)]}'
{
  "log": [
    {
      "commit": "fa28237cfcc5827553044cbd6ee52e33692b0faa",
      "tree": "2e34678548e5323eef7392a94a7415e1754cbd1e",
      "parents": [
        "0a0a5af30b9831e4f049610b5a2d9d5108ff027a"
      ],
      "author": {
        "name": "Paul Mackerras",
        "email": "paulus@samba.org",
        "time": "Thu Jan 24 08:35:13 2008 +1100"
      },
      "committer": {
        "name": "Paul Mackerras",
        "email": "paulus@samba.org",
        "time": "Thu Jan 24 10:06:01 2008 +1100"
      },
      "message": "[POWERPC] Provide a way to protect 4k subpages when using 64k pages\n\nUsing 64k pages on 64-bit PowerPC systems makes life difficult for\nemulators that are trying to emulate an ISA, such as x86, which use a\nsmaller page size, since the emulator can no longer use the MMU and\nthe normal system calls for controlling page protections.  Of course,\nthe emulator can emulate the MMU by checking and possibly remapping\nthe address for each memory access in software, but that is pretty\nslow.\n\nThis provides a facility for such programs to control the access\npermissions on individual 4k sub-pages of 64k pages.  The idea is\nthat the emulator supplies an array of protection masks to apply to a\nspecified range of virtual addresses.  These masks are applied at the\nlevel where hardware PTEs are inserted into the hardware page table\nbased on the Linux PTEs, so the Linux PTEs are not affected.  Note\nthat this new mechanism does not allow any access that would otherwise\nbe prohibited; it can only prohibit accesses that would otherwise be\nallowed.  This new facility is only available on 64-bit PowerPC and\nonly when the kernel is configured for 64k pages.\n\nThe masks are supplied using a new subpage_prot system call, which\ntakes a starting virtual address and length, and a pointer to an array\nof protection masks in memory.  The array has a 32-bit word per 64k\npage to be protected; each 32-bit word consists of 16 2-bit fields,\nfor which 0 allows any access (that is otherwise allowed), 1 prevents\nwrite accesses, and 2 or 3 prevent any access.\n\nImplicit in this is that the regions of the address space that are\nprotected are switched to use 4k hardware pages rather than 64k\nhardware pages (on machines with hardware 64k page support).  In fact\nthe whole process is switched to use 4k hardware pages when the\nsubpage_prot system call is used, but this could be improved in future\nto switch only the affected segments.\n\nThe subpage protection bits are stored in a 3 level tree akin to the\npage table tree.  The top level of this tree is stored in a structure\nthat is appended to the top level of the page table tree, i.e., the\npgd array.  Since it will often only be 32-bit addresses (below 4GB)\nthat are protected, the pointers to the first four bottom level pages\nare also stored in this structure (each bottom level page contains the\nprotection bits for 1GB of address space), so the protection bits for\naddresses below 4GB can be accessed with one fewer loads than those\nfor higher addresses.\n\nSigned-off-by: Paul Mackerras \u003cpaulus@samba.org\u003e\n"
    },
    {
      "commit": "a4c28ab7445f5ca60e56ffd90edb3e9fc1330b71",
      "tree": "d7ccd52c688f014c320a55c1b6fa512424b147f3",
      "parents": [
        "66b30922c8a2c880fe61080c5bf87ae6615b9f64"
      ],
      "author": {
        "name": "Akinobu Mita",
        "email": "mita@fixstars.com",
        "time": "Tue May 29 20:46:51 2007 +1000"
      },
      "committer": {
        "name": "Paul Mackerras",
        "email": "paulus@samba.org",
        "time": "Sat Jun 02 21:01:56 2007 +1000"
      },
      "message": "[POWERPC] Fix return from pte_alloc_one() in out-of-memory case\n\npte_alloc_one() is expected to return NULL if out of memory.\nBut it returns virt_to_page(NULL), which is not NULL.\nThis fixes it.\n\nCc: Paul Mackerras \u003cpaulus@samba.org\u003e\nSigned-off-by: Akinobu Mita \u003cmita@fixstars.com\u003e\nSigned-off-by: Paul Mackerras \u003cpaulus@samba.org\u003e\n"
    },
    {
      "commit": "517e22638c282bb07c52a11f928961ed4822196b",
      "tree": "7eab8eb1242ee18f75c325077f26bdcb86133512",
      "parents": [
        "f1fa74f4afe96b0e4ac2beaa61fa4f4667acdcbb"
      ],
      "author": {
        "name": "Hugh Dickins",
        "email": "hugh@veritas.com",
        "time": "Wed May 09 14:38:48 2007 +1000"
      },
      "committer": {
        "name": "Paul Mackerras",
        "email": "paulus@samba.org",
        "time": "Wed May 09 16:35:00 2007 +1000"
      },
      "message": "[POWERPC] Don\u0027t use SLAB/SLUB for PTE pages\n\nThe SLUB allocator relies on struct page fields first_page and slab,\noverwritten by ptl when SPLIT_PTLOCK: so the SLUB allocator cannot then\nbe used for the lowest level of pagetable pages.  This was obstructing\nSLUB on PowerPC, which uses kmem_caches for its pagetables.  So convert\nits pte level to use normal gfp pages (whereas pmd, pud and 64k-page pgd\nwant partpages, so continue to use kmem_caches for pmd, pud and pgd).\n\nSigned-off-by: Hugh Dickins \u003chugh@veritas.com\u003e\nSigned-off-by: Benjamin Herrenschmidt \u003cbenh@kernel.crashing.org\u003e\nSigned-off-by: Paul Mackerras \u003cpaulus@samba.org\u003e\n"
    },
    {
      "commit": "f88df14b1f15cdeffa060580a40c1ce3e13bb79e",
      "tree": "0619f32c2be79a85792537ad4410cc8d729f4f75",
      "parents": [
        "69d48b409cac747cc0707b05b769e38488a6ad35"
      ],
      "author": {
        "name": "David Gibson",
        "email": "david@gibson.dropbear.id.au",
        "time": "Mon Apr 30 16:30:56 2007 +1000"
      },
      "committer": {
        "name": "Paul Mackerras",
        "email": "paulus@samba.org",
        "time": "Wed May 02 20:04:30 2007 +1000"
      },
      "message": "[POWERPC] Remove arch/powerpc\u0027s dependence on asm-ppc/pg{alloc,table}.h\n\nCurrently, all 32-bit powerpc platforms use asm-ppc/pgtable.h and\nasm-ppc/pgalloc.h, even when otherwise compiled with ARCH\u003dpowerpc.\nThose asm-ppc files are a fairly nasty tangle of #ifdefs including a\nbunch of things which shouldn\u0027t be necessary any more in arch/powerpc.\n\nCleaning up that mess is going to take a while, but this patch is a\nfirst step.  It separates the asm-powerpc/pg{alloc,table}.h into 64\nbit and 32 bit versions in asm-powerpc, which the basic .h files in\nasm-powerpc select based on config.  We make a few tiny tweaks to the\ninnards of the files along the way, making the outermost ifdefs\n(double-inclusion protection and __KERNEL__) a little cleaner, and\n#including asm-generic/pgtable.h from the top-level\nasm-powerpc/pgtable.h (since both the old 32-bit and 64-bit versions\nended with such an #include).\n\nSigned-off-by: David Gibson \u003cdavid@gibson.dropbear.id.au\u003e\nSigned-off-by: Paul Mackerras \u003cpaulus@samba.org\u003e\n"
    }
  ]
}