resources: introduce generic page_is_ram()

It's based on walk_system_ram_range(), for archs that don't have
their own page_is_ram().

The static verions in MIPS and SCORE are also made global.

v4: prefer plain 1 instead of PAGE_IS_RAM (H. Peter Anvin)
v3: add comment (KAMEZAWA Hiroyuki)
    "AFAIK, this "System RAM" information has been used for kdump to
    grab valid memory area and seems good for the kernel itself."
v2: add PAGE_IS_RAM macro (Américo Wang)

Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Américo Wang <xiyou.wangcong@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: Yinghai Lu <yinghai@kernel.org>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
LKML-Reference: <20100122081619.GA6431@localhost>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

4 files changed, 17 insertions, 2 deletions

diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 15aa1902a788..4d72aabe8352 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -294,7 +294,7 @@ void __init fixrange_init(unsigned long start, unsigned long end,
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
         int i;
 
diff --git a/arch/score/mm/init.c b/arch/score/mm/init.c
index 4e3dcd0c4716..f684a590c21d 100644
--- a/arch/score/mm/init.c
+++ b/arch/score/mm/init.c
@@ -59,7 +59,7 @@ static unsigned long setup_zero_page(void)
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
         if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
                 return 1;
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 83aa81297ea3..11ef7952b63a 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -188,5 +188,7 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
                 void *arg, int (*func)(unsigned long, unsigned long, void *));
 
+extern int page_is_ram(unsigned long pfn);
+
 #endif /* __ASSEMBLY__ */
 #endif  /* _LINUX_IOPORT_H */
diff --git a/kernel/resource.c b/kernel/resource.c
index fb11a58b9594..b4d637a55256 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -297,6 +297,19 @@ int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 
 #endif
 
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+        return 1;
+}
+/*
+ * This generic page_is_ram() returns true if specified address is
+ * registered as "System RAM" in iomem_resource list.
+ */
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+        return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
+}
+
 /*
  * Find empty slot in the resource tree given range and alignment.
  */