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Subject[PATCH 4/4] powerpc/mm: Remove stale_map[] handling on non SMP processors
Date
stale_map[] bits are only set in steal_context_smp() so
on UP processors this map is useless. Only manage it for SMP
processors.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/mm/mmu_context_nohash.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c
index 625c17049483..3f13f07f64dd 100644
--- a/arch/powerpc/mm/mmu_context_nohash.c
+++ b/arch/powerpc/mm/mmu_context_nohash.c
@@ -88,7 +88,9 @@

static unsigned int next_context, nr_free_contexts;
static unsigned long *context_map;
+#ifdef CONFIG_SMP
static unsigned long *stale_map[NR_CPUS];
+#endif
static struct mm_struct **context_mm;
static DEFINE_RAW_SPINLOCK(context_lock);

@@ -169,7 +171,9 @@ static unsigned int steal_context_smp(unsigned int id)
static unsigned int steal_all_contexts(void)
{
struct mm_struct *mm;
+#ifdef CONFIG_SMP
int cpu = smp_processor_id();
+#endif
unsigned int id;

for (id = FIRST_CONTEXT; id <= LAST_CONTEXT; id++) {
@@ -187,7 +191,9 @@ static unsigned int steal_all_contexts(void)
mm->context.active = 0;
#endif
}
+#ifdef CONFIG_SMP
__clear_bit(id, stale_map[cpu]);
+#endif
}

/* Flush the TLB for all contexts (not to be used on SMP) */
@@ -206,7 +212,9 @@ static unsigned int steal_all_contexts(void)
static unsigned int steal_context_up(unsigned int id)
{
struct mm_struct *mm;
+#ifdef CONFIG_SMP
int cpu = smp_processor_id();
+#endif

/* Pick up the victim mm */
mm = context_mm[id];
@@ -220,7 +228,9 @@ static unsigned int steal_context_up(unsigned int id)
mm->context.id = MMU_NO_CONTEXT;

/* XXX This clear should ultimately be part of local_flush_tlb_mm */
+#ifdef CONFIG_SMP
__clear_bit(id, stale_map[cpu]);
+#endif

return id;
}
@@ -259,7 +269,10 @@ static void context_check_map(void) { }
void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
- unsigned int i, id, cpu = smp_processor_id();
+ unsigned int id;
+#ifdef CONFIG_SMP
+ unsigned int i, cpu = smp_processor_id();
+#endif
unsigned long *map;

/* No lockless fast path .. yet */
@@ -333,6 +346,7 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next,
/* If that context got marked stale on this CPU, then flush the
* local TLB for it and unmark it before we use it
*/
+#ifdef CONFIG_SMP
if (test_bit(id, stale_map[cpu])) {
pr_hardcont(" | stale flush %d [%d..%d]",
id, cpu_first_thread_sibling(cpu),
@@ -347,6 +361,7 @@ void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next,
__clear_bit(id, stale_map[i]);
}
}
+#endif

/* Flick the MMU and release lock */
pr_hardcont(" -> %d\n", id);
@@ -452,9 +467,7 @@ void __init mmu_context_init(void)
*/
context_map = memblock_virt_alloc(CTX_MAP_SIZE, 0);
context_mm = memblock_virt_alloc(sizeof(void *) * (LAST_CONTEXT + 1), 0);
-#ifndef CONFIG_SMP
- stale_map[0] = memblock_virt_alloc(CTX_MAP_SIZE, 0);
-#else
+#ifdef CONFIG_SMP
stale_map[boot_cpuid] = memblock_virt_alloc(CTX_MAP_SIZE, 0);

cpuhp_setup_state_nocalls(CPUHP_POWERPC_MMU_CTX_PREPARE,
--
2.13.3
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