linux/arch/x86/include/asm/irqflags.h
Steven Rostedt e08fbb78f0 tracing, x86/irq: Do not trace arch_local_{*,irq_*}() functions
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>
2011-07-07 19:22:32 +02:00

210 lines
4.0 KiB
C

#ifndef _X86_IRQFLAGS_H_
#define _X86_IRQFLAGS_H_
#include <asm/processor-flags.h>
#ifndef __ASSEMBLY__
/*
* Interrupt control:
*/
static inline unsigned long native_save_fl(void)
{
unsigned long flags;
/*
* "=rm" is safe here, because "pop" adjusts the stack before
* it evaluates its effective address -- this is part of the
* documented behavior of the "pop" instruction.
*/
asm volatile("# __raw_save_flags\n\t"
"pushf ; pop %0"
: "=rm" (flags)
: /* no input */
: "memory");
return flags;
}
static inline void native_restore_fl(unsigned long flags)
{
asm volatile("push %0 ; popf"
: /* no output */
:"g" (flags)
:"memory", "cc");
}
static inline void native_irq_disable(void)
{
asm volatile("cli": : :"memory");
}
static inline void native_irq_enable(void)
{
asm volatile("sti": : :"memory");
}
static inline void native_safe_halt(void)
{
asm volatile("sti; hlt": : :"memory");
}
static inline void native_halt(void)
{
asm volatile("hlt": : :"memory");
}
#endif
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#else
#ifndef __ASSEMBLY__
#include <linux/types.h>
static inline notrace unsigned long arch_local_save_flags(void)
{
return native_save_fl();
}
static inline notrace void arch_local_irq_restore(unsigned long flags)
{
native_restore_fl(flags);
}
static inline notrace void arch_local_irq_disable(void)
{
native_irq_disable();
}
static inline notrace void arch_local_irq_enable(void)
{
native_irq_enable();
}
/*
* Used in the idle loop; sti takes one instruction cycle
* to complete:
*/
static inline void arch_safe_halt(void)
{
native_safe_halt();
}
/*
* Used when interrupts are already enabled or to
* shutdown the processor:
*/
static inline void halt(void)
{
native_halt();
}
/*
* For spinlocks, etc:
*/
static inline notrace unsigned long arch_local_irq_save(void)
{
unsigned long flags = arch_local_save_flags();
arch_local_irq_disable();
return flags;
}
#else
#define ENABLE_INTERRUPTS(x) sti
#define DISABLE_INTERRUPTS(x) cli
#ifdef CONFIG_X86_64
#define SWAPGS swapgs
/*
* Currently paravirt can't handle swapgs nicely when we
* don't have a stack we can rely on (such as a user space
* stack). So we either find a way around these or just fault
* and emulate if a guest tries to call swapgs directly.
*
* Either way, this is a good way to document that we don't
* have a reliable stack. x86_64 only.
*/
#define SWAPGS_UNSAFE_STACK swapgs
#define PARAVIRT_ADJUST_EXCEPTION_FRAME /* */
#define INTERRUPT_RETURN iretq
#define USERGS_SYSRET64 \
swapgs; \
sysretq;
#define USERGS_SYSRET32 \
swapgs; \
sysretl
#define ENABLE_INTERRUPTS_SYSEXIT32 \
swapgs; \
sti; \
sysexit
#else
#define INTERRUPT_RETURN iret
#define ENABLE_INTERRUPTS_SYSEXIT sti; sysexit
#define GET_CR0_INTO_EAX movl %cr0, %eax
#endif
#endif /* __ASSEMBLY__ */
#endif /* CONFIG_PARAVIRT */
#ifndef __ASSEMBLY__
static inline int arch_irqs_disabled_flags(unsigned long flags)
{
return !(flags & X86_EFLAGS_IF);
}
static inline int arch_irqs_disabled(void)
{
unsigned long flags = arch_local_save_flags();
return arch_irqs_disabled_flags(flags);
}
#else
#ifdef CONFIG_X86_64
#define ARCH_LOCKDEP_SYS_EXIT call lockdep_sys_exit_thunk
#define ARCH_LOCKDEP_SYS_EXIT_IRQ \
TRACE_IRQS_ON; \
sti; \
SAVE_REST; \
LOCKDEP_SYS_EXIT; \
RESTORE_REST; \
cli; \
TRACE_IRQS_OFF;
#else
#define ARCH_LOCKDEP_SYS_EXIT \
pushl %eax; \
pushl %ecx; \
pushl %edx; \
call lockdep_sys_exit; \
popl %edx; \
popl %ecx; \
popl %eax;
#define ARCH_LOCKDEP_SYS_EXIT_IRQ
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
# define TRACE_IRQS_ON call trace_hardirqs_on_thunk;
# define TRACE_IRQS_OFF call trace_hardirqs_off_thunk;
#else
# define TRACE_IRQS_ON
# define TRACE_IRQS_OFF
#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define LOCKDEP_SYS_EXIT ARCH_LOCKDEP_SYS_EXIT
# define LOCKDEP_SYS_EXIT_IRQ ARCH_LOCKDEP_SYS_EXIT_IRQ
# else
# define LOCKDEP_SYS_EXIT
# define LOCKDEP_SYS_EXIT_IRQ
# endif
#endif /* __ASSEMBLY__ */
#endif