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

From: Steven Rostedt
Date: Wed Jun 10 2009 - 08:55:23 EST


On Wed, 10 Jun 2009, Frederic Weisbecker wrote:

> 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.

func_offset is more intuitive, I'll switch it to that. Or maybe
"funcoffset" or just "funcoff". OK, maybe not ;-)



>
>
> >
> > 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.

Yeah, I spent about twenty minutes trying to find the "%pf" until I
realized it was not in yet :-(

-- Steve

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