From f3dae07e442a8131a5485b6a38db2aa22a7a48cf Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 11 May 2015 17:52:13 +0200 Subject: sched/preempt, futex: Disable preemption in UP futex_atomic_op_inuser() explicitly Let's explicitly disable/enable preemption in the !CONFIG_SMP version of futex_atomic_op_inuser, to prepare for pagefault_disable() not touching preemption anymore. Otherwise we might break mutual exclusion when relying on a get_user()/ put_user() implementation. 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/1431359540-32227-9-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- include/asm-generic/futex.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index b59b5a52637e..358601750fe7 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -8,8 +8,7 @@ #ifndef CONFIG_SMP /* * The following implementation only for uniprocessor machines. - * For UP, it's relies on the fact that pagefault_disable() also disables - * preemption to ensure mutual exclusion. + * It relies on preempt_disable() ensuring mutual exclusion. * */ @@ -38,6 +37,7 @@ futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr) if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) oparg = 1 << oparg; + preempt_disable(); pagefault_disable(); ret = -EFAULT; @@ -72,6 +72,7 @@ futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr) out_pagefault_enable: pagefault_enable(); + preempt_enable(); if (ret == 0) { switch (cmp) { -- cgit v1.2.3 From d9b9ff8c18891d74dc7076800bde81b774f7d032 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 11 May 2015 17:52:14 +0200 Subject: sched/preempt, futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly Let's explicitly disable/enable preemption in the !CONFIG_SMP version of futex_atomic_cmpxchg_inatomic(), to prepare for pagefault_disable() not touching preemption anymore. This is needed for this function to be callable from both, atomic and non-atomic context. Otherwise we might break mutual exclusion when relying on a get_user()/ put_user() implementation. 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/1431359540-32227-10-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- include/asm-generic/futex.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/asm-generic') diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index 358601750fe7..e56272c919b5 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -107,6 +107,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, { u32 val; + preempt_disable(); if (unlikely(get_user(val, uaddr) != 0)) return -EFAULT; @@ -114,6 +115,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, return -EFAULT; *uval = val; + preempt_enable(); return 0; } -- cgit v1.2.3 From 4eaca0a887eaee04fc7a3866d0f5b51b34030dfa Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 4 Jun 2015 17:39:08 +0200 Subject: preempt: Use preempt_schedule_context() as the official tracing preemption point preempt_schedule_context() is a tracing safe preemption point but it's only used when CONFIG_CONTEXT_TRACKING=y. Other configs have tracing recursion issues since commit: b30f0e3ffedf ("sched/preempt: Optimize preemption operations on __schedule() callers") introduced function based preemp_count_*() ops. Lets make it available on all configs and give it a more appropriate name for its new position. Reported-by: Fengguang Wu Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1433432349-1021-3-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/preempt.h | 8 +++----- arch/x86/kernel/i386_ksyms_32.c | 4 +--- arch/x86/kernel/x8664_ksyms_64.c | 4 +--- arch/x86/lib/thunk_32.S | 4 +--- arch/x86/lib/thunk_64.S | 4 +--- include/asm-generic/preempt.h | 7 ++----- include/linux/preempt.h | 6 +----- kernel/sched/core.c | 8 +++----- 8 files changed, 13 insertions(+), 32 deletions(-) (limited to 'include/asm-generic') diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index 8f3271842533..dca71714f860 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -99,11 +99,9 @@ static __always_inline bool should_resched(void) extern asmlinkage void ___preempt_schedule(void); # define __preempt_schedule() asm ("call ___preempt_schedule") extern asmlinkage void preempt_schedule(void); -# ifdef CONFIG_CONTEXT_TRACKING - extern asmlinkage void ___preempt_schedule_context(void); -# define __preempt_schedule_context() asm ("call ___preempt_schedule_context") - extern asmlinkage void preempt_schedule_context(void); -# endif + extern asmlinkage void ___preempt_schedule_notrace(void); +# define __preempt_schedule_notrace() asm ("call ___preempt_schedule_notrace") + extern asmlinkage void preempt_schedule_notrace(void); #endif #endif /* __ASM_PREEMPT_H */ diff --git a/arch/x86/kernel/i386_ksyms_32.c b/arch/x86/kernel/i386_ksyms_32.c index 05fd74f537d6..64341aa485ae 100644 --- a/arch/x86/kernel/i386_ksyms_32.c +++ b/arch/x86/kernel/i386_ksyms_32.c @@ -40,7 +40,5 @@ EXPORT_SYMBOL(empty_zero_page); #ifdef CONFIG_PREEMPT EXPORT_SYMBOL(___preempt_schedule); -#ifdef CONFIG_CONTEXT_TRACKING -EXPORT_SYMBOL(___preempt_schedule_context); -#endif +EXPORT_SYMBOL(___preempt_schedule_notrace); #endif diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c index 37d8fa4438f0..a0695be19864 100644 --- a/arch/x86/kernel/x8664_ksyms_64.c +++ b/arch/x86/kernel/x8664_ksyms_64.c @@ -75,7 +75,5 @@ EXPORT_SYMBOL(native_load_gs_index); #ifdef CONFIG_PREEMPT EXPORT_SYMBOL(___preempt_schedule); -#ifdef CONFIG_CONTEXT_TRACKING -EXPORT_SYMBOL(___preempt_schedule_context); -#endif +EXPORT_SYMBOL(___preempt_schedule_notrace); #endif diff --git a/arch/x86/lib/thunk_32.S b/arch/x86/lib/thunk_32.S index 5eb715087b80..e407941d0488 100644 --- a/arch/x86/lib/thunk_32.S +++ b/arch/x86/lib/thunk_32.S @@ -38,8 +38,6 @@ #ifdef CONFIG_PREEMPT THUNK ___preempt_schedule, preempt_schedule -#ifdef CONFIG_CONTEXT_TRACKING - THUNK ___preempt_schedule_context, preempt_schedule_context -#endif + THUNK ___preempt_schedule_notrace, preempt_schedule_notrace #endif diff --git a/arch/x86/lib/thunk_64.S b/arch/x86/lib/thunk_64.S index f89ba4e93025..2198902329b5 100644 --- a/arch/x86/lib/thunk_64.S +++ b/arch/x86/lib/thunk_64.S @@ -49,9 +49,7 @@ #ifdef CONFIG_PREEMPT THUNK ___preempt_schedule, preempt_schedule -#ifdef CONFIG_CONTEXT_TRACKING - THUNK ___preempt_schedule_context, preempt_schedule_context -#endif + THUNK ___preempt_schedule_notrace, preempt_schedule_notrace #endif #if defined(CONFIG_TRACE_IRQFLAGS) \ diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h index eb6f9e6c3075..d0a7a4753db2 100644 --- a/include/asm-generic/preempt.h +++ b/include/asm-generic/preempt.h @@ -79,11 +79,8 @@ static __always_inline bool should_resched(void) #ifdef CONFIG_PREEMPT extern asmlinkage void preempt_schedule(void); #define __preempt_schedule() preempt_schedule() - -#ifdef CONFIG_CONTEXT_TRACKING -extern asmlinkage void preempt_schedule_context(void); -#define __preempt_schedule_context() preempt_schedule_context() -#endif +extern asmlinkage void preempt_schedule_notrace(void); +#define __preempt_schedule_notrace() preempt_schedule_notrace() #endif /* CONFIG_PREEMPT */ #endif /* __ASM_PREEMPT_H */ diff --git a/include/linux/preempt.h b/include/linux/preempt.h index a1a00e14c14f..7686dd63bc35 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -204,15 +204,11 @@ do { \ #ifdef CONFIG_PREEMPT -#ifndef CONFIG_CONTEXT_TRACKING -#define __preempt_schedule_context() __preempt_schedule() -#endif - #define preempt_enable_notrace() \ do { \ barrier(); \ if (unlikely(__preempt_count_dec_and_test())) \ - __preempt_schedule_context(); \ + __preempt_schedule_notrace(); \ } while (0) #else #define preempt_enable_notrace() \ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4e925ea10c0c..af0a5a6cee98 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2937,9 +2937,8 @@ asmlinkage __visible void __sched notrace preempt_schedule(void) NOKPROBE_SYMBOL(preempt_schedule); EXPORT_SYMBOL(preempt_schedule); -#ifdef CONFIG_CONTEXT_TRACKING /** - * preempt_schedule_context - preempt_schedule called by tracing + * preempt_schedule_notrace - preempt_schedule called by tracing * * The tracing infrastructure uses preempt_enable_notrace to prevent * recursion and tracing preempt enabling caused by the tracing @@ -2952,7 +2951,7 @@ EXPORT_SYMBOL(preempt_schedule); * instead of preempt_schedule() to exit user context if needed before * calling the scheduler. */ -asmlinkage __visible void __sched notrace preempt_schedule_context(void) +asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) { enum ctx_state prev_ctx; @@ -2980,8 +2979,7 @@ asmlinkage __visible void __sched notrace preempt_schedule_context(void) __preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); } while (need_resched()); } -EXPORT_SYMBOL_GPL(preempt_schedule_context); -#endif /* CONFIG_CONTEXT_TRACKING */ +EXPORT_SYMBOL_GPL(preempt_schedule_notrace); #endif /* CONFIG_PREEMPT */ -- cgit v1.2.3