Re: [PATCH 08/11] tracing: add func and symfunc to tag format

From: Frederic Weisbecker
Date: Wed Jun 10 2009 - 03:49:16 EST


On Wed, Jun 10, 2009 at 01:42:14AM -0400, Steven Rostedt wrote:
> From: Steven Rostedt <srostedt@xxxxxxxxxx>
>
> This adds a way to print out a function name from a pointer the same way
> that the Linux printf "%pF" does. Well the symfunc tag does.
>
> If we change kmalloc and kfree formats to:
>
> TP_FORMAT("call_site=<symfunc:call_site> ptr=<ptr:ptr> bytes_req=<int:bytes_req> "
>
> and
>
> TP_FORMAT("call_site=<func:call_site> ptr=<ptr:ptr>")
>
> respectively, we would get something like:
>
> kmalloc: call_site=__alloc_skb+0x70/0x160 ptr=ffff88003d830800 bytes_req=680
> kfree: call_site=skb_release_data ptr=ffff88003d830800


Nice!

I thought about func and func_offset, but symfunc seems enough.


>
> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> ---
> kernel/trace/trace_output.c | 2 +-
> kernel/trace/trace_output.h | 4 ++++
> kernel/trace/trace_read_binary.c | 27 +++++++++++++++++++++++++--
> 3 files changed, 30 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> index 7938f3a..39d5eeb 100644
> --- a/kernel/trace/trace_output.c
> +++ b/kernel/trace/trace_output.c
> @@ -326,7 +326,7 @@ static inline const char *kretprobed(const char *name)
> }
> #endif /* CONFIG_KRETPROBES */
>
> -static int
> +int
> seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
> {
> #ifdef CONFIG_KALLSYMS
> diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h
> index d38bec4..412eee8 100644
> --- a/kernel/trace/trace_output.h
> +++ b/kernel/trace/trace_output.h
> @@ -47,5 +47,9 @@ do { \
> return TRACE_TYPE_PARTIAL_LINE; \
> } while (0)
>
> +/* until we have a way with sprintf to do this */
> +int seq_print_sym_short(struct trace_seq *s, const char *fmt,
> + unsigned long address);
> +
> #endif
>
> diff --git a/kernel/trace/trace_read_binary.c b/kernel/trace/trace_read_binary.c
> index f3fdac8..9ff4ed8 100644
> --- a/kernel/trace/trace_read_binary.c
> +++ b/kernel/trace/trace_read_binary.c
> @@ -10,7 +10,7 @@
> #include <linux/module.h>
> #include <linux/ctype.h>
>
> -#include "trace.h"
> +#include "trace_output.h"
>
> static DEFINE_MUTEX(buffer_lock);
> static struct trace_seq buffer;
> @@ -23,7 +23,8 @@ static struct trace_seq buffer;
> * COMMAND := <TYPE:FIELD> | <mask:FIELD:DELIM:MASKS> | <sym:FIELD:SYMBOLS> |
> * <if:FIELD:TRUE:FALSE> | <ifmask:FIELD:MASK:TRUE:FALSE> |
> * <nsec2sec:PRECISION:FIELD> | <nsec2usec:PRECISION:FIELD> |
> - * <nsec2msec:PRECISION:FIELD> | <major:FIELD> | <minor:FIELD>
> + * <nsec2msec:PRECISION:FIELD> | <major:FIELD> | <minor:FIELD> |
> + * <func:FIELD> | <symfunc:FIELD>
> * TYPE := int | uint | hex | ptr | string | strarray
> * FIELD := defined by the event structure
> * MASKS := MASK=NAME,MASKS | MASK=NAME
> @@ -43,6 +44,8 @@ static struct trace_seq buffer;
> * uint : Same as int, but for unsigned.
> * hex : Print the field as a hex (ie. 0x4ab)
> * ptr : Print the field as a hex but without the '0x'.
> + * symfunc : Print a ptr like the "%pF" does.
> + * func : Like symfunc but without the address.
> * string : Used with dynamic sized strings (__string)
> * strarray : Used with static sized arrays (__array ( char , item, len)).
> * if : If the field is non zero, print the TRUE text,
> @@ -80,6 +83,8 @@ enum field_types {
> FIELD_IS_HEX,
> FIELD_IS_MINOR,
> FIELD_IS_MAJOR,
> + FIELD_IS_FUNC,
> + FIELD_IS_SYMFUNC,
> FIELD_IS_NSEC2SEC,
> FIELD_IS_NSEC2USEC,
> FIELD_IS_NSEC2MSEC,
> @@ -412,6 +417,8 @@ handle_field(struct ftrace_event_call *event,
> case FIELD_IS_HEX:
> case FIELD_IS_MINOR:
> case FIELD_IS_MAJOR:
> + case FIELD_IS_FUNC:
> + case FIELD_IS_SYMFUNC:
> case FIELD_IS_STRING:
> case FIELD_IS_STRARRAY:
> field = find_field(event, fmt, end - fmt);
> @@ -594,6 +601,12 @@ ftrace_initialize_print(struct ftrace_event_call *event, const char *fmt, ...)
> else if (strncmp(fmt, "ifmask:", 7) == 0)
> field_type = FIELD_IS_IFMASK;
>
> + else if (strncmp(fmt, "func:", 5) == 0)
> + field_type = FIELD_IS_FUNC;
> +
> + else if (strncmp(fmt, "symfunc:", 8) == 0)
> + field_type = FIELD_IS_SYMFUNC;
> +
> else if (strncmp(fmt, "nsec2sec:", 9) == 0)
> field_type = FIELD_IS_NSEC2SEC;
>
> @@ -785,6 +798,8 @@ ftrace_read_binary(struct trace_seq *s, struct ftrace_event_call *event,
> case FIELD_IS_UINT:
> case FIELD_IS_HEX:
> case FIELD_IS_PTR:
> + case FIELD_IS_FUNC:
> + case FIELD_IS_SYMFUNC:
> case FIELD_IS_MAJOR:
> case FIELD_IS_MINOR:
> field = info->data.field;
> @@ -837,6 +852,14 @@ ftrace_read_binary(struct trace_seq *s, struct ftrace_event_call *event,
> trace_seq_printf(s, "%u", MINOR(val));
> break;
>
> + case FIELD_IS_SYMFUNC:
> + trace_seq_printf(s, "%pF", (void *)val);
> + break;
> +
> + case FIELD_IS_FUNC:
> + seq_print_sym_short(s, "%s", val);


May be after the merge window it would be nice to start use %pf (for
now it's on another branch).
I'll have more time to do such things in about two weeks.



> + break;
> +
> default:
> /* hex should only print the size specified */
> if (mask)
> --
> 1.6.3.1
>
> --

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