1 files changed, 100 insertions, 0 deletions
diff --git a/arch/s390/kernel/mem_detect.c b/arch/s390/kernel/mem_detect.c
new file mode 100644
index 0000000..18ed7ab
--- /dev/null
+++ b/arch/s390/kernel/mem_detect.c
@@ -0,0 +1,100 @@
+/*
+ *    Copyright IBM Corp. 2008
+ *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <asm/ipl.h>
+#include <asm/sclp.h>
+#include <asm/setup.h>
+
+static int memory_fast_detect(struct mem_chunk *chunk)
+{
+	unsigned long val0 = 0;
+	unsigned long val1 = 0xc;
+	int rc = -EOPNOTSUPP;
+
+	if (ipl_flags & IPL_NSS_VALID)
+		return -EOPNOTSUPP;
+	asm volatile(
+		"	diag	%1,%2,0x260\n"
+		"0:	lhi	%0,0\n"
+		"1:\n"
+		EX_TABLE(0b,1b)
+		: "+d" (rc), "+d" (val0), "+d" (val1) : : "cc");
+
+	if (rc || val0 != val1)
+		return -EOPNOTSUPP;
+	chunk->size = val0 + 1;
+	return 0;
+}
+
+static inline int tprot(unsigned long addr)
+{
+	int rc = -EFAULT;
+
+	asm volatile(
+		"	tprot	0(%1),0\n"
+		"0:	ipm	%0\n"
+		"	srl	%0,28\n"
+		"1:\n"
+		EX_TABLE(0b,1b)
+		: "+d" (rc) : "a" (addr) : "cc");
+	return rc;
+}
+
+#define ADDR2G (1ULL << 31)
+
+static void find_memory_chunks(struct mem_chunk chunk[])
+{
+	unsigned long long memsize, rnmax, rzm;
+	unsigned long addr = 0, size;
+	int i = 0, type;
+
+	rzm = sclp_get_rzm();
+	rnmax = sclp_get_rnmax();
+	memsize = rzm * rnmax;
+	if (!rzm)
+		rzm = 1ULL << 17;
+	if (sizeof(long) == 4) {
+		rzm = min(ADDR2G, rzm);
+		memsize = memsize ? min(ADDR2G, memsize) : ADDR2G;
+	}
+	do {
+		size = 0;
+		type = tprot(addr);
+		do {
+			size += rzm;
+			if (memsize && addr + size >= memsize)
+				break;
+		} while (type == tprot(addr + size));
+		if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
+			chunk[i].addr = addr;
+			chunk[i].size = size;
+			chunk[i].type = type;
+			i++;
+		}
+		addr += size;
+	} while (addr < memsize && i < MEMORY_CHUNKS);
+}
+
+void detect_memory_layout(struct mem_chunk chunk[])
+{
+	unsigned long flags, cr0;
+
+	memset(chunk, 0, MEMORY_CHUNKS * sizeof(struct mem_chunk));
+	if (memory_fast_detect(&chunk[0]) == 0)
+		return;
+	/* 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.
+	 */
+	flags = __raw_local_irq_stnsm(0xf8);
+	__ctl_store(cr0, 0, 0);
+	__ctl_clear_bit(0, 28);
+	find_memory_chunks(chunk);
+	__ctl_load(cr0, 0, 0);
+	__raw_local_irq_ssm(flags);
+}
+EXPORT_SYMBOL(detect_memory_layout);