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* arm64: kernel v4.6-rc1 hangs on QEMU
@ 2016-03-29 22:05 Yury Norov
  2016-03-29 22:12 ` Arnd Bergmann
  0 siblings, 1 reply; 6+ messages in thread
From: Yury Norov @ 2016-03-29 22:05 UTC (permalink / raw)
  To: linux-arm-kernel; +Cc: linux-kernel

Hi,

Checked  for both v4.6-rc1 and current master (1993b17).
Config: arm64 defconfig
QEMU: QEMU emulator version 2.3.0 (Debian 1:2.3+dfsg-5ubuntu9.2)

Stacktrace:
#0  arch_counter_get_cntvct () at
./arch/arm64/include/asm/arch_timer.h:121
#1  __delay (cycles=1024) at arch/arm64/lib/delay.c:31
#2  0xffffff8008340970 in __const_udelay (xloops=<optimized out>) at
arch/arm64/lib/delay.c:41
#3  0xffffff800815420c in panic (fmt=<optimized out>) at
kernel/panic.c:257
#4  0xffffff80080be588 in do_exit (code=11) at kernel/exit.c:666
#5  0xffffff8008089d08 in die (str=<optimized out>, regs=0xffffff8008aebe20 <init_thread_union+15904>, err=143867376) at arch/arm64/kernel/traps.c:298
#6  0xffffff8008089dec in arm64_notify_die (str=<optimized out>, regs=<optimized out>, info=<optimized out>, err=<optimized out>) at arch/arm64/kernel/traps.c:309
#7  0xffffff800808212c in do_undefinstr (regs=0xffffff8008aebe20 <init_thread_union+15904>) at arch/arm64/kernel/traps.c:399
#8  0xffffff8008a1fe08 in cpuinfo_store_boot_cpu () at arch/arm64/kernel/cpuinfo.c:252
#9  0xffffff8008a1fe08 in cpuinfo_store_boot_cpu () at arch/arm64/kernel/cpuinfo.c:252
#10 0xffffff8008a20388 in smp_prepare_boot_cpu () at arch/arm64/kernel/smp.c:403
#11 0xffffff8008a1d6ec in start_kernel () at init/main.c:511
#12 0xffffff80080811d8 in __mmap_switched () at arch/arm64/kernel/head.S:437
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Corefile can be found at:
https://drive.google.com/file/d/0B93nHerV55yNdFp5em54TEVnU2c/view?usp=sharing

Yury.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: arm64: kernel v4.6-rc1 hangs on QEMU
  2016-03-29 22:05 arm64: kernel v4.6-rc1 hangs on QEMU Yury Norov
@ 2016-03-29 22:12 ` Arnd Bergmann
  2016-03-29 22:22   ` Yury Norov
  0 siblings, 1 reply; 6+ messages in thread
From: Arnd Bergmann @ 2016-03-29 22:12 UTC (permalink / raw)
  To: linux-arm-kernel; +Cc: Yury Norov, linux-kernel

On Wednesday 30 March 2016 01:05:02 Yury Norov wrote:
> Checked  for both v4.6-rc1 and current master (1993b17).
> Config: arm64 defconfig
> QEMU: QEMU emulator version 2.3.0 (Debian 1:2.3+dfsg-5ubuntu9.2)
> 
> Stacktrace:
> #0  arch_counter_get_cntvct () at
> ./arch/arm64/include/asm/arch_timer.h:121
> #1  __delay (cycles=1024) at arch/arm64/lib/delay.c:31
> #2  0xffffff8008340970 in __const_udelay (xloops=<optimized out>) at
> arch/arm64/lib/delay.c:41
> #3  0xffffff800815420c in panic (fmt=<optimized out>) at
> kernel/panic.c:257
> #4  0xffffff80080be588 in do_exit (code=11) at kernel/exit.c:666
> #5  0xffffff8008089d08 in die (str=<optimized out>, regs=0xffffff8008aebe20 <init_thread_union+15904>, err=143867376) at arch/arm64/kernel/traps.c:298
> #6  0xffffff8008089dec in arm64_notify_die (str=<optimized out>, regs=<optimized out>, info=<optimized out>, err=<optimized out>) at arch/arm64/kernel/traps.c:309
> #7  0xffffff800808212c in do_undefinstr (regs=0xffffff8008aebe20 <init_thread_union+15904>) at arch/arm64/kernel/traps.c:399
> #8  0xffffff8008a1fe08 in cpuinfo_store_boot_cpu () at arch/arm64/kernel/cpuinfo.c:252
> #9  0xffffff8008a1fe08 in cpuinfo_store_boot_cpu () at arch/arm64/kernel/cpuinfo.c:252
> #10 0xffffff8008a20388 in smp_prepare_boot_cpu () at arch/arm64/kernel/smp.c:403
> #11 0xffffff8008a1d6ec in start_kernel () at init/main.c:511
> #12 0xffffff80080811d8 in __mmap_switched () at arch/arm64/kernel/head.S:437
> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
> 

Undefined instruction in cpuinfo_store_boot_cpu() could be related
to the SYS_ID_AA64MMFR2_EL1 access that was recently added.

What does the architecture say about reading unknown cpuid registers?

	Arnd

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: arm64: kernel v4.6-rc1 hangs on QEMU
  2016-03-29 22:12 ` Arnd Bergmann
@ 2016-03-29 22:22   ` Yury Norov
  2016-03-29 22:32     ` Arnd Bergmann
  0 siblings, 1 reply; 6+ messages in thread
From: Yury Norov @ 2016-03-29 22:22 UTC (permalink / raw)
  To: Arnd Bergmann; +Cc: linux-arm-kernel, linux-kernel, alexey.klimov

On Wed, Mar 30, 2016 at 12:12:30AM +0200, Arnd Bergmann wrote:
> On Wednesday 30 March 2016 01:05:02 Yury Norov wrote:
> > Checked  for both v4.6-rc1 and current master (1993b17).
> > Config: arm64 defconfig
> > QEMU: QEMU emulator version 2.3.0 (Debian 1:2.3+dfsg-5ubuntu9.2)
> > 
> > Stacktrace:
> > #0  arch_counter_get_cntvct () at
> > ./arch/arm64/include/asm/arch_timer.h:121
> > #1  __delay (cycles=1024) at arch/arm64/lib/delay.c:31
> > #2  0xffffff8008340970 in __const_udelay (xloops=<optimized out>) at
> > arch/arm64/lib/delay.c:41
> > #3  0xffffff800815420c in panic (fmt=<optimized out>) at
> > kernel/panic.c:257
> > #4  0xffffff80080be588 in do_exit (code=11) at kernel/exit.c:666
> > #5  0xffffff8008089d08 in die (str=<optimized out>, regs=0xffffff8008aebe20 <init_thread_union+15904>, err=143867376) at arch/arm64/kernel/traps.c:298
> > #6  0xffffff8008089dec in arm64_notify_die (str=<optimized out>, regs=<optimized out>, info=<optimized out>, err=<optimized out>) at arch/arm64/kernel/traps.c:309
> > #7  0xffffff800808212c in do_undefinstr (regs=0xffffff8008aebe20 <init_thread_union+15904>) at arch/arm64/kernel/traps.c:399
> > #8  0xffffff8008a1fe08 in cpuinfo_store_boot_cpu () at arch/arm64/kernel/cpuinfo.c:252
> > #9  0xffffff8008a1fe08 in cpuinfo_store_boot_cpu () at arch/arm64/kernel/cpuinfo.c:252
> > #10 0xffffff8008a20388 in smp_prepare_boot_cpu () at arch/arm64/kernel/smp.c:403
> > #11 0xffffff8008a1d6ec in start_kernel () at init/main.c:511
> > #12 0xffffff80080811d8 in __mmap_switched () at arch/arm64/kernel/head.S:437
> > Backtrace stopped: previous frame identical to this frame (corrupt stack?)
> > 
> 
> Undefined instruction in cpuinfo_store_boot_cpu() could be related
> to the SYS_ID_AA64MMFR2_EL1 access that was recently added.
> 
> What does the architecture say about reading unknown cpuid registers?
> 
> 	Arnd

ThunderX has some unimplemented system registers. AFAIR, attempt to access it
causes data abort.

Yury.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: arm64: kernel v4.6-rc1 hangs on QEMU
  2016-03-29 22:22   ` Yury Norov
@ 2016-03-29 22:32     ` Arnd Bergmann
  2016-03-29 22:52       ` Yury Norov
  0 siblings, 1 reply; 6+ messages in thread
From: Arnd Bergmann @ 2016-03-29 22:32 UTC (permalink / raw)
  To: Yury Norov; +Cc: linux-arm-kernel, linux-kernel, alexey.klimov

On Wednesday 30 March 2016 01:22:17 Yury Norov wrote:
> > 
> > Undefined instruction in cpuinfo_store_boot_cpu() could be related
> > to the SYS_ID_AA64MMFR2_EL1 access that was recently added.
> > 
> > What does the architecture say about reading unknown cpuid registers?
> > 
> >       Arnd
> 
> ThunderX has some unimplemented system registers. AFAIR, attempt to access it
> causes data abort.

Ok, if that is the case, maybe the read_cpuid() macro can be changed
so it contains a fixup for the trap? That should handle both data abort
and undefinstr.

	Arnd

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: arm64: kernel v4.6-rc1 hangs on QEMU
  2016-03-29 22:32     ` Arnd Bergmann
@ 2016-03-29 22:52       ` Yury Norov
  2016-03-30  6:44         ` Kefeng Wang
  0 siblings, 1 reply; 6+ messages in thread
From: Yury Norov @ 2016-03-29 22:52 UTC (permalink / raw)
  To: Arnd Bergmann; +Cc: linux-arm-kernel, linux-kernel, alexey.klimov

On Wed, Mar 30, 2016 at 12:32:42AM +0200, Arnd Bergmann wrote:
> On Wednesday 30 March 2016 01:22:17 Yury Norov wrote:
> > > 
> > > Undefined instruction in cpuinfo_store_boot_cpu() could be related
> > > to the SYS_ID_AA64MMFR2_EL1 access that was recently added.
> > > 
> > > What does the architecture say about reading unknown cpuid registers?
> > > 
> > >       Arnd
> > 
> > ThunderX has some unimplemented system registers. AFAIR, attempt to access it
> > causes data abort.
> 
> Ok, if that is the case, maybe the read_cpuid() macro can be changed
> so it contains a fixup for the trap? That should handle both data abort
> and undefinstr.
> 
> 	Arnd

Sounds alluring, but not clear what we'd return that way. I mean, how
we'd distinguish between correct value and error code (0, -1 or whatever).
But I think, we can do like this:

        val = read_cpuid_safe(reg, impossible_val);
        if (val == impossible_val)
                goto err;

I think it will work for many cases.

Yury.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: arm64: kernel v4.6-rc1 hangs on QEMU
  2016-03-29 22:52       ` Yury Norov
@ 2016-03-30  6:44         ` Kefeng Wang
  0 siblings, 0 replies; 6+ messages in thread
From: Kefeng Wang @ 2016-03-30  6:44 UTC (permalink / raw)
  To: Yury Norov, Arnd Bergmann; +Cc: linux-arm-kernel, linux-kernel, alexey.klimov



On 2016/3/30 6:52, Yury Norov wrote:
> On Wed, Mar 30, 2016 at 12:32:42AM +0200, Arnd Bergmann wrote:
>> On Wednesday 30 March 2016 01:22:17 Yury Norov wrote:
>>>>
>>>> Undefined instruction in cpuinfo_store_boot_cpu() could be related
>>>> to the SYS_ID_AA64MMFR2_EL1 access that was recently added.
>>>>

please use new qemu with
commit e20d84c1407d43d5a2e2ac95dbb46db3b0af8f9f
Author: Peter Maydell <peter.maydell@linaro.org>
Date:   Fri Feb 19 14:07:43 2016 +0000

    target-arm: Make reserved ranges in ID_AA64* spaces RAZ, not UNDEF

    The v8 ARM ARM defines that unused spaces in the ID_AA64* system
    register ranges are Reserved and must RAZ, rather than being UNDEF.
    Implement this.

    In particular, ARM v8.2 adds a new feature register ID_AA64MMFR2,
    and newer versions of the Linux kernel will attempt to read this,
    which causes them not to boot up on versions of QEMU missing this fix.

    Since the encoding .opc0 = 3, .opc1 = 0, .crn = 0, .crm = 2, .opc2 = 6
    is actually defined in ARMv8 (as ID_MMFR4), we give it an entry in
    the ARMCPU struct so CPUs can override it, though since none do
    this too will just RAZ.


see https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg04574.html

>>>> What does the architecture say about reading unknown cpuid registers?
>>>>
>>>>       Arnd
>>>
>>> ThunderX has some unimplemented system registers. AFAIR, attempt to access it
>>> causes data abort.
>>
>> Ok, if that is the case, maybe the read_cpuid() macro can be changed
>> so it contains a fixup for the trap? That should handle both data abort
>> and undefinstr.
>>
>> 	Arnd
> 
> Sounds alluring, but not clear what we'd return that way. I mean, how
> we'd distinguish between correct value and error code (0, -1 or whatever).
> But I think, we can do like this:
> 
>         val = read_cpuid_safe(reg, impossible_val);
>         if (val == impossible_val)
>                 goto err;
> 
> I think it will work for many cases.
> 
> Yury.
> 
> 

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-03-30  6:44 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-03-29 22:05 arm64: kernel v4.6-rc1 hangs on QEMU Yury Norov
2016-03-29 22:12 ` Arnd Bergmann
2016-03-29 22:22   ` Yury Norov
2016-03-29 22:32     ` Arnd Bergmann
2016-03-29 22:52       ` Yury Norov
2016-03-30  6:44         ` Kefeng Wang

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