81d68a96a3
This patch adds latency tracing for critical timings (how long interrupts are disabled for). "irqsoff" is added to /debugfs/tracing/available_tracers Note: tracing_max_latency also holds the max latency for irqsoff (in usecs). (default to large number so one must start latency tracing) tracing_thresh threshold (in usecs) to always print out if irqs off is detected to be longer than stated here. If irq_thresh is non-zero, then max_irq_latency is ignored. Here's an example of a trace with ftrace_enabled = 0 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 Signed-off-by: Ingo Molnar <mingo@elte.hu> -------------------------------------------------------------------- latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1d.s3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1d.s3 100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1d.s3 100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= And this is a trace with ftrace_enabled == 1 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 -------------------------------------------------------------------- latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1dNs3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000]) swapper-0 1dNs3 46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000]) swapper-0 1dNs3 47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000]) swapper-0 1dNs3 47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47) swapper-0 1dNs3 97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50) swapper-0 1dNs3 98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000]) swapper-0 1dNs3 99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000]) swapper-0 1dNs3 101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
221 lines
4.3 KiB
C
221 lines
4.3 KiB
C
#ifndef _X86_IRQFLAGS_H_
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#define _X86_IRQFLAGS_H_
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#include <asm/processor-flags.h>
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#ifndef __ASSEMBLY__
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/*
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* Interrupt control:
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*/
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static inline unsigned long native_save_fl(void)
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{
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unsigned long flags;
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asm volatile("# __raw_save_flags\n\t"
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"pushf ; pop %0"
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: "=g" (flags)
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: /* no input */
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: "memory");
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return flags;
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}
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static inline void native_restore_fl(unsigned long flags)
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{
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asm volatile("push %0 ; popf"
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: /* no output */
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:"g" (flags)
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:"memory", "cc");
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}
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static inline void native_irq_disable(void)
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{
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asm volatile("cli": : :"memory");
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}
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static inline void native_irq_enable(void)
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{
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asm volatile("sti": : :"memory");
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}
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static inline void native_safe_halt(void)
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{
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asm volatile("sti; hlt": : :"memory");
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}
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static inline void native_halt(void)
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{
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asm volatile("hlt": : :"memory");
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}
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#endif
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#ifdef CONFIG_PARAVIRT
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#include <asm/paravirt.h>
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#else
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#ifndef __ASSEMBLY__
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static inline unsigned long __raw_local_save_flags(void)
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{
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return native_save_fl();
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}
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static inline void raw_local_irq_restore(unsigned long flags)
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{
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native_restore_fl(flags);
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}
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static inline void raw_local_irq_disable(void)
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{
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native_irq_disable();
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}
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static inline void raw_local_irq_enable(void)
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{
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native_irq_enable();
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}
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/*
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* Used in the idle loop; sti takes one instruction cycle
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* to complete:
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*/
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static inline void raw_safe_halt(void)
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{
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native_safe_halt();
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}
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/*
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* Used when interrupts are already enabled or to
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* shutdown the processor:
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*/
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static inline void halt(void)
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{
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native_halt();
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}
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/*
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* For spinlocks, etc:
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*/
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static inline unsigned long __raw_local_irq_save(void)
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{
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unsigned long flags = __raw_local_save_flags();
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raw_local_irq_disable();
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return flags;
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}
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#else
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#define ENABLE_INTERRUPTS(x) sti
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#define DISABLE_INTERRUPTS(x) cli
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#ifdef CONFIG_X86_64
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#define INTERRUPT_RETURN iretq
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#define ENABLE_INTERRUPTS_SYSCALL_RET \
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movq %gs:pda_oldrsp, %rsp; \
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swapgs; \
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sysretq;
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#else
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#define INTERRUPT_RETURN iret
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#define ENABLE_INTERRUPTS_SYSCALL_RET sti; sysexit
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#define GET_CR0_INTO_EAX movl %cr0, %eax
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#endif
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#endif /* __ASSEMBLY__ */
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#endif /* CONFIG_PARAVIRT */
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#ifndef __ASSEMBLY__
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#define raw_local_save_flags(flags) \
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do { (flags) = __raw_local_save_flags(); } while (0)
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#define raw_local_irq_save(flags) \
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do { (flags) = __raw_local_irq_save(); } while (0)
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static inline int raw_irqs_disabled_flags(unsigned long flags)
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{
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return !(flags & X86_EFLAGS_IF);
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}
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static inline int raw_irqs_disabled(void)
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{
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unsigned long flags = __raw_local_save_flags();
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return raw_irqs_disabled_flags(flags);
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}
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/*
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* makes the traced hardirq state match with the machine state
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*
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* should be a rarely used function, only in places where its
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* otherwise impossible to know the irq state, like in traps.
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*/
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static inline void trace_hardirqs_fixup_flags(unsigned long flags)
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{
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if (raw_irqs_disabled_flags(flags))
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trace_hardirqs_off();
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else
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trace_hardirqs_on();
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}
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static inline void trace_hardirqs_fixup(void)
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{
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unsigned long flags = __raw_local_save_flags();
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trace_hardirqs_fixup_flags(flags);
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}
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#else
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#ifdef CONFIG_X86_64
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/*
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* Currently paravirt can't handle swapgs nicely when we
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* don't have a stack we can rely on (such as a user space
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* stack). So we either find a way around these or just fault
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* and emulate if a guest tries to call swapgs directly.
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*
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* Either way, this is a good way to document that we don't
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* have a reliable stack. x86_64 only.
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*/
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#define SWAPGS_UNSAFE_STACK swapgs
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#define ARCH_LOCKDEP_SYS_EXIT call lockdep_sys_exit_thunk
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#define ARCH_LOCKDEP_SYS_EXIT_IRQ \
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TRACE_IRQS_ON; \
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sti; \
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SAVE_REST; \
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LOCKDEP_SYS_EXIT; \
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RESTORE_REST; \
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cli; \
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TRACE_IRQS_OFF;
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#else
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#define ARCH_LOCKDEP_SYS_EXIT \
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pushl %eax; \
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pushl %ecx; \
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pushl %edx; \
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call lockdep_sys_exit; \
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popl %edx; \
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popl %ecx; \
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popl %eax;
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#define ARCH_LOCKDEP_SYS_EXIT_IRQ
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#endif
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#ifdef CONFIG_TRACE_IRQFLAGS
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# define TRACE_IRQS_ON call trace_hardirqs_on_thunk;
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# define TRACE_IRQS_OFF call trace_hardirqs_off_thunk;
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#else
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# define TRACE_IRQS_ON
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# define TRACE_IRQS_OFF
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#endif
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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# define LOCKDEP_SYS_EXIT ARCH_LOCKDEP_SYS_EXIT
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# define LOCKDEP_SYS_EXIT_IRQ ARCH_LOCKDEP_SYS_EXIT_IRQ
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# else
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# define LOCKDEP_SYS_EXIT
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# define LOCKDEP_SYS_EXIT_IRQ
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# endif
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#endif /* __ASSEMBLY__ */
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#endif
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