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ARM: head-common.S: use PC-relative insn sequence for idmap creation

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Replace the open coded PC relative offset calculations involving
__turn_mmu_on and __turn_mmu_on_end with a pair of adr_l invocations.
This removes some open coded arithmetic involving virtual addresses,
avoids literal pools on v7+, and slightly reduces the footprint of the
code.

Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Ard Biesheuvel 2020-09-14 11:25:16 +03:00
parent 62c4a2e202
commit 172c34c9ff
1 changed files with 2 additions and 10 deletions
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12
arch/arm/kernel/head.S
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@ -224,11 +224,8 @@ __create_page_tables:
* Create identity mapping to cater for __enable_mmu.
* This identity mapping will be removed by paging_init().
*/
adr r0, __turn_mmu_on_loc
ldmia r0, {r3, r5, r6}
sub r0, r0, r3 @ virt->phys offset
add r5, r5, r0 @ phys __turn_mmu_on
add r6, r6, r0 @ phys __turn_mmu_on_end
adr_l r5, __turn_mmu_on @ _pa(__turn_mmu_on)
adr_l r6, __turn_mmu_on_end @ _pa(__turn_mmu_on_end)
mov r5, r5, lsr #SECTION_SHIFT
mov r6, r6, lsr #SECTION_SHIFT
@ -351,11 +348,6 @@ __create_page_tables:
ret lr
ENDPROC(__create_page_tables)
.ltorg
.align
__turn_mmu_on_loc:
.long .
.long __turn_mmu_on
.long __turn_mmu_on_end
#if defined(CONFIG_SMP)
.text