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Commit 621a0147 authored by Will Deacon's avatar Will Deacon Committed by Russell King
Browse files

ARM: 7757/1: mm: don't flush icache in switch_mm with hardware broadcasting 



When scheduling an mm on a CPU where it hasn't previously been used, we
flush the icache on that CPU so that any code loaded previously on
a different core can be safely executed.

For cores with hardware broadcasting of cache maintenance operations,
this is clearly unnecessary, since the inner-shareable invalidation in
__sync_icache_dcache will affect all CPUs.

This patch conditionalises the icache flush in switch_mm based on
cache_ops_need_broadcast().

Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reported-by: default avatarAlbin Tonnerre <albin.tonnerre@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 2874865c

arch/arm/include/asm/mmu_context.h

+9 −4
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <asm/cacheflush.h>

#include <asm/cachetype.h>

#include <asm/proc-fns.h>

#include <asm/smp_plat.h>

#include <asm-generic/mm_hooks.h>



void __check_vmalloc_seq(struct mm_struct *mm);
@@ -98,12 +99,16 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next, 
#ifdef CONFIG_MMU

	unsigned int cpu = smp_processor_id();



#ifdef CONFIG_SMP

	/* check for possible thread migration */

	if (!cpumask_empty(mm_cpumask(next)) &&

	/*

	 * __sync_icache_dcache doesn't broadcast the I-cache invalidation,

	 * so check for possible thread migration and invalidate the I-cache

	 * if we're new to this CPU.

	 */

	if (cache_ops_need_broadcast() &&

	    !cpumask_empty(mm_cpumask(next)) &&

	    !cpumask_test_cpu(cpu, mm_cpumask(next)))

		__flush_icache_all();

#endif



	if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {

		check_and_switch_context(next, tsk);

		if (cache_is_vivt())