[PATCH] pc-bios/s390-ccw: Use reset_psw pointer instead of hard-coded null pointer

[Thomas Huth <thuth@redhat.com>]

When compiling the s390-ccw bios with clang, it emits a warning like this:

 pc-bios/s390-ccw/jump2ipl.c:86:9: warning: indirection of non-volatile null
  pointer will be deleted, not trap [-Wnull-dereference]
     if (*((uint64_t *)0) & RESET_PSW_MASK) {
         ^~~~~~~~~~~~~~~~
 pc-bios/s390-ccw/jump2ipl.c:86:9: note: consider using __builtin_trap() or
  qualifying pointer with 'volatile'

We could add a "volatile" here to shut it up, but on the other hand,
we also have a pointer variable called "reset_psw" in this file already
that points to the PSW at address 0, so we can simply use that pointer
variable instead.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 pc-bios/s390-ccw/jump2ipl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
index b9c70d64a5..de1541ea5d 100644
--- a/pc-bios/s390-ccw/jump2ipl.c
+++ b/pc-bios/s390-ccw/jump2ipl.c
@@ -83,7 +83,7 @@ void jump_to_low_kernel(void)
     }
 
     /* Trying to get PSW at zero address */
-    if (*((uint64_t *)0) & RESET_PSW_MASK) {
+    if (*reset_psw & RESET_PSW_MASK) {
         /*
          * Surely nobody will try running directly from lowcore, so
          * let's use 0 as an indication that we want to load the reset
-- 
2.27.0