Commit 8ea41b11 authored Jul 15, 2017 by Ard Biesheuvel Committed by Mark Rutland Aug 15, 2017

arm64: assembler: allow adr_this_cpu to use the stack pointer



Given that adr_this_cpu already requires a temp register in addition
to the destination register, tweak the instruction sequence so that sp
may be used as well.

This will simplify switching to per-cpu stacks in subsequent patches. While
this limits the range of adr_this_cpu, to +/-4GiB, we don't currently use
adr_this_cpu in modules, and this is not problematic for the main kernel image.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[Mark: add more commit text]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>

parent b11e5759

arch/arm64/include/asm/assembler.h

+7 −1

Original line number	Diff line number	Diff line
		@@ -230,12 +230,18 @@ lr .req x30 // link register
		.endm

		/*
		* @dst: Result of per_cpu(sym, smp_processor_id())
		* @dst: Result of per_cpu(sym, smp_processor_id()), can be SP for
		* non-module code
		* @sym: The name of the per-cpu variable
		* @tmp: scratch register
		*/
		.macro adr_this_cpu, dst, sym, tmp
		#ifndef MODULE
		adrp \tmp, \sym
		add \dst, \tmp, #:lo12:\sym
		#else
		adr_l \dst, \sym
		#endif
		mrs \tmp, tpidr_el1
		add \dst, \dst, \tmp
		.endm

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