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UPSTREAM: arm64: smp: prepare for smp_processor_id() rework

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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>

Bug: 38331309
Change-Id: I43304d06602216fbb5b968ff83e0face11e238f5
(cherry picked from commit 580efaa7cc)
Signed-off-by: Zubin Mithra <zsm@google.com>
This commit is contained in:
Mark Rutland
2016-11-03 20:23:10 +00:00
committed by Amit Pundir
parent b3181a8474
commit 0b2ea94d16
1 changed files with 4 additions and 3 deletions
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7
arch/arm64/kernel/smp.c
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@@ -177,7 +177,10 @@ static void smp_store_cpu_info(unsigned int cpuid)
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
@@ -186,8 +189,6 @@ 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.