From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Giancarlo Ferrari <giancarlo.ferrari89@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
rppt@kernel.org, penberg@kernel.org, geert@linux-m68k.org,
giancarlo.ferrari@nokia.com
Subject: Re: [PATCH] ARM: kexec: Fix panic after TLB are invalidated
Date: Mon, 1 Feb 2021 11:34:36 +0000 [thread overview]
Message-ID: <20210201113436.GE1463@shell.armlinux.org.uk> (raw)
In-Reply-To: <1612140296-12546-1-git-send-email-giancarlo.ferrari89@gmail.com>
I wish others who know this code would get involved, and such stuff
wasn't left to me to research and work out whether a patch is correct
or not.
On Mon, Feb 01, 2021 at 12:44:56AM +0000, Giancarlo Ferrari wrote:
> machine_kexec() need to set rw permission in text and rodata sections
> to assign some variables (e.g. kexec_start_address). To do that at
> the end (after flushing pdm in memory, etc.) it needs to invalidate
> TLB [section] entries.
>
> If during the TLB invalidation an interrupt occours, which might cause
> a context switch, there is the risk to inject invalid TLBs, with ro
> permissions.
>
> When trying to assign .text labels, this lead to the following:
>
> Unable to handle kernel paging request at virtual address 80112f38
> pgd = fd7ef03e
> [80112f38] *pgd=0001141e(bad)
> Internal error: Oops: 80d [#1] PREEMPT SMP ARM
> ...
>
> Signed-off-by: Giancarlo Ferrari <giancarlo.ferrari89@gmail.com>
I don't know this code very well, but I don't think this patch is
correct. What happens if we have CRASH_DUMP enabled, and we enter this
function with IRQs already disabled? Should we really be re-enabling
IRQs?
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2021-02-01 11:36 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-01 0:44 [PATCH] ARM: kexec: Fix panic after TLB are invalidated Giancarlo Ferrari
2021-02-01 11:34 ` Russell King - ARM Linux admin [this message]
2021-02-01 12:47 ` Mark Rutland
2021-02-01 13:03 ` Russell King - ARM Linux admin
2021-02-01 13:57 ` Mark Rutland
2021-02-01 16:08 ` Russell King - ARM Linux admin
2021-02-01 16:32 ` Mark Rutland
2021-02-01 16:37 ` Russell King - ARM Linux admin
2021-02-01 20:07 ` Giancarlo Ferrari
2021-02-01 20:16 ` Russell King - ARM Linux admin
2021-02-01 22:18 ` Giancarlo Ferrari
2021-02-04 23:48 ` Giancarlo Ferrari
2021-02-05 0:18 ` Russell King - ARM Linux admin
2021-02-05 0:40 ` Giancarlo Ferrari
2021-02-05 0:45 ` Giancarlo Ferrari
2021-02-05 9:44 ` Russell King - ARM Linux admin
2021-02-05 14:36 ` Giancarlo Ferrari
2021-02-01 14:39 ` Giancarlo Ferrari
2021-02-01 15:30 ` Mark Rutland
2021-02-01 19:09 ` Giancarlo Ferrari
-- strict thread matches above, loose matches on Subject: below --
2021-01-12 16:49 Giancarlo Ferrari
2021-02-01 10:10 ` Giancarlo Ferrari
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