From: Thomas Huth <thuth@redhat.com>
To: qemu-devel@nongnu.org, Peter Maydell <peter.maydell@linaro.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
qemu-s390x@nongnu.org, cohuck@redhat.com
Subject: [PULL 3/9] pc-bios/s390-ccw: Use reset_psw pointer instead of hard-coded null pointer
Date: Mon, 10 May 2021 09:35:18 +0200 [thread overview]
Message-ID: <20210510073524.85951-4-thuth@redhat.com> (raw)
In-Reply-To: <20210510073524.85951-1-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.
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210423142440.582188-1-thuth@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
pc-bios/s390-ccw/jump2ipl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
index b9c70d64a5..73e4367e09 100644
--- a/pc-bios/s390-ccw/jump2ipl.c
+++ b/pc-bios/s390-ccw/jump2ipl.c
@@ -82,8 +82,8 @@ void jump_to_low_kernel(void)
jump_to_IPL_code(KERN_IMAGE_START);
}
- /* Trying to get PSW at zero address */
- if (*((uint64_t *)0) & RESET_PSW_MASK) {
+ /* Trying to get PSW at zero address (pointed to by reset_psw) */
+ 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
next prev parent reply other threads:[~2021-05-10 7:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 7:35 [PULL 0/9] s390-ccw bios update Thomas Huth
2021-05-10 7:35 ` [PULL 1/9] pc-bios/s390-ccw: don't try to read the next block if end of chunk is reached Thomas Huth
2021-05-10 7:35 ` [PULL 2/9] pc-bios/s390-ccw/bootmap: Silence compiler warning from Clang Thomas Huth
2021-05-10 7:35 ` Thomas Huth [this message]
2021-05-10 7:35 ` [PULL 4/9] pc-bios/s390-ccw/netboot: Use "-Wl, " prefix to pass parameter to the linker Thomas Huth
2021-05-10 7:35 ` [PULL 5/9] pc-bios/s390-ccw: Silence warning from Clang by marking panic() as noreturn Thomas Huth
2021-05-10 7:35 ` [PULL 6/9] pc-bios/s390-ccw: Fix the cc-option macro in the Makefile Thomas Huth
2021-05-10 7:35 ` [PULL 7/9] pc-bios/s390-ccw: Silence GCC 11 stringop-overflow warning Thomas Huth
2021-05-10 7:35 ` [PULL 8/9] pc-bios/s390-ccw: Allow building with Clang, too Thomas Huth
2021-05-12 11:53 ` Philippe Mathieu-Daudé
2021-05-12 13:40 ` Thomas Huth
2021-05-12 14:00 ` Thomas Huth
2021-05-12 14:51 ` Thomas Huth
2021-05-12 14:09 ` Philippe Mathieu-Daudé
2021-05-10 7:35 ` [PULL 9/9] pc-bios/s390: Update the s390-ccw bios binaries with the Clang and other fixes Thomas Huth
2021-05-12 7:53 ` [PULL 0/9] s390-ccw bios update Peter Maydell
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