powerpc/mm: Cleanup initialization of hugepages on powerpc

This patch simplifies the logic used to initialize hugepages on
powerpc.  The somewhat oddly named set_huge_psize() is renamed to
add_huge_page_size() and now does all necessary verification of
whether it's given a valid hugepage sizes (instead of just some) and
instantiates the generic hstate structure (but no more).

hugetlbpage_init() now steps through the available pagesizes, checks
if they're valid for hugepages by calling add_huge_page_size() and
initializes the kmem_caches for the hugepage pagetables.  This means
we can now eliminate the mmu_huge_psizes array, since we no longer
need to pass the sizing information for the pagetable caches from
set_huge_psize() into hugetlbpage_init()

Determination of the default huge page size is also moved from the
hash code into the general hugepage code.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 62 insertions, 66 deletions

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 95220a5dee58..a7161c07886d 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -37,27 +37,17 @@
 static unsigned long gpage_freearray[MAX_NUMBER_GPAGES];
 static unsigned nr_gpages;
 
-/* Array of valid huge page sizes - non-zero value(hugepte_shift) is
- * stored for the huge page sizes that are valid.
- */
-static unsigned int mmu_huge_psizes[MMU_PAGE_COUNT] = { }; /* initialize all to 0 */
-
 /* Flag to mark huge PD pointers.  This means pmd_bad() and pud_bad()
  * will choke on pointers to hugepte tables, which is handy for
  * catching screwups early. */
 
 static inline int shift_to_mmu_psize(unsigned int shift)
 {
-        switch (shift) {
-#ifndef CONFIG_PPC_64K_PAGES
-        case PAGE_SHIFT_64K:
-            return MMU_PAGE_64K;
-#endif
-        case PAGE_SHIFT_16M:
-            return MMU_PAGE_16M;
-        case PAGE_SHIFT_16G:
-            return MMU_PAGE_16G;
-        }
+        int psize;
+
+        for (psize = 0; psize < MMU_PAGE_COUNT; ++psize)
+                if (mmu_psize_defs[psize].shift == shift)
+                        return psize;
         return -1;
 }
 
@@ -502,8 +492,6 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
         struct hstate *hstate = hstate_file(file);
         int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));
 
-        if (!mmu_huge_psizes[mmu_psize])
-                return -EINVAL;
         return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1, 0);
 }
 
@@ -666,47 +654,46 @@ repeat:
         return err;
 }
 
-static void __init set_huge_psize(int psize)
+static int __init add_huge_page_size(unsigned long long size)
 {
-        unsigned pdshift;
+        int shift = __ffs(size);
+        int mmu_psize;
 
         /* Check that it is a page size supported by the hardware and
-         * that it fits within pagetable limits. */
-        if (mmu_psize_defs[psize].shift &&
-                mmu_psize_defs[psize].shift < SID_SHIFT_1T &&
-                (mmu_psize_defs[psize].shift > MIN_HUGEPTE_SHIFT ||
-                 mmu_psize_defs[psize].shift == PAGE_SHIFT_64K ||
-                 mmu_psize_defs[psize].shift == PAGE_SHIFT_16G)) {
-                /* Return if huge page size has already been setup or is the
-                 * same as the base page size. */
-                if (mmu_huge_psizes[psize] ||
-                   mmu_psize_defs[psize].shift == PAGE_SHIFT)
-                        return;
-                hugetlb_add_hstate(mmu_psize_defs[psize].shift - PAGE_SHIFT);
+         * that it fits within pagetable and slice limits. */
+        if (!is_power_of_2(size)
+            || (shift > SLICE_HIGH_SHIFT) || (shift <= PAGE_SHIFT))
+                return -EINVAL;
 
-                if (mmu_psize_defs[psize].shift < PMD_SHIFT)
-                        pdshift = PMD_SHIFT;
-                else if (mmu_psize_defs[psize].shift < PUD_SHIFT)
-                        pdshift = PUD_SHIFT;
-                else
-                        pdshift = PGDIR_SHIFT;
-                mmu_huge_psizes[psize] = pdshift - mmu_psize_defs[psize].shift;
-        }
+        if ((mmu_psize = shift_to_mmu_psize(shift)) < 0)
+                return -EINVAL;
+
+#ifdef CONFIG_SPU_FS_64K_LS
+        /* Disable support for 64K huge pages when 64K SPU local store
+         * support is enabled as the current implementation conflicts.
+         */
+        if (shift == PAGE_SHIFT_64K)
+                return -EINVAL;
+#endif /* CONFIG_SPU_FS_64K_LS */
+
+        BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);
+
+        /* Return if huge page size has already been setup */
+        if (size_to_hstate(size))
+                return 0;
+
+        hugetlb_add_hstate(shift - PAGE_SHIFT);
+
+        return 0;
 }
 
 static int __init hugepage_setup_sz(char *str)
 {
         unsigned long long size;
-        int mmu_psize;
-        int shift;
 
         size = memparse(str, &str);
 
-        shift = __ffs(size);
-        mmu_psize = shift_to_mmu_psize(shift);
-        if (mmu_psize >= 0 && mmu_psize_defs[mmu_psize].shift)
-                set_huge_psize(mmu_psize);
-        else
+        if (add_huge_page_size(size) != 0)
                 printk(KERN_WARNING "Invalid huge page size specified(%llu)\n", size);
 
         return 1;
@@ -720,30 +707,39 @@ static int __init hugetlbpage_init(void)
         if (!cpu_has_feature(CPU_FTR_16M_PAGE))
                 return -ENODEV;
 
-        /* Add supported huge page sizes.  Need to change
-         *  HUGE_MAX_HSTATE if the number of supported huge page sizes
-         *  changes.
-         */
-        set_huge_psize(MMU_PAGE_16M);
-        set_huge_psize(MMU_PAGE_16G);
+        for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
+                unsigned shift;
+                unsigned pdshift;
 
-        /* Temporarily disable support for 64K huge pages when 64K SPU local
-         * store support is enabled as the current implementation conflicts.
-         */
-#ifndef CONFIG_SPU_FS_64K_LS
-        set_huge_psize(MMU_PAGE_64K);
-#endif
+                if (!mmu_psize_defs[psize].shift)
+                        continue;
 
-        for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
-                if (mmu_huge_psizes[psize]) {
-                        pgtable_cache_add(mmu_huge_psizes[psize], NULL);
-                        if (!PGT_CACHE(mmu_huge_psizes[psize]))
-                                panic("hugetlbpage_init(): could not create "
-                                      "pgtable cache for %d bit pagesize\n",
-                                      mmu_psize_to_shift(psize));
-                }
+                shift = mmu_psize_to_shift(psize);
+
+                if (add_huge_page_size(1ULL << shift) < 0)
+                        continue;
+
+                if (shift < PMD_SHIFT)
+                        pdshift = PMD_SHIFT;
+                else if (shift < PUD_SHIFT)
+                        pdshift = PUD_SHIFT;
+                else
+                        pdshift = PGDIR_SHIFT;
+
+                pgtable_cache_add(pdshift - shift, NULL);
+                if (!PGT_CACHE(pdshift - shift))
+                        panic("hugetlbpage_init(): could not create "
+                              "pgtable cache for %d bit pagesize\n", shift);
         }
 
+        /* Set default large page size. Currently, we pick 16M or 1M
+         * depending on what is available
+         */
+        if (mmu_psize_defs[MMU_PAGE_16M].shift)
+                HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_16M].shift;
+        else if (mmu_psize_defs[MMU_PAGE_1M].shift)
+                HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_1M].shift;
+
         return 0;
 }