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85e3e7fbbb
All NMI contexts are handled the same as the safe context: store the
message and defer printing. There is no need to have special NMI
context tracking for this. Using in_nmi() is enough.
There are several parts of the kernel that are manually calling into
the printk NMI context tracking in order to cause general printk
deferred printing:
arch/arm/kernel/smp.c
arch/powerpc/kexec/crash.c
kernel/trace/trace.c
For arm/kernel/smp.c and powerpc/kexec/crash.c, provide a new
function pair printk_deferred_enter/exit that explicitly achieves the
same objective.
For ftrace, remove the printk context manipulation completely. It was
added in commit 03fc7f9c99 ("printk/nmi: Prevent deadlock when
accessing the main log buffer in NMI"). The purpose was to enforce
storing messages directly into the ring buffer even in NMI context.
It really should have only modified the behavior in NMI context.
There is no need for a special behavior any longer. All messages are
always stored directly now. The console deferring is handled
transparently in vprintk().
Signed-off-by: John Ogness <john.ogness@linutronix.de>
[pmladek@suse.com: Remove special handling in ftrace.c completely.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210715193359.25946-5-john.ogness@linutronix.de
152 lines
3.4 KiB
C
152 lines
3.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef LINUX_HARDIRQ_H
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#define LINUX_HARDIRQ_H
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#include <linux/context_tracking_state.h>
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#include <linux/preempt.h>
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#include <linux/lockdep.h>
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#include <linux/ftrace_irq.h>
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#include <linux/sched.h>
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#include <linux/vtime.h>
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#include <asm/hardirq.h>
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extern void synchronize_irq(unsigned int irq);
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extern bool synchronize_hardirq(unsigned int irq);
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#ifdef CONFIG_NO_HZ_FULL
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void __rcu_irq_enter_check_tick(void);
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#else
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static inline void __rcu_irq_enter_check_tick(void) { }
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#endif
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static __always_inline void rcu_irq_enter_check_tick(void)
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{
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if (context_tracking_enabled())
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__rcu_irq_enter_check_tick();
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}
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/*
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* It is safe to do non-atomic ops on ->hardirq_context,
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* because NMI handlers may not preempt and the ops are
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* always balanced, so the interrupted value of ->hardirq_context
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* will always be restored.
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*/
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#define __irq_enter() \
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do { \
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preempt_count_add(HARDIRQ_OFFSET); \
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lockdep_hardirq_enter(); \
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account_hardirq_enter(current); \
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} while (0)
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/*
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* Like __irq_enter() without time accounting for fast
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* interrupts, e.g. reschedule IPI where time accounting
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* is more expensive than the actual interrupt.
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*/
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#define __irq_enter_raw() \
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do { \
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preempt_count_add(HARDIRQ_OFFSET); \
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lockdep_hardirq_enter(); \
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} while (0)
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/*
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* Enter irq context (on NO_HZ, update jiffies):
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*/
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void irq_enter(void);
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/*
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* Like irq_enter(), but RCU is already watching.
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*/
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void irq_enter_rcu(void);
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/*
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* Exit irq context without processing softirqs:
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*/
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#define __irq_exit() \
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do { \
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account_hardirq_exit(current); \
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lockdep_hardirq_exit(); \
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preempt_count_sub(HARDIRQ_OFFSET); \
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} while (0)
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/*
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* Like __irq_exit() without time accounting
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*/
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#define __irq_exit_raw() \
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do { \
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lockdep_hardirq_exit(); \
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preempt_count_sub(HARDIRQ_OFFSET); \
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} while (0)
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/*
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* Exit irq context and process softirqs if needed:
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*/
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void irq_exit(void);
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/*
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* Like irq_exit(), but return with RCU watching.
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*/
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void irq_exit_rcu(void);
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#ifndef arch_nmi_enter
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#define arch_nmi_enter() do { } while (0)
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#define arch_nmi_exit() do { } while (0)
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#endif
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#ifdef CONFIG_TINY_RCU
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static inline void rcu_nmi_enter(void) { }
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static inline void rcu_nmi_exit(void) { }
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#else
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extern void rcu_nmi_enter(void);
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extern void rcu_nmi_exit(void);
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#endif
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/*
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* NMI vs Tracing
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* --------------
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*
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* We must not land in a tracer until (or after) we've changed preempt_count
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* such that in_nmi() becomes true. To that effect all NMI C entry points must
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* be marked 'notrace' and call nmi_enter() as soon as possible.
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*/
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/*
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* nmi_enter() can nest up to 15 times; see NMI_BITS.
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*/
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#define __nmi_enter() \
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do { \
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lockdep_off(); \
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arch_nmi_enter(); \
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BUG_ON(in_nmi() == NMI_MASK); \
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__preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \
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} while (0)
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#define nmi_enter() \
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do { \
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__nmi_enter(); \
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lockdep_hardirq_enter(); \
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rcu_nmi_enter(); \
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instrumentation_begin(); \
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ftrace_nmi_enter(); \
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instrumentation_end(); \
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} while (0)
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#define __nmi_exit() \
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do { \
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BUG_ON(!in_nmi()); \
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__preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET); \
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arch_nmi_exit(); \
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lockdep_on(); \
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} while (0)
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#define nmi_exit() \
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do { \
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instrumentation_begin(); \
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ftrace_nmi_exit(); \
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instrumentation_end(); \
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rcu_nmi_exit(); \
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lockdep_hardirq_exit(); \
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__nmi_exit(); \
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} while (0)
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#endif /* LINUX_HARDIRQ_H */
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