1 files changed, 20 insertions, 3 deletions

diff --git a/arch/s390/mm/mem_detect.c b/arch/s390/mm/mem_detect.c
index 854c08448de..ec00576bf8d 100644
--- a/arch/s390/mm/mem_detect.c
+++ b/arch/s390/mm/mem_detect.c
@@ -12,7 +12,7 @@
 
 #define ADDR2G (1ULL << 31)
 
-static void find_memory_chunks(struct mem_chunk chunk[])
+static void find_memory_chunks(struct mem_chunk chunk[], unsigned long maxsize)
 {
 	unsigned long long memsize, rnmax, rzm;
 	unsigned long addr = 0, size;
@@ -27,6 +27,8 @@ static void find_memory_chunks(struct mem_chunk chunk[])
 		rzm = min(ADDR2G, rzm);
 		memsize = memsize ? min(ADDR2G, memsize) : ADDR2G;
 	}
+	if (maxsize)
+		memsize = memsize ? min((unsigned long)memsize, maxsize) : maxsize;
 	do {
 		size = 0;
 		type = tprot(addr);
@@ -36,6 +38,8 @@ static void find_memory_chunks(struct mem_chunk chunk[])
 				break;
 		} while (type == tprot(addr + size));
 		if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
+			if (memsize && (addr + size > memsize))
+				size = memsize - addr;
 			chunk[i].addr = addr;
 			chunk[i].size = size;
 			chunk[i].type = type;
@@ -45,7 +49,20 @@ static void find_memory_chunks(struct mem_chunk chunk[])
 	} while (addr < memsize && i < MEMORY_CHUNKS);
 }
 
-void detect_memory_layout(struct mem_chunk chunk[])
+/**
+ * detect_memory_layout - fill mem_chunk array with memory layout data
+ * @chunk: mem_chunk array to be filled
+ * @maxsize: maximum address where memory detection should stop
+ *
+ * Fills the passed in memory chunk array with the memory layout of the
+ * machine. The array must have a size of at least MEMORY_CHUNKS and will
+ * be fully initialized afterwards.
+ * If the maxsize paramater has a value > 0 memory detection will stop at
+ * that address. It is guaranteed that all chunks have an ending address
+ * that is smaller than maxsize.
+ * If maxsize is 0 all memory will be detected.
+ */
+void detect_memory_layout(struct mem_chunk chunk[], unsigned long maxsize)
 {
 	unsigned long flags, flags_dat, cr0;
 
@@ -69,7 +86,7 @@ void detect_memory_layout(struct mem_chunk chunk[])
 	}
 	__ctl_store(cr0, 0, 0);
 	__ctl_clear_bit(0, 28);
-	find_memory_chunks(chunk);
+	find_memory_chunks(chunk, maxsize);
 	__ctl_load(cr0, 0, 0);
 out:
 	__arch_local_irq_ssm(flags_dat);