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tracing/probes: Add fprobe events for tracing function entry and exit.

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Add fprobe events for tracing function entry and exit instead of kprobe
events. With this change, we can continue to trace function entry/exit
even if the CONFIG_KPROBES_ON_FTRACE is not available. Since
CONFIG_KPROBES_ON_FTRACE requires the CONFIG_DYNAMIC_FTRACE_WITH_REGS,
it is not available if the architecture only supports
CONFIG_DYNAMIC_FTRACE_WITH_ARGS. And that means kprobe events can not
probe function entry/exit effectively on such architecture.
But this can be solved if the dynamic events supports fprobe events.

The fprobe event is a new dynamic events which is only for the function
(symbol) entry and exit. This event accepts non register fetch arguments
so that user can trace the function arguments and return values.

The fprobe events syntax is here;

 f[:[GRP/][EVENT]] FUNCTION [FETCHARGS]
 f[MAXACTIVE][:[GRP/][EVENT]] FUNCTION%return [FETCHARGS]

E.g.

 # echo 'f vfs_read $arg1'  >> dynamic_events
 # echo 'f vfs_read%return $retval'  >> dynamic_events
 # cat dynamic_events
 f:fprobes/vfs_read__entry vfs_read arg1=$arg1
 f:fprobes/vfs_read__exit vfs_read%return arg1=$retval
 # echo 1 > events/fprobes/enable
 # head -n 20 trace | tail
 #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
 #              | |         |   |||||     |         |
              sh-142     [005] ...1.   448.386420: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
              sh-142     [005] .....   448.386436: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
              sh-142     [005] ...1.   448.386451: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
              sh-142     [005] .....   448.386458: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
              sh-142     [005] ...1.   448.386469: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
              sh-142     [005] .....   448.386476: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
              sh-142     [005] ...1.   448.602073: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
              sh-142     [005] .....   448.602089: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1

Link: https://lore.kernel.org/all/168507469754.913472.6112857614708350210.stgit@mhiramat.roam.corp.google.com/

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/all/202302011530.7vm4O8Ro-lkp@intel.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
This commit is contained in:
Masami Hiramatsu (Google) 2023-06-06 21:39:55 +09:00
parent 30460c21ed
commit 334e5519c3
12 changed files with 1109 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/fprobe.h
View File

@ -66,6 +66,7 @@ int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter
int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num);
int register_fprobe_syms(struct fprobe *fp, const char **syms, int num);
int unregister_fprobe(struct fprobe *fp);
bool fprobe_is_registered(struct fprobe *fp);
#else
static inline int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter)
{
@ -83,6 +84,10 @@ static inline int unregister_fprobe(struct fprobe *fp)
{
return -EOPNOTSUPP;
}
static inline bool fprobe_is_registered(struct fprobe *fp)
{
return false;
}
#endif
/**

3
include/linux/trace_events.h
View File

@ -318,6 +318,7 @@ enum {
TRACE_EVENT_FL_KPROBE_BIT,
TRACE_EVENT_FL_UPROBE_BIT,
TRACE_EVENT_FL_EPROBE_BIT,
TRACE_EVENT_FL_FPROBE_BIT,
TRACE_EVENT_FL_CUSTOM_BIT,
};
@ -332,6 +333,7 @@ enum {
* KPROBE - Event is a kprobe
* UPROBE - Event is a uprobe
* EPROBE - Event is an event probe
* FPROBE - Event is an function probe
* CUSTOM - Event is a custom event (to be attached to an exsiting tracepoint)
* This is set when the custom event has not been attached
* to a tracepoint yet, then it is cleared when it is.
@ -346,6 +348,7 @@ enum {
TRACE_EVENT_FL_KPROBE = (1 << TRACE_EVENT_FL_KPROBE_BIT),
TRACE_EVENT_FL_UPROBE = (1 << TRACE_EVENT_FL_UPROBE_BIT),
TRACE_EVENT_FL_EPROBE = (1 << TRACE_EVENT_FL_EPROBE_BIT),
TRACE_EVENT_FL_FPROBE = (1 << TRACE_EVENT_FL_FPROBE_BIT),
TRACE_EVENT_FL_CUSTOM = (1 << TRACE_EVENT_FL_CUSTOM_BIT),
};

14
kernel/trace/Kconfig
View File

@ -650,6 +650,20 @@ config BLK_DEV_IO_TRACE
If unsure, say N.
config FPROBE_EVENTS
depends on FPROBE
depends on HAVE_REGS_AND_STACK_ACCESS_API
bool "Enable fprobe-based dynamic events"
select TRACING
select PROBE_EVENTS
select DYNAMIC_EVENTS
default y
help
This allows user to add tracing events on the function entry and
exit via ftrace interface. The syntax is same as the kprobe events
and the kprobe events on function entry and exit will be
transparently converted to this fprobe events.
config KPROBE_EVENTS
depends on KPROBES
depends on HAVE_REGS_AND_STACK_ACCESS_API

1
kernel/trace/Makefile
View File

@ -104,6 +104,7 @@ obj-$(CONFIG_BOOTTIME_TRACING) += trace_boot.o
obj-$(CONFIG_FTRACE_RECORD_RECURSION) += trace_recursion_record.o
obj-$(CONFIG_FPROBE) += fprobe.o
obj-$(CONFIG_RETHOOK) += rethook.o
obj-$(CONFIG_FPROBE_EVENTS) += trace_fprobe.o
obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o
obj-$(CONFIG_RV) += rv/

11
kernel/trace/fprobe.c
View File

@ -348,6 +348,14 @@ int register_fprobe_syms(struct fprobe *fp, const char **syms, int num)
}
EXPORT_SYMBOL_GPL(register_fprobe_syms);
bool fprobe_is_registered(struct fprobe *fp)
{
if (!fp || (fp->ops.saved_func != fprobe_handler &&
fp->ops.saved_func != fprobe_kprobe_handler))
return false;
return true;
}
/**
* unregister_fprobe() - Unregister fprobe from ftrace
* @fp: A fprobe data structure to be unregistered.
@ -360,8 +368,7 @@ int unregister_fprobe(struct fprobe *fp)
{
int ret;
if (!fp || (fp->ops.saved_func != fprobe_handler &&
fp->ops.saved_func != fprobe_kprobe_handler))
if (!fprobe_is_registered(fp))
return -EINVAL;
/*

8
kernel/trace/trace.c
View File

@ -5672,10 +5672,16 @@ static const char readme_msg[] =
" uprobe_events\t\t- Create/append/remove/show the userspace dynamic events\n"
"\t\t\t Write into this file to define/undefine new trace events.\n"
#endif
#if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
#if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS) || \
defined(CONFIG_FPROBE_EVENTS)
"\t accepts: event-definitions (one definition per line)\n"
#if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
"\t Format: p[:[<group>/][<event>]] <place> [<args>]\n"
"\t r[maxactive][:[<group>/][<event>]] <place> [<args>]\n"
#endif
#ifdef CONFIG_FPROBE_EVENTS
"\t f[:[<group>/][<event>]] <func-name>[%return] [<args>]\n"
#endif
#ifdef CONFIG_HIST_TRIGGERS
"\t s:[synthetic/]<event> <field> [<field>]\n"
#endif

11
kernel/trace/trace.h
View File

@ -148,6 +148,17 @@ struct kretprobe_trace_entry_head {
unsigned long ret_ip;
};
struct fentry_trace_entry_head {
struct trace_entry ent;
unsigned long ip;
};
struct fexit_trace_entry_head {
struct trace_entry ent;
unsigned long func;
unsigned long ret_ip;
};
#define TRACE_BUF_SIZE 1024
struct trace_array;

1053
kernel/trace/trace_fprobe.c Normal file
View File

File diff suppressed because it is too large Load Diff

2
kernel/trace/trace_kprobe.c
View File

@ -764,7 +764,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
if (isdigit(argv[0][1])) {
if (!is_return) {
trace_probe_log_err(1, MAXACT_NO_KPROBE);
trace_probe_log_err(1, BAD_MAXACT_TYPE);
goto parse_error;
}
if (event)

4
kernel/trace/trace_probe.c
View File

@ -393,8 +393,8 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
break;
case '%': /* named register */
if (flags & TPARG_FL_TPOINT) {
/* eprobes do not handle registers */
if (flags & (TPARG_FL_TPOINT | TPARG_FL_FPROBE)) {
/* eprobe and fprobe do not handle registers */
trace_probe_log_err(offs, BAD_VAR);
break;
}

3
kernel/trace/trace_probe.h
View File

@ -367,6 +367,7 @@ int trace_probe_print_args(struct trace_seq *s, struct probe_arg *args, int nr_a
#define TPARG_FL_FENTRY BIT(2)
#define TPARG_FL_TPOINT BIT(3)
#define TPARG_FL_USER BIT(4)
#define TPARG_FL_FPROBE BIT(5)
#define TPARG_FL_MASK GENMASK(4, 0)
extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i,
@ -409,7 +410,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
C(REFCNT_OPEN_BRACE, "Reference counter brace is not closed"), \
C(BAD_REFCNT_SUFFIX, "Reference counter has wrong suffix"), \
C(BAD_UPROBE_OFFS, "Invalid uprobe offset"), \
C(MAXACT_NO_KPROBE, "Maxactive is not for kprobe"), \
C(BAD_MAXACT_TYPE, "Maxactive is only for function exit"), \
C(BAD_MAXACT, "Invalid maxactive number"), \
C(MAXACT_TOO_BIG, "Maxactive is too big"), \
C(BAD_PROBE_ADDR, "Invalid probed address or symbol"), \

2
tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
View File

@ -8,7 +8,7 @@ check_error() { # command-with-error-pos-by-^
}
if grep -q 'r\[maxactive\]' README; then
check_error 'p^100 vfs_read' # MAXACT_NO_KPROBE
check_error 'p^100 vfs_read' # BAD_MAXACT_TYPE
check_error 'r^1a111 vfs_read' # BAD_MAXACT
check_error 'r^100000 vfs_read' # MAXACT_TOO_BIG
fi