649 lines
19 KiB
Diff
649 lines
19 KiB
Diff
From 697b9317be3ef90ddc0997cc0d6db44380a8ce31 Mon Sep 17 00:00:00 2001
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From: David Hildenbrand <dahi@linux.vnet.ibm.com>
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Date: Mon, 11 May 2015 17:52:11 +0200
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Subject: [PATCH 06/14] mm: use pagefault_disable() to check for disabled
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pagefaults in the handler
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.0/patches-4.0.4-rt1.tar.xz
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Introduce faulthandler_disabled() and use it to check for irq context and
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disabled pagefaults (via pagefault_disable()) in the pagefault handlers.
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Please note that we keep the in_atomic() checks in place - to detect
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whether in irq context (in which case preemption is always properly
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disabled).
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In contrast, preempt_disable() should never be used to disable pagefaults.
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With !CONFIG_PREEMPT_COUNT, preempt_disable() doesn't modify the preempt
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counter, and therefore the result of in_atomic() differs.
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We validate that condition by using might_fault() checks when calling
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might_sleep().
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Therefore, add a comment to faulthandler_disabled(), describing why this
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is needed.
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faulthandler_disabled() and pagefault_disable() are defined in
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linux/uaccess.h, so let's properly add that include to all relevant files.
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This patch is based on a patch from Thomas Gleixner.
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Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
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---
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arch/alpha/mm/fault.c | 5 ++---
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arch/arc/mm/fault.c | 2 +-
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arch/arm/mm/fault.c | 2 +-
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arch/arm64/mm/fault.c | 2 +-
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arch/avr32/mm/fault.c | 4 ++--
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arch/cris/mm/fault.c | 6 +++---
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arch/frv/mm/fault.c | 4 ++--
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arch/ia64/mm/fault.c | 4 ++--
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arch/m32r/mm/fault.c | 8 ++++----
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arch/m68k/mm/fault.c | 4 ++--
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arch/metag/mm/fault.c | 2 +-
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arch/microblaze/mm/fault.c | 8 ++++----
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arch/mips/mm/fault.c | 4 ++--
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arch/mn10300/mm/fault.c | 4 ++--
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arch/nios2/mm/fault.c | 2 +-
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arch/parisc/kernel/traps.c | 4 ++--
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arch/parisc/mm/fault.c | 4 ++--
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arch/powerpc/mm/fault.c | 9 +++++----
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arch/s390/mm/fault.c | 2 +-
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arch/score/mm/fault.c | 3 ++-
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arch/sh/mm/fault.c | 5 +++--
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arch/sparc/mm/fault_32.c | 4 ++--
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arch/sparc/mm/fault_64.c | 4 ++--
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arch/sparc/mm/init_64.c | 2 +-
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arch/tile/mm/fault.c | 4 ++--
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arch/um/kernel/trap.c | 4 ++--
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arch/unicore32/mm/fault.c | 2 +-
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arch/x86/mm/fault.c | 5 +++--
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arch/xtensa/mm/fault.c | 4 ++--
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include/linux/uaccess.h | 12 ++++++++++++
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30 files changed, 72 insertions(+), 57 deletions(-)
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--- a/arch/alpha/mm/fault.c
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+++ b/arch/alpha/mm/fault.c
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@@ -23,8 +23,7 @@
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#include <linux/smp.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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-
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-#include <asm/uaccess.h>
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+#include <linux/uaccess.h>
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extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
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@@ -107,7 +106,7 @@ do_page_fault(unsigned long address, uns
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/* If we're in an interrupt context, or have no user context,
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we must not take the fault. */
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- if (!mm || in_atomic())
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+ if (!mm || faulthandler_disabled())
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goto no_context;
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#ifdef CONFIG_ALPHA_LARGE_VMALLOC
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--- a/arch/arc/mm/fault.c
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+++ b/arch/arc/mm/fault.c
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@@ -86,7 +86,7 @@ void do_page_fault(unsigned long address
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(regs))
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--- a/arch/arm/mm/fault.c
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+++ b/arch/arm/mm/fault.c
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@@ -276,7 +276,7 @@ do_page_fault(unsigned long addr, unsign
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(regs))
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--- a/arch/arm64/mm/fault.c
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+++ b/arch/arm64/mm/fault.c
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@@ -211,7 +211,7 @@ static int __kprobes do_page_fault(unsig
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* If we're in an interrupt or have no user context, we must not take
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* the fault.
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(regs))
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--- a/arch/avr32/mm/fault.c
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+++ b/arch/avr32/mm/fault.c
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@@ -14,11 +14,11 @@
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#include <linux/pagemap.h>
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#include <linux/kdebug.h>
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#include <linux/kprobes.h>
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+#include <linux/uaccess.h>
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#include <asm/mmu_context.h>
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#include <asm/sysreg.h>
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#include <asm/tlb.h>
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-#include <asm/uaccess.h>
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#ifdef CONFIG_KPROBES
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static inline int notify_page_fault(struct pt_regs *regs, int trap)
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@@ -81,7 +81,7 @@ asmlinkage void do_page_fault(unsigned l
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* If we're in an interrupt or have no user context, we must
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* not take the fault...
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*/
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- if (in_atomic() || !mm || regs->sr & SYSREG_BIT(GM))
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+ if (faulthandler_disabled() || !mm || regs->sr & SYSREG_BIT(GM))
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goto no_context;
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local_irq_enable();
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--- a/arch/cris/mm/fault.c
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+++ b/arch/cris/mm/fault.c
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@@ -8,7 +8,7 @@
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <linux/wait.h>
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-#include <asm/uaccess.h>
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+#include <linux/uaccess.h>
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#include <arch/system.h>
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extern int find_fixup_code(struct pt_regs *);
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@@ -109,11 +109,11 @@ do_page_fault(unsigned long address, str
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info.si_code = SEGV_MAPERR;
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/*
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- * If we're in an interrupt or "atomic" operation or have no
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+ * If we're in an interrupt, have pagefaults disabled or have no
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* user context, we must not take the fault.
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(regs))
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--- a/arch/frv/mm/fault.c
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+++ b/arch/frv/mm/fault.c
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@@ -19,9 +19,9 @@
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#include <linux/kernel.h>
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#include <linux/ptrace.h>
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#include <linux/hardirq.h>
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+#include <linux/uaccess.h>
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#include <asm/pgtable.h>
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-#include <asm/uaccess.h>
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#include <asm/gdb-stub.h>
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/*****************************************************************************/
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@@ -78,7 +78,7 @@ asmlinkage void do_page_fault(int datamm
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(__frame))
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--- a/arch/ia64/mm/fault.c
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+++ b/arch/ia64/mm/fault.c
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@@ -11,10 +11,10 @@
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#include <linux/kprobes.h>
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#include <linux/kdebug.h>
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#include <linux/prefetch.h>
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+#include <linux/uaccess.h>
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#include <asm/pgtable.h>
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#include <asm/processor.h>
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-#include <asm/uaccess.h>
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extern int die(char *, struct pt_regs *, long);
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@@ -96,7 +96,7 @@ ia64_do_page_fault (unsigned long addres
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/*
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* If we're in an interrupt or have no user context, we must not take the fault..
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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#ifdef CONFIG_VIRTUAL_MEM_MAP
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--- a/arch/m32r/mm/fault.c
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+++ b/arch/m32r/mm/fault.c
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@@ -24,9 +24,9 @@
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#include <linux/vt_kern.h> /* For unblank_screen() */
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#include <linux/highmem.h>
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#include <linux/module.h>
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+#include <linux/uaccess.h>
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#include <asm/m32r.h>
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-#include <asm/uaccess.h>
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#include <asm/hardirq.h>
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#include <asm/mmu_context.h>
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#include <asm/tlbflush.h>
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@@ -111,10 +111,10 @@ asmlinkage void do_page_fault(struct pt_
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mm = tsk->mm;
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/*
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- * If we're in an interrupt or have no user context or are running in an
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- * atomic region then we must not take the fault..
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+ * If we're in an interrupt or have no user context or have pagefaults
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+ * disabled then we must not take the fault.
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto bad_area_nosemaphore;
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if (error_code & ACE_USERMODE)
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--- a/arch/m68k/mm/fault.c
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+++ b/arch/m68k/mm/fault.c
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@@ -10,10 +10,10 @@
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#include <linux/ptrace.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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+#include <linux/uaccess.h>
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#include <asm/setup.h>
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#include <asm/traps.h>
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-#include <asm/uaccess.h>
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#include <asm/pgalloc.h>
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extern void die_if_kernel(char *, struct pt_regs *, long);
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@@ -81,7 +81,7 @@ int do_page_fault(struct pt_regs *regs,
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(regs))
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--- a/arch/metag/mm/fault.c
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+++ b/arch/metag/mm/fault.c
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@@ -105,7 +105,7 @@ int do_page_fault(struct pt_regs *regs,
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mm = tsk->mm;
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(regs))
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--- a/arch/microblaze/mm/fault.c
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+++ b/arch/microblaze/mm/fault.c
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@@ -107,14 +107,14 @@ void do_page_fault(struct pt_regs *regs,
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if ((error_code & 0x13) == 0x13 || (error_code & 0x11) == 0x11)
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is_write = 0;
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- if (unlikely(in_atomic() || !mm)) {
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+ if (unlikely(faulthandler_disabled() || !mm)) {
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if (kernel_mode(regs))
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goto bad_area_nosemaphore;
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- /* in_atomic() in user mode is really bad,
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+ /* faulthandler_disabled() in user mode is really bad,
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as is current->mm == NULL. */
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- pr_emerg("Page fault in user mode with in_atomic(), mm = %p\n",
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- mm);
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+ pr_emerg("Page fault in user mode with faulthandler_disabled(), mm = %p\n",
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+ mm);
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pr_emerg("r15 = %lx MSR = %lx\n",
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regs->r15, regs->msr);
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die("Weird page fault", regs, SIGSEGV);
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--- a/arch/mips/mm/fault.c
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+++ b/arch/mips/mm/fault.c
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@@ -21,10 +21,10 @@
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#include <linux/module.h>
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#include <linux/kprobes.h>
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#include <linux/perf_event.h>
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+#include <linux/uaccess.h>
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#include <asm/branch.h>
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#include <asm/mmu_context.h>
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-#include <asm/uaccess.h>
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#include <asm/ptrace.h>
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#include <asm/highmem.h> /* For VMALLOC_END */
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#include <linux/kdebug.h>
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@@ -94,7 +94,7 @@ static void __kprobes __do_page_fault(st
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto bad_area_nosemaphore;
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if (user_mode(regs))
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--- a/arch/mn10300/mm/fault.c
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+++ b/arch/mn10300/mm/fault.c
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@@ -23,8 +23,8 @@
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#include <linux/interrupt.h>
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#include <linux/init.h>
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#include <linux/vt_kern.h> /* For unblank_screen() */
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+#include <linux/uaccess.h>
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-#include <asm/uaccess.h>
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#include <asm/pgalloc.h>
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#include <asm/hardirq.h>
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#include <asm/cpu-regs.h>
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@@ -168,7 +168,7 @@ asmlinkage void do_page_fault(struct pt_
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto no_context;
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if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
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--- a/arch/nios2/mm/fault.c
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+++ b/arch/nios2/mm/fault.c
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@@ -77,7 +77,7 @@ asmlinkage void do_page_fault(struct pt_
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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- if (in_atomic() || !mm)
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+ if (faulthandler_disabled() || !mm)
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goto bad_area_nosemaphore;
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if (user_mode(regs))
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--- a/arch/parisc/kernel/traps.c
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+++ b/arch/parisc/kernel/traps.c
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@@ -26,9 +26,9 @@
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#include <linux/console.h>
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#include <linux/bug.h>
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#include <linux/ratelimit.h>
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+#include <linux/uaccess.h>
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#include <asm/assembly.h>
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-#include <asm/uaccess.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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#include <asm/traps.h>
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@@ -800,7 +800,7 @@ void notrace handle_interruption(int cod
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* unless pagefault_disable() was called before.
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*/
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- if (fault_space == 0 && !in_atomic())
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+ if (fault_space == 0 && !faulthandler_disabled())
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{
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pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
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parisc_terminate("Kernel Fault", regs, code, fault_address);
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--- a/arch/parisc/mm/fault.c
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+++ b/arch/parisc/mm/fault.c
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@@ -15,8 +15,8 @@
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#include <linux/sched.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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+#include <linux/uaccess.h>
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-#include <asm/uaccess.h>
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#include <asm/traps.h>
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/* Various important other fields */
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@@ -207,7 +207,7 @@ void do_page_fault(struct pt_regs *regs,
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int fault;
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unsigned int flags;
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- if (in_atomic())
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+ if (pagefault_disabled())
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goto no_context;
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tsk = current;
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--- a/arch/powerpc/mm/fault.c
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+++ b/arch/powerpc/mm/fault.c
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@@ -33,13 +33,13 @@
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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/uaccess.h>
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#include <asm/tlbflush.h>
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#include <asm/siginfo.h>
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#include <asm/debug.h>
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@@ -272,15 +272,16 @@ int __kprobes do_page_fault(struct pt_re
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if (!arch_irq_disabled_regs(regs))
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local_irq_enable();
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- if (in_atomic() || mm == NULL) {
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+ if (faulthandler_disabled() || mm == NULL) {
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if (!user_mode(regs)) {
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rc = SIGSEGV;
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goto bail;
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}
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- /* in_atomic() in user mode is really bad,
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+ /* faulthandler_disabled() in user mode is really bad,
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as is current->mm == NULL. */
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printk(KERN_EMERG "Page fault in user mode with "
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- "in_atomic() = %d mm = %p\n", in_atomic(), mm);
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+ "faulthandler_disabled() = %d mm = %p\n",
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+ faulthandler_disabled(), mm);
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printk(KERN_EMERG "NIP = %lx MSR = %lx\n",
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regs->nip, regs->msr);
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die("Weird page fault", regs, SIGSEGV);
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--- a/arch/s390/mm/fault.c
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+++ b/arch/s390/mm/fault.c
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@@ -435,7 +435,7 @@ static inline int do_exception(struct pt
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* user context.
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*/
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fault = VM_FAULT_BADCONTEXT;
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- if (unlikely(!user_space_fault(regs) || in_atomic() || !mm))
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+ if (unlikely(!user_space_fault(regs) || faulthandler_disabled() || !mm))
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goto out;
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address = trans_exc_code & __FAIL_ADDR_MASK;
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--- a/arch/score/mm/fault.c
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+++ b/arch/score/mm/fault.c
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@@ -34,6 +34,7 @@
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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+#include <linux/uaccess.h>
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/*
|
|
* This routine handles page faults. It determines the address,
|
|
@@ -73,7 +74,7 @@ asmlinkage void do_page_fault(struct pt_
|
|
* If we're in an interrupt or have no user
|
|
* context, we must not take the fault..
|
|
*/
|
|
- if (in_atomic() || !mm)
|
|
+ if (pagefault_disabled() || !mm)
|
|
goto bad_area_nosemaphore;
|
|
|
|
if (user_mode(regs))
|
|
--- a/arch/sh/mm/fault.c
|
|
+++ b/arch/sh/mm/fault.c
|
|
@@ -17,6 +17,7 @@
|
|
#include <linux/kprobes.h>
|
|
#include <linux/perf_event.h>
|
|
#include <linux/kdebug.h>
|
|
+#include <linux/uaccess.h>
|
|
#include <asm/io_trapped.h>
|
|
#include <asm/mmu_context.h>
|
|
#include <asm/tlbflush.h>
|
|
@@ -438,9 +439,9 @@ asmlinkage void __kprobes do_page_fault(
|
|
|
|
/*
|
|
* If we're in an interrupt, have no user context or are running
|
|
- * in an atomic region then we must not take the fault:
|
|
+ * with pagefaults disabled then we must not take the fault:
|
|
*/
|
|
- if (unlikely(in_atomic() || !mm)) {
|
|
+ if (unlikely(faulthandler_disabled() || !mm)) {
|
|
bad_area_nosemaphore(regs, error_code, address);
|
|
return;
|
|
}
|
|
--- a/arch/sparc/mm/fault_32.c
|
|
+++ b/arch/sparc/mm/fault_32.c
|
|
@@ -21,6 +21,7 @@
|
|
#include <linux/perf_event.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/kdebug.h>
|
|
+#include <linux/uaccess.h>
|
|
|
|
#include <asm/page.h>
|
|
#include <asm/pgtable.h>
|
|
@@ -29,7 +30,6 @@
|
|
#include <asm/setup.h>
|
|
#include <asm/smp.h>
|
|
#include <asm/traps.h>
|
|
-#include <asm/uaccess.h>
|
|
|
|
#include "mm_32.h"
|
|
|
|
@@ -196,7 +196,7 @@ asmlinkage void do_sparc_fault(struct pt
|
|
* If we're in an interrupt or have no user
|
|
* context, we must not take the fault..
|
|
*/
|
|
- if (in_atomic() || !mm)
|
|
+ if (pagefault_disabled() || !mm)
|
|
goto no_context;
|
|
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
|
|
--- a/arch/sparc/mm/fault_64.c
|
|
+++ b/arch/sparc/mm/fault_64.c
|
|
@@ -22,12 +22,12 @@
|
|
#include <linux/kdebug.h>
|
|
#include <linux/percpu.h>
|
|
#include <linux/context_tracking.h>
|
|
+#include <linux/uaccess.h>
|
|
|
|
#include <asm/page.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/openprom.h>
|
|
#include <asm/oplib.h>
|
|
-#include <asm/uaccess.h>
|
|
#include <asm/asi.h>
|
|
#include <asm/lsu.h>
|
|
#include <asm/sections.h>
|
|
@@ -330,7 +330,7 @@ asmlinkage void __kprobes do_sparc64_fau
|
|
* If we're in an interrupt or have no user
|
|
* context, we must not take the fault..
|
|
*/
|
|
- if (in_atomic() || !mm)
|
|
+ if (faulthandler_disabled() || !mm)
|
|
goto intr_or_no_mm;
|
|
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
|
|
--- a/arch/sparc/mm/init_64.c
|
|
+++ b/arch/sparc/mm/init_64.c
|
|
@@ -2706,7 +2706,7 @@ void hugetlb_setup(struct pt_regs *regs)
|
|
struct mm_struct *mm = current->mm;
|
|
struct tsb_config *tp;
|
|
|
|
- if (in_atomic() || !mm) {
|
|
+ if (faulthandler_disabled() || !mm) {
|
|
const struct exception_table_entry *entry;
|
|
|
|
entry = search_exception_tables(regs->tpc);
|
|
--- a/arch/tile/mm/fault.c
|
|
+++ b/arch/tile/mm/fault.c
|
|
@@ -353,9 +353,9 @@ static int handle_page_fault(struct pt_r
|
|
|
|
/*
|
|
* If we're in an interrupt, have no user context or are running in an
|
|
- * atomic region then we must not take the fault.
|
|
+ * region with pagefaults disabled then we must not take the fault.
|
|
*/
|
|
- if (in_atomic() || !mm) {
|
|
+ if (pagefault_disabled() || !mm) {
|
|
vma = NULL; /* happy compiler */
|
|
goto bad_area_nosemaphore;
|
|
}
|
|
--- a/arch/um/kernel/trap.c
|
|
+++ b/arch/um/kernel/trap.c
|
|
@@ -35,10 +35,10 @@ int handle_page_fault(unsigned long addr
|
|
*code_out = SEGV_MAPERR;
|
|
|
|
/*
|
|
- * If the fault was during atomic operation, don't take the fault, just
|
|
+ * If the fault was with pagefaults disabled, don't take the fault, just
|
|
* fail.
|
|
*/
|
|
- if (in_atomic())
|
|
+ if (faulthandler_disabled())
|
|
goto out_nosemaphore;
|
|
|
|
if (is_user)
|
|
--- a/arch/unicore32/mm/fault.c
|
|
+++ b/arch/unicore32/mm/fault.c
|
|
@@ -218,7 +218,7 @@ static int do_pf(unsigned long addr, uns
|
|
* If we're in an interrupt or have no user
|
|
* context, we must not take the fault..
|
|
*/
|
|
- if (in_atomic() || !mm)
|
|
+ if (faulthandler_disabled() || !mm)
|
|
goto no_context;
|
|
|
|
if (user_mode(regs))
|
|
--- a/arch/x86/mm/fault.c
|
|
+++ b/arch/x86/mm/fault.c
|
|
@@ -13,6 +13,7 @@
|
|
#include <linux/hugetlb.h> /* hstate_index_to_shift */
|
|
#include <linux/prefetch.h> /* prefetchw */
|
|
#include <linux/context_tracking.h> /* exception_enter(), ... */
|
|
+#include <linux/uaccess.h> /* faulthandler_disabled() */
|
|
|
|
#include <asm/traps.h> /* dotraplinkage, ... */
|
|
#include <asm/pgalloc.h> /* pgd_*(), ... */
|
|
@@ -1126,9 +1127,9 @@ static noinline void
|
|
|
|
/*
|
|
* If we're in an interrupt, have no user context or are running
|
|
- * in an atomic region then we must not take the fault:
|
|
+ * in a region with pagefaults disabled then we must not take the fault
|
|
*/
|
|
- if (unlikely(in_atomic() || !mm)) {
|
|
+ if (unlikely(faulthandler_disabled() || !mm)) {
|
|
bad_area_nosemaphore(regs, error_code, address);
|
|
return;
|
|
}
|
|
--- a/arch/xtensa/mm/fault.c
|
|
+++ b/arch/xtensa/mm/fault.c
|
|
@@ -15,10 +15,10 @@
|
|
#include <linux/mm.h>
|
|
#include <linux/module.h>
|
|
#include <linux/hardirq.h>
|
|
+#include <linux/uaccess.h>
|
|
#include <asm/mmu_context.h>
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/hardirq.h>
|
|
-#include <asm/uaccess.h>
|
|
#include <asm/pgalloc.h>
|
|
|
|
DEFINE_PER_CPU(unsigned long, asid_cache) = ASID_USER_FIRST;
|
|
@@ -57,7 +57,7 @@ void do_page_fault(struct pt_regs *regs)
|
|
/* If we're in an interrupt or have no user
|
|
* context, we must not take the fault..
|
|
*/
|
|
- if (in_atomic() || !mm) {
|
|
+ if (faulthandler_disabled() || !mm) {
|
|
bad_page_fault(regs, address, SIGSEGV);
|
|
return;
|
|
}
|
|
--- a/include/linux/uaccess.h
|
|
+++ b/include/linux/uaccess.h
|
|
@@ -59,6 +59,18 @@ static inline void pagefault_enable(void
|
|
*/
|
|
#define pagefault_disabled() (current->pagefault_disabled != 0)
|
|
|
|
+/*
|
|
+ * The pagefault handler is in general disabled by pagefault_disable() or
|
|
+ * when in irq context (via in_atomic()).
|
|
+ *
|
|
+ * This function should only be used by the fault handlers. Other users should
|
|
+ * stick to pagefault_disabled().
|
|
+ * Please NEVER use preempt_disable() to disable the fault handler. With
|
|
+ * !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
|
|
+ * in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
|
|
+ */
|
|
+#define faulthandler_disabled() (pagefault_disabled() || in_atomic())
|
|
+
|
|
#ifndef ARCH_HAS_NOCACHE_UACCESS
|
|
|
|
static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
|