Messages in this thread | | | Date | Tue, 15 Jun 2021 15:26:14 +0100 | From | Will Deacon <> | Subject | Re: [PATCH] arm64/mm: Fix ttbr0 values stored in struct thread_info for software-pan |
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On Tue, Jun 15, 2021 at 03:25:39PM +0100, Catalin Marinas wrote: > On Tue, Jun 15, 2021 at 03:02:58PM +0530, Anshuman Khandual wrote: > > When using CONFIG_ARM64_SW_TTBR0_PAN, a task's thread_info::ttbr0 must be > > the TTBR0_EL1 value used to run userspace. With 52-bit PAs, the PA must be > > packed into the TTBR using phys_to_ttbr(), but we forget to do this in some > > of the SW PAN code. Thus, if the value is installed into TTBR0_EL1 (as may > > happen in the uaccess routines), this could result in UNPREDICTABLE > > behaviour. > > > > Since hardware with 52-bit PA support almost certainly has HW PAN, which > > will be used in preference, this shouldn't be a practical issue, but let's > > fix this for consistency. > > I'm ok with fixing this for consistency. We should never hit those paths > unless someone built hardware with 52-bit PA (8.2) but without PAN (8.1) > and it would not be architecture compliant. > > I'll leave it with Will for 5.14, it's no a fix that needs urgent > queuing. > > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cheers, I'll pick it up.
Will
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