From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm64: kernel: fix __cpu_suspend mm switch on warm-boot
Date: Sun, 21 Dec 2014 10:50:43 +0000 [thread overview]
Message-ID: <20141221105042.GI23242@arm.com> (raw)
In-Reply-To: <1419008627-1918-1-git-send-email-lorenzo.pieralisi@arm.com>
On Fri, Dec 19, 2014 at 05:03:47PM +0000, Lorenzo Pieralisi wrote:
> On arm64 the TTBR0_EL1 register is set to either the reserved TTBR0
> page tables on boot or to the active_mm mappings belonging to user space
> processes, it must never be set to swapper_pg_dir page tables mappings.
>
> When a CPU is booted its active_mm is set to init_mm even though its
> TTBR0_EL1 points at the reserved TTBR0 page mappings. This implies
> that when __cpu_suspend is triggered the active_mm can point at
> init_mm even if the current TTBR0_EL1 register contains the reserved
> TTBR0_EL1 mappings.
In reality, this is only an issue on the ASID rollover path, right? I
had grand plans to remove the use of a reserved ttbr value from that
code entirely. Obviously that shouldn't hold up this fix, but it would be
nice to understand the relationship (i.e. whether or not I can revert this
patch if/when I improve the ASID allocator).
Will
next prev parent reply other threads:[~2014-12-21 10:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-19 17:03 [PATCH] arm64: kernel: fix __cpu_suspend mm switch on warm-boot Lorenzo Pieralisi
2014-12-21 10:50 ` Will Deacon [this message]
2014-12-21 11:56 ` Catalin Marinas
2014-12-21 15:48 ` Will Deacon
2014-12-22 9:49 ` Lorenzo Pieralisi
2014-12-22 11:07 ` Catalin Marinas
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