[Crash-utility] [PATCH 1/3] crash: add fuction get_cpus_active

[Liu Hua]

This patch introduces a method to get the number of CPUs on
cpu_active_map. It is useful to determine online CPUs for ARM
platform.

Signed-off-by: Liu Hua <sdu.liu at huawei.com>
---
 defs.h   |  1 +
 kernel.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/defs.h b/defs.h
index b5cff61..03b11a8 100644
--- a/defs.h
+++ b/defs.h
@@ -4792,6 +4792,7 @@ void set_cpu(int);
 void clear_machdep_cache(void);
 struct stack_hook *gather_text_list(struct bt_info *);
 int get_cpus_online(void);
+int get_cpus_active(void);
 int get_cpus_present(void);
 int get_cpus_possible(void);
 int get_highest_cpu_online(void);
diff --git a/kernel.c b/kernel.c
index 9ed280e..fcdb905 100644
--- a/kernel.c
+++ b/kernel.c
@@ -7934,6 +7934,40 @@ get_highest_cpu_online()
 }
 
 /*
+ *  If it exists, return the number of cpus in the cpu_active_map.
+ */
+int
+get_cpus_active()
+{
+	int i, len, active;
+	char *buf;
+	ulong *maskptr, addr;
+
+	if (!(addr = cpu_map_addr("active")))
+		return 0;
+
+	len = cpu_map_size("active");
+	buf = GETBUF(len);
+
+	active = 0;
+
+	if (readmem(addr, KVADDR, buf, len,
+		"cpu_active_map", RETURN_ON_ERROR)) {
+
+		maskptr = (ulong *)buf;
+		for (i = 0; i < (len/sizeof(ulong)); i++, maskptr++)
+			active += count_bits_long(*maskptr);
+
+		if (CRASHDEBUG(1))
+			error(INFO, "get_cpus_active: active: %d\n", active);
+	}
+
+	FREEBUF(buf);
+
+	return active;
+}
+
+/*
  *  If it exists, return the number of cpus in the cpu_present_map.
  */
 int
-- 
1.9.0