From: stefan@agner.ch (Stefan Agner)
To: linux-arm-kernel@lists.infradead.org
Subject: Crash on ARM: 8148/1 flush TLS and thumbee register
Date: Sun, 02 Nov 2014 23:03:14 +0100 [thread overview]
Message-ID: <3b91528704d24eb119ec6d80ad6ba07f@agner.ch> (raw)
In-Reply-To: <5425DA4D.4040301@mentor.com>
Hi all,
While working on Vybrid (vf610) Cortex-M4 support I also hit this crash
observed by Joachim:
...
Freeing unused kernel memory: 16K (8800a000 - 8800e000)
Unhandled exception: IPSR = 00000005 LR = fffffff1
CPU: 0 PID: 1 Comm: swapper Not tainted 3.18.0-rc1-00041-ga30465a #216
task: 8b838000 ti: 8b82a000 task.ti: 8b82a000
PC is at flush_thread+0x32/0x40
LR is at flush_thread+0x21/0x40
pc : [<8f00157a>] lr : [<8f001569>] psr: 4100000b
sp : 8b82be20 ip : 00000000 fp : 8b83c000
r10: 00000001 r9 : 88018c84 r8 : 8bb85000
r7 : 8b838000 r6 : 00000000 r5 : 8bb77400 r4 : 8b82a000
r3 : ffff0ff0 r2 : 8b82a000 r1 : 00000000 r0 : 88020354
xPSR: 4100000b
CPU: 0 PID: 1 Comm: swapper Not tainted 3.18.0-rc1-00041-ga30465a #216
[<8f002bc1>] (unwind_backtrace) from [<8f002033>] (show_stack+0xb/0xc)
[<8f002033>] (show_stack) from [<8f00265b>] (__invalid_entry+0x4b/0x4c)
Can reproduce it on 3.18-rc1, as well as 3.17.
Am 2014-09-26 23:27, schrieb Nathan Lynch:
<snip>
> Thanks for the report -- I see r3 has ffff0ff0 so I'm guessing this is
> set_tls attempting to clear the tls location in the kuser helper page,
> which I suppose isn't appropriate on MMU-less ARM?
I dug a bit deeper and found out that CONFIG_KUSER_HELPERS was enabled
on my build. Without CONFIG_KUSER_HELPERS, the kernel did not crash with
this patch (which makes sense, looking the code, the crashing code is
not executed in the !CONFIG_KUSER_HELPERS case)...
However, wouldn't a "depends on MMU" be required for
CONFIG_KUSER_HELPERS anyway? As far as I understood, this maps stuff
into the user space tasks address space, which is only possible with
MMU...
Also added Uwe Kleine-K?nig as he worked on !MMU Cortex-M3 support.
--
Stefan
next prev parent reply other threads:[~2014-11-02 22:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-26 20:57 Crash on ARM: 8148/1 flush TLS and thumbee register Joachim Eastwood
2014-09-26 21:27 ` Nathan Lynch
2014-11-02 22:03 ` Stefan Agner [this message]
2014-11-02 22:14 ` Russell King - ARM Linux
2014-11-03 7:47 ` Uwe Kleine-König
2014-11-03 14:34 ` Nathan Lynch
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