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Subject[PATCH v3 10/31] arm64: TLB maintenance functionality
Date
This patch adds the TLB maintenance functions. There is no distinction
made between the I and D TLBs. TLB maintenance operations are
automatically broadcast between CPUs in hardware. The inner-shareable
operations are always present, even on UP systems.

NOTE: Large part of this patch to be dropped once Peter Z's generic
mmu_gather patches are merged.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
---
arch/arm64/include/asm/tlb.h | 190 +++++++++++++++++++++++++++++++++++++
arch/arm64/include/asm/tlbflush.h | 122 ++++++++++++++++++++++++
arch/arm64/mm/tlb.S | 71 ++++++++++++++
3 files changed, 383 insertions(+), 0 deletions(-)
create mode 100644 arch/arm64/include/asm/tlb.h
create mode 100644 arch/arm64/include/asm/tlbflush.h
create mode 100644 arch/arm64/mm/tlb.S
diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
new file mode 100644
index 0000000..654f096
--- /dev/null
+++ b/arch/arm64/include/asm/tlb.h
@@ -0,0 +1,190 @@
+/*
+ * Based on arch/arm/include/asm/tlb.h
+ *
+ * Copyright (C) 2002 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_TLB_H
+#define __ASM_TLB_H
+
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+
+#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+
+#define MMU_GATHER_BUNDLE 8
+
+/*
+ * TLB handling. This allows us to remove pages from the page
+ * tables, and efficiently handle the TLB issues.
+ */
+struct mmu_gather {
+ struct mm_struct *mm;
+ unsigned int fullmm;
+ struct vm_area_struct *vma;
+ unsigned long range_start;
+ unsigned long range_end;
+ unsigned int nr;
+ unsigned int max;
+ struct page **pages;
+ struct page *local[MMU_GATHER_BUNDLE];
+};
+
+/*
+ * This is unnecessarily complex. There's three ways the TLB shootdown
+ * code is used:
+ * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region().
+ * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
+ * tlb->vma will be non-NULL.
+ * 2. Unmapping all vmas. See exit_mmap().
+ * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
+ * tlb->vma will be non-NULL. Additionally, page tables will be freed.
+ * 3. Unmapping argument pages. See shift_arg_pages().
+ * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
+ * tlb->vma will be NULL.
+ */
+static inline void tlb_flush(struct mmu_gather *tlb)
+{
+ if (tlb->fullmm || !tlb->vma)
+ flush_tlb_mm(tlb->mm);
+ else if (tlb->range_end > 0) {
+ flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
+ tlb->range_start = TASK_SIZE;
+ tlb->range_end = 0;
+ }
+}
+
+static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
+{
+ if (!tlb->fullmm) {
+ if (addr < tlb->range_start)
+ tlb->range_start = addr;
+ if (addr + PAGE_SIZE > tlb->range_end)
+ tlb->range_end = addr + PAGE_SIZE;
+ }
+}
+
+static inline void __tlb_alloc_page(struct mmu_gather *tlb)
+{
+ unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+
+ if (addr) {
+ tlb->pages = (void *)addr;
+ tlb->max = PAGE_SIZE / sizeof(struct page *);
+ }
+}
+
+static inline void tlb_flush_mmu(struct mmu_gather *tlb)
+{
+ tlb_flush(tlb);
+ free_pages_and_swap_cache(tlb->pages, tlb->nr);
+ tlb->nr = 0;
+ if (tlb->pages == tlb->local)
+ __tlb_alloc_page(tlb);
+}
+
+static inline void
+tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int fullmm)
+{
+ tlb->mm = mm;
+ tlb->fullmm = fullmm;
+ tlb->vma = NULL;
+ tlb->max = ARRAY_SIZE(tlb->local);
+ tlb->pages = tlb->local;
+ tlb->nr = 0;
+ __tlb_alloc_page(tlb);
+}
+
+static inline void
+tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
+{
+ tlb_flush_mmu(tlb);
+
+ /* keep the page table cache within bounds */
+ check_pgt_cache();
+
+ if (tlb->pages != tlb->local)
+ free_pages((unsigned long)tlb->pages, 0);
+}
+
+/*
+ * Memorize the range for the TLB flush.
+ */
+static inline void
+tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
+{
+ tlb_add_flush(tlb, addr);
+}
+
+/*
+ * In the case of tlb vma handling, we can optimise these away in the
+ * case where we're doing a full MM flush. When we're doing a munmap,
+ * the vmas are adjusted to only cover the region to be torn down.
+ */
+static inline void
+tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
+{
+ if (!tlb->fullmm) {
+ tlb->vma = vma;
+ tlb->range_start = TASK_SIZE;
+ tlb->range_end = 0;
+ }
+}
+
+static inline void
+tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
+{
+ if (!tlb->fullmm)
+ tlb_flush(tlb);
+}
+
+static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+ tlb->pages[tlb->nr++] = page;
+ VM_BUG_ON(tlb->nr > tlb->max);
+ return tlb->max - tlb->nr;
+}
+
+static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+ if (!__tlb_remove_page(tlb, page))
+ tlb_flush_mmu(tlb);
+}
+
+static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
+ unsigned long addr)
+{
+ pgtable_page_dtor(pte);
+ tlb_add_flush(tlb, addr);
+ tlb_remove_page(tlb, pte);
+}
+
+#ifndef CONFIG_ARM64_64K_PAGES
+static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
+ unsigned long addr)
+{
+ tlb_add_flush(tlb, addr);
+ tlb_remove_page(tlb, virt_to_page(pmdp));
+}
+#endif
+
+#define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr)
+#define pmd_free_tlb(tlb, pmdp, addr) __pmd_free_tlb(tlb, pmdp, addr)
+#define pud_free_tlb(tlb, pudp, addr) pud_free((tlb)->mm, pudp)
+
+#define tlb_migrate_finish(mm) do { } while (0)
+
+#endif
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
new file mode 100644
index 0000000..122d632
--- /dev/null
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -0,0 +1,122 @@
+/*
+ * Based on arch/arm/include/asm/tlbflush.h
+ *
+ * Copyright (C) 1999-2003 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_TLBFLUSH_H
+#define __ASM_TLBFLUSH_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/sched.h>
+#include <asm/cputype.h>
+
+extern void __cpu_flush_user_tlb_range(unsigned long, unsigned long, struct vm_area_struct *);
+extern void __cpu_flush_kern_tlb_range(unsigned long, unsigned long);
+
+extern struct cpu_tlb_fns cpu_tlb;
+
+/*
+ * TLB Management
+ * ==============
+ *
+ * The arch/arm64/mm/tlb.S files implement these methods.
+ *
+ * The TLB specific code is expected to perform whatever tests it needs
+ * to determine if it should invalidate the TLB for each call. Start
+ * addresses are inclusive and end addresses are exclusive; it is safe to
+ * round these addresses down.
+ *
+ * flush_tlb_all()
+ *
+ * Invalidate the entire TLB.
+ *
+ * flush_tlb_mm(mm)
+ *
+ * Invalidate all TLB entries in a particular address space.
+ * - mm - mm_struct describing address space
+ *
+ * flush_tlb_range(mm,start,end)
+ *
+ * Invalidate a range of TLB entries in the specified address
+ * space.
+ * - mm - mm_struct describing address space
+ * - start - start address (may not be aligned)
+ * - end - end address (exclusive, may not be aligned)
+ *
+ * flush_tlb_page(vaddr,vma)
+ *
+ * Invalidate the specified page in the specified address range.
+ * - vaddr - virtual address (may not be aligned)
+ * - vma - vma_struct describing address range
+ *
+ * flush_kern_tlb_page(kaddr)
+ *
+ * Invalidate the TLB entry for the specified page. The address
+ * will be in the kernels virtual memory space. Current uses
+ * only require the D-TLB to be invalidated.
+ * - kaddr - Kernel virtual memory address
+ */
+static inline void flush_tlb_all(void)
+{
+ dsb();
+ asm("tlbi vmalle1is");
+ dsb();
+ isb();
+}
+
+static inline void flush_tlb_mm(struct mm_struct *mm)
+{
+ unsigned long asid = (unsigned long)ASID(mm) << 48;
+
+ dsb();
+ asm("tlbi aside1is, %0" : : "r" (asid));
+ dsb();
+}
+
+static inline void flush_tlb_page(struct vm_area_struct *vma,
+ unsigned long uaddr)
+{
+ unsigned long addr = uaddr >> 12 |
+ ((unsigned long)ASID(vma->vm_mm) << 48);
+
+ dsb();
+ asm("tlbi vae1is, %0" : : "r" (addr));
+ dsb();
+}
+
+/*
+ * Convert calls to our calling convention.
+ */
+#define flush_tlb_range(vma,start,end) __cpu_flush_user_tlb_range(start,end,vma)
+#define flush_tlb_kernel_range(s,e) __cpu_flush_kern_tlb_range(s,e)
+
+/*
+ * On AArch64, the cache coherency is handled via the set_pte_at() function.
+ */
+static inline void update_mmu_cache(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep)
+{
+ /*
+ * set_pte() does not have a DSB, so make sure that the page table
+ * write is visible.
+ */
+ dsb();
+}
+
+#endif
+
+#endif
diff --git a/arch/arm64/mm/tlb.S b/arch/arm64/mm/tlb.S
new file mode 100644
index 0000000..8ae80a1
--- /dev/null
+++ b/arch/arm64/mm/tlb.S
@@ -0,0 +1,71 @@
+/*
+ * Based on arch/arm/mm/tlb.S
+ *
+ * Copyright (C) 1997-2002 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ * Written by Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
+#include <asm/page.h>
+#include <asm/tlbflush.h>
+#include "proc-macros.S"
+
+/*
+ * __cpu_flush_user_tlb_range(start, end, vma)
+ *
+ * Invalidate a range of TLB entries in the specified address space.
+ *
+ * - start - start address (may not be aligned)
+ * - end - end address (exclusive, may not be aligned)
+ * - vma - vma_struct describing address range
+ */
+ENTRY(__cpu_flush_user_tlb_range)
+ vma_vm_mm x3, x2 // get vma->vm_mm
+ mmid x3, x3 // get vm_mm->context.id
+ dsb sy
+ lsr x0, x0, #12 // align address
+ lsr x1, x1, #12
+ bfi x0, x3, #48, #16 // start VA and ASID
+ bfi x1, x3, #48, #16 // end VA and ASID
+1: tlbi vae1is, x0 // TLB invalidate by address and ASID
+ add x0, x0, #1
+ cmp x0, x1
+ b.lo 1b
+ dsb sy
+ ret
+ENDPROC(__cpu_flush_user_tlb_range)
+
+/*
+ * __cpu_flush_kern_tlb_range(start,end)
+ *
+ * Invalidate a range of kernel TLB entries.
+ *
+ * - start - start address (may not be aligned)
+ * - end - end address (exclusive, may not be aligned)
+ */
+ENTRY(__cpu_flush_kern_tlb_range)
+ dsb sy
+ lsr x0, x0, #12 // align address
+ lsr x1, x1, #12
+1: tlbi vaae1is, x0 // TLB invalidate by address
+ add x0, x0, #1
+ cmp x0, x1
+ b.lo 1b
+ dsb sy
+ isb
+ ret
+ENDPROC(__cpu_flush_kern_tlb_range)


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