![Anshuman Khandual](/assets/img/avatar_default.png)
Architectures which support kprobes have very similar boilerplate around
calling kprobe_fault_handler(). Use a helper function in kprobes.h to
unify them, based on the x86 code.
This changes the behaviour for other architectures when preemption is
enabled. Previously, they would have disabled preemption while calling
the kprobe handler. However, preemption would be disabled if this fault
was due to a kprobe, so we know the fault was not due to a kprobe
handler and can simply return failure.
This behaviour was introduced in commit a980c0ef9f
("x86/kprobes:
Refactor kprobes_fault() like kprobe_exceptions_notify()")
[anshuman.khandual@arm.com: export kprobe_fault_handler()]
Link: http://lkml.kernel.org/r/1561133358-8876-1-git-send-email-anshuman.khandual@arm.com
Link: http://lkml.kernel.org/r/1560420444-25737-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
687 lines
20 KiB
C
687 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* PowerPC version
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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*
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* Derived from "arch/i386/mm/fault.c"
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*
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* Modified by Cort Dougan and Paul Mackerras.
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*
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* Modified for PPC64 by Dave Engebretsen (engebret@ibm.com)
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*/
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/pagemap.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <linux/highmem.h>
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#include <linux/extable.h>
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#include <linux/kprobes.h>
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#include <linux/kdebug.h>
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#include <linux/perf_event.h>
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#include <linux/ratelimit.h>
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#include <linux/context_tracking.h>
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#include <linux/hugetlb.h>
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#include <linux/uaccess.h>
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#include <asm/firmware.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <asm/mmu.h>
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#include <asm/mmu_context.h>
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#include <asm/siginfo.h>
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#include <asm/debug.h>
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#include <asm/kup.h>
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/*
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* Check whether the instruction inst is a store using
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* an update addressing form which will update r1.
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*/
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static bool store_updates_sp(unsigned int inst)
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{
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/* check for 1 in the rA field */
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if (((inst >> 16) & 0x1f) != 1)
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return false;
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/* check major opcode */
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switch (inst >> 26) {
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case OP_STWU:
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case OP_STBU:
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case OP_STHU:
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case OP_STFSU:
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case OP_STFDU:
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return true;
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case OP_STD: /* std or stdu */
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return (inst & 3) == 1;
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case OP_31:
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/* check minor opcode */
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switch ((inst >> 1) & 0x3ff) {
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case OP_31_XOP_STDUX:
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case OP_31_XOP_STWUX:
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case OP_31_XOP_STBUX:
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case OP_31_XOP_STHUX:
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case OP_31_XOP_STFSUX:
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case OP_31_XOP_STFDUX:
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return true;
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}
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}
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return false;
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}
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/*
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* do_page_fault error handling helpers
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*/
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static int
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__bad_area_nosemaphore(struct pt_regs *regs, unsigned long address, int si_code)
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{
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/*
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* If we are in kernel mode, bail out with a SEGV, this will
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* be caught by the assembly which will restore the non-volatile
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* registers before calling bad_page_fault()
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*/
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if (!user_mode(regs))
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return SIGSEGV;
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_exception(SIGSEGV, regs, si_code, address);
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return 0;
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}
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static noinline int bad_area_nosemaphore(struct pt_regs *regs, unsigned long address)
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{
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return __bad_area_nosemaphore(regs, address, SEGV_MAPERR);
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}
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static int __bad_area(struct pt_regs *regs, unsigned long address, int si_code)
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{
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struct mm_struct *mm = current->mm;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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up_read(&mm->mmap_sem);
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return __bad_area_nosemaphore(regs, address, si_code);
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}
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static noinline int bad_area(struct pt_regs *regs, unsigned long address)
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{
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return __bad_area(regs, address, SEGV_MAPERR);
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}
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static int bad_key_fault_exception(struct pt_regs *regs, unsigned long address,
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int pkey)
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{
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/*
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* If we are in kernel mode, bail out with a SEGV, this will
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* be caught by the assembly which will restore the non-volatile
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* registers before calling bad_page_fault()
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*/
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if (!user_mode(regs))
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return SIGSEGV;
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_exception_pkey(regs, address, pkey);
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return 0;
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}
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static noinline int bad_access(struct pt_regs *regs, unsigned long address)
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{
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return __bad_area(regs, address, SEGV_ACCERR);
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}
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static int do_sigbus(struct pt_regs *regs, unsigned long address,
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vm_fault_t fault)
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{
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if (!user_mode(regs))
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return SIGBUS;
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current->thread.trap_nr = BUS_ADRERR;
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#ifdef CONFIG_MEMORY_FAILURE
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if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
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unsigned int lsb = 0; /* shutup gcc */
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pr_err("MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n",
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current->comm, current->pid, address);
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if (fault & VM_FAULT_HWPOISON_LARGE)
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lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
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if (fault & VM_FAULT_HWPOISON)
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lsb = PAGE_SHIFT;
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force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb);
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return 0;
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}
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#endif
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force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
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return 0;
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}
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static int mm_fault_error(struct pt_regs *regs, unsigned long addr,
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vm_fault_t fault)
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{
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/*
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* Kernel page fault interrupted by SIGKILL. We have no reason to
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* continue processing.
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*/
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if (fatal_signal_pending(current) && !user_mode(regs))
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return SIGKILL;
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/* Out of memory */
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if (fault & VM_FAULT_OOM) {
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/*
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* We ran out of memory, or some other thing happened to us that
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* made us unable to handle the page fault gracefully.
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*/
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if (!user_mode(regs))
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return SIGSEGV;
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pagefault_out_of_memory();
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} else {
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if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
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VM_FAULT_HWPOISON_LARGE))
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return do_sigbus(regs, addr, fault);
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else if (fault & VM_FAULT_SIGSEGV)
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return bad_area_nosemaphore(regs, addr);
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else
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BUG();
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}
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return 0;
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}
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/* Is this a bad kernel fault ? */
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static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, bool is_write)
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{
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int is_exec = TRAP(regs) == 0x400;
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/* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
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if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
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DSISR_PROTFAULT))) {
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pr_crit_ratelimited("kernel tried to execute %s page (%lx) - exploit attempt? (uid: %d)\n",
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address >= TASK_SIZE ? "exec-protected" : "user",
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address,
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from_kuid(&init_user_ns, current_uid()));
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// Kernel exec fault is always bad
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return true;
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}
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if (!is_exec && address < TASK_SIZE && (error_code & DSISR_PROTFAULT) &&
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!search_exception_tables(regs->nip)) {
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pr_crit_ratelimited("Kernel attempted to access user page (%lx) - exploit attempt? (uid: %d)\n",
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address,
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from_kuid(&init_user_ns, current_uid()));
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}
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// Kernel fault on kernel address is bad
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if (address >= TASK_SIZE)
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return true;
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// Fault on user outside of certain regions (eg. copy_tofrom_user()) is bad
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if (!search_exception_tables(regs->nip))
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return true;
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// Read/write fault in a valid region (the exception table search passed
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// above), but blocked by KUAP is bad, it can never succeed.
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if (bad_kuap_fault(regs, is_write))
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return true;
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// What's left? Kernel fault on user in well defined regions (extable
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// matched), and allowed by KUAP in the faulting context.
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return false;
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}
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static bool bad_stack_expansion(struct pt_regs *regs, unsigned long address,
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struct vm_area_struct *vma, unsigned int flags,
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bool *must_retry)
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{
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/*
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* N.B. The POWER/Open ABI allows programs to access up to
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* 288 bytes below the stack pointer.
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* The kernel signal delivery code writes up to about 1.5kB
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* below the stack pointer (r1) before decrementing it.
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* The exec code can write slightly over 640kB to the stack
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* before setting the user r1. Thus we allow the stack to
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* expand to 1MB without further checks.
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*/
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if (address + 0x100000 < vma->vm_end) {
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unsigned int __user *nip = (unsigned int __user *)regs->nip;
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/* get user regs even if this fault is in kernel mode */
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struct pt_regs *uregs = current->thread.regs;
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if (uregs == NULL)
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return true;
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/*
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* A user-mode access to an address a long way below
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* the stack pointer is only valid if the instruction
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* is one which would update the stack pointer to the
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* address accessed if the instruction completed,
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* i.e. either stwu rs,n(r1) or stwux rs,r1,rb
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* (or the byte, halfword, float or double forms).
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*
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* If we don't check this then any write to the area
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* between the last mapped region and the stack will
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* expand the stack rather than segfaulting.
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*/
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if (address + 2048 >= uregs->gpr[1])
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return false;
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if ((flags & FAULT_FLAG_WRITE) && (flags & FAULT_FLAG_USER) &&
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access_ok(nip, sizeof(*nip))) {
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unsigned int inst;
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int res;
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pagefault_disable();
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res = __get_user_inatomic(inst, nip);
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pagefault_enable();
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if (!res)
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return !store_updates_sp(inst);
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*must_retry = true;
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}
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return true;
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}
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return false;
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}
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static bool access_error(bool is_write, bool is_exec,
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struct vm_area_struct *vma)
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{
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/*
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* Allow execution from readable areas if the MMU does not
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* provide separate controls over reading and executing.
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*
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* Note: That code used to not be enabled for 4xx/BookE.
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* It is now as I/D cache coherency for these is done at
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* set_pte_at() time and I see no reason why the test
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* below wouldn't be valid on those processors. This -may-
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* break programs compiled with a really old ABI though.
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*/
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if (is_exec) {
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return !(vma->vm_flags & VM_EXEC) &&
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(cpu_has_feature(CPU_FTR_NOEXECUTE) ||
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!(vma->vm_flags & (VM_READ | VM_WRITE)));
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}
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if (is_write) {
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if (unlikely(!(vma->vm_flags & VM_WRITE)))
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return true;
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return false;
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}
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if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
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return true;
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/*
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* We should ideally do the vma pkey access check here. But in the
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* fault path, handle_mm_fault() also does the same check. To avoid
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* these multiple checks, we skip it here and handle access error due
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* to pkeys later.
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*/
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return false;
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}
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#ifdef CONFIG_PPC_SMLPAR
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static inline void cmo_account_page_fault(void)
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{
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if (firmware_has_feature(FW_FEATURE_CMO)) {
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u32 page_ins;
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preempt_disable();
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page_ins = be32_to_cpu(get_lppaca()->page_ins);
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page_ins += 1 << PAGE_FACTOR;
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get_lppaca()->page_ins = cpu_to_be32(page_ins);
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preempt_enable();
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}
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}
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#else
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static inline void cmo_account_page_fault(void) { }
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#endif /* CONFIG_PPC_SMLPAR */
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#ifdef CONFIG_PPC_BOOK3S
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static void sanity_check_fault(bool is_write, bool is_user,
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unsigned long error_code, unsigned long address)
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{
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/*
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* Userspace trying to access kernel address, we get PROTFAULT for that.
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*/
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if (is_user && address >= TASK_SIZE) {
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pr_crit_ratelimited("%s[%d]: User access of kernel address (%lx) - exploit attempt? (uid: %d)\n",
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current->comm, current->pid, address,
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from_kuid(&init_user_ns, current_uid()));
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return;
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}
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/*
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* For hash translation mode, we should never get a
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* PROTFAULT. Any update to pte to reduce access will result in us
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* removing the hash page table entry, thus resulting in a DSISR_NOHPTE
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* fault instead of DSISR_PROTFAULT.
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*
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* A pte update to relax the access will not result in a hash page table
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* entry invalidate and hence can result in DSISR_PROTFAULT.
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* ptep_set_access_flags() doesn't do a hpte flush. This is why we have
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* the special !is_write in the below conditional.
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*
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* For platforms that doesn't supports coherent icache and do support
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* per page noexec bit, we do setup things such that we do the
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* sync between D/I cache via fault. But that is handled via low level
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* hash fault code (hash_page_do_lazy_icache()) and we should not reach
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* here in such case.
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*
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* For wrong access that can result in PROTFAULT, the above vma->vm_flags
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* check should handle those and hence we should fall to the bad_area
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* handling correctly.
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*
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* For embedded with per page exec support that doesn't support coherent
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* icache we do get PROTFAULT and we handle that D/I cache sync in
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* set_pte_at while taking the noexec/prot fault. Hence this is WARN_ON
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* is conditional for server MMU.
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*
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* For radix, we can get prot fault for autonuma case, because radix
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* page table will have them marked noaccess for user.
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*/
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if (radix_enabled() || is_write)
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return;
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WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
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}
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#else
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static void sanity_check_fault(bool is_write, bool is_user,
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unsigned long error_code, unsigned long address) { }
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#endif /* CONFIG_PPC_BOOK3S */
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/*
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* Define the correct "is_write" bit in error_code based
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* on the processor family
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*/
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#if (defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
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#define page_fault_is_write(__err) ((__err) & ESR_DST)
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#define page_fault_is_bad(__err) (0)
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#else
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#define page_fault_is_write(__err) ((__err) & DSISR_ISSTORE)
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#if defined(CONFIG_PPC_8xx)
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#define page_fault_is_bad(__err) ((__err) & DSISR_NOEXEC_OR_G)
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#elif defined(CONFIG_PPC64)
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#define page_fault_is_bad(__err) ((__err) & DSISR_BAD_FAULT_64S)
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#else
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#define page_fault_is_bad(__err) ((__err) & DSISR_BAD_FAULT_32S)
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#endif
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#endif
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/*
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* For 600- and 800-family processors, the error_code parameter is DSISR
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* for a data fault, SRR1 for an instruction fault. For 400-family processors
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* the error_code parameter is ESR for a data fault, 0 for an instruction
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* fault.
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* For 64-bit processors, the error_code parameter is
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* - DSISR for a non-SLB data access fault,
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* - SRR1 & 0x08000000 for a non-SLB instruction access fault
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* - 0 any SLB fault.
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*
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* The return value is 0 if the fault was handled, or the signal
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* number if this is a kernel fault that can't be handled here.
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*/
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static int __do_page_fault(struct pt_regs *regs, unsigned long address,
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unsigned long error_code)
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{
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struct vm_area_struct * vma;
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struct mm_struct *mm = current->mm;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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int is_exec = TRAP(regs) == 0x400;
|
|
int is_user = user_mode(regs);
|
|
int is_write = page_fault_is_write(error_code);
|
|
vm_fault_t fault, major = 0;
|
|
bool must_retry = false;
|
|
bool kprobe_fault = kprobe_page_fault(regs, 11);
|
|
|
|
if (unlikely(debugger_fault_handler(regs) || kprobe_fault))
|
|
return 0;
|
|
|
|
if (unlikely(page_fault_is_bad(error_code))) {
|
|
if (is_user) {
|
|
_exception(SIGBUS, regs, BUS_OBJERR, address);
|
|
return 0;
|
|
}
|
|
return SIGBUS;
|
|
}
|
|
|
|
/* Additional sanity check(s) */
|
|
sanity_check_fault(is_write, is_user, error_code, address);
|
|
|
|
/*
|
|
* The kernel should never take an execute fault nor should it
|
|
* take a page fault to a kernel address or a page fault to a user
|
|
* address outside of dedicated places
|
|
*/
|
|
if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write)))
|
|
return SIGSEGV;
|
|
|
|
/*
|
|
* If we're in an interrupt, have no user context or are running
|
|
* in a region with pagefaults disabled then we must not take the fault
|
|
*/
|
|
if (unlikely(faulthandler_disabled() || !mm)) {
|
|
if (is_user)
|
|
printk_ratelimited(KERN_ERR "Page fault in user mode"
|
|
" with faulthandler_disabled()=%d"
|
|
" mm=%p\n",
|
|
faulthandler_disabled(), mm);
|
|
return bad_area_nosemaphore(regs, address);
|
|
}
|
|
|
|
/* We restore the interrupt state now */
|
|
if (!arch_irq_disabled_regs(regs))
|
|
local_irq_enable();
|
|
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
|
|
|
|
if (error_code & DSISR_KEYFAULT)
|
|
return bad_key_fault_exception(regs, address,
|
|
get_mm_addr_key(mm, address));
|
|
|
|
/*
|
|
* We want to do this outside mmap_sem, because reading code around nip
|
|
* can result in fault, which will cause a deadlock when called with
|
|
* mmap_sem held
|
|
*/
|
|
if (is_user)
|
|
flags |= FAULT_FLAG_USER;
|
|
if (is_write)
|
|
flags |= FAULT_FLAG_WRITE;
|
|
if (is_exec)
|
|
flags |= FAULT_FLAG_INSTRUCTION;
|
|
|
|
/* When running in the kernel we expect faults to occur only to
|
|
* addresses in user space. All other faults represent errors in the
|
|
* kernel and should generate an OOPS. Unfortunately, in the case of an
|
|
* erroneous fault occurring in a code path which already holds mmap_sem
|
|
* we will deadlock attempting to validate the fault against the
|
|
* address space. Luckily the kernel only validly references user
|
|
* space from well defined areas of code, which are listed in the
|
|
* exceptions table.
|
|
*
|
|
* As the vast majority of faults will be valid we will only perform
|
|
* the source reference check when there is a possibility of a deadlock.
|
|
* Attempt to lock the address space, if we cannot we then validate the
|
|
* source. If this is invalid we can skip the address space check,
|
|
* thus avoiding the deadlock.
|
|
*/
|
|
if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
|
|
if (!is_user && !search_exception_tables(regs->nip))
|
|
return bad_area_nosemaphore(regs, address);
|
|
|
|
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();
|
|
}
|
|
|
|
vma = find_vma(mm, address);
|
|
if (unlikely(!vma))
|
|
return bad_area(regs, address);
|
|
if (likely(vma->vm_start <= address))
|
|
goto good_area;
|
|
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
|
|
return bad_area(regs, address);
|
|
|
|
/* The stack is being expanded, check if it's valid */
|
|
if (unlikely(bad_stack_expansion(regs, address, vma, flags,
|
|
&must_retry))) {
|
|
if (!must_retry)
|
|
return bad_area(regs, address);
|
|
|
|
up_read(&mm->mmap_sem);
|
|
if (fault_in_pages_readable((const char __user *)regs->nip,
|
|
sizeof(unsigned int)))
|
|
return bad_area_nosemaphore(regs, address);
|
|
goto retry;
|
|
}
|
|
|
|
/* Try to expand it */
|
|
if (unlikely(expand_stack(vma, address)))
|
|
return bad_area(regs, address);
|
|
|
|
good_area:
|
|
if (unlikely(access_error(is_write, is_exec, vma)))
|
|
return bad_access(regs, address);
|
|
|
|
/*
|
|
* If for any reason at all we couldn't handle the fault,
|
|
* make sure we exit gracefully rather than endlessly redo
|
|
* the fault.
|
|
*/
|
|
fault = handle_mm_fault(vma, address, flags);
|
|
|
|
#ifdef CONFIG_PPC_MEM_KEYS
|
|
/*
|
|
* we skipped checking for access error due to key earlier.
|
|
* Check that using handle_mm_fault error return.
|
|
*/
|
|
if (unlikely(fault & VM_FAULT_SIGSEGV) &&
|
|
!arch_vma_access_permitted(vma, is_write, is_exec, 0)) {
|
|
|
|
int pkey = vma_pkey(vma);
|
|
|
|
up_read(&mm->mmap_sem);
|
|
return bad_key_fault_exception(regs, address, pkey);
|
|
}
|
|
#endif /* CONFIG_PPC_MEM_KEYS */
|
|
|
|
major |= fault & VM_FAULT_MAJOR;
|
|
|
|
/*
|
|
* Handle the retry right now, the mmap_sem has been released in that
|
|
* case.
|
|
*/
|
|
if (unlikely(fault & VM_FAULT_RETRY)) {
|
|
/* We retry only once */
|
|
if (flags & FAULT_FLAG_ALLOW_RETRY) {
|
|
/*
|
|
* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
|
|
* of starvation.
|
|
*/
|
|
flags &= ~FAULT_FLAG_ALLOW_RETRY;
|
|
flags |= FAULT_FLAG_TRIED;
|
|
if (!fatal_signal_pending(current))
|
|
goto retry;
|
|
}
|
|
|
|
/*
|
|
* User mode? Just return to handle the fatal exception otherwise
|
|
* return to bad_page_fault
|
|
*/
|
|
return is_user ? 0 : SIGBUS;
|
|
}
|
|
|
|
up_read(¤t->mm->mmap_sem);
|
|
|
|
if (unlikely(fault & VM_FAULT_ERROR))
|
|
return mm_fault_error(regs, address, fault);
|
|
|
|
/*
|
|
* Major/minor page fault accounting.
|
|
*/
|
|
if (major) {
|
|
current->maj_flt++;
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
|
|
cmo_account_page_fault();
|
|
} else {
|
|
current->min_flt++;
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
|
|
}
|
|
return 0;
|
|
}
|
|
NOKPROBE_SYMBOL(__do_page_fault);
|
|
|
|
int do_page_fault(struct pt_regs *regs, unsigned long address,
|
|
unsigned long error_code)
|
|
{
|
|
enum ctx_state prev_state = exception_enter();
|
|
int rc = __do_page_fault(regs, address, error_code);
|
|
exception_exit(prev_state);
|
|
return rc;
|
|
}
|
|
NOKPROBE_SYMBOL(do_page_fault);
|
|
|
|
/*
|
|
* bad_page_fault is called when we have a bad access from the kernel.
|
|
* It is called from the DSI and ISI handlers in head.S and from some
|
|
* of the procedures in traps.c.
|
|
*/
|
|
void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
|
|
{
|
|
const struct exception_table_entry *entry;
|
|
|
|
/* Are we prepared to handle this fault? */
|
|
if ((entry = search_exception_tables(regs->nip)) != NULL) {
|
|
regs->nip = extable_fixup(entry);
|
|
return;
|
|
}
|
|
|
|
/* kernel has accessed a bad area */
|
|
|
|
switch (TRAP(regs)) {
|
|
case 0x300:
|
|
case 0x380:
|
|
case 0xe00:
|
|
pr_alert("BUG: %s at 0x%08lx\n",
|
|
regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" :
|
|
"Unable to handle kernel data access", regs->dar);
|
|
break;
|
|
case 0x400:
|
|
case 0x480:
|
|
pr_alert("BUG: Unable to handle kernel instruction fetch%s",
|
|
regs->nip < PAGE_SIZE ? " (NULL pointer?)\n" : "\n");
|
|
break;
|
|
case 0x600:
|
|
pr_alert("BUG: Unable to handle kernel unaligned access at 0x%08lx\n",
|
|
regs->dar);
|
|
break;
|
|
default:
|
|
pr_alert("BUG: Unable to handle unknown paging fault at 0x%08lx\n",
|
|
regs->dar);
|
|
break;
|
|
}
|
|
printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",
|
|
regs->nip);
|
|
|
|
if (task_stack_end_corrupted(current))
|
|
printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");
|
|
|
|
die("Kernel access of bad area", regs, sig);
|
|
}
|