From 2cb7c9cb426660b5ed58b643d9e7dd5d50ba901f Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 11 May 2015 17:52:09 +0200 Subject: sched/preempt, mm/kmap: Explicitly disable/enable preemption in kmap_atomic_* The existing code relies on pagefault_disable() implicitly disabling preemption, so that no schedule will happen between kmap_atomic() and kunmap_atomic(). Let's make this explicit, to prepare for pagefault_disable() not touching preemption anymore. Reviewed-and-tested-by: Thomas Gleixner Signed-off-by: David Hildenbrand Signed-off-by: Peter Zijlstra (Intel) Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner 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/1431359540-32227-5-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- arch/parisc/include/asm/cacheflush.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/parisc') diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h index de65f66ea64e..ec2df4bab302 100644 --- a/arch/parisc/include/asm/cacheflush.h +++ b/arch/parisc/include/asm/cacheflush.h @@ -142,6 +142,7 @@ static inline void kunmap(struct page *page) static inline void *kmap_atomic(struct page *page) { + preempt_disable(); pagefault_disable(); return page_address(page); } @@ -150,6 +151,7 @@ static inline void __kunmap_atomic(void *addr) { flush_kernel_dcache_page_addr(addr); pagefault_enable(); + preempt_enable(); } #define kmap_atomic_prot(page, prot) kmap_atomic(page) -- cgit v1.2.3 From 70ffdb9393a7264a069265edded729078dcf0425 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 11 May 2015 17:52:11 +0200 Subject: mm/fault, arch: Use pagefault_disable() to check for disabled pagefaults in the handler 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 Signed-off-by: David Hildenbrand Signed-off-by: Peter Zijlstra (Intel) Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner 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 --- arch/alpha/mm/fault.c | 5 ++--- arch/arc/mm/fault.c | 2 +- arch/arm/mm/fault.c | 2 +- arch/arm64/mm/fault.c | 2 +- arch/avr32/mm/fault.c | 4 ++-- arch/cris/mm/fault.c | 6 +++--- arch/frv/mm/fault.c | 4 ++-- arch/ia64/mm/fault.c | 4 ++-- arch/m32r/mm/fault.c | 8 ++++---- arch/m68k/mm/fault.c | 4 ++-- arch/metag/mm/fault.c | 2 +- arch/microblaze/mm/fault.c | 8 ++++---- arch/mips/mm/fault.c | 4 ++-- arch/mn10300/mm/fault.c | 4 ++-- arch/nios2/mm/fault.c | 2 +- arch/parisc/kernel/traps.c | 4 ++-- arch/parisc/mm/fault.c | 4 ++-- arch/powerpc/mm/fault.c | 9 +++++---- arch/s390/mm/fault.c | 2 +- arch/score/mm/fault.c | 3 ++- arch/sh/mm/fault.c | 5 +++-- arch/sparc/mm/fault_32.c | 4 ++-- arch/sparc/mm/fault_64.c | 4 ++-- arch/sparc/mm/init_64.c | 2 +- arch/tile/mm/fault.c | 4 ++-- arch/um/kernel/trap.c | 4 ++-- arch/unicore32/mm/fault.c | 2 +- arch/x86/mm/fault.c | 5 +++-- arch/xtensa/mm/fault.c | 4 ++-- include/linux/uaccess.h | 12 ++++++++++++ 30 files changed, 72 insertions(+), 57 deletions(-) (limited to 'arch/parisc') diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c index 9d0ac091a52a..4a905bd667e2 100644 --- a/arch/alpha/mm/fault.c +++ b/arch/alpha/mm/fault.c @@ -23,8 +23,7 @@ #include #include #include - -#include +#include 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 diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c index 6a2e006cbcce..d948e4e9d89c 100644 --- a/arch/arc/mm/fault.c +++ b/arch/arc/mm/fault.c @@ -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)) diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 6333d9c17875..0d629b8f973f 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -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)) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 96da13167d4a..0948d327d013 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -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)) diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c index d223a8b57c1e..c03533937a9f 100644 --- a/arch/avr32/mm/fault.c +++ b/arch/avr32/mm/fault.c @@ -14,11 +14,11 @@ #include #include #include +#include #include #include #include -#include #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(); diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c index 83f12f2ed9e3..3066d40a6db1 100644 --- a/arch/cris/mm/fault.c +++ b/arch/cris/mm/fault.c @@ -8,7 +8,7 @@ #include #include #include -#include +#include #include 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)) diff --git a/arch/frv/mm/fault.c b/arch/frv/mm/fault.c index ec4917ddf678..61d99767fe16 100644 --- a/arch/frv/mm/fault.c +++ b/arch/frv/mm/fault.c @@ -19,9 +19,9 @@ #include #include #include +#include #include -#include #include /*****************************************************************************/ @@ -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)) diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c index ba5ba7accd0d..70b40d1205a6 100644 --- a/arch/ia64/mm/fault.c +++ b/arch/ia64/mm/fault.c @@ -11,10 +11,10 @@ #include #include #include +#include #include #include -#include 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 diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c index e3d4d4890104..8f9875b7933d 100644 --- a/arch/m32r/mm/fault.c +++ b/arch/m32r/mm/fault.c @@ -24,9 +24,9 @@ #include /* For unblank_screen() */ #include #include +#include #include -#include #include #include #include @@ -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) diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c index b2f04aee46ec..6a94cdd0c830 100644 --- a/arch/m68k/mm/fault.c +++ b/arch/m68k/mm/fault.c @@ -10,10 +10,10 @@ #include #include #include +#include #include #include -#include #include 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)) diff --git a/arch/metag/mm/fault.c b/arch/metag/mm/fault.c index 2de5dc695a87..f57edca63609 100644 --- a/arch/metag/mm/fault.c +++ b/arch/metag/mm/fault.c @@ -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)) diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c index d46a5ebb7570..177dfc003643 100644 --- a/arch/microblaze/mm/fault.c +++ b/arch/microblaze/mm/fault.c @@ -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); diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c index 7ff8637e530d..36c0f26fac6b 100644 --- a/arch/mips/mm/fault.c +++ b/arch/mips/mm/fault.c @@ -21,10 +21,10 @@ #include #include #include +#include #include #include -#include #include #include /* For VMALLOC_END */ #include @@ -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)) diff --git a/arch/mn10300/mm/fault.c b/arch/mn10300/mm/fault.c index 0c2cc5d39c8e..4a1d181ed32f 100644 --- a/arch/mn10300/mm/fault.c +++ b/arch/mn10300/mm/fault.c @@ -23,8 +23,8 @@ #include #include #include /* For unblank_screen() */ +#include -#include #include #include #include @@ -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) diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c index 0c9b6afe69e9..b51878b0c6b8 100644 --- a/arch/nios2/mm/fault.c +++ b/arch/nios2/mm/fault.c @@ -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)) diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c index 47ee620d15d2..6548fd1d2e62 100644 --- a/arch/parisc/kernel/traps.c +++ b/arch/parisc/kernel/traps.c @@ -26,9 +26,9 @@ #include #include #include +#include #include -#include #include #include #include @@ -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); diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c index e5120e653240..15503adddf4f 100644 --- a/arch/parisc/mm/fault.c +++ b/arch/parisc/mm/fault.c @@ -15,8 +15,8 @@ #include #include #include +#include -#include #include /* 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; diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index b396868d2aa7..6d535973b200 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -33,13 +33,13 @@ #include #include #include +#include #include #include #include #include #include -#include #include #include #include @@ -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); diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index 76515bcea2f1..4c8f5d7f9c23 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -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; diff --git a/arch/score/mm/fault.c b/arch/score/mm/fault.c index 6860beb2a280..37a6c2e0e969 100644 --- a/arch/score/mm/fault.c +++ b/arch/score/mm/fault.c @@ -34,6 +34,7 @@ #include #include #include +#include /* * 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)) diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c index a58fec9b55e0..79d8276377d1 100644 --- a/arch/sh/mm/fault.c +++ b/arch/sh/mm/fault.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -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; } diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c index 70d817154fe8..c399e7b3b035 100644 --- a/arch/sparc/mm/fault_32.c +++ b/arch/sparc/mm/fault_32.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -29,7 +30,6 @@ #include #include #include -#include #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); diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c index 479823249429..e9268ea1a68d 100644 --- a/arch/sparc/mm/fault_64.c +++ b/arch/sparc/mm/fault_64.c @@ -22,12 +22,12 @@ #include #include #include +#include #include #include #include #include -#include #include #include #include @@ -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); diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c index 4ca0d6ba5ec8..cee9b77ddd05 100644 --- 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); diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c index e83cc999da02..3f4f58d34a92 100644 --- a/arch/tile/mm/fault.c +++ b/arch/tile/mm/fault.c @@ -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; } diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c index 8e4daf44e980..f9c9e5a6beba 100644 --- a/arch/um/kernel/trap.c +++ b/arch/um/kernel/trap.c @@ -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) diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c index 0dc922dba915..afccef5529cc 100644 --- a/arch/unicore32/mm/fault.c +++ b/arch/unicore32/mm/fault.c @@ -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)) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 181c53bac3a7..9dc909841739 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -13,6 +13,7 @@ #include /* hstate_index_to_shift */ #include /* prefetchw */ #include /* exception_enter(), ... */ +#include /* faulthandler_disabled() */ #include /* dotraplinkage, ... */ #include /* 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; } diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c index 9e3571a6535c..83a44a33cfa1 100644 --- a/arch/xtensa/mm/fault.c +++ b/arch/xtensa/mm/fault.c @@ -15,10 +15,10 @@ #include #include #include +#include #include #include #include -#include #include 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; } diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 23290cc93a24..90786d2d74e5 100644 --- 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, -- cgit v1.2.3