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Subject: highmem: Store ptes right away in the task struct
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 12 Feb 2013 11:32:38 +0100
Get rid of the per cpu variable and store the idx and the pte content
right away in the task struct. Shortens the context switch code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/process_32.c | 63 +++++++++++++++++++------------------------
arch/x86/mm/highmem_32.c | 6 +++-
arch/x86/mm/iomap_32.c | 6 +++-
include/linux/highmem.h | 25 ++++++++++++++---
mm/highmem.c | 6 ++--
5 files changed, 64 insertions(+), 42 deletions(-)
Index: linux-stable/arch/x86/kernel/process_32.c
===================================================================
--- linux-stable.orig/arch/x86/kernel/process_32.c
+++ linux-stable/arch/x86/kernel/process_32.c
@@ -198,6 +198,34 @@ start_thread(struct pt_regs *regs, unsig
}
EXPORT_SYMBOL_GPL(start_thread);
+#ifdef CONFIG_PREEMPT_RT_FULL
+static void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
+{
+ int i;
+
+ /*
+ * Clear @prev's kmap_atomic mappings
+ */
+ for (i = 0; i < prev_p->kmap_idx; i++) {
+ int idx = i + KM_TYPE_NR * smp_processor_id();
+ pte_t *ptep = kmap_pte - idx;
+
+ kpte_clear_flush(ptep, __fix_to_virt(FIX_KMAP_BEGIN + idx));
+ }
+ /*
+ * Restore @next_p's kmap_atomic mappings
+ */
+ for (i = 0; i < next_p->kmap_idx; i++) {
+ int idx = i + KM_TYPE_NR * smp_processor_id();
+
+ set_pte(kmap_pte - idx, next_p->kmap_pte[i]);
+ }
+}
+#else
+static inline void
+switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p) { }
+#endif
+
/*
* switch_to(x,y) should switch tasks from x to y.
@@ -277,40 +305,7 @@ __switch_to(struct task_struct *prev_p,
task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
__switch_to_xtra(prev_p, next_p, tss);
-#ifdef CONFIG_PREEMPT_RT_FULL
- /*
- * Save @prev's kmap_atomic stack
- */
- prev_p->kmap_idx = __this_cpu_read(__kmap_atomic_idx);
- if (unlikely(prev_p->kmap_idx)) {
- int i;
-
- for (i = 0; i < prev_p->kmap_idx; i++) {
- int idx = i + KM_TYPE_NR * smp_processor_id();
-
- pte_t *ptep = kmap_pte - idx;
- prev_p->kmap_pte[i] = *ptep;
- kpte_clear_flush(ptep, __fix_to_virt(FIX_KMAP_BEGIN + idx));
- }
-
- __this_cpu_write(__kmap_atomic_idx, 0);
- }
-
- /*
- * Restore @next_p's kmap_atomic stack
- */
- if (unlikely(next_p->kmap_idx)) {
- int i;
-
- __this_cpu_write(__kmap_atomic_idx, next_p->kmap_idx);
-
- for (i = 0; i < next_p->kmap_idx; i++) {
- int idx = i + KM_TYPE_NR * smp_processor_id();
-
- set_pte(kmap_pte - idx, next_p->kmap_pte[i]);
- }
- }
-#endif
+ switch_kmaps(prev_p, next_p);
/*
* Leave lazy mode, flushing any hypercalls made here.
Index: linux-stable/arch/x86/mm/highmem_32.c
===================================================================
--- linux-stable.orig/arch/x86/mm/highmem_32.c
+++ linux-stable/arch/x86/mm/highmem_32.c
@@ -31,6 +31,7 @@ EXPORT_SYMBOL(kunmap);
*/
void *kmap_atomic_prot(struct page *page, pgprot_t prot)
{
+ pte_t pte = mk_pte(page, prot);
unsigned long vaddr;
int idx, type;
@@ -44,7 +45,10 @@ void *kmap_atomic_prot(struct page *page
idx = type + KM_TYPE_NR*smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
WARN_ON(!pte_none(*(kmap_pte-idx)));
- set_pte(kmap_pte-idx, mk_pte(page, prot));
+#ifdef CONFIG_PREEMPT_RT_FULL
+ current->kmap_pte[type] = pte;
+#endif
+ set_pte(kmap_pte-idx, pte);
arch_flush_lazy_mmu_mode();
return (void *)vaddr;
Index: linux-stable/arch/x86/mm/iomap_32.c
===================================================================
--- linux-stable.orig/arch/x86/mm/iomap_32.c
+++ linux-stable/arch/x86/mm/iomap_32.c
@@ -56,6 +56,7 @@ EXPORT_SYMBOL_GPL(iomap_free);
void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
{
+ pte_t pte = pfn_pte(pfn, prot);
unsigned long vaddr;
int idx, type;
@@ -64,7 +65,10 @@ void *kmap_atomic_prot_pfn(unsigned long
type = kmap_atomic_idx_push();
idx = type + KM_TYPE_NR * smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
- set_pte(kmap_pte - idx, pfn_pte(pfn, prot));
+#ifdef CONFIG_PREEMPT_RT_FULL
+ current->kmap_pte[type] = pte;
+#endif
+ set_pte(kmap_pte - idx, pte);
arch_flush_lazy_mmu_mode();
return (void *)vaddr;
Index: linux-stable/include/linux/highmem.h
===================================================================
--- linux-stable.orig/include/linux/highmem.h
+++ linux-stable/include/linux/highmem.h
@@ -85,32 +85,49 @@ static inline void __kunmap_atomic(void
#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
+#ifndef CONFIG_PREEMPT_RT_FULL
DECLARE_PER_CPU(int, __kmap_atomic_idx);
+#endif
static inline int kmap_atomic_idx_push(void)
{
+#ifndef CONFIG_PREEMPT_RT_FULL
int idx = __this_cpu_inc_return(__kmap_atomic_idx) - 1;
-#ifdef CONFIG_DEBUG_HIGHMEM
+# ifdef CONFIG_DEBUG_HIGHMEM
WARN_ON_ONCE(in_irq() && !irqs_disabled());
BUG_ON(idx > KM_TYPE_NR);
-#endif
+# endif
return idx;
+#else
+ return current->kmap_idx++;
+#endif
}
static inline int kmap_atomic_idx(void)
{
+#ifndef CONFIG_PREEMPT_RT_FULL
return __this_cpu_read(__kmap_atomic_idx) - 1;
+#else
+ return current->kmap_idx - 1;
+#endif
}
static inline void kmap_atomic_idx_pop(void)
{
-#ifdef CONFIG_DEBUG_HIGHMEM
+#ifndef CONFIG_PREEMPT_RT_FULL
+# ifdef CONFIG_DEBUG_HIGHMEM
int idx = __this_cpu_dec_return(__kmap_atomic_idx);
BUG_ON(idx < 0);
-#else
+# else
__this_cpu_dec(__kmap_atomic_idx);
+# endif
+#else
+ current->kmap_idx--;
+# ifdef CONFIG_DEBUG_HIGHMEM
+ BUG_ON(current->kmap_idx < 0);
+# endif
#endif
}
Index: linux-stable/mm/highmem.c
===================================================================
--- linux-stable.orig/mm/highmem.c
+++ linux-stable/mm/highmem.c
@@ -29,10 +29,11 @@
#include <linux/kgdb.h>
#include <asm/tlbflush.h>
-
+#ifndef CONFIG_PREEMPT_RT_FULL
#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
DEFINE_PER_CPU(int, __kmap_atomic_idx);
#endif
+#endif
/*
* Virtual_count is not a pure "count".
@@ -47,8 +48,9 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
unsigned long totalhigh_pages __read_mostly;
EXPORT_SYMBOL(totalhigh_pages);
-
+#ifndef CONFIG_PREEMPT_RT_FULL
EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);
+#endif
unsigned int nr_free_highpages (void)
{
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