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ARM: head.S: use PC-relative insn sequence for secondary_data

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

Note that it also removes a stale comment about the contents of r6.

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 11:25:23 +03:00
parent 172c34c9ff
commit 91580f0dbf
1 changed files with 4 additions and 15 deletions
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19
arch/arm/kernel/head.S
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@ -383,10 +383,8 @@ ENTRY(secondary_startup)
/*
* Use the page tables supplied from __cpu_up.
*/
adr r4, __secondary_data
ldmia r4, {r5, r7, r12} @ address to jump to after
sub lr, r4, r5 @ mmu has been enabled
add r3, r7, lr
adr_l r3, secondary_data
mov_l r12, __secondary_switched
ldrd r4, r5, [r3, #0] @ get secondary_data.pgdir
ARM_BE8(eor r4, r4, r5) @ Swap r5 and r4 in BE:
ARM_BE8(eor r5, r4, r5) @ it can be done in 3 steps
@ -401,22 +399,13 @@ ARM_BE8(eor r4, r4, r5) @ without using a temp reg.
ENDPROC(secondary_startup)
ENDPROC(secondary_startup_arm)
/*
* r6 = &secondary_data
*/
ENTRY(__secondary_switched)
ldr sp, [r7, #12] @ get secondary_data.stack
ldr_l r7, secondary_data + 12 @ get secondary_data.stack
mov sp, r7
mov fp, #0
b secondary_start_kernel
ENDPROC(__secondary_switched)
.align
.type __secondary_data, %object
__secondary_data:
.long .
.long secondary_data
.long __secondary_switched
#endif /* defined(CONFIG_SMP) */