releases/3.16.7/sparc64-kill-unnecessary-tables-and-increase-max_banks.patch

   1 From foo@baz Tue Oct 28 11:19:22 CST 2014
   2 From: "David S. Miller" <davem@davemloft.net>
   3 Date: Sat, 27 Sep 2014 21:30:57 -0700
   4 Subject: sparc64: Kill unnecessary tables and increase MAX_BANKS.
   5
   6 From: "David S. Miller" <davem@davemloft.net>
   7
   8 [ Upstream commit d195b71bad4347d2df51072a537f922546a904f1 ]
   9
  10 swapper_low_pmd_dir and swapper_pud_dir are actually completely
  11 useless and unnecessary.
  12
  13 We just need swapper_pg_dir[].  Naturally the other page table chunks
  14 will be allocated on an as-needed basis.  Since the kernel actually
  15 accesses these tables in the PAGE_OFFSET view, there is not even a TLB
  16 locality advantage of placing them in the kernel image.
  17
  18 Use the hard coded vmlinux.ld.S slot for swapper_pg_dir which is
  19 naturally page aligned.
  20
  21 Increase MAX_BANKS to 1024 in order to handle heavily fragmented
  22 virtual guests.
  23
  24 Even with this MAX_BANKS increase, the kernel is 20K+ smaller.
  25
  26 Signed-off-by: David S. Miller <davem@davemloft.net>
  27 Acked-by: Bob Picco <bob.picco@oracle.com>
  28 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  29 ---
  30  arch/sparc/include/asm/pgtable_64.h |    1 -
  31  arch/sparc/kernel/vmlinux.lds.S     |    5 +++--
  32  arch/sparc/mm/init_64.c             |   25 ++-----------------------
  33  3 files changed, 5 insertions(+), 26 deletions(-)
  34
  35 --- a/arch/sparc/include/asm/pgtable_64.h
  36 +++ b/arch/sparc/include/asm/pgtable_64.h
  37 @@ -927,7 +927,6 @@ static inline void __set_pte_at(struct m
  38  #endif
  39
  40  extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
  41 -extern pmd_t swapper_low_pmd_dir[PTRS_PER_PMD];
  42
  43  void paging_init(void);
  44  unsigned long find_ecache_flush_span(unsigned long size);
  45 --- a/arch/sparc/kernel/vmlinux.lds.S
  46 +++ b/arch/sparc/kernel/vmlinux.lds.S
  47 @@ -35,8 +35,9 @@ jiffies = jiffies_64;
  48
  49  SECTIONS
  50  {
  51 -       /* swapper_low_pmd_dir is sparc64 only */
  52 -       swapper_low_pmd_dir = 0x0000000000402000;
  53 +#ifdef CONFIG_SPARC64
  54 +       swapper_pg_dir = 0x0000000000402000;
  55 +#endif
  56         . = INITIAL_ADDRESS;
  57         .text TEXTSTART :
  58         {
  59 --- a/arch/sparc/mm/init_64.c
  60 +++ b/arch/sparc/mm/init_64.c
  61 @@ -86,7 +86,7 @@ extern struct tsb swapper_tsb[KERNEL_TSB
  62
  63  static unsigned long cpu_pgsz_mask;
  64
  65 -#define MAX_BANKS      32
  66 +#define MAX_BANKS      1024
  67
  68  static struct linux_prom64_registers pavail[MAX_BANKS];
  69  static int pavail_ents;
  70 @@ -1942,12 +1942,6 @@ static void __init sun4v_linear_pte_xor_
  71
  72  static unsigned long last_valid_pfn;
  73
  74 -/* These must be page aligned in order to not trigger the
  75 - * alignment tests of pgd_bad() and pud_bad().
  76 - */
  77 -pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__ ((aligned (PAGE_SIZE)));
  78 -static pud_t swapper_pud_dir[PTRS_PER_PUD] __attribute__ ((aligned (PAGE_SIZE)));
  79 -
  80  static void sun4u_pgprot_init(void);
  81  static void sun4v_pgprot_init(void);
  82
  83 @@ -1955,8 +1949,6 @@ void __init paging_init(void)
  84  {
  85         unsigned long end_pfn, shift, phys_base;
  86         unsigned long real_end, i;
  87 -       pud_t *pud;
  88 -       pmd_t *pmd;
  89         int node;
  90
  91         setup_page_offset();
  92 @@ -2051,20 +2043,7 @@ void __init paging_init(void)
  93          */
  94         init_mm.pgd += ((shift) / (sizeof(pgd_t)));
  95
  96 -       memset(swapper_low_pmd_dir, 0, sizeof(swapper_low_pmd_dir));
  97 -
  98 -       /* The kernel page tables we publish into what the rest of the
  99 -        * world sees must be adjusted so that they see the PAGE_OFFSET
 100 -        * address of these in-kerenel data structures.  However right
 101 -        * here we must access them from the kernel image side, because
 102 -        * the trap tables haven't been taken over and therefore we cannot
 103 -        * take TLB misses in the PAGE_OFFSET linear mappings yet.
 104 -        */
 105 -       pud = swapper_pud_dir + (shift / sizeof(pud_t));
 106 -       pgd_set(&swapper_pg_dir[0], pud);
 107 -
 108 -       pmd = swapper_low_pmd_dir + (shift / sizeof(pmd_t));
 109 -       pud_set(&swapper_pud_dir[0], pmd);
 110 +       memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
 111
 112         inherit_prom_mappings();
 113