src/patches/suse-2.6.27.25/patches.xen/xen3-x86-fix-kmap-contig.patch

   1 From: Nick Piggin <npiggin@suse.de>
   2 Subject: x86: contiguous kmap fix
   3 References: bnc#449812
   4 Patch-mainline: perhaps 2.6.30 (maybe .29)
   5
   6 The early fixmap pmd entry inserted at the very top of the KVA is casing the
   7 subsequent fixmap mapping code to not provide physically linear pte pages over
   8 the kmap atomic portion of the fixmap (which relies on said property to calculate
   9 pte address).
  10
  11 This has caused weird boot failures in kmap_atomic much later in the boot
  12 process (initial userspace faults) on a 32-bit PAE system with a larger number
  13 of CPUs (smaller CPU counts tend not to run over into the next page so don't
  14 show up the problem).
  15
  16 Solve this by attempting to clear out the page table, and copy any of its
  17 entries to the new one. Also, add a bug if a nonlinear condition is encountered
  18 and can't be resolved, which might save some hours of debugging if this fragile
  19 scheme ever breaks again...
  20
  21 Signed-off-by: Nick Piggin <npiggin@suse.de>
  22
  23 Once we have such logic, we can also use it to eliminate the early ioremap
  24 trickery around the page table setup for the fixmap area. This also fixes
  25 potential issues with FIX_* entries sharing the leaf page table with the early
  26 ioremap ones getting discarded by early_ioremap_clear() and not restored by
  27 early_ioremap_reset(). It at once eliminates the temporary (and configuration,
  28 namely NR_CPUS, dependent) unavailability of early fixed mappings during the
  29 time the fixmap area page tables get constructed.
  30
  31 Finally, also replace the hard coded calculation of the initial table space
  32 needed for the fixmap area with a proper one, allowing kernels configured for
  33 large CPU counts to actually boot.
  34
  35 Signed-off-by: Jan Beulich <jbeulich@novell.com>
  36
  37 Automatically created from "patches.arch/x86-fix-kmap-contig.patch" by xen-port-patches.py
  38
  39 --- sle11-2009-04-20.orig/arch/x86/mm/init_32-xen.c     2009-04-24 13:36:23.000000000 +0200
  40 +++ sle11-2009-04-20/arch/x86/mm/init_32-xen.c  2009-02-17 18:06:20.000000000 +0100
  41 @@ -148,6 +148,52 @@ static pte_t * __init one_page_table_ini
  42         return pte_offset_kernel(pmd, 0);
  43  }
  44
  45 +static pte_t *__init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
  46 +                                          unsigned long vaddr, pte_t *lastpte)
  47 +{
  48 +#ifdef CONFIG_HIGHMEM
  49 +       /*
  50 +        * Something (early fixmap) may already have put a pte
  51 +        * page here, which causes the page table allocation
  52 +        * to become nonlinear. Attempt to fix it, and if it
  53 +        * is still nonlinear then we have to bug.
  54 +        */
  55 +       int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
  56 +       int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
  57 +
  58 +       if (pmd_idx_kmap_begin != pmd_idx_kmap_end
  59 +           && (vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin
  60 +           && (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end
  61 +           && ((__pa(pte) >> PAGE_SHIFT) < table_start
  62 +               || (__pa(pte) >> PAGE_SHIFT) >= table_end)) {
  63 +               pte_t *newpte;
  64 +               unsigned long phys;
  65 +               int i;
  66 +
  67 +               BUG_ON(after_init_bootmem);
  68 +               newpte = alloc_low_page(&phys);
  69 +               for (i = 0; i < PTRS_PER_PTE; i++)
  70 +                       set_pte(newpte + i, pte[i]);
  71 +
  72 +               paravirt_alloc_pte(&init_mm, __pa(newpte) >> PAGE_SHIFT);
  73 +               make_lowmem_page_readonly(newpte,
  74 +                                         XENFEAT_writable_page_tables);
  75 +               set_pmd(pmd, __pmd(__pa(newpte)|_PAGE_TABLE));
  76 +               BUG_ON(newpte != pte_offset_kernel(pmd, 0));
  77 +               __flush_tlb_all();
  78 +
  79 +               paravirt_release_pte(__pa(pte) >> PAGE_SHIFT);
  80 +               make_lowmem_page_writable(pte,
  81 +                                         XENFEAT_writable_page_tables);
  82 +               pte = newpte;
  83 +       }
  84 +       BUG_ON(vaddr < fix_to_virt(FIX_KMAP_BEGIN - 1)
  85 +              && vaddr > fix_to_virt(FIX_KMAP_END)
  86 +              && lastpte && lastpte + PTRS_PER_PTE != pte);
  87 +#endif
  88 +       return pte;
  89 +}
  90 +
  91  /*
  92   * This function initializes a certain range of kernel virtual memory
  93   * with new bootmem page tables, everywhere page tables are missing in
  94 @@ -164,6 +210,7 @@ page_table_range_init(unsigned long star
  95         unsigned long vaddr;
  96         pgd_t *pgd;
  97         pmd_t *pmd;
  98 +       pte_t *pte = NULL;
  99
 100         vaddr = start;
 101         pgd_idx = pgd_index(vaddr);
 102 @@ -175,8 +222,9 @@ page_table_range_init(unsigned long star
 103                 pmd = pmd + pmd_index(vaddr);
 104                 for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
 105                                                         pmd++, pmd_idx++) {
 106 -                       if (vaddr < hypervisor_virt_start)
 107 -                               one_page_table_init(pmd);
 108 +                       BUG_ON(vaddr >= hypervisor_virt_start);
 109 +                       pte = page_table_kmap_check(one_page_table_init(pmd),
 110 +                                                   pmd, vaddr, pte);
 111
 112                         vaddr += PMD_SIZE;
 113                 }
 114 @@ -443,7 +491,6 @@ static void __init early_ioremap_page_ta
 115          * Fixed mappings, only the page table structure has to be
 116          * created - mappings will be set by set_fixmap():
 117          */
 118 -       early_ioremap_clear();
 119         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 120         end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
 121         page_table_range_init(vaddr, end, pgd_base);
 122 @@ -790,10 +837,7 @@ static void __init find_early_table_spac
 123         tables += PAGE_ALIGN(ptes * sizeof(pte_t));
 124
 125         /* for fixmap */
 126 -       tables += PAGE_SIZE
 127 -                 * ((((FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK)
 128 -                     - (__fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK))
 129 -                    >> PMD_SHIFT);
 130 +       tables += PAGE_ALIGN(__end_of_fixed_addresses * sizeof(pte_t));
 131
 132         table_start = extend_init_mapping(tables);
 133
 134 --- sle11-2009-04-20.orig/arch/x86/mm/ioremap-xen.c     2009-04-24 13:36:23.000000000 +0200
 135 +++ sle11-2009-04-20/arch/x86/mm/ioremap-xen.c  2009-01-16 10:45:51.000000000 +0100
 136 @@ -669,35 +669,9 @@ void __init early_ioremap_init(void)
 137  }
 138
 139  #ifdef CONFIG_X86_32
 140 -void __init early_ioremap_clear(void)
 141 -{
 142 -       pmd_t *pmd;
 143 -
 144 -       if (early_ioremap_debug)
 145 -               printk(KERN_INFO "early_ioremap_clear()\n");
 146 -
 147 -       pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
 148 -       pmd_clear(pmd);
 149 -       make_lowmem_page_writable(bm_pte, XENFEAT_writable_page_tables);
 150 -       /* paravirt_release_pte(__pa(bm_pte) >> PAGE_SHIFT); */
 151 -       __flush_tlb_all();
 152 -}
 153 -
 154  void __init early_ioremap_reset(void)
 155  {
 156 -       enum fixed_addresses idx;
 157 -       unsigned long addr, phys;
 158 -       pte_t *pte;
 159 -
 160         after_paging_init = 1;
 161 -       for (idx = FIX_BTMAP_BEGIN; idx >= FIX_BTMAP_END; idx--) {
 162 -               addr = fix_to_virt(idx);
 163 -               pte = early_ioremap_pte(addr);
 164 -               if (pte_present(*pte)) {
 165 -                       phys = __pte_val(*pte) & PAGE_MASK;
 166 -                       set_fixmap(idx, phys);
 167 -               }
 168 -       }
 169  }
 170  #endif /* CONFIG_X86_32 */
 171
 172 --- sle11-2009-04-20.orig/include/asm-x86/mach-xen/asm/io.h     2009-04-24 13:36:23.000000000 +0200
 173 +++ sle11-2009-04-20/include/asm-x86/mach-xen/asm/io.h  2009-04-24 13:36:29.000000000 +0200
 174 @@ -12,7 +12,6 @@
 175   */
 176  #ifndef __ASSEMBLY__
 177  extern void early_ioremap_init(void);
 178 -extern void early_ioremap_clear(void);
 179  extern void early_ioremap_reset(void);
 180  extern void *early_ioremap(unsigned long offset, unsigned long size);
 181  extern void early_iounmap(void *addr, unsigned long size);
 182 @@ -131,7 +130,6 @@ extern void __iomem *ioremap_wc(unsigned
 183   * A boot-time mapping is currently limited to at most 16 pages.
 184   */
 185  extern void early_ioremap_init(void);
 186 -extern void early_ioremap_clear(void);
 187  extern void early_ioremap_reset(void);
 188  extern void *early_ioremap(unsigned long offset, unsigned long size);
 189  extern void early_iounmap(void *addr, unsigned long size);