copypage-xscale.c 3.6 KB

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  1. /*
  2. * linux/arch/arm/lib/copypage-xscale.S
  3. *
  4. * Copyright (C) 1995-2005 Russell King
  5. *
  6. * This program is free software; you can redistribute it and/or modify
  7. * it under the terms of the GNU General Public License version 2 as
  8. * published by the Free Software Foundation.
  9. *
  10. * This handles the mini data cache, as found on SA11x0 and XScale
  11. * processors. When we copy a user page page, we map it in such a way
  12. * that accesses to this page will not touch the main data cache, but
  13. * will be cached in the mini data cache. This prevents us thrashing
  14. * the main data cache on page faults.
  15. */
  16. #include <linux/init.h>
  17. #include <linux/mm.h>
  18. #include <asm/page.h>
  19. #include <asm/pgtable.h>
  20. #include <asm/tlbflush.h>
  21. #include <asm/cacheflush.h>
  22. #include "mm.h"
  23. /*
  24. * 0xffff8000 to 0xffffffff is reserved for any ARM architecture
  25. * specific hacks for copying pages efficiently.
  26. */
  27. #define COPYPAGE_MINICACHE 0xffff8000
  28. #define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
  29. L_PTE_CACHEABLE)
  30. static DEFINE_SPINLOCK(minicache_lock);
  31. /*
  32. * XScale mini-dcache optimised copy_user_page
  33. *
  34. * We flush the destination cache lines just before we write the data into the
  35. * corresponding address. Since the Dcache is read-allocate, this removes the
  36. * Dcache aliasing issue. The writes will be forwarded to the write buffer,
  37. * and merged as appropriate.
  38. */
  39. static void __attribute__((naked))
  40. mc_copy_user_page(void *from, void *to)
  41. {
  42. /*
  43. * Strangely enough, best performance is achieved
  44. * when prefetching destination as well. (NP)
  45. */
  46. asm volatile(
  47. "stmfd sp!, {r4, r5, lr} \n\
  48. mov lr, %2 \n\
  49. pld [r0, #0] \n\
  50. pld [r0, #32] \n\
  51. pld [r1, #0] \n\
  52. pld [r1, #32] \n\
  53. 1: pld [r0, #64] \n\
  54. pld [r0, #96] \n\
  55. pld [r1, #64] \n\
  56. pld [r1, #96] \n\
  57. 2: ldrd r2, [r0], #8 \n\
  58. ldrd r4, [r0], #8 \n\
  59. mov ip, r1 \n\
  60. strd r2, [r1], #8 \n\
  61. ldrd r2, [r0], #8 \n\
  62. strd r4, [r1], #8 \n\
  63. ldrd r4, [r0], #8 \n\
  64. strd r2, [r1], #8 \n\
  65. strd r4, [r1], #8 \n\
  66. mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
  67. ldrd r2, [r0], #8 \n\
  68. mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
  69. ldrd r4, [r0], #8 \n\
  70. mov ip, r1 \n\
  71. strd r2, [r1], #8 \n\
  72. ldrd r2, [r0], #8 \n\
  73. strd r4, [r1], #8 \n\
  74. ldrd r4, [r0], #8 \n\
  75. strd r2, [r1], #8 \n\
  76. strd r4, [r1], #8 \n\
  77. mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
  78. subs lr, lr, #1 \n\
  79. mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
  80. bgt 1b \n\
  81. beq 2b \n\
  82. ldmfd sp!, {r4, r5, pc} "
  83. :
  84. : "r" (from), "r" (to), "I" (PAGE_SIZE / 64 - 1));
  85. }
  86. void xscale_mc_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr)
  87. {
  88. struct page *page = virt_to_page(kfrom);
  89. if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
  90. __flush_dcache_page(page_mapping(page), page);
  91. spin_lock(&minicache_lock);
  92. set_pte_ext(TOP_PTE(COPYPAGE_MINICACHE), pfn_pte(__pa(kfrom) >> PAGE_SHIFT, minicache_pgprot), 0);
  93. flush_tlb_kernel_page(COPYPAGE_MINICACHE);
  94. mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
  95. spin_unlock(&minicache_lock);
  96. }
  97. /*
  98. * XScale optimised clear_user_page
  99. */
  100. void __attribute__((naked))
  101. xscale_mc_clear_user_page(void *kaddr, unsigned long vaddr)
  102. {
  103. asm volatile(
  104. "mov r1, %0 \n\
  105. mov r2, #0 \n\
  106. mov r3, #0 \n\
  107. 1: mov ip, r0 \n\
  108. strd r2, [r0], #8 \n\
  109. strd r2, [r0], #8 \n\
  110. strd r2, [r0], #8 \n\
  111. strd r2, [r0], #8 \n\
  112. mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
  113. subs r1, r1, #1 \n\
  114. mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
  115. bne 1b \n\
  116. mov pc, lr"
  117. :
  118. : "I" (PAGE_SIZE / 32));
  119. }
  120. struct cpu_user_fns xscale_mc_user_fns __initdata = {
  121. .cpu_clear_user_page = xscale_mc_clear_user_page,
  122. .cpu_copy_user_page = xscale_mc_copy_user_page,
  123. };