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From: Mark Rutland <mark.rutland@arm.com>
To: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, Jaxson.Han@arm.com,
	robin.murphy@arm.com, vladimir.murzin@arm.com, Wei.Chen@arm.com
Subject: Re: [bootwrapper PATCH v2 06/13] aarch64: initialize SCTLR_ELx for the boot-wrapper
Date: Wed, 19 Jan 2022 12:42:34 +0000	[thread overview]
Message-ID: <YegHOqpe24imKuMN@FVFF77S0Q05N> (raw)
In-Reply-To: <20220117121557.GA87485@C02TD0UTHF1T.local>

On Mon, Jan 17, 2022 at 12:15:57PM +0000, Mark Rutland wrote:
> On Fri, Jan 14, 2022 at 06:12:47PM +0000, Andre Przywara wrote:
> > On Fri, 14 Jan 2022 10:56:46 +0000
> > Mark Rutland <mark.rutland@arm.com> wrote:

> > > +
> > > +#define SCTLR_EL1_RES1		(BIT(29) | BIT(28) | BIT(23) | BIT(22) | \
> > > +				 BIT(11) | BIT(8) | BIT(7) | BIT(4))
> > 
> > - The kernel sets TSCXT(bit[20]), and the ARM ARM says that the value
> > should be RES1 if FEAT_CSV2_* is not implemented. Should we copy this?
> 
> Yes, we should. I'll go and fold that in.
> 
> > - The kernel clears ITD(bit[7]), and the ARM ARM says it's *Otherwise* RES1
> > (no AArch32 in EL0). I feel like we should not disable IT instructions in
> > EL0 needlessly?
> 
> Per the ARM ARM the bit resets to an UNKNOWN value, and so per our usual
> policy the kernel must initialize that before it can depend upon it, and
> IIUC you say the kernel already does so.
> 
> So it shouldn't matter what the boot-wrapper does, and for consitency, I
> think the boot-wrapper should set this to 0b1.
> 
> > - I also feel like we should set CP15BEN(bit[5]), for similar reasons.
> 
> I agree.

I thought you meant it was also RES1 in the same case as ITD. It's actually
RES0 when there's no AArch32 EL0 support, so I'm not going to add it to
SCTLR_EL1_RES1.

I have added TSCXT (bit[20]) and ITD (bit[7]), as above, as those are RES1 in
some contexts.

THanks,
Mark.

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  parent reply	other threads:[~2022-01-19 12:43 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-14 10:56 [bootwrapper PATCH v2 00/13] Cleanups and improvements Mark Rutland
2022-01-14 10:56 ` [bootwrapper PATCH v2 01/13] Document entry requirements Mark Rutland
2022-01-14 10:56 ` [bootwrapper PATCH v2 02/13] Add bit-field macros Mark Rutland
2022-01-17 12:11   ` Steven Price
2022-01-17 13:28     ` Mark Rutland
2022-01-14 10:56 ` [bootwrapper PATCH v2 03/13] aarch64: add system register accessors Mark Rutland
2022-01-14 15:32   ` Andre Przywara
2022-01-14 10:56 ` [bootwrapper PATCH v2 04/13] aarch32: add coprocessor accessors Mark Rutland
2022-01-14 10:56 ` [bootwrapper PATCH v2 05/13] aarch64: add mov_64 macro Mark Rutland
2022-01-14 15:50   ` Andre Przywara
2022-01-14 10:56 ` [bootwrapper PATCH v2 06/13] aarch64: initialize SCTLR_ELx for the boot-wrapper Mark Rutland
2022-01-14 18:12   ` Andre Przywara
2022-01-17 12:15     ` Mark Rutland
2022-01-17 13:05       ` Mark Rutland
2022-01-18 12:37         ` Andre Przywara
2022-01-25 13:32           ` Mark Rutland
2022-01-19 12:42       ` Mark Rutland [this message]
2022-01-14 10:56 ` [bootwrapper PATCH v2 07/13] Rework common init C code Mark Rutland
2022-01-17 16:23   ` Andre Przywara
2022-01-14 10:56 ` [bootwrapper PATCH v2 08/13] Announce boot-wrapper mode / exception level Mark Rutland
2022-01-17 14:39   ` Andre Przywara
2022-01-17 15:50     ` Mark Rutland
2022-01-14 10:56 ` [bootwrapper PATCH v2 09/13] aarch64: move the bulk of EL3 initialization to C Mark Rutland
2022-01-17 14:31   ` Andre Przywara
2022-01-17 18:08     ` Mark Rutland
2022-01-17 18:31       ` Andre Przywara
2022-01-18 16:50         ` Mark Brown
2022-01-19 15:22           ` Mark Rutland
2022-01-14 10:56 ` [bootwrapper PATCH v2 10/13] aarch32: move the bulk of Secure PL1 " Mark Rutland
2022-01-17 14:52   ` Andre Przywara
2022-01-14 10:56 ` [bootwrapper PATCH v2 11/13] Announce locations of memory objects Mark Rutland
2022-01-14 15:30   ` Andre Przywara
2022-01-14 16:04     ` Robin Murphy
2022-01-14 16:30       ` Mark Rutland
2022-01-14 16:21     ` Mark Rutland
2022-01-17 14:59   ` Andre Przywara
2022-01-14 10:56 ` [bootwrapper PATCH v2 12/13] Rework bootmethod initialization Mark Rutland
2022-01-17 17:43   ` Andre Przywara
2022-01-25 14:00     ` Mark Rutland
2022-01-14 10:56 ` [bootwrapper PATCH v2 13/13] Unify start_el3 & start_no_el3 Mark Rutland
2022-01-17 17:43   ` Andre Przywara
2022-01-14 15:09 ` [bootwrapper PATCH v2 00/13] Cleanups and improvements Andre Przywara
2022-01-14 15:23   ` Mark Rutland

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