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arm64: setup: name mair register

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In __cpu_setup we conditionally manipulate the MAIR_EL1 value in x5
before later reusing x5 as a scratch register for unrelated temporary
variables.

To make this a bit clearer, let's move the MAIR_EL1 value into a named
register `mair`. To simplify the register allocation, this is placed in
the highest available caller-saved scratch register, x17. As it is no
longer clobbered by other usage, we can write the value to MAIR_EL1 at
the end of the function as we do for TCR_EL1 rather than part-way though
feature discovery.

There should be no functional change as as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210326180137.43119-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Rutland 2021-03-26 18:01:36 +00:00 committed by Catalin Marinas
parent b07f349966
commit 776e49af60
1 changed files with 6 additions and 3 deletions
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9
arch/arm64/mm/proc.S
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@ -421,7 +421,8 @@ SYM_FUNC_START(__cpu_setup)
/*
* Memory region attributes
*/
mov_q x5, MAIR_EL1_SET
mair .req x17
mov_q mair, MAIR_EL1_SET
#ifdef CONFIG_ARM64_MTE
mte_tcr .req x20
@ -438,7 +439,7 @@ SYM_FUNC_START(__cpu_setup)
/* Normal Tagged memory type at the corresponding MAIR index */
mov x10, #MAIR_ATTR_NORMAL_TAGGED
bfi x5, x10, #(8 * MT_NORMAL_TAGGED), #8
bfi mair, x10, #(8 * MT_NORMAL_TAGGED), #8
/* initialize GCR_EL1: all non-zero tags excluded by default */
mov x10, #(SYS_GCR_EL1_RRND | SYS_GCR_EL1_EXCL_MASK)
@ -452,7 +453,6 @@ SYM_FUNC_START(__cpu_setup)
mov_q mte_tcr, TCR_KASAN_HW_FLAGS
1:
#endif
msr mair_el1, x5
/*
* Set/prepare TCR and TTBR. TCR_EL1.T1SZ gets further
* adjusted if the kernel is compiled with 52bit VA support.
@ -492,10 +492,13 @@ SYM_FUNC_START(__cpu_setup)
orr x10, x10, #TCR_HA // hardware Access flag update
1:
#endif /* CONFIG_ARM64_HW_AFDBM */
msr mair_el1, mair
msr tcr_el1, x10
/*
* Prepare SCTLR
*/
mov_q x0, INIT_SCTLR_EL1_MMU_ON
ret // return to head.S
.unreq mair
SYM_FUNC_END(__cpu_setup)