v4.19.13 snapshot.
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
new file mode 100644
index 0000000..3232afb
--- /dev/null
+++ b/arch/arm/mm/fault.c
@@ -0,0 +1,652 @@
+/*
+ * linux/arch/arm/mm/fault.c
+ *
+ * Copyright (C) 1995 Linus Torvalds
+ * Modifications for ARM processor (c) 1995-2004 Russell King
+ *
+ * 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/extable.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/signal.h>
+#include <linux/sched/debug.h>
+#include <linux/highmem.h>
+#include <linux/perf_event.h>
+
+#include <asm/pgtable.h>
+#include <asm/system_misc.h>
+#include <asm/system_info.h>
+#include <asm/tlbflush.h>
+
+#include "fault.h"
+
+#ifdef CONFIG_MMU
+
+#ifdef CONFIG_KPROBES
+static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
+{
+ int ret = 0;
+
+ if (!user_mode(regs)) {
+ /* kprobe_running() needs smp_processor_id() */
+ preempt_disable();
+ if (kprobe_running() && kprobe_fault_handler(regs, fsr))
+ ret = 1;
+ preempt_enable();
+ }
+
+ return ret;
+}
+#else
+static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
+{
+ return 0;
+}
+#endif
+
+/*
+ * This is useful to 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=%08llx",
+ addr, (long long)pgd_val(*pgd));
+
+ do {
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ if (pgd_none(*pgd))
+ break;
+
+ if (pgd_bad(*pgd)) {
+ pr_cont("(bad)");
+ break;
+ }
+
+ pud = pud_offset(pgd, addr);
+ if (PTRS_PER_PUD != 1)
+ pr_cont(", *pud=%08llx", (long long)pud_val(*pud));
+
+ if (pud_none(*pud))
+ break;
+
+ if (pud_bad(*pud)) {
+ pr_cont("(bad)");
+ break;
+ }
+
+ pmd = pmd_offset(pud, addr);
+ if (PTRS_PER_PMD != 1)
+ pr_cont(", *pmd=%08llx", (long long)pmd_val(*pmd));
+
+ if (pmd_none(*pmd))
+ break;
+
+ if (pmd_bad(*pmd)) {
+ pr_cont("(bad)");
+ break;
+ }
+
+ /* We must not map this if we have highmem enabled */
+ if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
+ break;
+
+ pte = pte_offset_map(pmd, addr);
+ pr_cont(", *pte=%08llx", (long long)pte_val(*pte));
+#ifndef CONFIG_ARM_LPAE
+ pr_cont(", *ppte=%08llx",
+ (long long)pte_val(pte[PTE_HWTABLE_PTRS]));
+#endif
+ pte_unmap(pte);
+ } while(0);
+
+ pr_cont("\n");
+}
+#else /* CONFIG_MMU */
+void show_pte(struct mm_struct *mm, unsigned long addr)
+{ }
+#endif /* CONFIG_MMU */
+
+/*
+ * Oops. 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 fsr,
+ 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, fsr);
+ 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 fsr, unsigned int sig, int code,
+ struct pt_regs *regs)
+{
+ struct siginfo si;
+
+ if (addr > TASK_SIZE)
+ harden_branch_predictor();
+
+ clear_siginfo(&si);
+
+#ifdef CONFIG_DEBUG_USER
+ if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||
+ ((user_debug & UDBG_BUS) && (sig == SIGBUS))) {
+ printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
+ tsk->comm, sig, addr, fsr);
+ show_pte(tsk->mm, addr);
+ show_regs(regs);
+ }
+#endif
+
+ tsk->thread.address = addr;
+ tsk->thread.error_code = fsr;
+ tsk->thread.trap_no = 14;
+ 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 fsr, 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, fsr, SIGSEGV, SEGV_MAPERR, regs);
+ else
+ __do_kernel_fault(mm, addr, fsr, regs);
+}
+
+#ifdef CONFIG_MMU
+#define VM_FAULT_BADMAP 0x010000
+#define VM_FAULT_BADACCESS 0x020000
+
+/*
+ * 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 fsr, struct vm_area_struct *vma)
+{
+ unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
+
+ if (fsr & FSR_WRITE)
+ mask = VM_WRITE;
+ if (fsr & FSR_LNX_PF)
+ mask = VM_EXEC;
+
+ return vma->vm_flags & mask ? false : true;
+}
+
+static vm_fault_t __kprobes
+__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
+ unsigned int flags, struct task_struct *tsk)
+{
+ struct vm_area_struct *vma;
+ vm_fault_t 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(fsr, vma)) {
+ fault = VM_FAULT_BADACCESS;
+ goto out;
+ }
+
+ return handle_mm_fault(vma, addr & PAGE_MASK, flags);
+
+check_stack:
+ /* Don't allow expansion below FIRST_USER_ADDRESS */
+ if (vma->vm_flags & VM_GROWSDOWN &&
+ addr >= FIRST_USER_ADDRESS && !expand_stack(vma, addr))
+ goto good_area;
+out:
+ return fault;
+}
+
+static int __kprobes
+do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ int sig, code;
+ vm_fault_t fault;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+
+ if (notify_page_fault(regs, fsr))
+ return 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 (faulthandler_disabled() || !mm)
+ goto no_context;
+
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if (fsr & FSR_WRITE)
+ flags |= FAULT_FLAG_WRITE;
+
+ /*
+ * 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->ARM_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->ARM_pc))
+ goto no_context;
+#endif
+ }
+
+ fault = __do_page_fault(mm, addr, fsr, 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)) {
+ if (!user_mode(regs))
+ goto no_context;
+ 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 (!(fault & VM_FAULT_ERROR) && 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;
+ flags |= FAULT_FLAG_TRIED;
+ goto retry;
+ }
+ }
+
+ up_read(&mm->mmap_sem);
+
+ /*
+ * Handle the "normal" case first - VM_FAULT_MAJOR
+ */
+ if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
+ 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_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 (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, fsr, sig, code, regs);
+ return 0;
+
+no_context:
+ __do_kernel_fault(mm, addr, fsr, regs);
+ return 0;
+}
+#else /* CONFIG_MMU */
+static int
+do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ return 0;
+}
+#endif /* CONFIG_MMU */
+
+/*
+ * 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.
+ */
+#ifdef CONFIG_MMU
+static int __kprobes
+do_translation_fault(unsigned long addr, unsigned int fsr,
+ struct pt_regs *regs)
+{
+ unsigned int index;
+ pgd_t *pgd, *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+
+ if (addr < TASK_SIZE)
+ return do_page_fault(addr, fsr, regs);
+
+ if (user_mode(regs))
+ goto bad_area;
+
+ index = pgd_index(addr);
+
+ pgd = cpu_get_pgd() + index;
+ pgd_k = init_mm.pgd + index;
+
+ if (pgd_none(*pgd_k))
+ goto bad_area;
+ if (!pgd_present(*pgd))
+ set_pgd(pgd, *pgd_k);
+
+ pud = pud_offset(pgd, addr);
+ pud_k = pud_offset(pgd_k, addr);
+
+ if (pud_none(*pud_k))
+ goto bad_area;
+ if (!pud_present(*pud))
+ set_pud(pud, *pud_k);
+
+ pmd = pmd_offset(pud, addr);
+ pmd_k = pmd_offset(pud_k, addr);
+
+#ifdef CONFIG_ARM_LPAE
+ /*
+ * Only one hardware entry per PMD with LPAE.
+ */
+ index = 0;
+#else
+ /*
+ * On ARM one Linux PGD entry contains two hardware entries (see page
+ * tables layout in pgtable.h). We normally guarantee that we always
+ * fill both L1 entries. But create_mapping() doesn't follow the rule.
+ * It can create inidividual L1 entries, so here we have to call
+ * pmd_none() check for the entry really corresponded to address, not
+ * for the first of pair.
+ */
+ index = (addr >> SECTION_SHIFT) & 1;
+#endif
+ if (pmd_none(pmd_k[index]))
+ goto bad_area;
+
+ copy_pmd(pmd, pmd_k);
+ return 0;
+
+bad_area:
+ do_bad_area(addr, fsr, regs);
+ return 0;
+}
+#else /* CONFIG_MMU */
+static int
+do_translation_fault(unsigned long addr, unsigned int fsr,
+ struct pt_regs *regs)
+{
+ return 0;
+}
+#endif /* CONFIG_MMU */
+
+/*
+ * Some section permission faults need to be handled gracefully.
+ * They can happen due to a __{get,put}_user during an oops.
+ */
+#ifndef CONFIG_ARM_LPAE
+static int
+do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ do_bad_area(addr, fsr, regs);
+ return 0;
+}
+#endif /* CONFIG_ARM_LPAE */
+
+/*
+ * This abort handler always returns "fault".
+ */
+static int
+do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ return 1;
+}
+
+struct fsr_info {
+ int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
+ int sig;
+ int code;
+ const char *name;
+};
+
+/* FSR definition */
+#ifdef CONFIG_ARM_LPAE
+#include "fsr-3level.c"
+#else
+#include "fsr-2level.c"
+#endif
+
+void __init
+hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
+ int sig, int code, const char *name)
+{
+ if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
+ BUG();
+
+ fsr_info[nr].fn = fn;
+ fsr_info[nr].sig = sig;
+ fsr_info[nr].code = code;
+ fsr_info[nr].name = name;
+}
+
+/*
+ * Dispatch a data abort to the relevant handler.
+ */
+asmlinkage void
+do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
+ struct siginfo info;
+
+ if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
+ return;
+
+ pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n",
+ inf->name, fsr, addr);
+ show_pte(current->mm, addr);
+
+ clear_siginfo(&info);
+ info.si_signo = inf->sig;
+ info.si_errno = 0;
+ info.si_code = inf->code;
+ info.si_addr = (void __user *)addr;
+ arm_notify_die("", regs, &info, fsr, 0);
+}
+
+void __init
+hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
+ int sig, int code, const char *name)
+{
+ if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info))
+ BUG();
+
+ ifsr_info[nr].fn = fn;
+ ifsr_info[nr].sig = sig;
+ ifsr_info[nr].code = code;
+ ifsr_info[nr].name = name;
+}
+
+asmlinkage void
+do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
+{
+ const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
+ struct siginfo info;
+
+ if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
+ return;
+
+ pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
+ inf->name, ifsr, addr);
+
+ clear_siginfo(&info);
+ info.si_signo = inf->sig;
+ info.si_errno = 0;
+ info.si_code = inf->code;
+ info.si_addr = (void __user *)addr;
+ arm_notify_die("", regs, &info, ifsr, 0);
+}
+
+/*
+ * Abort handler to be used only during first unmasking of asynchronous aborts
+ * on the boot CPU. This makes sure that the machine will not die if the
+ * firmware/bootloader left an imprecise abort pending for us to trip over.
+ */
+static int __init early_abort_handler(unsigned long addr, unsigned int fsr,
+ struct pt_regs *regs)
+{
+ pr_warn("Hit pending asynchronous external abort (FSR=0x%08x) during "
+ "first unmask, this is most likely caused by a "
+ "firmware/bootloader bug.\n", fsr);
+
+ return 0;
+}
+
+void __init early_abt_enable(void)
+{
+ fsr_info[FSR_FS_AEA].fn = early_abort_handler;
+ local_abt_enable();
+ fsr_info[FSR_FS_AEA].fn = do_bad;
+}
+
+#ifndef CONFIG_ARM_LPAE
+static int __init exceptions_init(void)
+{
+ if (cpu_architecture() >= CPU_ARCH_ARMv6) {
+ hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR,
+ "I-cache maintenance fault");
+ }
+
+ if (cpu_architecture() >= CPU_ARCH_ARMv7) {
+ /*
+ * TODO: Access flag faults introduced in ARMv6K.
+ * Runtime check for 'K' extension is needed
+ */
+ hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR,
+ "section access flag fault");
+ hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR,
+ "section access flag fault");
+ }
+
+ return 0;
+}
+
+arch_initcall(exceptions_init);
+#endif