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mm/fault, arch: Use pagefault_disable() to check for disabled pagefaults in the handler

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Introduce faulthandler_disabled() and use it to check for irq context and
disabled pagefaults (via pagefault_disable()) in the pagefault handlers.

Please note that we keep the in_atomic() checks in place - to detect
whether in irq context (in which case preemption is always properly
disabled).

In contrast, preempt_disable() should never be used to disable pagefaults.
With !CONFIG_PREEMPT_COUNT, preempt_disable() doesn't modify the preempt
counter, and therefore the result of in_atomic() differs.
We validate that condition by using might_fault() checks when calling
might_sleep().

Therefore, add a comment to faulthandler_disabled(), describing why this
is needed.

faulthandler_disabled() and pagefault_disable() are defined in
linux/uaccess.h, so let's properly add that include to all relevant files.

This patch is based on a patch from Thomas Gleixner.

Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: borntraeger@de.ibm.com
Cc: daniel.vetter@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: hocko@suse.cz
Cc: hughd@google.com
Cc: mst@redhat.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: schwidefsky@de.ibm.com
Cc: yang.shi@windriver.com
Link: http://lkml.kernel.org/r/1431359540-32227-7-git-send-email-dahi@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
David Hildenbrand 2015-05-11 17:52:11 +02:00 • committed by Ingo Molnar
commit 70ffdb9393
30 changed files with 72 additions and 57 deletions
Download patch file Download diff file Expand all files Collapse all files

5
arch/alpha/mm/fault.c
View file

@ -23,8 +23,7 @@
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/uaccess.h>
extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
@ -107,7 +106,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
/* If we're in an interrupt context, or have no user context,
we must not take the fault. */
if (!mm || in_atomic())
if (!mm || faulthandler_disabled())
goto no_context;
#ifdef CONFIG_ALPHA_LARGE_VMALLOC

2
arch/arc/mm/fault.c
View file

@ -86,7 +86,7 @@ void do_page_fault(unsigned long address, 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)
goto no_context;
if (user_mode(regs))

2
arch/arm/mm/fault.c
View file

@ -276,7 +276,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, 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)
goto no_context;
if (user_mode(regs))

2
arch/arm64/mm/fault.c
View file

@ -211,7 +211,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
* 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))

4
arch/avr32/mm/fault.c
View file

@ -14,11 +14,11 @@
#include <linux/pagemap.h>
#include <linux/kdebug.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/sysreg.h>
#include <asm/tlb.h>
#include <asm/uaccess.h>
#ifdef CONFIG_KPROBES
static inline int notify_page_fault(struct pt_regs *regs, int trap)
@ -81,7 +81,7 @@ asmlinkage void do_page_fault(unsigned long ecr, 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 || regs->sr & SYSREG_BIT(GM))
if (faulthandler_disabled() || !mm || regs->sr & SYSREG_BIT(GM))
goto no_context;
local_irq_enable();

6
arch/cris/mm/fault.c
View file

@ -8,7 +8,7 @@
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/wait.h>
#include <asm/uaccess.h>
#include <linux/uaccess.h>
#include <arch/system.h>
extern int find_fixup_code(struct pt_regs *);
@ -109,11 +109,11 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
info.si_code = SEGV_MAPERR;
/*
* If we're in an interrupt or "atomic" operation or have no
* If we're in an interrupt, have pagefaults disabled 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))

4
arch/frv/mm/fault.c
View file

@ -19,9 +19,9 @@
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/hardirq.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/gdb-stub.h>
/*****************************************************************************/
@ -78,7 +78,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
* 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(__frame))

4
arch/ia64/mm/fault.c
View file

@ -11,10 +11,10 @@
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/prefetch.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
extern int die(char *, struct pt_regs *, long);
@ -96,7 +96,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
/*
* 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;
#ifdef CONFIG_VIRTUAL_MEM_MAP

8
arch/m32r/mm/fault.c
View file

@ -24,9 +24,9 @@
#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <asm/m32r.h>
#include <asm/uaccess.h>
#include <asm/hardirq.h>
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
@ -111,10 +111,10 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
mm = tsk->mm;
/*
* If we're in an interrupt or have no user context or are running in an
* atomic region then we must not take the fault..
* If we're in an interrupt or have no user context or have pagefaults
* disabled then we must not take the fault.
*/
if (in_atomic() || !mm)
if (faulthandler_disabled() || !mm)
goto bad_area_nosemaphore;
if (error_code & ACE_USERMODE)

4
arch/m68k/mm/fault.c
View file

@ -10,10 +10,10 @@
#include <linux/ptrace.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <asm/setup.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
extern void die_if_kernel(char *, struct pt_regs *, long);
@ -81,7 +81,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
* 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))

2
arch/metag/mm/fault.c
View file

@ -105,7 +105,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
mm = tsk->mm;
if (in_atomic() || !mm)
if (faulthandler_disabled() || !mm)
goto no_context;
if (user_mode(regs))

6
arch/microblaze/mm/fault.c
View file

@ -107,13 +107,13 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
if ((error_code & 0x13) == 0x13 || (error_code & 0x11) == 0x11)
is_write = 0;
if (unlikely(in_atomic() || !mm)) {
if (unlikely(faulthandler_disabled() || !mm)) {
if (kernel_mode(regs))
goto bad_area_nosemaphore;
/* in_atomic() in user mode is really bad,
/* faulthandler_disabled() in user mode is really bad,
as is current->mm == NULL. */
pr_emerg("Page fault in user mode with in_atomic(), mm = %p\n",
pr_emerg("Page fault in user mode with faulthandler_disabled(), mm = %p\n",
mm);
pr_emerg("r15 = %lx MSR = %lx\n",
regs->r15, regs->msr);

4
arch/mips/mm/fault.c
View file

@ -21,10 +21,10 @@
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/perf_event.h>
#include <linux/uaccess.h>
#include <asm/branch.h>
#include <asm/mmu_context.h>
#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/highmem.h> /* For VMALLOC_END */
#include <linux/kdebug.h>
@ -94,7 +94,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
* 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 bad_area_nosemaphore;
if (user_mode(regs))

4
arch/mn10300/mm/fault.c
View file

@ -23,8 +23,8 @@
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/vt_kern.h> /* For unblank_screen() */
#include <linux/uaccess.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/hardirq.h>
#include <asm/cpu-regs.h>
@ -168,7 +168,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
* 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 ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)

2
arch/nios2/mm/fault.c
View file

@ -77,7 +77,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
* 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 bad_area_nosemaphore;
if (user_mode(regs))

4
arch/parisc/kernel/traps.c
View file

@ -26,9 +26,9 @@
#include <linux/console.h>
#include <linux/bug.h>
#include <linux/ratelimit.h>
#include <linux/uaccess.h>
#include <asm/assembly.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/traps.h>
@ -800,7 +800,7 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
* unless pagefault_disable() was called before.
*/
if (fault_space == 0 && !in_atomic())
if (fault_space == 0 && !faulthandler_disabled())
{
pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
parisc_terminate("Kernel Fault", regs, code, fault_address);

4
arch/parisc/mm/fault.c
View file

@ -15,8 +15,8 @@
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <asm/uaccess.h>
#include <asm/traps.h>
/* Various important other fields */
@ -207,7 +207,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
int fault;
unsigned int flags;
if (in_atomic())
if (pagefault_disabled())
goto no_context;
tsk = current;

9
arch/powerpc/mm/fault.c
View file

@ -33,13 +33,13 @@
#include <linux/ratelimit.h>
#include <linux/context_tracking.h>
#include <linux/hugetlb.h>
#include <linux/uaccess.h>
#include <asm/firmware.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/uaccess.h>
#include <asm/tlbflush.h>
#include <asm/siginfo.h>
#include <asm/debug.h>
@ -272,15 +272,16 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
if (!arch_irq_disabled_regs(regs))
local_irq_enable();
if (in_atomic() || mm == NULL) {
if (faulthandler_disabled() || mm == NULL) {
if (!user_mode(regs)) {
rc = SIGSEGV;
goto bail;
}
/* in_atomic() in user mode is really bad,
/* faulthandler_disabled() in user mode is really bad,
as is current->mm == NULL. */
printk(KERN_EMERG "Page fault in user mode with "
"in_atomic() = %d mm = %p\n", in_atomic(), mm);
"faulthandler_disabled() = %d mm = %p\n",
faulthandler_disabled(), mm);
printk(KERN_EMERG "NIP = %lx MSR = %lx\n",
regs->nip, regs->msr);
die("Weird page fault", regs, SIGSEGV);

2
arch/s390/mm/fault.c
View file

@ -399,7 +399,7 @@ static inline int do_exception(struct pt_regs *regs, int access)
* user context.
*/
fault = VM_FAULT_BADCONTEXT;
if (unlikely(!user_space_fault(regs) || in_atomic() || !mm))
if (unlikely(!user_space_fault(regs) || faulthandler_disabled() || !mm))
goto out;
address = trans_exc_code & __FAIL_ADDR_MASK;

3
arch/score/mm/fault.c
View file

@ -34,6 +34,7 @@
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
/*
* This routine handles page faults. It determines the address,
@ -73,7 +74,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
* 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))

5
arch/sh/mm/fault.c
View file

@ -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(struct pt_regs *regs,
/*
* 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;
}

4
arch/sparc/mm/fault_32.c
View file

@ -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_regs *regs, int text_fault, int write,
* 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);

4
arch/sparc/mm/fault_64.c
View file

@ -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_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)
goto intr_or_no_mm;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);

2
arch/sparc/mm/init_64.c
View file

@ -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);

4
arch/tile/mm/fault.c
View file

@ -354,9 +354,9 @@ static int handle_page_fault(struct pt_regs *regs,
/*
* 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;
}

4
arch/um/kernel/trap.c
View file

@ -35,10 +35,10 @@ int handle_page_fault(unsigned long address, unsigned long ip,
*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)

2
arch/unicore32/mm/fault.c
View file

@ -218,7 +218,7 @@ static int do_pf(unsigned long addr, unsigned int fsr, 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)
goto no_context;
if (user_mode(regs))

5
arch/x86/mm/fault.c
View file

@ -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 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
/*
* 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;
}

4
arch/xtensa/mm/fault.c
View file

@ -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;
}

12
include/linux/uaccess.h
View file

@ -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,