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    Subject[PATCH v3 06/31] arm64: MMU fault handling and page table management
    Date
    This patch adds support for the handling of the MMU faults (exception
    entry code introduced by a previous patch) and page table management.

    The user translation table is pointed to by TTBR0 and the kernel one
    (swapper_pg_dir) by TTBR1. There is no translation information shared or
    address space overlapping between user and kernel page tables.

    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/page.h | 67 +++++
    arch/arm64/include/asm/pgalloc.h | 113 ++++++++
    arch/arm64/mm/copypage.c | 34 +++
    arch/arm64/mm/extable.c | 17 ++
    arch/arm64/mm/fault.c | 534 ++++++++++++++++++++++++++++++++++++++
    arch/arm64/mm/mm.h | 2 +
    arch/arm64/mm/mmap.c | 144 ++++++++++
    arch/arm64/mm/pgd.c | 54 ++++
    8 files changed, 965 insertions(+), 0 deletions(-)
    create mode 100644 arch/arm64/include/asm/page.h
    create mode 100644 arch/arm64/include/asm/pgalloc.h
    create mode 100644 arch/arm64/mm/copypage.c
    create mode 100644 arch/arm64/mm/extable.c
    create mode 100644 arch/arm64/mm/fault.c
    create mode 100644 arch/arm64/mm/mm.h
    create mode 100644 arch/arm64/mm/mmap.c
    create mode 100644 arch/arm64/mm/pgd.c

    diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
    new file mode 100644
    index 0000000..46bf666
    --- /dev/null
    +++ b/arch/arm64/include/asm/page.h
    @@ -0,0 +1,67 @@
    +/*
    + * Based on arch/arm/include/asm/page.h
    + *
    + * Copyright (C) 1995-2003 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_PAGE_H
    +#define __ASM_PAGE_H
    +
    +/* PAGE_SHIFT determines the page size */
    +#ifdef CONFIG_ARM64_64K_PAGES
    +#define PAGE_SHIFT 16
    +#else
    +#define PAGE_SHIFT 12
    +#endif
    +#define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
    +#define PAGE_MASK (~(PAGE_SIZE-1))
    +
    +/* We do define AT_SYSINFO_EHDR but don't use the gate mechanism */
    +#define __HAVE_ARCH_GATE_AREA 1
    +
    +#ifndef __ASSEMBLY__
    +
    +#ifdef CONFIG_ARM64_64K_PAGES
    +#include <asm/pgtable-2level-types.h>
    +#else
    +#include <asm/pgtable-3level-types.h>
    +#endif
    +
    +extern void __cpu_clear_user_page(void *p, unsigned long user);
    +extern void __cpu_copy_user_page(void *to, const void *from,
    + unsigned long user);
    +extern void copy_page(void *to, const void *from);
    +extern void clear_page(void *to);
    +
    +#define clear_user_page(addr,vaddr,pg) __cpu_clear_user_page(addr, vaddr)
    +#define copy_user_page(to,from,vaddr,pg) __cpu_copy_user_page(to, from, vaddr)
    +
    +typedef struct page *pgtable_t;
    +
    +#ifdef CONFIG_HAVE_ARCH_PFN_VALID
    +extern int pfn_valid(unsigned long);
    +#endif
    +
    +#include <asm/memory.h>
    +
    +#endif /* !__ASSEMBLY__ */
    +
    +#define VM_DATA_DEFAULT_FLAGS \
    + (((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0) | \
    + VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
    +
    +#include <asm-generic/getorder.h>
    +
    +#endif
    diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
    new file mode 100644
    index 0000000..f214069
    --- /dev/null
    +++ b/arch/arm64/include/asm/pgalloc.h
    @@ -0,0 +1,113 @@
    +/*
    + * Based on arch/arm/include/asm/pgalloc.h
    + *
    + * Copyright (C) 2000-2001 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_PGALLOC_H
    +#define __ASM_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)
    +
    +#ifndef CONFIG_ARM64_64K_PAGES
    +
    +static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
    +{
    + return (pmd_t *)get_zeroed_page(GFP_KERNEL | __GFP_REPEAT);
    +}
    +
    +static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
    +{
    + BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
    + free_page((unsigned long)pmd);
    +}
    +
    +static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
    +{
    + set_pud(pud, __pud(__pa(pmd) | PMD_TYPE_TABLE));
    +}
    +
    +#endif /* CONFIG_ARM64_64K_PAGES */
    +
    +extern pgd_t *pgd_alloc(struct mm_struct *mm);
    +extern void pgd_free(struct mm_struct *mm, pgd_t *pgd);
    +
    +#define PGALLOC_GFP (GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO)
    +
    +static inline pte_t *
    +pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
    +{
    + return (pte_t *)__get_free_page(PGALLOC_GFP);
    +}
    +
    +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)
    + pgtable_page_ctor(pte);
    +
    + return pte;
    +}
    +
    +/*
    + * Free a 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, phys_addr_t pte,
    + pmdval_t prot)
    +{
    + set_pmd(pmdp, __pmd(pte | prot));
    +}
    +
    +/*
    + * 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)
    +{
    + /*
    + * The pmd must be loaded with the physical address of the PTE table
    + */
    + __pmd_populate(pmdp, __pa(ptep), PMD_TYPE_TABLE);
    +}
    +
    +static inline void
    +pmd_populate(struct mm_struct *mm, pmd_t *pmdp, pgtable_t ptep)
    +{
    + __pmd_populate(pmdp, page_to_phys(ptep), PMD_TYPE_TABLE);
    +}
    +#define pmd_pgtable(pmd) pmd_page(pmd)
    +
    +#endif
    diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c
    new file mode 100644
    index 0000000..9aecbac
    --- /dev/null
    +++ b/arch/arm64/mm/copypage.c
    @@ -0,0 +1,34 @@
    +/*
    + * Based on arch/arm/mm/copypage.c
    + *
    + * Copyright (C) 2002 Deep Blue Solutions Ltd, All Rights Reserved.
    + * 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/>.
    + */
    +
    +#include <linux/mm.h>
    +
    +#include <asm/page.h>
    +#include <asm/cacheflush.h>
    +
    +void __cpu_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr)
    +{
    + copy_page(kto, kfrom);
    + __flush_dcache_area(kto, PAGE_SIZE);
    +}
    +
    +void __cpu_clear_user_page(void *kaddr, unsigned long vaddr)
    +{
    + clear_page(kaddr);
    +}
    diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c
    new file mode 100644
    index 0000000..7944427
    --- /dev/null
    +++ b/arch/arm64/mm/extable.c
    @@ -0,0 +1,17 @@
    +/*
    + * Based on arch/arm/mm/extable.c
    + */
    +
    +#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->pc = fixup->fixup;
    +
    + return fixup != NULL;
    +}
    diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
    new file mode 100644
    index 0000000..1909a69
    --- /dev/null
    +++ b/arch/arm64/mm/fault.c
    @@ -0,0 +1,534 @@
    +/*
    + * Based on arch/arm/mm/fault.c
    + *
    + * Copyright (C) 1995 Linus Torvalds
    + * Copyright (C) 1995-2004 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/>.
    + */
    +
    +#include <linux/module.h>
    +#include <linux/signal.h>
    +#include <linux/mm.h>
    +#include <linux/hardirq.h>
    +#include <linux/init.h>
    +#include <linux/kprobes.h>
    +#include <linux/uaccess.h>
    +#include <linux/page-flags.h>
    +#include <linux/sched.h>
    +#include <linux/highmem.h>
    +#include <linux/perf_event.h>
    +
    +#include <asm/exception.h>
    +#include <asm/debug-monitors.h>
    +#include <asm/system_misc.h>
    +#include <asm/pgtable.h>
    +#include <asm/tlbflush.h>
    +
    +/*
    + * Dump out the page tables associated with 'addr' in mm 'mm'.
    + */
    +void show_pte(struct mm_struct *mm, unsigned long addr)
    +{
    + pgd_t *pgd;
    +
    + if (!mm)
    + mm = &init_mm;
    +
    + pr_alert("pgd = %p\n", mm->pgd);
    + pgd = pgd_offset(mm, addr);
    + pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd));
    +
    + do {
    + pud_t *pud;
    + pmd_t *pmd;
    + pte_t *pte;
    +
    + if (pgd_none_or_clear_bad(pgd))
    + break;
    +
    + pud = pud_offset(pgd, addr);
    + if (pud_none_or_clear_bad(pud))
    + break;
    +
    + pmd = pmd_offset(pud, addr);
    + printk(", *pmd=%016llx", pmd_val(*pmd));
    + if (pmd_none_or_clear_bad(pmd))
    + break;
    +
    + pte = pte_offset_map(pmd, addr);
    + printk(", *pte=%016llx", pte_val(*pte));
    + pte_unmap(pte);
    + } while(0);
    +
    + printk("\n");
    +}
    +
    +/*
    + * The kernel tried to access some page that wasn't present.
    + */
    +static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
    + unsigned int esr, struct pt_regs *regs)
    +{
    + /*
    + * Are we prepared to handle this kernel fault?
    + */
    + if (fixup_exception(regs))
    + return;
    +
    + /*
    + * No handler, we'll have to terminate things with extreme prejudice.
    + */
    + bust_spinlocks(1);
    + pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
    + (addr < PAGE_SIZE) ? "NULL pointer dereference" :
    + "paging request", addr);
    +
    + show_pte(mm, addr);
    + die("Oops", regs, esr);
    + bust_spinlocks(0);
    + do_exit(SIGKILL);
    +}
    +
    +/*
    + * Something tried to access memory that isn't in our memory map. User mode
    + * accesses just cause a SIGSEGV
    + */
    +static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
    + unsigned int esr, unsigned int sig, int code,
    + struct pt_regs *regs)
    +{
    + struct siginfo si;
    +
    + if (show_unhandled_signals) {
    + pr_info("%s[%d]: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
    + tsk->comm, task_pid_nr(tsk), sig, addr, esr);
    + show_pte(tsk->mm, addr);
    + show_regs(regs);
    + }
    +
    + tsk->thread.fault_address = addr;
    + si.si_signo = sig;
    + si.si_errno = 0;
    + si.si_code = code;
    + si.si_addr = (void __user *)addr;
    + force_sig_info(sig, &si, tsk);
    +}
    +
    +void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
    +{
    + struct task_struct *tsk = current;
    + struct mm_struct *mm = tsk->active_mm;
    +
    + /*
    + * If we are in kernel mode at this point, we have no context to
    + * handle this fault with.
    + */
    + if (user_mode(regs))
    + __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
    + else
    + __do_kernel_fault(mm, addr, esr, regs);
    +}
    +
    +#define VM_FAULT_BADMAP 0x010000
    +#define VM_FAULT_BADACCESS 0x020000
    +
    +#define ESR_WRITE (1 << 6)
    +#define ESR_LNX_EXEC (1 << 24)
    +
    +/*
    + * Check that the permissions on the VMA allow for the fault which occurred.
    + * If we encountered a write fault, we must have write permission, otherwise
    + * we allow any permission.
    + */
    +static inline bool access_error(unsigned int esr, struct vm_area_struct *vma)
    +{
    + unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
    +
    + if (esr & ESR_WRITE)
    + mask = VM_WRITE;
    + if (esr & ESR_LNX_EXEC)
    + mask = VM_EXEC;
    +
    + return vma->vm_flags & mask ? false : true;
    +}
    +
    +static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
    + unsigned int esr, unsigned int flags,
    + struct task_struct *tsk)
    +{
    + struct vm_area_struct *vma;
    + int fault;
    +
    + vma = find_vma(mm, addr);
    + fault = VM_FAULT_BADMAP;
    + if (unlikely(!vma))
    + goto out;
    + if (unlikely(vma->vm_start > addr))
    + goto check_stack;
    +
    + /*
    + * Ok, we have a good vm_area for this memory access, so we can handle
    + * it.
    + */
    +good_area:
    + if (access_error(esr, vma)) {
    + fault = VM_FAULT_BADACCESS;
    + goto out;
    + }
    +
    + return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
    +
    +check_stack:
    + if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
    + goto good_area;
    +out:
    + return fault;
    +}
    +
    +static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
    + struct pt_regs *regs)
    +{
    + struct task_struct *tsk;
    + struct mm_struct *mm;
    + int fault, sig, code;
    + int write = esr & ESR_WRITE;
    + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
    + (write ? FAULT_FLAG_WRITE : 0);
    +
    + tsk = current;
    + mm = tsk->mm;
    +
    + /* Enable interrupts if they were enabled in the parent context. */
    + if (interrupts_enabled(regs))
    + local_irq_enable();
    +
    + /*
    + * If we're in an interrupt or have no user context, we must not take
    + * the fault.
    + */
    + if (in_atomic() || !mm)
    + goto no_context;
    +
    + /*
    + * As per x86, we may deadlock here. However, since the kernel only
    + * validly references user space from well defined areas of the code,
    + * we can bug out early if this is from code which shouldn't.
    + */
    + if (!down_read_trylock(&mm->mmap_sem)) {
    + if (!user_mode(regs) && !search_exception_tables(regs->pc))
    + goto no_context;
    +retry:
    + down_read(&mm->mmap_sem);
    + } else {
    + /*
    + * The above down_read_trylock() might have succeeded in which
    + * case, we'll have missed the might_sleep() from down_read().
    + */
    + might_sleep();
    +#ifdef CONFIG_DEBUG_VM
    + if (!user_mode(regs) && !search_exception_tables(regs->pc))
    + goto no_context;
    +#endif
    + }
    +
    + fault = __do_page_fault(mm, addr, esr, flags, tsk);
    +
    + /*
    + * If we need to retry but a fatal signal is pending, handle the
    + * signal first. We do not need to release the mmap_sem because it
    + * would already be released in __lock_page_or_retry in mm/filemap.c.
    + */
    + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
    + return 0;
    +
    + /*
    + * Major/minor page fault accounting is only done on the initial
    + * attempt. If we go through a retry, it is extremely likely that the
    + * page will be found in page cache at that point.
    + */
    +
    + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
    + if (flags & FAULT_FLAG_ALLOW_RETRY) {
    + if (fault & VM_FAULT_MAJOR) {
    + tsk->maj_flt++;
    + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
    + addr);
    + } else {
    + tsk->min_flt++;
    + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
    + addr);
    + }
    + if (fault & VM_FAULT_RETRY) {
    + /*
    + * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
    + * starvation.
    + */
    + flags &= ~FAULT_FLAG_ALLOW_RETRY;
    + goto retry;
    + }
    + }
    +
    + up_read(&mm->mmap_sem);
    +
    + /*
    + * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
    + */
    + if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
    + VM_FAULT_BADACCESS))))
    + return 0;
    +
    + if (fault & VM_FAULT_OOM) {
    + /*
    + * We ran out of memory, call the OOM killer, and return to
    + * userspace (which will retry the fault, or kill us if we got
    + * oom-killed).
    + */
    + pagefault_out_of_memory();
    + return 0;
    + }
    +
    + /*
    + * If we are in kernel mode at this point, we have no context to
    + * handle this fault with.
    + */
    + if (!user_mode(regs))
    + goto no_context;
    +
    + if (fault & VM_FAULT_SIGBUS) {
    + /*
    + * We had some memory, but were unable to successfully fix up
    + * this page fault.
    + */
    + sig = SIGBUS;
    + code = BUS_ADRERR;
    + } else {
    + /*
    + * Something tried to access memory that isn't in our memory
    + * map.
    + */
    + sig = SIGSEGV;
    + code = fault == VM_FAULT_BADACCESS ?
    + SEGV_ACCERR : SEGV_MAPERR;
    + }
    +
    + __do_user_fault(tsk, addr, esr, sig, code, regs);
    + return 0;
    +
    +no_context:
    + __do_kernel_fault(mm, addr, esr, regs);
    + return 0;
    +}
    +
    +/*
    + * First Level Translation Fault Handler
    + *
    + * We enter here because the first level page table doesn't contain a valid
    + * entry for the address.
    + *
    + * If the address is in kernel space (>= TASK_SIZE), then we are probably
    + * faulting in the vmalloc() area.
    + *
    + * If the init_task's first level page tables contains the relevant entry, we
    + * copy the it to this task. If not, we send the process a signal, fixup the
    + * exception, or oops the kernel.
    + *
    + * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
    + * or a critical region, and should only copy the information from the master
    + * page table, nothing more.
    + */
    +static int __kprobes do_translation_fault(unsigned long addr,
    + unsigned int esr,
    + struct pt_regs *regs)
    +{
    + if (addr < TASK_SIZE)
    + return do_page_fault(addr, esr, regs);
    +
    + do_bad_area(addr, esr, regs);
    + return 0;
    +}
    +
    +/*
    + * Some section permission faults need to be handled gracefully. They can
    + * happen due to a __{get,put}_user during an oops.
    + */
    +static int do_sect_fault(unsigned long addr, unsigned int esr,
    + struct pt_regs *regs)
    +{
    + do_bad_area(addr, esr, regs);
    + return 0;
    +}
    +
    +/*
    + * This abort handler always returns "fault".
    + */
    +static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
    +{
    + return 1;
    +}
    +
    +static struct fault_info {
    + int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
    + int sig;
    + int code;
    + const char *name;
    +} fault_info[] = {
    + { do_bad, SIGBUS, 0, "ttbr address size fault" },
    + { do_bad, SIGBUS, 0, "level 1 address size fault" },
    + { do_bad, SIGBUS, 0, "level 2 address size fault" },
    + { do_bad, SIGBUS, 0, "level 3 address size fault" },
    + { do_translation_fault, SIGSEGV, SEGV_MAPERR, "input address range fault" },
    + { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" },
    + { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" },
    + { do_page_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" },
    + { do_bad, SIGBUS, 0, "reserved access flag fault" },
    + { do_bad, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" },
    + { do_bad, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" },
    + { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" },
    + { do_bad, SIGBUS, 0, "reserved permission fault" },
    + { do_bad, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" },
    + { do_sect_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" },
    + { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" },
    + { do_bad, SIGBUS, 0, "synchronous external abort" },
    + { do_bad, SIGBUS, 0, "asynchronous external abort" },
    + { do_bad, SIGBUS, 0, "unknown 18" },
    + { do_bad, SIGBUS, 0, "unknown 19" },
    + { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
    + { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
    + { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
    + { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
    + { do_bad, SIGBUS, 0, "synchronous parity error" },
    + { do_bad, SIGBUS, 0, "asynchronous parity error" },
    + { do_bad, SIGBUS, 0, "unknown 26" },
    + { do_bad, SIGBUS, 0, "unknown 27" },
    + { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
    + { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
    + { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
    + { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
    + { do_bad, SIGBUS, 0, "unknown 32" },
    + { do_bad, SIGBUS, BUS_ADRALN, "alignment fault" },
    + { do_bad, SIGBUS, 0, "debug event" },
    + { do_bad, SIGBUS, 0, "unknown 35" },
    + { do_bad, SIGBUS, 0, "unknown 36" },
    + { do_bad, SIGBUS, 0, "unknown 37" },
    + { do_bad, SIGBUS, 0, "unknown 38" },
    + { do_bad, SIGBUS, 0, "unknown 39" },
    + { do_bad, SIGBUS, 0, "unknown 40" },
    + { do_bad, SIGBUS, 0, "unknown 41" },
    + { do_bad, SIGBUS, 0, "unknown 42" },
    + { do_bad, SIGBUS, 0, "unknown 43" },
    + { do_bad, SIGBUS, 0, "unknown 44" },
    + { do_bad, SIGBUS, 0, "unknown 45" },
    + { do_bad, SIGBUS, 0, "unknown 46" },
    + { do_bad, SIGBUS, 0, "unknown 47" },
    + { do_bad, SIGBUS, 0, "unknown 48" },
    + { do_bad, SIGBUS, 0, "unknown 49" },
    + { do_bad, SIGBUS, 0, "unknown 50" },
    + { do_bad, SIGBUS, 0, "unknown 51" },
    + { do_bad, SIGBUS, 0, "implementation fault (lockdown abort)" },
    + { do_bad, SIGBUS, 0, "unknown 53" },
    + { do_bad, SIGBUS, 0, "unknown 54" },
    + { do_bad, SIGBUS, 0, "unknown 55" },
    + { do_bad, SIGBUS, 0, "unknown 56" },
    + { do_bad, SIGBUS, 0, "unknown 57" },
    + { do_bad, SIGBUS, 0, "implementation fault (coprocessor abort)" },
    + { do_bad, SIGBUS, 0, "unknown 59" },
    + { do_bad, SIGBUS, 0, "unknown 60" },
    + { do_bad, SIGBUS, 0, "unknown 61" },
    + { do_bad, SIGBUS, 0, "unknown 62" },
    + { do_bad, SIGBUS, 0, "unknown 63" },
    +};
    +
    +/*
    + * Dispatch a data abort to the relevant handler.
    + */
    +asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
    + struct pt_regs *regs)
    +{
    + const struct fault_info *inf = fault_info + (esr & 63);
    + struct siginfo info;
    +
    + if (!inf->fn(addr, esr, regs))
    + return;
    +
    + pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
    + inf->name, esr, addr);
    +
    + info.si_signo = inf->sig;
    + info.si_errno = 0;
    + info.si_code = inf->code;
    + info.si_addr = (void __user *)addr;
    + arm64_notify_die("", regs, &info, esr);
    +}
    +
    +/*
    + * Handle stack alignment exceptions.
    + */
    +asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
    + unsigned int esr,
    + struct pt_regs *regs)
    +{
    + struct siginfo info;
    +
    + info.si_signo = SIGBUS;
    + info.si_errno = 0;
    + info.si_code = BUS_ADRALN;
    + info.si_addr = (void __user *)addr;
    + arm64_notify_die("", regs, &info, esr);
    +}
    +
    +static struct fault_info debug_fault_info[] = {
    + { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" },
    + { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" },
    + { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" },
    + { do_bad, SIGBUS, 0, "unknown 3" },
    + { do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" },
    + { do_bad, SIGTRAP, 0, "aarch32 vector catch" },
    + { do_bad, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" },
    + { do_bad, SIGBUS, 0, "unknown 7" },
    +};
    +
    +void __init hook_debug_fault_code(int nr,
    + int (*fn)(unsigned long, unsigned int, struct pt_regs *),
    + int sig, int code, const char *name)
    +{
    + BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
    +
    + debug_fault_info[nr].fn = fn;
    + debug_fault_info[nr].sig = sig;
    + debug_fault_info[nr].code = code;
    + debug_fault_info[nr].name = name;
    +}
    +
    +asmlinkage int __exception do_debug_exception(unsigned long addr,
    + unsigned int esr,
    + struct pt_regs *regs)
    +{
    + const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
    + struct siginfo info;
    +
    + if (!inf->fn(addr, esr, regs))
    + return 1;
    +
    + pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
    + inf->name, esr, addr);
    +
    + info.si_signo = inf->sig;
    + info.si_errno = 0;
    + info.si_code = inf->code;
    + info.si_addr = (void __user *)addr;
    + arm64_notify_die("", regs, &info, esr);
    +
    + return 0;
    +}
    diff --git a/arch/arm64/mm/mm.h b/arch/arm64/mm/mm.h
    new file mode 100644
    index 0000000..c84f68b
    --- /dev/null
    +++ b/arch/arm64/mm/mm.h
    @@ -0,0 +1,2 @@
    +extern void __flush_dcache_page(struct address_space *mapping, struct page *page);
    +extern void __init bootmem_init(void);
    diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
    new file mode 100644
    index 0000000..7c7be78
    --- /dev/null
    +++ b/arch/arm64/mm/mmap.c
    @@ -0,0 +1,144 @@
    +/*
    + * Based on arch/arm/mm/mmap.c
    + *
    + * 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/>.
    + */
    +
    +#include <linux/elf.h>
    +#include <linux/fs.h>
    +#include <linux/mm.h>
    +#include <linux/mman.h>
    +#include <linux/export.h>
    +#include <linux/shm.h>
    +#include <linux/sched.h>
    +#include <linux/io.h>
    +#include <linux/personality.h>
    +#include <linux/random.h>
    +
    +#include <asm/cputype.h>
    +
    +/*
    + * Leave enough space between the mmap area and the stack to honour ulimit in
    + * the face of randomisation.
    + */
    +#define MIN_GAP (SZ_128M + ((STACK_RND_MASK << PAGE_SHIFT) + 1))
    +#define MAX_GAP (STACK_TOP/6*5)
    +
    +static int mmap_is_legacy(void)
    +{
    + if (current->personality & ADDR_COMPAT_LAYOUT)
    + return 1;
    +
    + if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
    + return 1;
    +
    + return sysctl_legacy_va_layout;
    +}
    +
    +/*
    + * Since get_random_int() returns the same value within a 1 jiffy window, we
    + * will almost always get the same randomisation for the stack and mmap
    + * region. This will mean the relative distance between stack and mmap will be
    + * the same.
    + *
    + * To avoid this we can shift the randomness by 1 bit.
    + */
    +static unsigned long mmap_rnd(void)
    +{
    + unsigned long rnd = 0;
    +
    + if (current->flags & PF_RANDOMIZE)
    + rnd = (long)get_random_int() & (STACK_RND_MASK >> 1);
    +
    + return rnd << (PAGE_SHIFT + 1);
    +}
    +
    +static unsigned long mmap_base(void)
    +{
    + unsigned long gap = rlimit(RLIMIT_STACK);
    +
    + if (gap < MIN_GAP)
    + gap = MIN_GAP;
    + else if (gap > MAX_GAP)
    + gap = MAX_GAP;
    +
    + return PAGE_ALIGN(STACK_TOP - gap - mmap_rnd());
    +}
    +
    +/*
    + * This function, called very early during the creation of a new process VM
    + * image, sets up which VM layout function to use:
    + */
    +void arch_pick_mmap_layout(struct mm_struct *mm)
    +{
    + /*
    + * Fall back to the standard layout if the personality bit is set, or
    + * if the expected stack growth is unlimited:
    + */
    + if (mmap_is_legacy()) {
    + mm->mmap_base = TASK_UNMAPPED_BASE;
    + mm->get_unmapped_area = arch_get_unmapped_area;
    + mm->unmap_area = arch_unmap_area;
    + } else {
    + mm->mmap_base = mmap_base();
    + mm->get_unmapped_area = arch_get_unmapped_area_topdown;
    + mm->unmap_area = arch_unmap_area_topdown;
    + }
    +}
    +EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
    +
    +
    +/*
    + * You really shouldn't be using read() or write() on /dev/mem. This might go
    + * away in the future.
    + */
    +int valid_phys_addr_range(unsigned long addr, size_t size)
    +{
    + if (addr < PHYS_OFFSET)
    + return 0;
    + if (addr + size > __pa(high_memory - 1) + 1)
    + return 0;
    +
    + return 1;
    +}
    +
    +/*
    + * Do not allow /dev/mem mappings beyond the supported physical range.
    + */
    +int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
    +{
    + return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
    +}
    +
    +#ifdef CONFIG_STRICT_DEVMEM
    +
    +#include <linux/ioport.h>
    +
    +/*
    + * devmem_is_allowed() checks to see if /dev/mem access to a certain address
    + * is valid. The argument is a physical page number. We mimic x86 here by
    + * disallowing access to system RAM as well as device-exclusive MMIO regions.
    + * This effectively disable read()/write() on /dev/mem.
    + */
    +int devmem_is_allowed(unsigned long pfn)
    +{
    + if (iomem_is_exclusive(pfn << PAGE_SHIFT))
    + return 0;
    + if (!page_is_ram(pfn))
    + return 1;
    + return 0;
    +}
    +
    +#endif
    diff --git a/arch/arm64/mm/pgd.c b/arch/arm64/mm/pgd.c
    new file mode 100644
    index 0000000..7083cda
    --- /dev/null
    +++ b/arch/arm64/mm/pgd.c
    @@ -0,0 +1,54 @@
    +/*
    + * PGD allocation/freeing
    + *
    + * Copyright (C) 2012 ARM Ltd.
    + * Author: 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/mm.h>
    +#include <linux/gfp.h>
    +#include <linux/highmem.h>
    +#include <linux/slab.h>
    +
    +#include <asm/pgalloc.h>
    +#include <asm/page.h>
    +#include <asm/tlbflush.h>
    +
    +#include "mm.h"
    +
    +#define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t))
    +
    +pgd_t *pgd_alloc(struct mm_struct *mm)
    +{
    + pgd_t *new_pgd;
    +
    + if (PGD_SIZE == PAGE_SIZE)
    + new_pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
    + else
    + new_pgd = kzalloc(PGD_SIZE, GFP_KERNEL);
    +
    + if (!new_pgd)
    + return NULL;
    +
    + return new_pgd;
    +}
    +
    +void pgd_free(struct mm_struct *mm, pgd_t *pgd)
    +{
    + if (PGD_SIZE == PAGE_SIZE)
    + free_page((unsigned long)pgd);
    + else
    + kfree(pgd);
    +}


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