[S390] kernel: Add OS info memory interface

In order to allow kdump based stand-alone dump, some information
has to be passed from the old kernel to the new dump kernel. This
is done via a the struct "os_info" that contains the following fields:
 * crashkernel base and size
 * reipl block
 * vmcoreinfo
 * init function
A pointer to os_info is stored at a well known storage location
and the whole structure as well as all fields are secured with
checksums.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 27 insertions, 10 deletions

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index c383ce440d99..cc1172b26873 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -14,6 +14,7 @@
 #include <linux/bootmem.h>
 #include <linux/elf.h>
 #include <asm/ipl.h>
+#include <asm/os_info.h>
 
 #define PTR_ADD(x, y) (((char *) (x)) + ((unsigned long) (y)))
 #define PTR_SUB(x, y) (((char *) (x)) - ((unsigned long) (y)))
@@ -51,7 +52,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 /*
  * Copy memory from old kernel
  */
-static int copy_from_oldmem(void *dest, void *src, size_t count)
+int copy_from_oldmem(void *dest, void *src, size_t count)
 {
         unsigned long copied = 0;
         int rc;
@@ -224,28 +225,44 @@ static void *nt_prpsinfo(void *ptr)
 }
 
 /*
- * Initialize vmcoreinfo note (new kernel)
+ * Get vmcoreinfo using lowcore->vmcore_info (new kernel)
  */
-static void *nt_vmcoreinfo(void *ptr)
+static void *get_vmcoreinfo_old(unsigned long *size)
 {
         char nt_name[11], *vmcoreinfo;
         Elf64_Nhdr note;
         void *addr;
 
         if (copy_from_oldmem(&addr, &S390_lowcore.vmcore_info, sizeof(addr)))
-                return ptr;
+                return NULL;
         memset(nt_name, 0, sizeof(nt_name));
         if (copy_from_oldmem(&note, addr, sizeof(note)))
-                return ptr;
+                return NULL;
         if (copy_from_oldmem(nt_name, addr + sizeof(note), sizeof(nt_name) - 1))
-                return ptr;
+                return NULL;
         if (strcmp(nt_name, "VMCOREINFO") != 0)
-                return ptr;
-        vmcoreinfo = kzalloc_panic(note.n_descsz + 1);
+                return NULL;
+        vmcoreinfo = kzalloc_panic(note.n_descsz);
         if (copy_from_oldmem(vmcoreinfo, addr + 24, note.n_descsz))
+                return NULL;
+        *size = note.n_descsz;
+        return vmcoreinfo;
+}
+
+/*
+ * Initialize vmcoreinfo note (new kernel)
+ */
+static void *nt_vmcoreinfo(void *ptr)
+{
+        unsigned long size;
+        void *vmcoreinfo;
+
+        vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
+        if (!vmcoreinfo)
+                vmcoreinfo = get_vmcoreinfo_old(&size);
+        if (!vmcoreinfo)
                 return ptr;
-        vmcoreinfo[note.n_descsz + 1] = 0;
-        return nt_init(ptr, 0, vmcoreinfo, note.n_descsz, "VMCOREINFO");
+        return nt_init(ptr, 0, vmcoreinfo, size, "VMCOREINFO");
 }
 
 /*