From 217c14ad3eb91aefe07954e7e9a6b211bbce9c3f Mon Sep 17 00:00:00 2001
From: Cao jin <caoj.fnst@cn.fujitsu.com>
Date: Thu, 1 Mar 2018 23:53:33 -0500
Subject: [PATCH] util/mmap-alloc: check parameter before using

Backports commit 4a3ecf201a1a49a804e8506df5906e446707c3b1 from qemu
---
 qemu/util/mmap-alloc.c | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/qemu/util/mmap-alloc.c b/qemu/util/mmap-alloc.c
index 00b2d8cd..46b89c3c 100644
--- a/qemu/util/mmap-alloc.c
+++ b/qemu/util/mmap-alloc.c
@@ -12,17 +12,32 @@
 
 #include "qemu/osdep.h"
 #include "qemu/mmap-alloc.h"
+#include "qemu/host-utils.h"
 #include <sys/mman.h>
 
 void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared)
 {
-    /*
-     * Note: this always allocates at least one extra page of virtual address
-     * space, even if size is already aligned.
-     */
-    size_t total = size + align;
-    void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
-    size_t offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
+     /*
+      * Note: this always allocates at least one extra page of virtual address
+      * space, even if size is already aligned.
+      */
+     size_t total = size + align;
+ #if defined(__powerpc64__) && defined(__linux__)
+     /* On ppc64 mappings in the same segment (aka slice) must share the same
+      * page size. Since we will be re-allocating part of this segment
+      * from the supplied fd, we should make sure to use the same page size, to
+      * this end we mmap the supplied fd.  In this case, set MAP_NORESERVE to
+      * avoid allocating backing store memory.
+      * We do this unless we are using the system page size, in which case
+      * anonymous memory is OK.
+      */
+     int anonfd = fd == -1 || qemu_fd_getpagesize(fd) == getpagesize() ? -1 : fd;
+     int flags = anonfd == -1 ? MAP_ANONYMOUS : MAP_NORESERVE;
+     void *ptr = mmap(0, total, PROT_NONE, flags | MAP_PRIVATE, anonfd, 0);
+ #else
+     void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ #endif
+    size_t offset;
     void *ptr1;
 
     if (ptr == MAP_FAILED) {
@@ -30,10 +45,11 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared)
     }
 
     /* Make sure align is a power of 2 */
-    assert(!(align & (align - 1)));
+    assert(is_power_of_2(align));
     /* Always align to host page size */
     assert(align >= getpagesize());
 
+    offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
     ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
                 MAP_FIXED |
                 (fd == -1 ? MAP_ANONYMOUS : 0) |