Date: Tue, 15 Nov 2016 16:54:16 +0100
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: next: s390 crash due to 's390: move sys_call_table and
 last_break from thread_info to thread_struct'
In-Reply-To: <20161115153554.GA22064@roeck-us.net>
References: <20161115153554.GA22064@roeck-us.net>
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On Tue, 15 Nov 2016 07:35:54 -0800
Guenter Roeck <linux@roeck-us.net> wrote:

> Hi Martin,
> 
> my s390 qemu boot test crashes in -next as follows.
> 
> Kernel stack overflow.
> CPU: 0 PID: 923 Comm: modprobe Not tainted 4.9.0-rc5-next-20161115 #1
> Hardware name: QEMU             QEMU                  QEMU             (KVM)
> task: 000000001d805100 task.stack: 000000001d898000
> Krnl PSW : 0404e00180000000 0000000000ac2b42 (pgm_check_handler+0xd6/0x1b4)
>            R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3
> Krnl GPRS: 0000000000000020 0000000000000000 0000000000000004 0000000000000000
>            0000000000400034 0000000000000000 000000007ff3b350 0000000000000001
>            0404e00180000000 0000000000ac2b42 0000000000ac2ad0 000000007ff38178
>            000000001d805100 0000000000ac335e 0000000000000200 000000007ff380d8
> Krnl Code: 0000000000ac2b34: a7840005		brc	8,ac2b3e
>            0000000000ac2b38: d2ffe0e8d000	mvc	232(256,%r14),0(%r13)
>           #0000000000ac2b3e: 41b0f0a0		la	%r11,160(%r15)
>           >0000000000ac2b42: eb07b0180024	stmg	%r0,%r7,24(%r11)
>            0000000000ac2b48: d23fb0580200	mvc	88(64,%r11),512
>            0000000000ac2b4e: eb89b0080024	stmg	%r8,%r9,8(%r11)
>            0000000000ac2b54: d203b0a0008c	mvc	160(4,%r11),140
>            0000000000ac2b5a: d207b0a800a8	mvc	168(8,%r11),168
> Call Trace:
> no locks held by modprobe/923.
> Last Breaking-Event-Address:
>  [<0000000000000000>]           (null)
>  Kernel panic - not syncing: Corrupt kernel stack, can't continue.
> 
> Bisect points to commit 1914608db9 ("s390: move sys_call_table and last_break
> from thread_info to thread_struct"). Reverting that patch fixes the problem.
> 
> Configuration is s390:defconfig with CONFIG_MARCH_Z900=y.
> 
> Bisect log is attached.
> A complete log is at:
> http://kerneltests.org/builders/qemu-s390-next/builds/252/steps/qemubuildcommand/logs/stdio

Thanks for the report. Builds for Z900 and Z990 are borked. This hunk

@@ -287,7 +292,13 @@ ENTRY(system_call)
        mvc     __PT_INT_CODE(4,%r11),__LC_SVC_ILC
        stg     %r14,__PT_FLAGS(%r11)
 .Lsysc_do_svc:
-       lg      %r10,__TI_sysc_table(%r12)      # address of system call table
+       # load address of system call table
+#ifdef CONFIG_HAVE_MARCH_Z990_FEATURES
+       lg      %r10,__TASK_thread+__THREAD_sysc_table(%r12)
+#else
+       lghi    %r10,__TASK_thread
+       lg      %r10,__THREAD_sysc_table(%r10,%r12)
+#endif
        llgh    %r8,__PT_INT_CODE+2(%r11)
        slag    %r8,%r8,2                       # shift and test for svc 0
        jnz     .Lsysc_nr_ok

makes ill use of %r10 in the #else part. Should be fixed now and tomorrows -next
tree will have the fix. Thanks again.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.