Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 719 insertions, 0 deletions

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
new file mode 100644
index 000000000..e62cc4be5
--- /dev/null
+++ b/arch/arm/mm/fault.c
@@ -0,0 +1,719 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/mm/fault.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *  Modifications for ARM processor (c) 1995-2004 Russell King
+ */
+#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 <linux/kfence.h>
+
+#include <asm/system_misc.h>
+#include <asm/system_info.h>
+#include <asm/tlbflush.h>
+
+#include "fault.h"
+
+#ifdef CONFIG_MMU
+
+bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
+{
+	unsigned long addr = (unsigned long)unsafe_src;
+
+	return addr >= TASK_SIZE && ULONG_MAX - addr >= size;
+}
+
+/*
+ * This is useful to dump out the page tables associated with
+ * 'addr' in mm 'mm'.
+ */
+void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
+{
+	pgd_t *pgd;
+
+	if (!mm)
+		mm = &init_mm;
+
+	pgd = pgd_offset(mm, addr);
+	printk("%s[%08lx] *pgd=%08llx", lvl, addr, (long long)pgd_val(*pgd));
+
+	do {
+		p4d_t *p4d;
+		pud_t *pud;
+		pmd_t *pmd;
+		pte_t *pte;
+
+		p4d = p4d_offset(pgd, addr);
+		if (p4d_none(*p4d))
+			break;
+
+		if (p4d_bad(*p4d)) {
+			pr_cont("(bad)");
+			break;
+		}
+
+		pud = pud_offset(p4d, 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);
+		if (!pte)
+			break;
+
+		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(const char *lvl, struct mm_struct *mm, unsigned long addr)
+{ }
+#endif					/* CONFIG_MMU */
+
+static inline bool is_write_fault(unsigned int fsr)
+{
+	return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
+}
+
+static void die_kernel_fault(const char *msg, struct mm_struct *mm,
+			     unsigned long addr, unsigned int fsr,
+			     struct pt_regs *regs)
+{
+	bust_spinlocks(1);
+	pr_alert("8<--- cut here ---\n");
+	pr_alert("Unable to handle kernel %s at virtual address %08lx when %s\n",
+		 msg, addr, fsr & FSR_LNX_PF ? "execute" : str_write_read(fsr & FSR_WRITE));
+
+	show_pte(KERN_ALERT, mm, addr);
+	die("Oops", regs, fsr);
+	bust_spinlocks(0);
+	make_task_dead(SIGKILL);
+}
+
+/*
+ * 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)
+{
+	const char *msg;
+	/*
+	 * Are we prepared to handle this kernel fault?
+	 */
+	if (fixup_exception(regs))
+		return;
+
+	/*
+	 * No handler, we'll have to terminate things with extreme prejudice.
+	 */
+	if (addr < PAGE_SIZE) {
+		msg = "NULL pointer dereference";
+	} else if (is_permission_fault(fsr) && fsr & FSR_LNX_PF) {
+		msg = "execution of memory";
+	} else {
+		if (is_translation_fault(fsr) &&
+		    kfence_handle_page_fault(addr, is_write_fault(fsr), regs))
+			return;
+
+		msg = "paging request";
+	}
+
+	die_kernel_fault(msg, mm, addr, fsr, regs);
+}
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * User mode accesses just cause a SIGSEGV. Ensure interrupts are enabled
+ * for preempt RT.
+ */
+static void
+__do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
+		int code, struct pt_regs *regs)
+{
+	struct task_struct *tsk = current;
+
+	local_irq_enable();
+
+#ifdef CONFIG_DEBUG_USER
+	if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||
+	    ((user_debug & UDBG_BUS)  && (sig == SIGBUS))) {
+		pr_err("8<--- cut here ---\n");
+		pr_err("%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
+		       tsk->comm, sig, addr, fsr);
+		show_pte(KERN_ERR, tsk->mm, addr);
+		show_regs(regs);
+	}
+#endif
+#ifndef CONFIG_KUSER_HELPERS
+	if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000))
+		printk_ratelimited(KERN_DEBUG
+				   "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n",
+				   tsk->comm, addr);
+#endif
+
+	tsk->thread.address = addr;
+	tsk->thread.error_code = fsr;
+	tsk->thread.trap_no = 14;
+	force_sig_fault(sig, code, (void __user *)addr);
+}
+
+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(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
+	else
+		__do_kernel_fault(mm, addr, fsr, regs);
+}
+
+#ifdef CONFIG_MMU
+#ifdef CONFIG_CPU_TTBR0_PAN
+static inline bool ttbr0_usermode_access_allowed(struct pt_regs *regs)
+{
+	struct svc_pt_regs *svcregs;
+
+	/* If we are in user mode: permission granted */
+	if (user_mode(regs))
+		return true;
+
+	/* uaccess state saved above pt_regs on SVC exception entry */
+	svcregs = to_svc_pt_regs(regs);
+
+	return !(svcregs->ttbcr & TTBCR_EPD0);
+}
+#else
+static inline bool ttbr0_usermode_access_allowed(struct pt_regs *regs)
+{
+	return true;
+}
+#endif
+
+/*
+ * Handle a vmalloc fault, copying the non-leaf page table entries from
+ * init_mm.pgd. Any kernel context can trigger this, so we must not sleep
+ * or enable interrupts. Having two CPUs execute this for the same page is
+ * no problem, we'll just copy the same data twice.
+ *
+ * Returns false on failure.
+ */
+static bool __kprobes __maybe_unused vmalloc_fault(unsigned long addr)
+{
+	unsigned int index;
+	pgd_t *pgd, *pgd_k;
+	p4d_t *p4d, *p4d_k;
+	pud_t *pud, *pud_k;
+	pmd_t *pmd, *pmd_k;
+
+	index = pgd_index(addr);
+
+	pgd = cpu_get_pgd() + index;
+	pgd_k = init_mm.pgd + index;
+
+	p4d = p4d_offset(pgd, addr);
+	p4d_k = p4d_offset(pgd_k, addr);
+
+	if (p4d_none(*p4d_k))
+		return false;
+	if (!p4d_present(*p4d))
+		set_p4d(p4d, *p4d_k);
+
+	pud = pud_offset(p4d, addr);
+	pud_k = pud_offset(p4d_k, addr);
+
+	if (pud_none(*pud_k))
+		return false;
+	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]))
+		return false;
+
+	copy_pmd(pmd, pmd_k);
+
+	return true;
+}
+
+static int __kprobes
+do_kernel_address_page_fault(struct mm_struct *mm, unsigned long addr,
+			     unsigned int fsr, struct pt_regs *regs)
+{
+	if (user_mode(regs)) {
+		/*
+		 * Fault from user mode for a kernel space address. User mode
+		 * should not be faulting in kernel space, which includes the
+		 * vector/khelper page. Handle the branch predictor hardening
+		 * while interrupts are still disabled, then send a SIGSEGV.
+		 * Note that __do_user_fault() will enable interrupts.
+		 */
+		harden_branch_predictor();
+		__do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
+	} else {
+		/*
+		 * Fault from kernel mode. Enable interrupts if they were
+		 * enabled in the parent context. Section (upper page table)
+		 * translation faults are handled via do_translation_fault(),
+		 * so we will only get here for a non-present kernel space
+		 * PTE or PTE permission fault. This may happen in exceptional
+		 * circumstances and need the fixup tables to be walked.
+		 */
+		if (interrupts_enabled(regs))
+			local_irq_enable();
+
+		__do_kernel_fault(mm, addr, fsr, regs);
+	}
+
+	return 0;
+}
+
+static int __kprobes
+do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	int sig, code;
+	vm_fault_t fault;
+	unsigned int flags = FAULT_FLAG_DEFAULT;
+	vm_flags_t vm_flags = VM_ACCESS_FLAGS;
+
+	if (kprobe_page_fault(regs, fsr))
+		return 0;
+
+	/*
+	 * Handle kernel addresses faults separately, which avoids touching
+	 * the mmap lock from contexts that are not able to sleep.
+	 */
+	if (addr >= TASK_SIZE)
+		return do_kernel_address_page_fault(mm, addr, fsr, regs);
+
+	/* 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 (is_write_fault(fsr)) {
+		flags |= FAULT_FLAG_WRITE;
+		vm_flags = VM_WRITE;
+	}
+
+	if (fsr & FSR_LNX_PF) {
+		vm_flags = VM_EXEC;
+
+		if (is_permission_fault(fsr) && !user_mode(regs))
+			die_kernel_fault("execution of memory",
+					 mm, addr, fsr, regs);
+	}
+
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
+
+	/*
+	 * Privileged access aborts with CONFIG_CPU_TTBR0_PAN enabled are
+	 * routed via the translation fault mechanism. Check whether uaccess
+	 * is disabled while in kernel mode.
+	 */
+	if (!ttbr0_usermode_access_allowed(regs))
+		goto no_context;
+
+	if (!(flags & FAULT_FLAG_USER))
+		goto lock_mmap;
+
+	vma = lock_vma_under_rcu(mm, addr);
+	if (!vma)
+		goto lock_mmap;
+
+	if (!(vma->vm_flags & vm_flags)) {
+		vma_end_read(vma);
+		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+		fault = 0;
+		code = SEGV_ACCERR;
+		goto bad_area;
+	}
+	fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs);
+	if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
+		vma_end_read(vma);
+
+	if (!(fault & VM_FAULT_RETRY)) {
+		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+		goto done;
+	}
+	count_vm_vma_lock_event(VMA_LOCK_RETRY);
+	if (fault & VM_FAULT_MAJOR)
+		flags |= FAULT_FLAG_TRIED;
+
+	/* Quick path to respond to signals */
+	if (fault_signal_pending(fault, regs)) {
+		if (!user_mode(regs))
+			goto no_context;
+		return 0;
+	}
+lock_mmap:
+
+retry:
+	vma = lock_mm_and_find_vma(mm, addr, regs);
+	if (unlikely(!vma)) {
+		fault = 0;
+		code = SEGV_MAPERR;
+		goto bad_area;
+	}
+
+	/*
+	 * ok, we have a good vm_area for this memory access, check the
+	 * permissions on the VMA allow for the fault which occurred.
+	 */
+	if (!(vma->vm_flags & vm_flags)) {
+		mmap_read_unlock(mm);
+		fault = 0;
+		code = SEGV_ACCERR;
+		goto bad_area;
+	}
+
+	fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
+
+	/* If we need to retry but a fatal signal is pending, handle the
+	 * signal first. We do not need to release the mmap_lock because
+	 * it would already be released in __lock_page_or_retry in
+	 * mm/filemap.c. */
+	if (fault_signal_pending(fault, regs)) {
+		if (!user_mode(regs))
+			goto no_context;
+		return 0;
+	}
+
+	/* The fault is fully completed (including releasing mmap lock) */
+	if (fault & VM_FAULT_COMPLETED)
+		return 0;
+
+	if (!(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_RETRY) {
+			flags |= FAULT_FLAG_TRIED;
+			goto retry;
+		}
+	}
+
+	mmap_read_unlock(mm);
+done:
+
+	/* Handle the "normal" case first */
+	if (likely(!(fault & VM_FAULT_ERROR)))
+		return 0;
+
+	code = SEGV_MAPERR;
+bad_area:
+	/*
+	 * 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;
+	}
+
+	__do_user_fault(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 this is a user address (addr < TASK_SIZE), we handle this as a
+ * normal page fault. This leaves the remainder of the function to handle
+ * kernel address translation faults.
+ *
+ * Since user mode is not permitted to access kernel addresses, pass these
+ * directly to do_kernel_address_page_fault() to handle.
+ *
+ * Otherwise, we're probably faulting in the vmalloc() area, so try to fix
+ * that up via vmalloc_fault().
+ *
+ * If vmalloc_fault() fails, that means the non-leaf page tables did not
+ * contain an entry for this address, so handle this via
+ * do_kernel_address_page_fault().
+ */
+#ifdef CONFIG_MMU
+static int __kprobes
+do_translation_fault(unsigned long addr, unsigned int fsr,
+		     struct pt_regs *regs)
+{
+	if (addr < TASK_SIZE)
+		return do_page_fault(addr, fsr, regs);
+
+	if (!user_mode(regs) && vmalloc_fault(addr))
+		return 0;
+
+	do_kernel_address_page_fault(current->mm, 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)
+{
+	/*
+	 * If this is a kernel address, but from user mode, then userspace
+	 * is trying bad stuff. Invoke the branch predictor handling.
+	 * Interrupts are disabled here.
+	 */
+	if (addr >= TASK_SIZE && user_mode(regs))
+		harden_branch_predictor();
+
+	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);
+
+	if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
+		return;
+
+	pr_alert("8<--- cut here ---\n");
+	pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n",
+		inf->name, fsr, addr);
+	show_pte(KERN_ALERT, current->mm, addr);
+
+	arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
+		       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);
+
+	if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
+		return;
+
+	pr_alert("8<--- cut here ---\n");
+	pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
+		inf->name, ifsr, addr);
+
+	arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
+		       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