recipes-bsp/linux/linux-omap/linus/0003-ARM-get-rid-of-kmap_high_l1_vipt.patch

   1 From 39af22a79232373764904576f31572f1db76af10 Mon Sep 17 00:00:00 2001
   2 From: Nicolas Pitre <nicolas.pitre@linaro.org>
   3 Date: Wed, 15 Dec 2010 15:14:45 -0500
   4 Subject: [PATCH 03/66] ARM: get rid of kmap_high_l1_vipt()
   5
   6 Since commit 3e4d3af501 "mm: stack based kmap_atomic()", it is no longer
   7 necessary to carry an ad hoc version of kmap_atomic() added in commit
   8 7e5a69e83b "ARM: 6007/1: fix highmem with VIPT cache and DMA" to cope
   9 with reentrancy.
  10
  11 In fact, it is now actively wrong to rely on fixed kmap type indices
  12 (namely KM_L1_CACHE) as kmap_atomic() totally ignores them now and a
  13 concurrent instance of it may reuse any slot for any purpose.
  14
  15 Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
  16 ---
  17  arch/arm/include/asm/highmem.h |    3 -
  18  arch/arm/mm/dma-mapping.c      |    7 ++-
  19  arch/arm/mm/flush.c            |    7 ++-
  20  arch/arm/mm/highmem.c          |   87 ----------------------------------------
  21  4 files changed, 8 insertions(+), 96 deletions(-)
  22
  23 diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
  24 index 1fc684e..7080e2c 100644
  25 --- a/arch/arm/include/asm/highmem.h
  26 +++ b/arch/arm/include/asm/highmem.h
  27 @@ -25,9 +25,6 @@ extern void *kmap_high(struct page *page);
  28  extern void *kmap_high_get(struct page *page);
  29  extern void kunmap_high(struct page *page);
  30
  31 -extern void *kmap_high_l1_vipt(struct page *page, pte_t *saved_pte);
  32 -extern void kunmap_high_l1_vipt(struct page *page, pte_t saved_pte);
  33 -
  34  /*
  35   * The following functions are already defined by <linux/highmem.h>
  36   * when CONFIG_HIGHMEM is not set.
  37 diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
  38 index ac6a361..809f1bf 100644
  39 --- a/arch/arm/mm/dma-mapping.c
  40 +++ b/arch/arm/mm/dma-mapping.c
  41 @@ -17,6 +17,7 @@
  42  #include <linux/init.h>
  43  #include <linux/device.h>
  44  #include <linux/dma-mapping.h>
  45 +#include <linux/highmem.h>
  46
  47  #include <asm/memory.h>
  48  #include <asm/highmem.h>
  49 @@ -480,10 +481,10 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset,
  50                                 op(vaddr, len, dir);
  51                                 kunmap_high(page);
  52                         } else if (cache_is_vipt()) {
  53 -                               pte_t saved_pte;
  54 -                               vaddr = kmap_high_l1_vipt(page, &saved_pte);
  55 +                               /* unmapped pages might still be cached */
  56 +                               vaddr = kmap_atomic(page);
  57                                 op(vaddr + offset, len, dir);
  58 -                               kunmap_high_l1_vipt(page, saved_pte);
  59 +                               kunmap_atomic(vaddr);
  60                         }
  61                 } else {
  62                         vaddr = page_address(page) + offset;
  63 diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
  64 index 391ffae..c29f283 100644
  65 --- a/arch/arm/mm/flush.c
  66 +++ b/arch/arm/mm/flush.c
  67 @@ -10,6 +10,7 @@
  68  #include <linux/module.h>
  69  #include <linux/mm.h>
  70  #include <linux/pagemap.h>
  71 +#include <linux/highmem.h>
  72
  73  #include <asm/cacheflush.h>
  74  #include <asm/cachetype.h>
  75 @@ -180,10 +181,10 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page)
  76                         __cpuc_flush_dcache_area(addr, PAGE_SIZE);
  77                         kunmap_high(page);
  78                 } else if (cache_is_vipt()) {
  79 -                       pte_t saved_pte;
  80 -                       addr = kmap_high_l1_vipt(page, &saved_pte);
  81 +                       /* unmapped pages might still be cached */
  82 +                       addr = kmap_atomic(page);
  83                         __cpuc_flush_dcache_area(addr, PAGE_SIZE);
  84 -                       kunmap_high_l1_vipt(page, saved_pte);
  85 +                       kunmap_atomic(addr);
  86                 }
  87         }
  88
  89 diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
  90 index c435fd9..807c057 100644
  91 --- a/arch/arm/mm/highmem.c
  92 +++ b/arch/arm/mm/highmem.c
  93 @@ -140,90 +140,3 @@ struct page *kmap_atomic_to_page(const void *ptr)
  94         pte = TOP_PTE(vaddr);
  95         return pte_page(*pte);
  96  }
  97 -
  98 -#ifdef CONFIG_CPU_CACHE_VIPT
  99 -
 100 -#include <linux/percpu.h>
 101 -
 102 -/*
 103 - * The VIVT cache of a highmem page is always flushed before the page
 104 - * is unmapped. Hence unmapped highmem pages need no cache maintenance
 105 - * in that case.
 106 - *
 107 - * However unmapped pages may still be cached with a VIPT cache, and
 108 - * it is not possible to perform cache maintenance on them using physical
 109 - * addresses unfortunately.  So we have no choice but to set up a temporary
 110 - * virtual mapping for that purpose.
 111 - *
 112 - * Yet this VIPT cache maintenance may be triggered from DMA support
 113 - * functions which are possibly called from interrupt context. As we don't
 114 - * want to keep interrupt disabled all the time when such maintenance is
 115 - * taking place, we therefore allow for some reentrancy by preserving and
 116 - * restoring the previous fixmap entry before the interrupted context is
 117 - * resumed.  If the reentrancy depth is 0 then there is no need to restore
 118 - * the previous fixmap, and leaving the current one in place allow it to
 119 - * be reused the next time without a TLB flush (common with DMA).
 120 - */
 121 -
 122 -static DEFINE_PER_CPU(int, kmap_high_l1_vipt_depth);
 123 -
 124 -void *kmap_high_l1_vipt(struct page *page, pte_t *saved_pte)
 125 -{
 126 -       unsigned int idx, cpu;
 127 -       int *depth;
 128 -       unsigned long vaddr, flags;
 129 -       pte_t pte, *ptep;
 130 -
 131 -       if (!in_interrupt())
 132 -               preempt_disable();
 133 -
 134 -       cpu = smp_processor_id();
 135 -       depth = &per_cpu(kmap_high_l1_vipt_depth, cpu);
 136 -
 137 -       idx = KM_L1_CACHE + KM_TYPE_NR * cpu;
 138 -       vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 139 -       ptep = TOP_PTE(vaddr);
 140 -       pte = mk_pte(page, kmap_prot);
 141 -
 142 -       raw_local_irq_save(flags);
 143 -       (*depth)++;
 144 -       if (pte_val(*ptep) == pte_val(pte)) {
 145 -               *saved_pte = pte;
 146 -       } else {
 147 -               *saved_pte = *ptep;
 148 -               set_pte_ext(ptep, pte, 0);
 149 -               local_flush_tlb_kernel_page(vaddr);
 150 -       }
 151 -       raw_local_irq_restore(flags);
 152 -
 153 -       return (void *)vaddr;
 154 -}
 155 -
 156 -void kunmap_high_l1_vipt(struct page *page, pte_t saved_pte)
 157 -{
 158 -       unsigned int idx, cpu = smp_processor_id();
 159 -       int *depth = &per_cpu(kmap_high_l1_vipt_depth, cpu);
 160 -       unsigned long vaddr, flags;
 161 -       pte_t pte, *ptep;
 162 -
 163 -       idx = KM_L1_CACHE + KM_TYPE_NR * cpu;
 164 -       vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 165 -       ptep = TOP_PTE(vaddr);
 166 -       pte = mk_pte(page, kmap_prot);
 167 -
 168 -       BUG_ON(pte_val(*ptep) != pte_val(pte));
 169 -       BUG_ON(*depth <= 0);
 170 -
 171 -       raw_local_irq_save(flags);
 172 -       (*depth)--;
 173 -       if (*depth != 0 && pte_val(pte) != pte_val(saved_pte)) {
 174 -               set_pte_ext(ptep, saved_pte, 0);
 175 -               local_flush_tlb_kernel_page(vaddr);
 176 -       }
 177 -       raw_local_irq_restore(flags);
 178 -
 179 -       if (!in_interrupt())
 180 -               preempt_enable();
 181 -}
 182 -
 183 -#endif  /* CONFIG_CPU_CACHE_VIPT */
 184 --
 185 1.6.6.1
 186