On Fri, 23 Aug 2013 11:37:43 -0400
Seiji Aguchi <seiji.agu...@hds.com> wrote:
> +#if !defined(_TRACE_PAGE_FAULT_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_PAGE_FAULT_H
> +
> +#include <linux/tracepoint.h>
> +
> +extern void trace_irq_vector_regfunc(void);
> +extern void trace_irq_vector_unregfunc(void);
> +
> +DECLARE_EVENT_CLASS(x86_exceptions,
> +
> + TP_PROTO(unsigned long address, struct pt_regs *regs,
> + unsigned long error_code),
> +
> + TP_ARGS(address, regs, error_code),
> +
> + TP_STRUCT__entry(
> + __field( unsigned long, address )
> + __field( struct pt_regs *, regs )
> + __field( unsigned long, error_code )
> + ),
> +
> + TP_fast_assign(
> + __entry->address = address;
> + __entry->regs = regs;
> + __entry->error_code = error_code;
> + ),
> +
> + TP_printk("address=0x%lx ip=0x%lx error_code=0x%lx",
> + __entry->address, __entry->regs->ip, __entry->error_code) );
This is sure to crash the kernel.
You just saved the address of a pointer to some task's stack in the
ring buffer. And then on output (which can happen a long time from when
it was recorded), you are dereferencing that same address!
That __entry->regs->ip *will* crash the kernel!
What you want is to save ip in the fast_assign:
__entry->ip = regs->ip
And then print that. Never dereference a pointer directly from the ring
buffer unless it's a constant value (like a global string).
-- Steve
> +
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