unicore32 core architecture: mm related: fault handling

This patch implements fault handling of memory management.
Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

arch/unicore32/include/asm/mmu.h

+/*
+ * linux/arch/unicore32/include/asm/mmu.h
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * 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.
+ */
+#ifndef __UNICORE_MMU_H__
+#define __UNICORE_MMU_H__
+
+typedef	unsigned long mm_context_t;
+
+#endif

arch/unicore32/include/asm/mmu_context.h

+/*
+ * linux/arch/unicore32/include/asm/mmu_context.h
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * 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.
+ */
+#ifndef __UNICORE_MMU_CONTEXT_H__
+#define __UNICORE_MMU_CONTEXT_H__
+
+#include <linux/compiler.h>
+#include <linux/sched.h>
+#include <linux/io.h>
+
+#include <asm/cacheflush.h>
+#include <asm/cpu-single.h>
+
+#define init_new_context(tsk, mm)	0
+
+#define destroy_context(mm)		do { } while (0)
+
+/*
+ * This is called when "tsk" is about to enter lazy TLB mode.
+ *
+ * mm:  describes the currently active mm context
+ * tsk: task which is entering lazy tlb
+ * cpu: cpu number which is entering lazy tlb
+ *
+ * tsk->mm will be NULL
+ */
+static inline void
+enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+}
+
+/*
+ * This is the actual mm switch as far as the scheduler
+ * is concerned.  No registers are touched.  We avoid
+ * calling the CPU specific function when the mm hasn't
+ * actually changed.
+ */
+static inline void
+switch_mm(struct mm_struct *prev, struct mm_struct *next,
+	  struct task_struct *tsk)
+{
+	unsigned int cpu = smp_processor_id();
+
+	if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next)
+		cpu_switch_mm(next->pgd, next);
+}
+
+#define deactivate_mm(tsk, mm)	do { } while (0)
+#define activate_mm(prev, next)	switch_mm(prev, next, NULL)
+
+/*
+ * We are inserting a "fake" vma for the user-accessible vector page so
+ * gdb and friends can get to it through ptrace and /proc/<pid>/mem.
+ * But we also want to remove it before the generic code gets to see it
+ * during process exit or the unmapping of it would  cause total havoc.
+ * (the macro is used as remove_vma() is static to mm/mmap.c)
+ */
+#define arch_exit_mmap(mm) \
+do { \
+	struct vm_area_struct *high_vma = find_vma(mm, 0xffff0000); \
+	if (high_vma) { \
+		BUG_ON(high_vma->vm_next);  /* it should be last */ \
+		if (high_vma->vm_prev) \
+			high_vma->vm_prev->vm_next = NULL; \
+		else \
+			mm->mmap = NULL; \
+		rb_erase(&high_vma->vm_rb, &mm->mm_rb); \
+		mm->mmap_cache = NULL; \
+		mm->map_count--; \
+		remove_vma(high_vma); \
+	} \
+} while (0)
+
+static inline void arch_dup_mmap(struct mm_struct *oldmm,
+				 struct mm_struct *mm)
+{
+}
+
+#endif

arch/unicore32/include/asm/pgalloc.h

+/*
+ * linux/arch/unicore32/include/asm/pgalloc.h
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * 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.
+ */
+#ifndef __UNICORE_PGALLOC_H__
+#define __UNICORE_PGALLOC_H__
+
+#include <asm/pgtable-hwdef.h>
+#include <asm/processor.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+#define check_pgt_cache()		do { } while (0)
+
+#define _PAGE_USER_TABLE	(PMD_TYPE_TABLE | PMD_PRESENT)
+#define _PAGE_KERNEL_TABLE	(PMD_TYPE_TABLE | PMD_PRESENT)
+
+extern pgd_t *get_pgd_slow(struct mm_struct *mm);
+extern void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd);
+
+#define pgd_alloc(mm)			get_pgd_slow(mm)
+#define pgd_free(mm, pgd)		free_pgd_slow(mm, pgd)
+
+#define PGALLOC_GFP	(GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO)
+
+/*
+ * Allocate one PTE table.
+ */
+static inline pte_t *
+pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
+{
+	pte_t *pte;
+
+	pte = (pte_t *)__get_free_page(PGALLOC_GFP);
+	if (pte)
+		clean_dcache_area(pte, PTRS_PER_PTE * sizeof(pte_t));
+
+	return pte;
+}
+
+static inline pgtable_t
+pte_alloc_one(struct mm_struct *mm, unsigned long addr)
+{
+	struct page *pte;
+
+	pte = alloc_pages(PGALLOC_GFP, 0);
+	if (pte) {
+		if (!PageHighMem(pte)) {
+			void *page = page_address(pte);
+			clean_dcache_area(page, PTRS_PER_PTE * sizeof(pte_t));
+		}
+		pgtable_page_ctor(pte);
+	}
+
+	return pte;
+}
+
+/*
+ * Free one PTE table.
+ */
+static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
+{
+	if (pte)
+		free_page((unsigned long)pte);
+}
+
+static inline void pte_free(struct mm_struct *mm, pgtable_t pte)
+{
+	pgtable_page_dtor(pte);
+	__free_page(pte);
+}
+
+static inline void __pmd_populate(pmd_t *pmdp, unsigned long pmdval)
+{
+	set_pmd(pmdp, __pmd(pmdval));
+	flush_pmd_entry(pmdp);
+}
+
+/*
+ * Populate the pmdp entry with a pointer to the pte.  This pmd is part
+ * of the mm address space.
+ */
+static inline void
+pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp, pte_t *ptep)
+{
+	unsigned long pte_ptr = (unsigned long)ptep;
+
+	/*
+	 * The pmd must be loaded with the physical
+	 * address of the PTE table
+	 */
+	__pmd_populate(pmdp, __pa(pte_ptr) | _PAGE_KERNEL_TABLE);
+}
+
+static inline void
+pmd_populate(struct mm_struct *mm, pmd_t *pmdp, pgtable_t ptep)
+{
+	__pmd_populate(pmdp,
+			page_to_pfn(ptep) << PAGE_SHIFT | _PAGE_USER_TABLE);
+}
+#define pmd_pgtable(pmd) pmd_page(pmd)
+
+#endif

arch/unicore32/include/asm/pgtable-hwdef.h

+/*
+ * linux/arch/unicore32/include/asm/pgtable-hwdef.h
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * 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.
+ */
+#ifndef __UNICORE_PGTABLE_HWDEF_H__
+#define __UNICORE_PGTABLE_HWDEF_H__
+
+/*
+ * Hardware page table definitions.
+ *
+ * + Level 1 descriptor (PMD)
+ *   - common
+ */
+#define PMD_TYPE_MASK		(3 << 0)
+#define PMD_TYPE_TABLE		(0 << 0)
+/*#define PMD_TYPE_LARGE	(1 << 0) */
+#define PMD_TYPE_INVALID	(2 << 0)
+#define PMD_TYPE_SECT		(3 << 0)
+
+#define PMD_PRESENT		(1 << 2)
+#define PMD_YOUNG		(1 << 3)
+
+/*#define PMD_SECT_DIRTY	(1 << 4) */
+#define PMD_SECT_CACHEABLE	(1 << 5)
+#define PMD_SECT_EXEC		(1 << 6)
+#define PMD_SECT_WRITE		(1 << 7)
+#define PMD_SECT_READ		(1 << 8)
+
+/*
+ * + Level 2 descriptor (PTE)
+ *   - common
+ */
+#define PTE_TYPE_MASK		(3 << 0)
+#define PTE_TYPE_SMALL		(0 << 0)
+#define PTE_TYPE_MIDDLE		(1 << 0)
+#define PTE_TYPE_LARGE		(2 << 0)
+#define PTE_TYPE_INVALID	(3 << 0)
+
+#define PTE_PRESENT		(1 << 2)
+#define PTE_FILE		(1 << 3)	/* only when !PRESENT */
+#define PTE_YOUNG		(1 << 3)
+#define PTE_DIRTY		(1 << 4)
+#define PTE_CACHEABLE		(1 << 5)
+#define PTE_EXEC		(1 << 6)
+#define PTE_WRITE		(1 << 7)
+#define PTE_READ		(1 << 8)
+
+#endif

arch/unicore32/mm/extable.c

+/*
+ * linux/arch/unicore32/mm/extable.c
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * 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.
+ */
+#include <linux/module.h>
+#include <linux/uaccess.h>
+
+int fixup_exception(struct pt_regs *regs)
+{
+	const struct exception_table_entry *fixup;
+
+	fixup = search_exception_tables(instruction_pointer(regs));
+	if (fixup)
+		regs->UCreg_pc = fixup->fixup;
+
+	return fixup != NULL;
+}

arch/unicore32/mm/pgd.c

+/*
+ * linux/arch/unicore32/mm/pgd.c
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * 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.
+ */
+#include <linux/mm.h>
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+
+#include <asm/pgalloc.h>
+#include <asm/page.h>
+#include <asm/tlbflush.h>
+
+#include "mm.h"
+
+#define FIRST_KERNEL_PGD_NR	(FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
+
+/*
+ * need to get a 4k page for level 1
+ */
+pgd_t *get_pgd_slow(struct mm_struct *mm)
+{
+	pgd_t *new_pgd, *init_pgd;
+	pmd_t *new_pmd, *init_pmd;
+	pte_t *new_pte, *init_pte;
+
+	new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 0);
+	if (!new_pgd)
+		goto no_pgd;
+
+	memset(new_pgd, 0, FIRST_KERNEL_PGD_NR * sizeof(pgd_t));
+
+	/*
+	 * Copy over the kernel and IO PGD entries
+	 */
+	init_pgd = pgd_offset_k(0);
+	memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
+		       (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
+
+	clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
+
+	if (!vectors_high()) {
+		/*
+		 * On UniCore, first page must always be allocated since it
+		 * contains the machine vectors.
+		 */
+		new_pmd = pmd_alloc(mm, (pud_t *)new_pgd, 0);
+		if (!new_pmd)
+			goto no_pmd;
+
+		new_pte = pte_alloc_map(mm, new_pmd, 0);
+		if (!new_pte)
+			goto no_pte;
+
+		init_pmd = pmd_offset((pud_t *)init_pgd, 0);
+		init_pte = pte_offset_map(init_pmd, 0);
+		set_pte(new_pte, *init_pte);
+		pte_unmap(init_pte);
+		pte_unmap(new_pte);
+	}
+
+	return new_pgd;
+
+no_pte:
+	pmd_free(mm, new_pmd);
+no_pmd:
+	free_pages((unsigned long)new_pgd, 0);
+no_pgd:
+	return NULL;
+}
+
+void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
+{
+	pmd_t *pmd;
+	pgtable_t pte;
+
+	if (!pgd)
+		return;
+
+	/* pgd is always present and good */
+	pmd = pmd_off(pgd, 0);
+	if (pmd_none(*pmd))
+		goto free;
+	if (pmd_bad(*pmd)) {
+		pmd_ERROR(*pmd);
+		pmd_clear(pmd);
+		goto free;
+	}
+
+	pte = pmd_pgtable(*pmd);
+	pmd_clear(pmd);
+	pte_free(mm, pte);
+	pmd_free(mm, pmd);
+free:
+	free_pages((unsigned long) pgd, 0);
+}