linux-kernel - Re: [tip:core/objtool 26/27] arch/x86/kernel/signal.c:357:16: sparse: got unsigned long long [usertype] *__pu

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Date:   Wed, 24 Apr 2019 18:00:46 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     kbuild test robot <lkp@...el.com>
Cc:     kbuild-all@...org, linux-kernel@...r.kernel.org,
        tipbuild@...or.com, Ingo Molnar <mingo@...nel.org>
Subject: Re: [tip:core/objtool 26/27] arch/x86/kernel/signal.c:357:16:
 sparse: got unsigned long long [usertype] *__pu_ptr

On Wed, Apr 24, 2019 at 08:38:53PM +0800, kbuild test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core/objtool
> head:   29da93fea3ea39ab9b12270cc6be1b70ef201c9e
> commit: 6ae865615fc43d014da2fd1f1bba7e81ee622d1b [26/27] x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation
> reproduce:
>         # apt-get install sparse
>         git checkout 6ae865615fc43d014da2fd1f1bba7e81ee622d1b
>         make ARCH=x86_64 allmodconfig
>         make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
> 
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@...el.com>
> 
> sparse warnings: (new ones prefixed by >>)
> 
>    arch/x86/kernel/signal.c:357:16: sparse: sparse: cast removes address space '<asn:1>' of expression
>    arch/x86/kernel/signal.c:357:16: sparse: sparse: cast removes address space '<asn:1>' of expression
>    arch/x86/kernel/signal.c:357:16: sparse: sparse: cast removes address space '<asn:1>' of expression
>    arch/x86/kernel/signal.c:357:16: sparse: sparse: cast removes address space '<asn:1>' of expression
>    arch/x86/kernel/signal.c:357:16: sparse: sparse: cast removes address space '<asn:1>' of expression
>    arch/x86/kernel/signal.c:357:16: sparse: sparse: cast removes address space '<asn:1>' of expression
>    arch/x86/kernel/signal.c:357:16: sparse: sparse: incorrect type in argument 1 (different address spaces) @@    expected void const volatile [noderef] <asn:1> * @@    got st volatile [noderef] <asn:1> * @@
>    arch/x86/kernel/signal.c:357:16: sparse:    expected void const volatile [noderef] <asn:1> *
> >> arch/x86/kernel/signal.c:357:16: sparse:    got unsigned long long [usertype] *__pu_ptr
>    arch/x86/kernel/signal.c:417:17: sparse: sparse: cast removes address space '<asn:1>' of expression
>    arch/x86/kernel/signal.c:417:17: sparse: sparse: incorrect type in argument 1 (different address spaces) @@    expected void const volatile [noderef] <asn:1> * @@    got st volatile [noderef] <asn:1> * @@
>    arch/x86/kernel/signal.c:417:17: sparse:    expected void const volatile [noderef] <asn:1> *
>    arch/x86/kernel/signal.c:417:17: sparse:    got unsigned long long [usertype] *

I'm not getting that; I have sparse version: 0.6.0 (Debian: 0.6.0-3)

But I suspect something like the below ought to cure that. But this is
not new from this patch, it's just that the sparse output changed
because some variable changed name.

---
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 364813cea647..1fd714b42a79 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -352,7 +352,7 @@ __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
 	 * reasons and because gdb uses it as a signature to notice
 	 * signal handler stack frames.
 	 */
-	err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
+	err |= __put_user(*((u64 __user *)&retcode), (u64 __user *)frame->retcode);
 
 	if (err)
 		return -EFAULT;