Re: [PATCH 2/2] tracing/events: Add kexec tracepoints

From: Eric W. Biederman
Date: Tue Sep 08 2009 - 21:27:58 EST


Li Zefan <lizf@xxxxxxxxxxxxxx> writes:

> When panic, save in ring buffer the time when crash happened,
> the panic message, etc. And the data can be retrieved from
> core dump file using flight-recorder, which is going to be a
> module of the crash utility.
>
> Also if we implement flight-recorder in perf tool, those trace
> outputs can be used by perf tool.

Please let's keep dynamic code out of crash_kexec if we can.

If this is just about timestamsp I don't see the point.

Eric



> ---
> include/trace/events/kexec.h | 51 ++++++++++++++++++++++++++++++++++++++++++
> kernel/kexec.c | 4 +++
> kernel/panic.c | 4 +++
> 3 files changed, 59 insertions(+), 0 deletions(-)
> create mode 100644 include/trace/events/kexec.h
>
> diff --git a/include/trace/events/kexec.h b/include/trace/events/kexec.h
> new file mode 100644
> index 0000000..c1d740a
> --- /dev/null
> +++ b/include/trace/events/kexec.h
> @@ -0,0 +1,51 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM kexec
> +
> +#if !defined(_TRACE_KEXEC_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_KEXEC_H
> +
> +#include <linux/kexec.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(panic,
> +
> + TP_PROTO(const char *msg),
> +
> + TP_ARGS(msg),
> +
> + TP_STRUCT__entry(
> + __string( msg, msg )
> + ),
> +
> + TP_fast_assign(
> + __assign_str(msg, msg);
> + ),
> +
> + TP_printk("%s", __get_str(msg))
> +);
> +
> +TRACE_EVENT(crash_kexec,
> +
> + TP_PROTO(struct kimage *image, struct pt_regs *regs),
> +
> + TP_ARGS(image, regs),
> +
> + TP_STRUCT__entry(
> + __field( void *, image )
> + __field( void *, ip )
> + ),
> +
> + TP_fast_assign(
> + __entry->image = image;
> + __entry->ip = regs ?
> + (void *)instruction_pointer(regs) : NULL;
> + ),
> +
> + TP_printk("image=%p, ip=%p", __entry->image, __entry->ip)
> +);
> +
> +#endif /* _TRACE_KEXEC_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> +
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index f336e21..3d7eda7 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -38,6 +38,8 @@
> #include <asm/system.h>
> #include <asm/sections.h>
>
> +#include <trace/events/kexec.h>
> +
> /* Per cpu memory for storing cpu states in case of system crash. */
> note_buf_t* crash_notes;
>
> @@ -1073,6 +1075,8 @@ void crash_kexec(struct pt_regs *regs)
> if (mutex_trylock(&kexec_mutex)) {
> if (kexec_crash_image) {
> struct pt_regs fixed_regs;
> +
> + trace_crash_kexec(kexec_crash_image, regs);
> crash_setup_regs(&fixed_regs, regs);
> crash_save_vmcoreinfo();
> machine_crash_shutdown(&fixed_regs);
> diff --git a/kernel/panic.c b/kernel/panic.c
> index 22ec502..c3baa23 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -23,6 +23,9 @@
> #include <linux/nmi.h>
> #include <linux/dmi.h>
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/kexec.h>
> +
> int panic_on_oops;
> static unsigned long tainted_mask;
> static int pause_on_oops;
> @@ -69,6 +72,7 @@ NORET_TYPE void panic(const char * fmt, ...)
> va_start(args, fmt);
> vsnprintf(buf, sizeof(buf), fmt, args);
> va_end(args);
> + trace_panic(buf);
> printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
> #ifdef CONFIG_DEBUG_BUGVERBOSE
> dump_stack();
> --
> 1.6.3
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