Tonight I put on a Jon Hopkins album, in recollection of my UK ARM Linux
colleagues perhaps, and started testing, and eventually wound up with this
one:
commit 621a0147d5c921f4cc33636ccd0602ad5d7cbfbc
Author: Will Deacon <will.deacon@xxxxxxx>
Date: Wed Jun 12 12:25:56 2013 +0100
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: Catalin Marinas <catalin.marinas@xxxxxxx>
Reported-by: Albin Tonnerre <albin.tonnerre@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
...
v3.11-rc2 boots with it reverted. What also works is v3.11-rc2 with the
below patch applied.
Would be pleased to boot-test anything you'd care to send my way, as long
as you can tolerate response latency jitter.
- Paul
diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index b5792b7..8dfb295 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -112,7 +112,7 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
* so check for possible thread migration and invalidate the I-cache
* if we're new to this CPU.
*/
- if (cache_ops_need_broadcast() &&
+ if (1 &&
!cpumask_empty(mm_cpumask(next)) &&
!cpumask_test_cpu(cpu, mm_cpumask(next)))
__flush_icache_all();
--
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