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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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