From: Andre Przywara <andre.przywara@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, Jaxson.Han@arm.com,
Wei.Chen@arm.com
Subject: Re: [bootwrapper PATCH 05/13] aarch64: add mov_64 macro
Date: Tue, 11 Jan 2022 14:41:49 +0000 [thread overview]
Message-ID: <20220111144149.6b519ede@donnerap.cambridge.arm.com> (raw)
In-Reply-To: <20220111130653.2331827-6-mark.rutland@arm.com>
On Tue, 11 Jan 2022 13:06:45 +0000
Mark Rutland <mark.rutland@arm.com> wrote:
Hi,
> In subsequent patches we'll need to load 64-bit values into GPRs before
> the CPU is in a known endianness, where we cannot use literal pools.
>
> In preparation for that, this patch adds a new `mov_64` macro to load a
> 64-bit value into a GPR using a sequence of MOV and MOVKs, which will
> function the same regardless of the CPU's endianness.
>
> At the same time, move the `cpuid` macro to use `mov_64` internally.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> ---
> arch/aarch64/common.S | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/aarch64/common.S b/arch/aarch64/common.S
> index c7171a9..3279fa9 100644
> --- a/arch/aarch64/common.S
> +++ b/arch/aarch64/common.S
> @@ -9,9 +9,17 @@
>
> #include <cpu.h>
>
> + /* Load a 64-bit value using immediates */
> + .macro mov_64 dest, val
> + mov \dest, #(((\val) >> 0) & 0xffff)
> + movk \dest, #(((\val) >> 16) & 0xffff), lsl #16
> + movk \dest, #(((\val) >> 32) & 0xffff), lsl #32
> + movk \dest, #(((\val) >> 48) & 0xffff), lsl #48
> + .endm
> +
Trusted Firmware has an (admittedly more complicated) version that only
uses as many instructions as needed, by skipping over halfwords that are
zero:
https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/include/arch/aarch64/asm_macros.S#n125
Does that sound useful for us?
Cheers,
Andre
> /* Put MPIDR into \dest, clobber \tmp and flags */
> .macro cpuid dest, tmp
> mrs \dest, mpidr_el1
> - ldr \tmp, =MPIDR_ID_BITS
> + mov_64 \tmp, MPIDR_ID_BITS
> ands \dest, \dest, \tmp
> .endm
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next prev parent reply other threads:[~2022-01-11 14:43 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-11 13:06 [bootwrapper PATCH 00/13] Cleanups and improvements Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 01/13] Document entry requirements Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 02/13] Add bit-field macros Mark Rutland
2022-01-11 14:40 ` Andre Przywara
2022-01-12 14:16 ` Mark Rutland
2022-01-14 18:13 ` Andre Przywara
2022-01-11 13:06 ` [bootwrapper PATCH 03/13] aarch64: add system register accessors Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 04/13] aarch32: add coprocessor accessors Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 05/13] aarch64: add mov_64 macro Mark Rutland
2022-01-11 14:41 ` Andre Przywara [this message]
2022-01-12 14:18 ` Mark Rutland
2022-01-14 15:37 ` Andre Przywara
2022-01-11 13:06 ` [bootwrapper PATCH 06/13] aarch64: initialize SCTLR_ELx for the boot-wrapper Mark Rutland
2022-01-11 14:38 ` Robin Murphy
2022-01-12 14:34 ` Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 07/13] Rework common init C code Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 08/13] Announce boot-wrapper mode / exception level Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 09/13] aarch64: move the bulk of EL3 initialization to C Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 10/13] aarch32: move the bulk of Secure PL1 " Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 11/13] Announce locations of memory objects Mark Rutland
2022-01-14 10:48 ` Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 12/13] Rework bootmethod initialization Mark Rutland
2022-01-11 13:06 ` [bootwrapper PATCH 13/13] Unify start_el3 & start_no_el3 Mark Rutland
2022-01-11 14:39 ` Robin Murphy
2022-01-12 14:37 ` Mark Rutland
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