powerpc: Hugetlb for BookE

Enable hugepages on Freescale BookE processors.  This allows the kernel to
use huge TLB entries to map pages, which can greatly reduce the number of
TLB misses and the amount of TLB thrashing experienced by applications with
large memory footprints.  Care should be taken when using this on FSL
processors, as the number of large TLB entries supported by the core is low
(16-64) on current processors.

The supported set of hugepage sizes include 4m, 16m, 64m, 256m, and 1g.
Page sizes larger than the max zone size are called "gigantic" pages and
must be allocated on the command line (and cannot be deallocated).

This is currently only fully implemented for Freescale 32-bit BookE
processors, but there is some infrastructure in the code for
64-bit BooKE.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 121 insertions, 0 deletions

diff --git a/arch/powerpc/mm/hugetlbpage-book3e.c b/arch/powerpc/mm/hugetlbpage-book3e.c
new file mode 100644
index 000000000000..1295b7c1cdac
--- /dev/null
+++ b/arch/powerpc/mm/hugetlbpage-book3e.c
@@ -0,0 +1,121 @@
+/*
+ * PPC Huge TLB Page Support for Book3E MMU
+ *
+ * Copyright (C) 2009 David Gibson, IBM Corporation.
+ * Copyright (C) 2011 Becky Bruce, Freescale Semiconductor
+ *
+ */
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+
+static inline int mmu_get_tsize(int psize)
+{
+	return mmu_psize_defs[psize].enc;
+}
+
+static inline int book3e_tlb_exists(unsigned long ea, unsigned long pid)
+{
+	int found = 0;
+
+	mtspr(SPRN_MAS6, pid << 16);
+	if (mmu_has_feature(MMU_FTR_USE_TLBRSRV)) {
+		asm volatile(
+			"li	%0,0\n"
+			"tlbsx.	0,%1\n"
+			"bne	1f\n"
+			"li	%0,1\n"
+			"1:\n"
+			: "=&r"(found) : "r"(ea));
+	} else {
+		asm volatile(
+			"tlbsx	0,%1\n"
+			"mfspr	%0,0x271\n"
+			"srwi	%0,%0,31\n"
+			: "=&r"(found) : "r"(ea));
+	}
+
+	return found;
+}
+
+void book3e_hugetlb_preload(struct mm_struct *mm, unsigned long ea, pte_t pte)
+{
+	unsigned long mas1, mas2;
+	u64 mas7_3;
+	unsigned long psize, tsize, shift;
+	unsigned long flags;
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	int index, lz, ncams;
+	struct vm_area_struct *vma;
+#endif
+
+	if (unlikely(is_kernel_addr(ea)))
+		return;
+
+#ifdef CONFIG_MM_SLICES
+	psize = mmu_get_tsize(get_slice_psize(mm, ea));
+	tsize = mmu_get_psize(psize);
+	shift = mmu_psize_defs[psize].shift;
+#else
+	vma = find_vma(mm, ea);
+	psize = vma_mmu_pagesize(vma);	/* returns actual size in bytes */
+	asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (psize));
+	shift = 31 - lz;
+	tsize = 21 - lz;
+#endif
+
+	/*
+	 * We can't be interrupted while we're setting up the MAS
+	 * regusters or after we've confirmed that no tlb exists.
+	 */
+	local_irq_save(flags);
+
+	if (unlikely(book3e_tlb_exists(ea, mm->context.id))) {
+		local_irq_restore(flags);
+		return;
+	}
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	ncams = mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY;
+
+	/* We have to use the CAM(TLB1) on FSL parts for hugepages */
+	index = __get_cpu_var(next_tlbcam_idx);
+	mtspr(SPRN_MAS0, MAS0_ESEL(index) | MAS0_TLBSEL(1));
+
+	/* Just round-robin the entries and wrap when we hit the end */
+	if (unlikely(index == ncams - 1))
+		__get_cpu_var(next_tlbcam_idx) = tlbcam_index;
+	else
+		__get_cpu_var(next_tlbcam_idx)++;
+#endif
+	mas1 = MAS1_VALID | MAS1_TID(mm->context.id) | MAS1_TSIZE(tsize);
+	mas2 = ea & ~((1UL << shift) - 1);
+	mas2 |= (pte_val(pte) >> PTE_WIMGE_SHIFT) & MAS2_WIMGE_MASK;
+	mas7_3 = (u64)pte_pfn(pte) << PAGE_SHIFT;
+	mas7_3 |= (pte_val(pte) >> PTE_BAP_SHIFT) & MAS3_BAP_MASK;
+	if (!pte_dirty(pte))
+		mas7_3 &= ~(MAS3_SW|MAS3_UW);
+
+	mtspr(SPRN_MAS1, mas1);
+	mtspr(SPRN_MAS2, mas2);
+
+	if (mmu_has_feature(MMU_FTR_USE_PAIRED_MAS)) {
+		mtspr(SPRN_MAS7_MAS3, mas7_3);
+	} else {
+		mtspr(SPRN_MAS7, upper_32_bits(mas7_3));
+		mtspr(SPRN_MAS3, lower_32_bits(mas7_3));
+	}
+
+	asm volatile ("tlbwe");
+
+	local_irq_restore(flags);
+}
+
+void flush_hugetlb_page(struct vm_area_struct *vma, unsigned long vmaddr)
+{
+	struct hstate *hstate = hstate_file(vma->vm_file);
+	unsigned long tsize = huge_page_shift(hstate) - 10;
+
+	__flush_tlb_page(vma ? vma->vm_mm : NULL, vmaddr, tsize, 0);
+
+}