s390/kdump: Allow copy_oldmem_page() copy to virtual memory

The kdump mmap patch series (git commit 83086978c63afd7c73e1c) changed the
requirements for copy_oldmem_page(). Now this function is used for copying
to virtual memory.

So implement vmalloc support for the s390 version of copy_oldmem_page().

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

1 files changed, 47 insertions, 4 deletions

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index f703d91bf720..d8f355657171 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -21,6 +21,48 @@
 #define PTR_SUB(x, y) (((char *) (x)) - ((unsigned long) (y)))
 #define PTR_DIFF(x, y) ((unsigned long)(((char *) (x)) - ((unsigned long) (y))))
 
+
+/*
+ * Return physical address for virtual address
+ */
+static inline void *load_real_addr(void *addr)
+{
+        unsigned long real_addr;
+
+        asm volatile(
+                   "    lra     %0,0(%1)\n"
+                   "    jz      0f\n"
+                   "    la      %0,0\n"
+                   "0:"
+                   : "=a" (real_addr) : "a" (addr) : "cc");
+        return (void *)real_addr;
+}
+
+/*
+ * Copy up to one page to vmalloc or real memory
+ */
+static ssize_t copy_page_real(void *buf, void *src, size_t csize)
+{
+        size_t size;
+
+        if (is_vmalloc_addr(buf)) {
+                BUG_ON(csize >= PAGE_SIZE);
+                /* If buf is not page aligned, copy first part */
+                size = min(roundup(__pa(buf), PAGE_SIZE) - __pa(buf), csize);
+                if (size) {
+                        if (memcpy_real(load_real_addr(buf), src, size))
+                                return -EFAULT;
+                        buf += size;
+                        src += size;
+                }
+                /* Copy second part */
+                size = csize - size;
+                return (size) ? memcpy_real(load_real_addr(buf), src, size) : 0;
+        } else {
+                return memcpy_real(buf, src, csize);
+        }
+}
+
 /*
  * Copy one page from "oldmem"
  *
@@ -32,6 +74,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
                          size_t csize, unsigned long offset, int userbuf)
 {
         unsigned long src;
+        int rc;
 
         if (!csize)
                 return 0;
@@ -43,11 +86,11 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
                  src < OLDMEM_BASE + OLDMEM_SIZE)
                 src -= OLDMEM_BASE;
         if (userbuf)
-                copy_to_user_real((void __force __user *) buf, (void *) src,
-                                  csize);
+                rc = copy_to_user_real((void __force __user *) buf,
+                                       (void *) src, csize);
         else
-                memcpy_real(buf, (void *) src, csize);
-        return csize;
+                rc = copy_page_real(buf, (void *) src, csize);
+        return (rc == 0) ? csize : rc;
 }
 
 /*