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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
parent ce01948eb8
commit 70ffdb9393
30 changed files with 72 additions and 57 deletions
Show Stats 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))

8
arch/microblaze/mm/fault.c
View File

@ -107,14 +107,14 @@ 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",
mm);
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);
die("Weird page fault", regs, SIGSEGV);

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,