s390/mem_detect: add DAT sanity check

Add sanity check: verify if the passed in array resides in vmalloc space.
If so print a warning and return to caller.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/mm/mem_detect.c b/arch/s390/mm/mem_detect.c
index fb216e11c25d22e7ba38e8f8599ca463db308e7b..854c08448de122485f336c8a3af3e1dabb1bd60a 100644 (file)
--- a/arch/s390/mm/mem_detect.c
+++ b/arch/s390/mm/mem_detect.c
@@ -50,16 +50,28 @@ void detect_memory_layout(struct mem_chunk chunk[])
        unsigned long flags, flags_dat, cr0;
 
        memset(chunk, 0, MEMORY_CHUNKS * sizeof(struct mem_chunk));
-       /* Disable IRQs, DAT and low address protection so tprot does the
+       /*
+        * Disable IRQs, DAT and low address protection so tprot does the
         * right thing and we don't get scheduled away with low address
         * protection disabled.
         */
        local_irq_save(flags);
        flags_dat = __arch_local_irq_stnsm(0xfb);
+       /*
+        * In case DAT was enabled, make sure chunk doesn't reside in vmalloc
+        * space. We have disabled DAT and any access to vmalloc area will
+        * cause an exception.
+        * If DAT was disabled we are called from early ipl code.
+        */
+       if (test_bit(5, &flags_dat)) {
+               if (WARN_ON_ONCE(is_vmalloc_or_module_addr(chunk)))
+                       goto out;
+       }
        __ctl_store(cr0, 0, 0);
        __ctl_clear_bit(0, 28);
        find_memory_chunks(chunk);
        __ctl_load(cr0, 0, 0);
+out:
        __arch_local_irq_ssm(flags_dat);
        local_irq_restore(flags);
 }