[RFC/PATCH 7/7] ARM: ARM11 MPCore: cpu_v6_set_pte_ext is not preempt safe
gdavis at mvista.com
gdavis at mvista.com
Thu Oct 6 22:38:41 EDT 2011
From: George G. Davis <gdavis at mvista.com>
If preemption and subsequent task migration occurs during calls to
cpu_v6_set_pte_ext on ARM11 MPCore machines, global memory state
can become inconsistent. To prevent inconsistent memory state on
these machines, disable preemption in cpu_v6_set_pte_ext.
This change depends on "ARM: Move get_thread_info macro definition
to <asm/assembler.h>".
Signed-off-by: George G. Davis <gdavis at mvista.com>
---
arch/arm/mm/proc-v6.S | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S
index a923aa0..57b359d 100644
--- a/arch/arm/mm/proc-v6.S
+++ b/arch/arm/mm/proc-v6.S
@@ -122,7 +122,18 @@ ENTRY(cpu_v6_switch_mm)
ENTRY(cpu_v6_set_pte_ext)
#ifdef CONFIG_MMU
+#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
+ stmdb sp!, {r4, r5}
+ get_thread_info r5
+ ldr r4, [r5, #TI_PREEMPT] @ get preempt count
+ add r3, r4, #1 @ increment it
+ str r3, [r5, #TI_PREEMPT] @ disable preempt
+#endif
armv6_set_pte_ext cpu_v6
+#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
+ str r4, [r5, #TI_PREEMPT] @ restore preempt count
+ ldmia sp!, {r4, r5}
+#endif
#endif
mov pc, lr
--
1.7.4.4
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