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I triggered a triple fault with gcc 4.5.1 because it did not honor the inline annotation to arch_local_save_flags() function and that function was added to the pool of functions traced by the function tracer. When preempt_schedule() called arch_local_save_flags() (called by irqs_disabled()), it was traced, but the first thing the function tracer does is disable preemption. When it enables preemption, the NEED_RESCHED flag will not have been cleared and the preemption check will trigger the call to preempt_schedule() again. Although the dynamic function tracer crashed immediately, the static version of the function tracer (CONFIG_DYNAMIC_FTRACE is not set) actually was able to show where the problem was. swapper-1 3.N.. 103885us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103886us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103886us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103887us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103887us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103888us : arch_local_save_flags <-preempt_schedule swapper-1 3.N.. 103888us : arch_local_save_flags <-preempt_schedule It went on for a while before it triple faulted with a corrupted stack. The arch_local_save_flags and arch_local_irq_* functions should not be traced. Even though they are marked as inline, gcc may still make them a function and enable tracing of them. The simple solution is to just mark them as notrace. I had to add the <linux/types.h> for this file to include the notrace tag. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20110702033852.733414762@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
210 lines
4.0 KiB
C
210 lines
4.0 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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/*
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* "=rm" is safe here, because "pop" adjusts the stack before
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* it evaluates its effective address -- this is part of the
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* documented behavior of the "pop" instruction.
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*/
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asm volatile("# __raw_save_flags\n\t"
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"pushf ; pop %0"
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: "=rm" (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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#include <linux/types.h>
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static inline notrace unsigned long arch_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 notrace void arch_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 notrace void arch_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 notrace void arch_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 arch_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 notrace unsigned long arch_local_irq_save(void)
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{
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unsigned long flags = arch_local_save_flags();
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arch_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 SWAPGS swapgs
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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 PARAVIRT_ADJUST_EXCEPTION_FRAME /* */
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#define INTERRUPT_RETURN iretq
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#define USERGS_SYSRET64 \
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swapgs; \
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sysretq;
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#define USERGS_SYSRET32 \
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swapgs; \
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sysretl
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#define ENABLE_INTERRUPTS_SYSEXIT32 \
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swapgs; \
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sti; \
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sysexit
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#else
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#define INTERRUPT_RETURN iret
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#define ENABLE_INTERRUPTS_SYSEXIT 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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static inline int arch_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 arch_irqs_disabled(void)
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{
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unsigned long flags = arch_local_save_flags();
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return arch_irqs_disabled_flags(flags);
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}
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#else
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#ifdef CONFIG_X86_64
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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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