[PATCH v2] hw/arm_sysctl: fix extracting 31th bit of val

[Anastasia Belova]

1 << 31 is casted to uint64_t while bitwise and with val.
So this value may become 0xffffffff80000000 but only
31th "start" bit is required.

Use the bitfield extract() API instead.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
---
v2: make extracting more clear
 hw/misc/arm_sysctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/misc/arm_sysctl.c b/hw/misc/arm_sysctl.c
index 69e379fa10..c4e93da3cd 100644
--- a/hw/misc/arm_sysctl.c
+++ b/hw/misc/arm_sysctl.c
@@ -520,7 +520,7 @@ static void arm_sysctl_write(void *opaque, hwaddr offset,
          * as zero.
          */
         s->sys_cfgctrl = val & ~((3 << 18) | (1 << 31));
-        if (val & (1 << 31)) {
+        if (extract64(val, 31, 1)) {
             /* Start bit set -- actually do something */
             unsigned int dcc = extract32(s->sys_cfgctrl, 26, 4);
             unsigned int function = extract32(s->sys_cfgctrl, 20, 6);
-- 
2.47.0