore_info, sizeof(addr)))
-               return 0;
-
-       if (copy_oldmem_kernel(&note, addr, sizeof(note)))
-               return 0;
+       const char *name = VMCOREINFO_NOTE_NAME;
+       unsigned long size;
+       void *vmcoreinfo;
 
-       memset(nt_name, 0, sizeof(nt_name));
-       if (copy_oldmem_kernel(nt_name, addr + sizeof(note),
-                              sizeof(nt_name) - 1))
-               return 0;
+       vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
+       if (vmcoreinfo)
+               return nt_size_name(size, name);
 
-       if (strcmp(nt_name, name) != 0)
+       vmcoreinfo = get_vmcoreinfo_old(&size);
+       if (!vmcoreinfo)
                return 0;
 
-       return nt_size_name(note.n_descsz, name);
+       kfree(vmcoreinfo);
+       return nt_size_name(size, name);
 }
 
 /*