x86, memblock: Add memblock_x86_find_in_range_size()

size is returned according free range.
Will be used to find free ranges for early_memtest and memory corruption check

Do not mess it up with lib/memblock.c yet.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/include/asm/memblock.h

@@ -0,0 +1,8 @@
+#ifndef _X86_MEMBLOCK_H
+#define _X86_MEMBLOCK_H
+
+#define ARCH_DISCARD_MEMBLOCK
+
+u64 memblock_x86_find_in_range_size(u64 start, u64 *sizep, u64 align);
+
+#endif

arch/x86/mm/Makefile

@@ -26,4 +26,6 @@ obj-$(CONFIG_NUMA)		+= numa.o numa_$(BITS).o
 obj-$(CONFIG_K8_NUMA)		+= k8topology_64.o
 obj-$(CONFIG_ACPI_NUMA)		+= srat_$(BITS).o
 
+obj-$(CONFIG_HAVE_MEMBLOCK)		+= memblock.o
+
 obj-$(CONFIG_MEMTEST)		+= memtest.o

arch/x86/mm/memblock.c

@@ -0,0 +1,87 @@
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/bitops.h>
+#include <linux/memblock.h>
+#include <linux/bootmem.h>
+#include <linux/mm.h>
+#include <linux/range.h>
+
+/* Check for already reserved areas */
+static inline bool __init bad_addr_size(u64 *addrp, u64 *sizep, u64 align)
+{
+	struct memblock_region *r;
+	u64 addr = *addrp, last;
+	u64 size = *sizep;
+	bool changed = false;
+
+again:
+	last = addr + size;
+	for_each_memblock(reserved, r) {
+		if (last > r->base && addr < r->base) {
+			size = r->base - addr;
+			changed = true;
+			goto again;
+		}
+		if (last > (r->base + r->size) && addr < (r->base + r->size)) {
+			addr = round_up(r->base + r->size, align);
+			size = last - addr;
+			changed = true;
+			goto again;
+		}
+		if (last <= (r->base + r->size) && addr >= r->base) {
+			(*sizep)++;
+			return false;
+		}
+	}
+	if (changed) {
+		*addrp = addr;
+		*sizep = size;
+	}
+	return changed;
+}
+
+static u64 __init __memblock_x86_find_in_range_size(u64 ei_start, u64 ei_last, u64 start,
+			 u64 *sizep, u64 align)
+{
+	u64 addr, last;
+
+	addr = round_up(ei_start, align);
+	if (addr < start)
+		addr = round_up(start, align);
+	if (addr >= ei_last)
+		goto out;
+	*sizep = ei_last - addr;
+	while (bad_addr_size(&addr, sizep, align) && addr + *sizep <= ei_last)
+		;
+	last = addr + *sizep;
+	if (last > ei_last)
+		goto out;
+
+	return addr;
+
+out:
+	return MEMBLOCK_ERROR;
+}
+
+/*
+ * Find next free range after start, and size is returned in *sizep
+ */
+u64 __init memblock_x86_find_in_range_size(u64 start, u64 *sizep, u64 align)
+{
+	struct memblock_region *r;
+
+	for_each_memblock(memory, r) {
+		u64 ei_start = r->base;
+		u64 ei_last = ei_start + r->size;
+		u64 addr;
+
+		addr = __memblock_x86_find_in_range_size(ei_start, ei_last, start,
+					 sizep, align);
+
+		if (addr != MEMBLOCK_ERROR)
+			return addr;
+	}
+
+	return MEMBLOCK_ERROR;
+}