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git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git
synced 2026-10-29 13:23:23 +01:00
Boqun Feng
3b0e2a22d4
With the changes that enable preempt count to track IRQ disabling
nesting, we don't have enough bits in 32-bit preempt count
implementation, as a result we move NMI nesting bits out of the 32-bit
preempt count. However on the architectures that can support 64-bit
preempt count implementation, we can keep the NMI nesting bits in the
32-bit preempt count and avoid maintaining NMI nesting bits outside of
the same cache line.
Therefore HAS_SEPARATE_PREEMPT_RESCHED_BITS is introduced to allow
architectures to select this. Note that under this Kconfig, preempt
count is maintained in a 64-bit word however preempt_count() still
remains as an int because all the effective bits still fit in
(previously we mask out NEED_RESCHED bit in preempt_count()). This
should make no functional changes for existing preempt_count() users.
Enable this for x86_64 along with the introduction of the Kconfig.
[boqun: Undo the __preempt_count_{add,sub}() optimization in 32-bit
preempt count since it may introduce {over,under}flow]
Originally-by: Peter Zijlstra <[email protected]>
Signed-off-by: Boqun Feng <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://patch.msgid.link/[email protected]
174 lines
4.0 KiB
C
174 lines
4.0 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_HAS_SEPARATE_PREEMPT_RESCHED_BITS
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static __always_inline void __preempt_count_nmi_enter(void)
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{
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__preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET);
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}
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static __always_inline void __preempt_count_nmi_exit(void)
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{
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__preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET);
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}
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#else
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DECLARE_PER_CPU(unsigned int, nmi_nesting);
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#define __preempt_count_nmi_enter() \
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do { \
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__preempt_count_add(HARDIRQ_OFFSET); \
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/* Maximum NMI nesting is 15. */ \
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BUG_ON(__this_cpu_read(nmi_nesting) >= 15); \
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__this_cpu_inc(nmi_nesting); \
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preempt_count_set(preempt_count() | NMI_MASK); \
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} while (0)
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#define __preempt_count_nmi_exit() \
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do { \
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__preempt_count_sub(HARDIRQ_OFFSET); \
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if (!__this_cpu_dec_return(nmi_nesting)) \
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preempt_count_set(preempt_count() & ~NMI_MASK); \
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} while (0)
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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 - nesting is tracked in a per-CPU counter.
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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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__preempt_count_nmi_enter(); \
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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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ct_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_nmi_exit(); \
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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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ct_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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