Commit 580efaa7 authored Nov 03, 2016 by Mark Rutland Committed by Catalin Marinas Nov 11, 2016

arm64: smp: prepare for smp_processor_id() rework



Subsequent patches will make smp_processor_id() use a percpu variable.
This will make smp_processor_id() dependent on the percpu offset, and
thus we cannot use smp_processor_id() to figure out what to initialise
the offset to.

Prepare for this by initialising the percpu offset based on
current::cpu, which will work regardless of how smp_processor_id() is
implemented. Also, make this relationship obvious by placing this code
together at the start of secondary_start_kernel().

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent 623b476f

arch/arm64/kernel/smp.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -208,7 +208,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
		asmlinkage void secondary_start_kernel(void)
		{
		struct mm_struct *mm = &init_mm;
		unsigned int cpu = smp_processor_id();
		unsigned int cpu;

		cpu = task_cpu(current);
		set_my_cpu_offset(per_cpu_offset(cpu));

		/*
		* All kernel threads share the same mm context; grab a
		@@ -217,8 +220,6 @@ asmlinkage void secondary_start_kernel(void)
		atomic_inc(&mm->mm_count);
		current->active_mm = mm;

		set_my_cpu_offset(per_cpu_offset(smp_processor_id()));

		/*
		* TTBR0 is only used for the identity mapping at this stage. Make it
		* point to zero page to avoid speculatively fetching new entries.

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