From 3c726f8dee6f55e96475574e9f645327e461884c Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Mon, 7 Nov 2005 11:06:55 +1100 Subject: [PATCH] ppc64: support 64k pages Adds a new CONFIG_PPC_64K_PAGES which, when enabled, changes the kernel base page size to 64K. The resulting kernel still boots on any hardware. On current machines with 4K pages support only, the kernel will maintain 16 "subpages" for each 64K page transparently. Note that while real 64K capable HW has been tested, the current patch will not enable it yet as such hardware is not released yet, and I'm still verifying with the firmware architects the proper to get the information from the newer hypervisors. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Linus Torvalds --- include/asm-ppc64/pgtable-64k.h | 87 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 include/asm-ppc64/pgtable-64k.h (limited to 'include/asm-ppc64/pgtable-64k.h') diff --git a/include/asm-ppc64/pgtable-64k.h b/include/asm-ppc64/pgtable-64k.h new file mode 100644 index 000000000000..c5f437c86b3c --- /dev/null +++ b/include/asm-ppc64/pgtable-64k.h @@ -0,0 +1,87 @@ +#include + + +#define PTE_INDEX_SIZE 12 +#define PMD_INDEX_SIZE 12 +#define PUD_INDEX_SIZE 0 +#define PGD_INDEX_SIZE 4 + +#define PTE_TABLE_SIZE (sizeof(real_pte_t) << PTE_INDEX_SIZE) +#define PMD_TABLE_SIZE (sizeof(pmd_t) << PMD_INDEX_SIZE) +#define PGD_TABLE_SIZE (sizeof(pgd_t) << PGD_INDEX_SIZE) + +#define PTRS_PER_PTE (1 << PTE_INDEX_SIZE) +#define PTRS_PER_PMD (1 << PMD_INDEX_SIZE) +#define PTRS_PER_PGD (1 << PGD_INDEX_SIZE) + +/* PMD_SHIFT determines what a second-level page table entry can map */ +#define PMD_SHIFT (PAGE_SHIFT + PTE_INDEX_SIZE) +#define PMD_SIZE (1UL << PMD_SHIFT) +#define PMD_MASK (~(PMD_SIZE-1)) + +/* PGDIR_SHIFT determines what a third-level page table entry can map */ +#define PGDIR_SHIFT (PMD_SHIFT + PMD_INDEX_SIZE) +#define PGDIR_SIZE (1UL << PGDIR_SHIFT) +#define PGDIR_MASK (~(PGDIR_SIZE-1)) + +/* Additional PTE bits (don't change without checking asm in hash_low.S) */ +#define _PAGE_HPTE_SUB 0x0ffff000 /* combo only: sub pages HPTE bits */ +#define _PAGE_HPTE_SUB0 0x08000000 /* combo only: first sub page */ +#define _PAGE_COMBO 0x10000000 /* this is a combo 4k page */ +#define _PAGE_F_SECOND 0x00008000 /* full page: hidx bits */ +#define _PAGE_F_GIX 0x00007000 /* full page: hidx bits */ + +/* PTE flags to conserve for HPTE identification */ +#define _PAGE_HPTEFLAGS (_PAGE_BUSY | _PAGE_HASHPTE | _PAGE_HPTE_SUB |\ + _PAGE_COMBO) + +/* Shift to put page number into pte. + * + * That gives us a max RPN of 32 bits, which means a max of 48 bits + * of addressable physical space. + * We could get 3 more bits here by setting PTE_RPN_SHIFT to 29 but + * 32 makes PTEs more readable for debugging for now :) + */ +#define PTE_RPN_SHIFT (32) +#define PTE_RPN_MAX (1UL << (64 - PTE_RPN_SHIFT)) +#define PTE_RPN_MASK (~((1UL<> ((index)<<2)) & 0xf) : ((pte_val((r).pte) >> 12) & 0xf)) +#define __rpte_to_pte(r) ((r).pte) +#define __rpte_sub_valid(rpte, index) \ + (pte_val(rpte.pte) & (_PAGE_HPTE_SUB0 >> (index))) + + +/* Trick: we set __end to va + 64k, which happens works for + * a 16M page as well as we want only one iteration + */ +#define pte_iterate_hashed_subpages(rpte, psize, va, index, shift) \ + do { \ + unsigned long __end = va + PAGE_SIZE; \ + unsigned __split = (psize == MMU_PAGE_4K || \ + psize == MMU_PAGE_64K_AP); \ + shift = mmu_psize_defs[psize].shift; \ + for (index = 0; va < __end; index++, va += (1 << shift)) { \ + if (!__split || __rpte_sub_valid(rpte, index)) do { \ + +#define pte_iterate_hashed_end() } while(0); } } while(0) + + +#endif /* __ASSEMBLY__ */ -- cgit v1.2.2 From 7d24f0b8a53261709938ffabe3e00f88f6498df9 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Mon, 7 Nov 2005 00:57:52 -0800 Subject: [PATCH] ppc64: Fix bug in SLB miss handler for hugepages This patch, however, should be applied on top of the 64k-page-size patch to fix some problems with hugepage (some pre-existing, another introduced by this patch). The patch fixes a bug in the SLB miss handler for hugepages on ppc64 introduced by the dynamic hugepage patch (commit id c594adad5653491813959277fb87a2fef54c4e05) due to a misunderstanding of the srd instruction's behaviour (mea culpa). The problem arises when a 64-bit process maps some hugepages in the low 4GB of the address space (unusual). In this case, as well as the 256M segment in question being marked for hugepages, other segments at 32G intervals will be incorrectly marked for hugepages. In the process, this patch tweaks the semantics of the hugepage bitmaps to be more sensible. Previously, an address below 4G was marked for hugepages if the appropriate segment bit in the "low areas" bitmask was set *or* if the low bit in the "high areas" bitmap was set (which would mark all addresses below 1TB for hugepage). With this patch, any given address is governed by a single bitmap. Addresses below 4GB are marked for hugepage if and only if their bit is set in the "low areas" bitmap (256M granularity). Addresses between 4GB and 1TB are marked for hugepage iff the low bit in the "high areas" bitmap is set. Higher addresses are marked for hugepage iff their bit in the "high areas" bitmap is set (1TB granularity). To avoid conflicts, this patch must be applied on top of BenH's pending patch for 64k base page size [0]. As such, this patch also addresses a hugepage problem introduced by that patch. That patch allows hugepages of 1MB in size on hardware which supports it, however, that won't work when using 4k pages (4 level pagetable), because in that case hugepage PTEs are stored at the PMD level, and each PMD entry maps 2MB. This patch simply disallows hugepages in that case (we can do something cleverer to re-enable them some other day). Built, booted, and a handful of hugepage related tests passed on POWER5 LPAR (both ARCH=powerpc and ARCH=ppc64). [0] http://gate.crashing.org/~benh/ppc64-64k-pages.diff Signed-off-by: David Gibson Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-ppc64/pgtable-64k.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/asm-ppc64/pgtable-64k.h') diff --git a/include/asm-ppc64/pgtable-64k.h b/include/asm-ppc64/pgtable-64k.h index c5f437c86b3c..154f1840ece4 100644 --- a/include/asm-ppc64/pgtable-64k.h +++ b/include/asm-ppc64/pgtable-64k.h @@ -14,6 +14,9 @@ #define PTRS_PER_PMD (1 << PMD_INDEX_SIZE) #define PTRS_PER_PGD (1 << PGD_INDEX_SIZE) +/* With 4k base page size, hugepage PTEs go at the PMD level */ +#define MIN_HUGEPTE_SHIFT PAGE_SHIFT + /* PMD_SHIFT determines what a second-level page table entry can map */ #define PMD_SHIFT (PAGE_SHIFT + PTE_INDEX_SIZE) #define PMD_SIZE (1UL << PMD_SHIFT) -- cgit v1.2.2