| Message ID | 20210630154729.129873-3-rostedt@goodmis.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | libtracefs: Facilitate adding and removing kprobes | expand |
On 30.06.21 г. 18:47, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" <rostedt@goodmis.org> > > Add a function to facilitate creating a kprobe event. It has the "raw" in > its name because it still requires knowing the format of the kprobe. But > does handle the kprobe naming better and writing to the kprobe_event file. > > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > --- > include/tracefs.h | 4 +++ > src/Makefile | 1 + > src/tracefs-kprobes.c | 70 +++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 75 insertions(+) > create mode 100644 src/tracefs-kprobes.c > > diff --git a/include/tracefs.h b/include/tracefs.h > index a21d2d2f22a6..bc504bcb0188 100644 > --- a/include/tracefs.h > +++ b/include/tracefs.h > @@ -214,4 +214,8 @@ int tracefs_tracer_clear(struct tracefs_instance *instance); > ssize_t tracefs_trace_pipe_stream(int fd, struct tracefs_instance *instance, int flags); > ssize_t tracefs_trace_pipe_print(struct tracefs_instance *instance, int flags); > void tracefs_trace_pipe_stop(struct tracefs_instance *instance); > + > +int tracefs_kprobe_raw(const char *system, const char *event, > + const char *addr, const char *format); > + > #endif /* _TRACE_FS_H */ > diff --git a/src/Makefile b/src/Makefile > index b4cff07efc50..0697a047f4bc 100644 > --- a/src/Makefile > +++ b/src/Makefile > @@ -8,6 +8,7 @@ OBJS += tracefs-instance.o > OBJS += tracefs-events.o > OBJS += tracefs-tools.o > OBJS += tracefs-marker.o > +OBJS += tracefs-kprobes.o > > OBJS := $(OBJS:%.o=$(bdir)/%.o) > DEPS := $(OBJS:$(bdir)/%.o=$(bdir)/.%.d) > diff --git a/src/tracefs-kprobes.c b/src/tracefs-kprobes.c > new file mode 100644 > index 000000000000..e4b28cff9f08 > --- /dev/null > +++ b/src/tracefs-kprobes.c > @@ -0,0 +1,70 @@ > +// SPDX-License-Identifier: LGPL-2.1 > +/* > + * Copyright (C) 2021 VMware Inc, Steven Rostedt <rostedt@goodmis.org> > + * > + * Updates: > + * Copyright (C) 2021, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com> > + * > + */ > +#include <stdio.h> > +#include <stdlib.h> > +#include <dirent.h> > +#include <unistd.h> > +#include <errno.h> > +#include <sys/stat.h> > +#include <fcntl.h> > +#include <limits.h> > + > +#include "tracefs.h" > +#include "tracefs-local.h" > + > +#define KPROBE_EVENTS "kprobe_events" > + > +/** > + * tracefs_kprobe_raw - Create a kprobe using raw format > + * @system: The system name (NULL for the default kprobes) > + * @event: The event to create (NULL to use @addr for the event) > + * @addr: The function and offset (or address) to insert the probe > + * @format: The raw format string to define the probe. > + * > + * Create a kprobe that will be in the @system group (or kprobes if > + * @system is NULL). Have the name of @event (or @addr if @event is > + * NULL). Will be inserted to @addr (function name, with or without > + * offset, or a address). And the @format will define the raw format > + * of the kprobe. See the Linux documentation file under: > + * Documentation/trace/kprobetrace.rst > + * > + * Return 0 on success, or -1 on error. > + * If the syntex of @format was incorrect, running > + * tracefs_error_last(NULL) may show what went wrong. > + * > + * errno will be set to EBADMSG if addr or format is NULL. > + */ > +int tracefs_kprobe_raw(const char *system, const char *event, > + const char *addr, const char *format) > +{ > + char *str; > + int ret; > + > + errno = EBADMSG; > + if (!addr || !format) > + return -1; > + > + if (!event) > + event = addr; > + > + if (system) > + ret = asprintf(&str, "p:%s/%s %s %s\n", > + system, event, addr, format); > + else > + ret = asprintf(&str, "p:%s %s %s\n", > + event, addr, format); I wonder what will be the way to register a "return value" ("r:") kprobe. Do you consider having a separate API for them? Thanks! Yordan > + > + if (ret < 0) > + return -1; > + > + ret = tracefs_instance_file_append(NULL, KPROBE_EVENTS, str); > + free(str); > + > + return ret < 0 ? ret : 0; > +} >
On Wed, 30 Jun 2021 22:46:19 +0300 "Yordan Karadzhov (VMware)" <y.karadz@gmail.com> wrote: > > +int tracefs_kprobe_raw(const char *system, const char *event, > > + const char *addr, const char *format) > > +{ > > + char *str; > > + int ret; > > + > > + errno = EBADMSG; > > + if (!addr || !format) > > + return -1; > > + > > + if (!event) > > + event = addr; > > + > > + if (system) > > + ret = asprintf(&str, "p:%s/%s %s %s\n", > > + system, event, addr, format); > > + else > > + ret = asprintf(&str, "p:%s %s %s\n", > > + event, addr, format); > > I wonder what will be the way to register a "return value" ("r:") > kprobe. Do you consider having a separate API for them? Yes, I was thinking about having a "tracefs_kretprobe_raw()" as well. I also thought of adding a flag in the parameter, but thought that a separate function would be better instead. I wanted to play with this interface before creating the retprobe one. If you are happy with the current design, I can add that too. -- Steve
On 30.06.21 г. 22:53, Steven Rostedt wrote: > On Wed, 30 Jun 2021 22:46:19 +0300 > "Yordan Karadzhov (VMware)" <y.karadz@gmail.com> wrote: > >>> +int tracefs_kprobe_raw(const char *system, const char *event, >>> + const char *addr, const char *format) >>> +{ >>> + char *str; >>> + int ret; >>> + >>> + errno = EBADMSG; >>> + if (!addr || !format) >>> + return -1; >>> + >>> + if (!event) >>> + event = addr; >>> + >>> + if (system) >>> + ret = asprintf(&str, "p:%s/%s %s %s\n", >>> + system, event, addr, format); >>> + else >>> + ret = asprintf(&str, "p:%s %s %s\n", >>> + event, addr, format); >> >> I wonder what will be the way to register a "return value" ("r:") >> kprobe. Do you consider having a separate API for them? > > Yes, I was thinking about having a "tracefs_kretprobe_raw()" as well. > > I also thought of adding a flag in the parameter, but thought that a > separate function would be better instead. > > I wanted to play with this interface before creating the retprobe one. > If you are happy with the current design, I can add that too. > The design looks good to me. Thanks! Y. > -- Steve >
diff --git a/include/tracefs.h b/include/tracefs.h index a21d2d2f22a6..bc504bcb0188 100644 --- a/include/tracefs.h +++ b/include/tracefs.h @@ -214,4 +214,8 @@ int tracefs_tracer_clear(struct tracefs_instance *instance); ssize_t tracefs_trace_pipe_stream(int fd, struct tracefs_instance *instance, int flags); ssize_t tracefs_trace_pipe_print(struct tracefs_instance *instance, int flags); void tracefs_trace_pipe_stop(struct tracefs_instance *instance); + +int tracefs_kprobe_raw(const char *system, const char *event, + const char *addr, const char *format); + #endif /* _TRACE_FS_H */ diff --git a/src/Makefile b/src/Makefile index b4cff07efc50..0697a047f4bc 100644 --- a/src/Makefile +++ b/src/Makefile @@ -8,6 +8,7 @@ OBJS += tracefs-instance.o OBJS += tracefs-events.o OBJS += tracefs-tools.o OBJS += tracefs-marker.o +OBJS += tracefs-kprobes.o OBJS := $(OBJS:%.o=$(bdir)/%.o) DEPS := $(OBJS:$(bdir)/%.o=$(bdir)/.%.d) diff --git a/src/tracefs-kprobes.c b/src/tracefs-kprobes.c new file mode 100644 index 000000000000..e4b28cff9f08 --- /dev/null +++ b/src/tracefs-kprobes.c @@ -0,0 +1,70 @@ +// SPDX-License-Identifier: LGPL-2.1 +/* + * Copyright (C) 2021 VMware Inc, Steven Rostedt <rostedt@goodmis.org> + * + * Updates: + * Copyright (C) 2021, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com> + * + */ +#include <stdio.h> +#include <stdlib.h> +#include <dirent.h> +#include <unistd.h> +#include <errno.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <limits.h> + +#include "tracefs.h" +#include "tracefs-local.h" + +#define KPROBE_EVENTS "kprobe_events" + +/** + * tracefs_kprobe_raw - Create a kprobe using raw format + * @system: The system name (NULL for the default kprobes) + * @event: The event to create (NULL to use @addr for the event) + * @addr: The function and offset (or address) to insert the probe + * @format: The raw format string to define the probe. + * + * Create a kprobe that will be in the @system group (or kprobes if + * @system is NULL). Have the name of @event (or @addr if @event is + * NULL). Will be inserted to @addr (function name, with or without + * offset, or a address). And the @format will define the raw format + * of the kprobe. See the Linux documentation file under: + * Documentation/trace/kprobetrace.rst + * + * Return 0 on success, or -1 on error. + * If the syntex of @format was incorrect, running + * tracefs_error_last(NULL) may show what went wrong. + * + * errno will be set to EBADMSG if addr or format is NULL. + */ +int tracefs_kprobe_raw(const char *system, const char *event, + const char *addr, const char *format) +{ + char *str; + int ret; + + errno = EBADMSG; + if (!addr || !format) + return -1; + + if (!event) + event = addr; + + if (system) + ret = asprintf(&str, "p:%s/%s %s %s\n", + system, event, addr, format); + else + ret = asprintf(&str, "p:%s %s %s\n", + event, addr, format); + + if (ret < 0) + return -1; + + ret = tracefs_instance_file_append(NULL, KPROBE_EVENTS, str); + free(str); + + return ret < 0 ? ret : 0; +}