Re: [PATCH -tip -v10 7/7] tracing: add kprobe-based event tracer

Frederic Weisbecker
2009-07-07T07:31:20Z

On Tue, Jun 30, 2009 at 09:09:23PM -0400, Masami Hiramatsu wrote:
> Add kprobes-based event tracer on ftrace.
>
> This tracer is similar to the events tracer which is based on Tracepoint
> infrastructure. Instead of Tracepoint, this tracer is based on kprobes(kprobe
> and kretprobe). It probes anywhere where kprobes can probe(this means, all
> functions body except for __kprobes functions).
>
> Similar to the events tracer, this tracer doesn't need to be activated via
> current_tracer, instead of that, just set probe points via
> /sys/kernel/debug/tracing/kprobe_events. And you can set filters on each
> probe events via /sys/kernel/debug/tracing/events/kprobes/<EVENT>/filter.
>
> This tracer supports following probe arguments for each probe.
>
> %REG : Fetch register REG
> sN : Fetch Nth entry of stack (N >= 0)
> @ADDR : Fetch memory at ADDR (ADDR should be in kernel)
> @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
> aN : Fetch function argument. (N >= 0)
> rv : Fetch return value.
> ra : Fetch return address.
> +|-offs(FETCHARG) : fetch memory at FETCHARG +|- offs address.
>
> See Documentation/trace/kprobes.txt for details.
>
> Changes from v9:
> - Select CONFIG_GENERIC_TRACER when CONFIG_KPROBE_TRACER=y.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Tom Zanussi <tzanussi@gmail.com>
> ---
>
> Documentation/trace/kprobes.txt | 138 ++++
> kernel/trace/Kconfig | 12
> kernel/trace/Makefile | 1
> kernel/trace/trace.h | 22 +
> kernel/trace/trace_event_types.h | 20 +
> kernel/trace/trace_kprobe.c | 1183 ++++++++++++++++++++++++++++++++++++++
> 6 files changed, 1376 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/trace/kprobes.txt
> create mode 100644 kernel/trace/trace_kprobe.c
>
> diff --git a/Documentation/trace/kprobes.txt b/Documentation/trace/kprobes.txt
> new file mode 100644
> index 0000000..3a90ebb
> --- /dev/null
> +++ b/Documentation/trace/kprobes.txt
> @@ -0,0 +1,138 @@
> + Kprobe-based Event Tracer
> + =========================
> +
> + Documentation is written by Masami Hiramatsu
> +
> +
> +Overview
> +--------
> +This tracer is similar to the events tracer which is based on Tracepoint
> +infrastructure. Instead of Tracepoint, this tracer is based on kprobes(kprobe
> +and kretprobe). It probes anywhere where kprobes can probe(this means, all
> +functions body except for __kprobes functions).
> +
> +Unlike the function tracer, this tracer can probe instructions inside of
> +kernel functions. It allows you to check which instruction has been executed.
> +
> +Unlike the Tracepoint based events tracer, this tracer can add and remove
> +probe points on the fly.
> +
> +Similar to the events tracer, this tracer doesn't need to be activated via
> +current_tracer, instead of that, just set probe points via
> +/sys/kernel/debug/tracing/kprobe_events. And you can set filters on each
> +probe events via /sys/kernel/debug/tracing/events/kprobes/<EVENT>/filter.
> +
> +
> +Synopsis of kprobe_events
> +-------------------------
> + p[:EVENT] SYMBOL[+offs|-offs]|MEMADDR [FETCHARGS] : set a probe
> + r[:EVENT] SYMBOL[+0] [FETCHARGS] : set a return probe
> +
> + EVENT : Event name
> + SYMBOL[+offs|-offs] : Symbol+offset where the probe is inserted
> + MEMADDR : Address where the probe is inserted
> +
> + FETCHARGS : Arguments
> + %REG : Fetch register REG
> + sN : Fetch Nth entry of stack (N >= 0)
> + @ADDR : Fetch memory at ADDR (ADDR should be in kernel)
> + @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
> + aN : Fetch function argument. (N >= 0)(*)
> + rv : Fetch return value.(**)
> + ra : Fetch return address.(**)
> + +|-offs(FETCHARG) : fetch memory at FETCHARG +|- offs address.(***)
> +
> + (*) aN may not correct on asmlinkaged functions and at the middle of
> + function body.
> + (**) only for return probe.
> + (***) this is useful for fetching a field of data structures.
> +
> +
> +Per-Probe Event Filtering
> +-------------------------
> + Per-probe event filtering feature allows you to set different filter on each
> +probe and gives you what arguments will be shown in trace buffer. If an event
> +name is specified right after 'p:' or 'r:' in kprobe_events, the tracer adds
> +an event under tracing/events/kprobes/<EVENT>, at the directory you can see
> +'id', 'enabled', 'format' and 'filter'.
> +
> +enabled:
> + You can enable/disable the probe by writing 1 or 0 on it.
> +
> +format:
> + It shows the format of this probe event. It also shows aliases of arguments
> + which you specified to kprobe_events.
> +
> +filter:
> + You can write filtering rules of this event. And you can use both of aliase
> + names and field names for describing filters.
> +
> +
> +Usage examples
> +--------------
> +To add a probe as a new event, write a new definition to kprobe_events
> +as below.
> +
> + echo p:myprobe do_sys_open a0 a1 a2 a3 > /sys/kernel/debug/tracing/kprobe_events
> +
> + This sets a kprobe on the top of do_sys_open() function with recording
> +1st to 4th arguments as "myprobe" event.
> +
> + echo r:myretprobe do_sys_open rv ra >> /sys/kernel/debug/tracing/kprobe_events
> +
> + This sets a kretprobe on the return point of do_sys_open() function with
> +recording return value and return address as "myretprobe" event.
> + You can see the format of these events via
> +/sys/kernel/debug/tracing/events/kprobes/<EVENT>/format.
> +
> + cat /sys/kernel/debug/tracing/events/kprobes/myprobe/format
> +name: myprobe
> +ID: 23
> +format:
> + field:unsigned short common_type; offset:0; size:2;
> + field:unsigned char common_flags; offset:2; size:1;
> + field:unsigned char common_preempt_count; offset:3; size:1;
> + field:int common_pid; offset:4; size:4;
> + field:int common_tgid; offset:8; size:4;
> +
> + field: unsigned long ip; offset:16;tsize:8;
> + field: int nargs; offset:24;tsize:4;
> + field: unsigned long arg0; offset:32;tsize:8;
> + field: unsigned long arg1; offset:40;tsize:8;
> + field: unsigned long arg2; offset:48;tsize:8;
> + field: unsigned long arg3; offset:56;tsize:8;
> +
> + alias: a0; original: arg0;
> + alias: a1; original: arg1;
> + alias: a2; original: arg2;
> + alias: a3; original: arg3;
> +
> +print fmt: "%lx: 0x%lx 0x%lx 0x%lx 0x%lx", ip, arg0, arg1, arg2, arg3
> +
> +
> + You can see that the event has 4 arguments and alias expressions
> +corresponding to it.
> +
> + echo > /sys/kernel/debug/tracing/kprobe_events
> +
> + This clears all probe points. and you can see the traced information via
> +/sys/kernel/debug/tracing/trace.
> +
> + cat /sys/kernel/debug/tracing/trace
> +# tracer: nop
> +#
> +# TASK-PID CPU# TIMESTAMP FUNCTION
> +# | | | | |
> + <...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: 0x3 0x7fffd1ec4440 0x8000 0x0
> + <...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: 0xfffffffffffffffe 0xffffffff81367a3a
> + <...>-1447 [001] 1038282.286885: do_sys_open+0x0/0xd6: 0xffffff9c 0x40413c 0x8000 0x1b6
> + <...>-1447 [001] 1038282.286915: sys_open+0x1b/0x1d <- do_sys_open: 0x3 0xffffffff81367a3a
> + <...>-1447 [001] 1038282.286969: do_sys_open+0x0/0xd6: 0xffffff9c 0x4041c6 0x98800 0x10
> + <...>-1447 [001] 1038282.286976: sys_open+0x1b/0x1d <- do_sys_open: 0x3 0xffffffff81367a3a
> +
> +
> + Each line shows when the kernel hits a probe, and <- SYMBOL means kernel
> +returns from SYMBOL(e.g. "sys_open+0x1b/0x1d <- do_sys_open" means kernel
> +returns from do_sys_open to sys_open+0x1b).
> +

I'm looking forward to use it for debugging :)

> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 860c712..60f3401 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -445,6 +445,18 @@ config BLK_DEV_IO_TRACE
>
> If unsure, say N.
>
> +config KPROBE_TRACER
> + depends on KPROBES
> + depends on X86
> + bool "Trace kprobes"
> + select TRACING
> + select GENERIC_TRACER
> + help
> + This tracer probes everywhere where kprobes can probe it, and
> + records various registers and memories specified by user.
> + This also allows you to trace kprobe probe points as a dynamic
> + defined events. It provides per-probe event filtering interface.
> +
> config DYNAMIC_FTRACE
> bool "enable/disable ftrace tracepoints dynamically"
> depends on FUNCTION_TRACER
> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> index ce3b1cd..8e6884d 100644
> --- a/kernel/trace/Makefile
> +++ b/kernel/trace/Makefile
> @@ -55,5 +55,6 @@ obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o
> obj-$(CONFIG_EVENT_PROFILE) += trace_event_profile.o
> obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
> obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
> +obj-$(CONFIG_KPROBE_TRACER) += trace_kprobe.o
>
> libftrace-y := ftrace.o
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 206cb7d..65945eb 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -45,6 +45,8 @@ enum trace_type {
> TRACE_POWER,
> TRACE_BLK,
> TRACE_KSYM,
> + TRACE_KPROBE,
> + TRACE_KRETPROBE,
>
> __TRACE_LAST_TYPE,
> };
> @@ -227,6 +229,22 @@ struct trace_ksym {
> char ksym_name[KSYM_NAME_LEN];
> char p_name[TASK_COMM_LEN];
> };
> +#define TRACE_KPROBE_ARGS 6
> +
> +struct kprobe_trace_entry {
> + struct trace_entry ent;
> + unsigned long ip;
> + int nargs;
> + unsigned long args[TRACE_KPROBE_ARGS];

I see that you actually make use of arg as a dynamic sizeable
array.
For clarity, args[TRACE_KPROBE_ARGS] could be args[0].

It's just a neat and wouldn't affect the code nor the data
but would be clearer for readers of that code.

> +};
> +
> +struct kretprobe_trace_entry {
> + struct trace_entry ent;
> + unsigned long func;
> + unsigned long ret_ip;
> + int nargs;
> + unsigned long args[TRACE_KPROBE_ARGS];
> +};

ditto

> /*
> * trace_flag_type is an enumeration that holds different
> @@ -344,6 +362,10 @@ extern void __ftrace_bad_type(void);
> IF_ASSIGN(var, ent, struct syscall_trace_exit, \
> TRACE_SYSCALL_EXIT); \
> IF_ASSIGN(var, ent, struct trace_ksym, TRACE_KSYM); \
> + IF_ASSIGN(var, ent, struct kprobe_trace_entry, \
> + TRACE_KPROBE); \
> + IF_ASSIGN(var, ent, struct kretprobe_trace_entry, \
> + TRACE_KRETPROBE); \
> __ftrace_bad_type(); \
> } while (0)
>
> diff --git a/kernel/trace/trace_event_types.h b/kernel/trace/trace_event_types.h
> index 6db005e..ec2e6f3 100644
> --- a/kernel/trace/trace_event_types.h
> +++ b/kernel/trace/trace_event_types.h
> @@ -175,4 +175,24 @@ TRACE_EVENT_FORMAT(kmem_free, TRACE_KMEM_FREE, kmemtrace_free_entry, ignore,
> TP_RAW_FMT("type:%u call_site:%lx ptr:%p")
> );
>
> +TRACE_EVENT_FORMAT(kprobe, TRACE_KPROBE, kprobe_trace_entry, ignore,
> + TRACE_STRUCT(
> + TRACE_FIELD(unsigned long, ip, ip)
> + TRACE_FIELD(int, nargs, nargs)
> + TRACE_FIELD_SPECIAL(unsigned long args[TRACE_KPROBE_ARGS],
> + args, TRACE_KPROBE_ARGS, args)
> + ),
> + TP_RAW_FMT("%08lx: args:0x%lx ...")
> +);
> +
> +TRACE_EVENT_FORMAT(kretprobe, TRACE_KRETPROBE, kretprobe_trace_entry, ignore,
> + TRACE_STRUCT(
> + TRACE_FIELD(unsigned long, func, func)
> + TRACE_FIELD(unsigned long, ret_ip, ret_ip)
> + TRACE_FIELD(int, nargs, nargs)
> + TRACE_FIELD_SPECIAL(unsigned long args[TRACE_KPROBE_ARGS],
> + args, TRACE_KPROBE_ARGS, args)
> + ),
> + TP_RAW_FMT("%08lx <- %08lx: args:0x%lx ...")
> +);
> #undef TRACE_SYSTEM
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> new file mode 100644
> index 0000000..0951512
> --- /dev/null
> +++ b/kernel/trace/trace_kprobe.c
> @@ -0,0 +1,1183 @@
> +/*
> + * kprobe based kernel tracer
> + *
> + * Created by Masami Hiramatsu <mhiramat@redhat.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> + */
> +
> +#include <linux/module.h>
> +#include <linux/uaccess.h>
> +#include <linux/kprobes.h>
> +#include <linux/seq_file.h>
> +#include <linux/slab.h>
> +#include <linux/smp.h>
> +#include <linux/debugfs.h>
> +#include <linux/types.h>
> +#include <linux/string.h>
> +#include <linux/ctype.h>
> +#include <linux/ptrace.h>
> +
> +#include "trace.h"
> +#include "trace_output.h"
> +
> +#define MAX_ARGSTR_LEN 63
> +
> +/* currently, trace_kprobe only supports X86. */
> +
> +struct fetch_func {
> + unsigned long (*func)(struct pt_regs *, void *);
> + void *data;
> +};
> +
> +static __kprobes unsigned long call_fetch(struct fetch_func *f,
> + struct pt_regs *regs)
> +{
> + return f->func(regs, f->data);
> +}
> +
> +/* fetch handlers */
> +static __kprobes unsigned long fetch_register(struct pt_regs *regs,
> + void *offset)
> +{
> + return regs_get_register(regs, (unsigned)((unsigned long)offset));
> +}
> +
> +static __kprobes unsigned long fetch_stack(struct pt_regs *regs,
> + void *num)
> +{
> + return regs_get_kernel_stack_nth(regs, (unsigned)((unsigned long)num));

You seem to often use unsigned as an implicit type.
Would be better to explicitly use unsigned int.

Anyway, I guess we can merge it in -tip and give it a try.

Thanks,
Frederic.

> +}
> +
> +static __kprobes unsigned long fetch_memory(struct pt_regs *regs, void *addr)
> +{
> + unsigned long retval;
> + if (probe_kernel_address(addr, retval))
> + return 0;
> + return retval;
> +}
> +
> +static __kprobes unsigned long fetch_argument(struct pt_regs *regs, void *num)
> +{
> + return regs_get_argument_nth(regs, (unsigned)((unsigned long)num));
> +}
> +
> +static __kprobes unsigned long fetch_retvalue(struct pt_regs *regs,
> + void *dummy)
> +{
> + return regs_return_value(regs);
> +}
> +
> +static __kprobes unsigned long fetch_ip(struct pt_regs *regs, void *dummy)
> +{
> + return instruction_pointer(regs);
> +}
> +
> +/* Memory fetching by symbol */
> +struct symbol_cache {
> + char *symbol;
> + long offset;
> + unsigned long addr;
> +};
> +
> +static unsigned long update_symbol_cache(struct symbol_cache *sc)
> +{
> + sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
> + if (sc->addr)
> + sc->addr += sc->offset;
> + return sc->addr;
> +}
> +
> +static void free_symbol_cache(struct symbol_cache *sc)
> +{
> + kfree(sc->symbol);
> + kfree(sc);
> +}
> +
> +static struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
> +{
> + struct symbol_cache *sc;
> + if (!sym || strlen(sym) == 0)
> + return NULL;
> + sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
> + if (!sc)
> + return NULL;
> +
> + sc->symbol = kstrdup(sym, GFP_KERNEL);
> + if (!sc->symbol) {
> + kfree(sc);
> + return NULL;
> + }
> + sc->offset = offset;
> +
> + update_symbol_cache(sc);
> + return sc;
> +}
> +
> +static __kprobes unsigned long fetch_symbol(struct pt_regs *regs, void *data)
> +{
> + struct symbol_cache *sc = data;
> + if (sc->addr)
> + return fetch_memory(regs, (void *)sc->addr);
> + else
> + return 0;
> +}
> +
> +/* Special indirect memory access interface */
> +struct indirect_fetch_data {
> + struct fetch_func orig;
> + long offset;
> +};
> +
> +static __kprobes unsigned long fetch_indirect(struct pt_regs *regs, void *data)
> +{
> + struct indirect_fetch_data *ind = data;
> + unsigned long addr;
> + addr = call_fetch(&ind->orig, regs);
> + if (addr) {
> + addr += ind->offset;
> + return fetch_memory(regs, (void *)addr);
> + } else
> + return 0;
> +}
> +
> +static __kprobes void free_indirect_fetch_data(struct indirect_fetch_data *data)
> +{
> + if (data->orig.func == fetch_indirect)
> + free_indirect_fetch_data(data->orig.data);
> + else if (data->orig.func == fetch_symbol)
> + free_symbol_cache(data->orig.data);
> + kfree(data);
> +}
> +
> +/**
> + * kprobe_trace_core
> + */
> +
> +struct trace_probe {
> + struct list_head list;
> + union {
> + struct kprobe kp;
> + struct kretprobe rp;
> + };
> + const char *symbol; /* symbol name */
> + unsigned int nr_args;
> + struct fetch_func args[TRACE_KPROBE_ARGS];
> + struct ftrace_event_call call;
> +};
> +
> +static int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs);
> +static int kretprobe_trace_func(struct kretprobe_instance *ri,
> + struct pt_regs *regs);
> +
> +static __kprobes int probe_is_return(struct trace_probe *tp)
> +{
> + return (tp->rp.handler == kretprobe_trace_func);
> +}
> +
> +static __kprobes const char *probe_symbol(struct trace_probe *tp)
> +{
> + return tp->symbol ? tp->symbol : "unknown";
> +}
> +
> +static __kprobes long probe_offset(struct trace_probe *tp)
> +{
> + return (probe_is_return(tp)) ? tp->rp.kp.offset : tp->kp.offset;
> +}
> +
> +static __kprobes void *probe_address(struct trace_probe *tp)
> +{
> + return (probe_is_return(tp)) ? tp->rp.kp.addr : tp->kp.addr;
> +}
> +
> +static int trace_arg_string(char *buf, size_t n, struct fetch_func *ff)
> +{
> + int ret = -EINVAL;
> + if (ff->func == fetch_argument)
> + ret = snprintf(buf, n, "a%lu", (unsigned long)ff->data);
> + else if (ff->func == fetch_register) {
> + const char *name;
> + name = regs_query_register_name((unsigned)((long)ff->data));
> + ret = snprintf(buf, n, "%%%s", name);
> + } else if (ff->func == fetch_stack)
> + ret = snprintf(buf, n, "s%lu", (unsigned long)ff->data);
> + else if (ff->func == fetch_memory)
> + ret = snprintf(buf, n, "@0x%p", ff->data);
> + else if (ff->func == fetch_symbol) {
> + struct symbol_cache *sc = ff->data;
> + ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
> + } else if (ff->func == fetch_retvalue)
> + ret = snprintf(buf, n, "rv");
> + else if (ff->func == fetch_ip)
> + ret = snprintf(buf, n, "ra");
> + else if (ff->func == fetch_indirect) {
> + struct indirect_fetch_data *id = ff->data;
> + ret = snprintf(buf, n, "%+ld(", id->offset);
> + if (ret > n)
> + goto end;
> + n -= ret;
> + ret = trace_arg_string(buf, n, &id->orig);
> + if (ret > n)
> + goto end;
> + n -= ret;
> + ret = snprintf(buf, n, ")");
> + }
> +end:
> + if (ret > n)
> + return -ENOSPC;
> + return 0;
> +}
> +
> +static int register_probe_event(struct trace_probe *tp);
> +static void unregister_probe_event(struct trace_probe *tp);
> +
> +static DEFINE_MUTEX(probe_lock);
> +static LIST_HEAD(probe_list);
> +
> +static struct trace_probe *alloc_trace_probe(const char *symbol,
> + const char *event)
> +{
> + struct trace_probe *tp;
> +
> + tp = kzalloc(sizeof(struct trace_probe), GFP_KERNEL);
> + if (!tp)
> + return ERR_PTR(-ENOMEM);
> +
> + if (symbol) {
> + tp->symbol = kstrdup(symbol, GFP_KERNEL);
> + if (!tp->symbol)
> + goto error;
> + }
> + if (event) {
> + tp->call.name = kstrdup(event, GFP_KERNEL);
> + if (!tp->call.name)
> + goto error;
> + }
> +
> + INIT_LIST_HEAD(&tp->list);
> + return tp;
> +error:
> + kfree(tp->symbol);
> + kfree(tp);
> + return ERR_PTR(-ENOMEM);
> +}
> +
> +static void free_trace_probe(struct trace_probe *tp)
> +{
> + int i;
> + for (i = 0; i < tp->nr_args; i++)
> + if (tp->args[i].func == fetch_symbol)
> + free_symbol_cache(tp->args[i].data);
> + else if (tp->args[i].func == fetch_indirect)
> + free_indirect_fetch_data(tp->args[i].data);
> +
> + kfree(tp->call.name);
> + kfree(tp->symbol);
> + kfree(tp);
> +}
> +
> +static struct trace_probe *find_probe_event(const char *event)
> +{
> + struct trace_probe *tp;
> + list_for_each_entry(tp, &probe_list, list)
> + if (tp->call.name && !strcmp(tp->call.name, event))
> + return tp;
> + return NULL;
> +}
> +
> +static void __unregister_trace_probe(struct trace_probe *tp)
> +{
> + if (probe_is_return(tp))
> + unregister_kretprobe(&tp->rp);
> + else
> + unregister_kprobe(&tp->kp);
> +}
> +
> +/* Unregister a trace_probe and probe_event: call with locking probe_lock */
> +static void unregister_trace_probe(struct trace_probe *tp)
> +{
> + if (tp->call.name)
> + unregister_probe_event(tp);
> + __unregister_trace_probe(tp);
> + list_del(&tp->list);
> +}
> +
> +/* Register a trace_probe and probe_event */
> +static int register_trace_probe(struct trace_probe *tp)
> +{
> + struct trace_probe *old_tp;
> + int ret;
> +
> + mutex_lock(&probe_lock);
> +
> + if (probe_is_return(tp))
> + ret = register_kretprobe(&tp->rp);
> + else
> + ret = register_kprobe(&tp->kp);
> +
> + if (ret) {
> + pr_warning("Could not insert probe(%d)\n", ret);
> + if (ret == -EILSEQ) {
> + pr_warning("Probing address(0x%p) is not an "
> + "instruction boundary.\n",
> + probe_address(tp));
> + ret = -EINVAL;
> + }
> + goto end;
> + }
> + /* register as an event */
> + if (tp->call.name) {
> + old_tp = find_probe_event(tp->call.name);
> + if (old_tp) {
> + /* delete old event */
> + unregister_trace_probe(old_tp);
> + free_trace_probe(old_tp);
> + }
> + ret = register_probe_event(tp);
> + if (ret) {
> + pr_warning("Faild to register probe event(%d)\n", ret);
> + __unregister_trace_probe(tp);
> + }
> + }
> + list_add_tail(&tp->list, &probe_list);
> +end:
> + mutex_unlock(&probe_lock);
> + return ret;
> +}
> +
> +/* Split symbol and offset. */
> +static int split_symbol_offset(char *symbol, long *offset)
> +{
> + char *tmp;
> + int ret;
> +
> + if (!offset)
> + return -EINVAL;
> +
> + tmp = strchr(symbol, '+');
> + if (!tmp)
> + tmp = strchr(symbol, '-');
> +
> + if (tmp) {
> + /* skip sign because strict_strtol doesn't accept '+' */
> + ret = strict_strtol(tmp + 1, 0, offset);
> + if (ret)
> + return ret;
> + if (*tmp == '-')
> + *offset = -(*offset);
> + *tmp = '\0';
> + } else
> + *offset = 0;
> + return 0;
> +}
> +
> +#define PARAM_MAX_ARGS 16
> +#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
> +
> +static int parse_trace_arg(char *arg, struct fetch_func *ff, int is_return)
> +{
> + int ret = 0;
> + unsigned long param;
> + long offset;
> + char *tmp;
> +
> + switch (arg[0]) {
> + case 'a': /* argument */
> + ret = strict_strtoul(arg + 1, 10, &param);
> + if (ret || param > PARAM_MAX_ARGS)
> + ret = -EINVAL;
> + else {
> + ff->func = fetch_argument;
> + ff->data = (void *)param;
> + }
> + break;
> + case 'r': /* retval or retaddr */
> + if (is_return && arg[1] == 'v') {
> + ff->func = fetch_retvalue;
> + ff->data = NULL;
> + } else if (is_return && arg[1] == 'a') {
> + ff->func = fetch_ip;
> + ff->data = NULL;
> + } else
> + ret = -EINVAL;
> + break;
> + case '%': /* named register */
> + ret = regs_query_register_offset(arg + 1);
> + if (ret >= 0) {
> + ff->func = fetch_register;
> + ff->data = (void *)(unsigned long)ret;
> + ret = 0;
> + }
> + break;
> + case 's': /* stack */
> + ret = strict_strtoul(arg + 1, 10, &param);
> + if (ret || param > PARAM_MAX_STACK)
> + ret = -EINVAL;
> + else {
> + ff->func = fetch_stack;
> + ff->data = (void *)param;
> + }
> + break;
> + case '@': /* memory or symbol */
> + if (isdigit(arg[1])) {
> + ret = strict_strtoul(arg + 1, 0, &param);
> + if (ret)
> + break;
> + ff->func = fetch_memory;
> + ff->data = (void *)param;
> + } else {
> + ret = split_symbol_offset(arg + 1, &offset);
> + if (ret)
> + break;
> + ff->data = alloc_symbol_cache(arg + 1,
> + offset);
> + if (ff->data)
> + ff->func = fetch_symbol;
> + else
> + ret = -EINVAL;
> + }
> + break;
> + case '+': /* indirect memory */
> + case '-':
> + tmp = strchr(arg, '(');
> + if (!tmp) {
> + ret = -EINVAL;
> + break;
> + }
> + *tmp = '\0';
> + ret = strict_strtol(arg + 1, 0, &offset);
> + if (ret)
> + break;
> + if (arg[0] == '-')
> + offset = -offset;
> + arg = tmp + 1;
> + tmp = strrchr(arg, ')');
> + if (tmp) {
> + struct indirect_fetch_data *id;
> + *tmp = '\0';
> + id = kzalloc(sizeof(struct indirect_fetch_data),
> + GFP_KERNEL);
> + if (!id)
> + return -ENOMEM;
> + id->offset = offset;
> + ret = parse_trace_arg(arg, &id->orig, is_return);
> + if (ret)
> + kfree(id);
> + else {
> + ff->func = fetch_indirect;
> + ff->data = (void *)id;
> + }
> + } else
> + ret = -EINVAL;
> + break;
> + default:
> + /* TODO: support custom handler */
> + ret = -EINVAL;
> + }
> + return ret;
> +}
> +
> +static int create_trace_probe(int argc, char **argv)
> +{
> + /*
> + * Argument syntax:
> + * - Add kprobe: p[:EVENT] SYMBOL[+OFFS|-OFFS]|ADDRESS [FETCHARGS]
> + * - Add kretprobe: r[:EVENT] SYMBOL[+0] [FETCHARGS]
> + * Fetch args:
> + * aN : fetch Nth of function argument. (N:0-)
> + * rv : fetch return value
> + * ra : fetch return address
> + * sN : fetch Nth of stack (N:0-)
> + * @ADDR : fetch memory at ADDR (ADDR should be in kernel)
> + * @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
> + * %REG : fetch register REG
> + * Indirect memory fetch:
> + * +|-offs(ARG) : fetch memory at ARG +|- offs address.
> + */
> + struct trace_probe *tp;
> + struct kprobe *kp;
> + int i, ret = 0;
> + int is_return = 0;
> + char *symbol = NULL, *event = NULL;
> + long offset = 0;
> + void *addr = NULL;
> +
> + if (argc < 2)
> + return -EINVAL;
> +
> + if (argv[0][0] == 'p')
> + is_return = 0;
> + else if (argv[0][0] == 'r')
> + is_return = 1;
> + else
> + return -EINVAL;
> +
> + if (argv[0][1] == ':') {
> + event = &argv[0][2];
> + if (strlen(event) == 0) {
> + pr_info("Event name is not specifiled\n");
> + return -EINVAL;
> + }
> + }
> +
> + if (isdigit(argv[1][0])) {
> + if (is_return)
> + return -EINVAL;
> + /* an address specified */
> + ret = strict_strtoul(&argv[0][2], 0, (unsigned long *)&addr);
> + if (ret)
> + return ret;
> + } else {
> + /* a symbol specified */
> + symbol = argv[1];
> + /* TODO: support .init module functions */
> + ret = split_symbol_offset(symbol, &offset);
> + if (ret)
> + return ret;
> + if (offset && is_return)
> + return -EINVAL;
> + }
> +
> + /* setup a probe */
> + tp = alloc_trace_probe(symbol, event);
> + if (IS_ERR(tp))
> + return PTR_ERR(tp);
> +
> + if (is_return) {
> + kp = &tp->rp.kp;
> + tp->rp.handler = kretprobe_trace_func;
> + } else {
> + kp = &tp->kp;
> + tp->kp.pre_handler = kprobe_trace_func;
> + }
> +
> + if (tp->symbol) {
> + kp->symbol_name = tp->symbol;
> + kp->offset = offset;
> + } else
> + kp->addr = addr;
> +
> + /* parse arguments */
> + argc -= 2; argv += 2; ret = 0;
> + for (i = 0; i < argc && i < TRACE_KPROBE_ARGS; i++) {
> + if (strlen(argv[i]) > MAX_ARGSTR_LEN) {
> + pr_info("Argument%d(%s) is too long.\n", i, argv[i]);
> + ret = -ENOSPC;
> + goto error;
> + }
> + ret = parse_trace_arg(argv[i], &tp->args[i], is_return);
> + if (ret)
> + goto error;
> + }
> + tp->nr_args = i;
> +
> + ret = register_trace_probe(tp);
> + if (ret)
> + goto error;
> + return 0;
> +
> +error:
> + free_trace_probe(tp);
> + return ret;
> +}
> +
> +static void cleanup_all_probes(void)
> +{
> + struct trace_probe *tp;
> + mutex_lock(&probe_lock);
> + /* TODO: Use batch unregistration */
> + while (!list_empty(&probe_list)) {
> + tp = list_entry(probe_list.next, struct trace_probe, list);
> + unregister_trace_probe(tp);
> + free_trace_probe(tp);
> + }
> + mutex_unlock(&probe_lock);
> +}
> +
> +
> +/* Probes listing interfaces */
> +static void *probes_seq_start(struct seq_file *m, loff_t *pos)
> +{
> + mutex_lock(&probe_lock);
> + return seq_list_start(&probe_list, *pos);
> +}
> +
> +static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
> +{
> + return seq_list_next(v, &probe_list, pos);
> +}
> +
> +static void probes_seq_stop(struct seq_file *m, void *v)
> +{
> + mutex_unlock(&probe_lock);
> +}
> +
> +static int probes_seq_show(struct seq_file *m, void *v)
> +{
> + struct trace_probe *tp = v;
> + int i, ret;
> + char buf[MAX_ARGSTR_LEN + 1];
> +
> + if (tp == NULL)
> + return 0;
> +
> + seq_printf(m, "%c", probe_is_return(tp) ? 'r' : 'p');
> + if (tp->call.name)
> + seq_printf(m, ":%s", tp->call.name);
> +
> + if (tp->symbol)
> + seq_printf(m, " %s%+ld", probe_symbol(tp), probe_offset(tp));
> + else
> + seq_printf(m, " 0x%p", probe_address(tp));
> +
> + for (i = 0; i < tp->nr_args; i++) {
> + ret = trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
> + if (ret) {
> + pr_warning("Argument%d is too long.\n", i);
> + break;
> + }
> + seq_printf(m, " %s", buf);
> + }
> + seq_printf(m, "\n");
> + return 0;
> +}
> +
> +static const struct seq_operations probes_seq_op = {
> + .start = probes_seq_start,
> + .next = probes_seq_next,
> + .stop = probes_seq_stop,
> + .show = probes_seq_show
> +};
> +
> +static int probes_open(struct inode *inode, struct file *file)
> +{
> + if ((file->f_mode & FMODE_WRITE) &&
> + !(file->f_flags & O_APPEND))
> + cleanup_all_probes();
> +
> + return seq_open(file, &probes_seq_op);
> +}
> +
> +static int command_trace_probe(const char *buf)
> +{
> + char **argv;
> + int argc = 0, ret = 0;
> +
> + argv = argv_split(GFP_KERNEL, buf, &argc);
> + if (!argv)
> + return -ENOMEM;
> +
> + if (argc)
> + ret = create_trace_probe(argc, argv);
> +
> + argv_free(argv);
> + return ret;
> +}
> +
> +#define WRITE_BUFSIZE 128
> +
> +static ssize_t probes_write(struct file *file, const char __user *buffer,
> + size_t count, loff_t *ppos)
> +{
> + char *kbuf, *tmp;
> + int ret;
> + size_t done;
> + size_t size;
> +
> + if (!count || count < 0)
> + return 0;
> +
> + kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
> + if (!kbuf)
> + return -ENOMEM;
> +
> + ret = done = 0;
> + do {
> + size = count - done;
> + if (size > WRITE_BUFSIZE)
> + size = WRITE_BUFSIZE;
> + if (copy_from_user(kbuf, buffer + done, size)) {
> + ret = -EFAULT;
> + goto out;
> + }
> + kbuf[size] = '\0';
> + tmp = strchr(kbuf, '\n');
> + if (!tmp) {
> + pr_warning("Line length is too long: "
> + "Should be less than %d.", WRITE_BUFSIZE);
> + ret = -EINVAL;
> + goto out;
> + }
> + *tmp = '\0';
> + size = tmp - kbuf + 1;
> + done += size;
> + /* Remove comments */
> + tmp = strchr(kbuf, '#');
> + if (tmp)
> + *tmp = '\0';
> +
> + ret = command_trace_probe(kbuf);
> + if (ret)
> + goto out;
> +
> + } while (done < count);
> + ret = done;
> +out:
> + kfree(kbuf);
> + return ret;
> +}
> +
> +static const struct file_operations kprobe_events_ops = {
> + .owner = THIS_MODULE,
> + .open = probes_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = seq_release,
> + .write = probes_write,
> +};
> +
> +/* Kprobe handler */
> +static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
> +{
> + struct trace_probe *tp = container_of(kp, struct trace_probe, kp);
> + struct kprobe_trace_entry *entry;
> + struct ring_buffer_event *event;
> + int size, i, pc;
> + unsigned long irq_flags;
> + struct ftrace_event_call *call = &event_kprobe;
> + if (&tp->call.name)
> + call = &tp->call;
> +
> + local_save_flags(irq_flags);
> + pc = preempt_count();
> +
> + size = sizeof(struct kprobe_trace_entry) -
> + (sizeof(unsigned long) * (TRACE_KPROBE_ARGS - tp->nr_args));
> +
> + event = trace_current_buffer_lock_reserve(TRACE_KPROBE, size,
> + irq_flags, pc);
> + if (!event)
> + return 0;
> +
> + entry = ring_buffer_event_data(event);
> + entry->nargs = tp->nr_args;
> + entry->ip = (unsigned long)kp->addr;
> + for (i = 0; i < tp->nr_args; i++)
> + entry->args[i] = call_fetch(&tp->args[i], regs);
> +
> + if (!filter_current_check_discard(call, entry, event))
> + trace_nowake_buffer_unlock_commit(event, irq_flags, pc);
> + return 0;
> +}
> +
> +/* Kretprobe handler */
> +static __kprobes int kretprobe_trace_func(struct kretprobe_instance *ri,
> + struct pt_regs *regs)
> +{
> + struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
> + struct kretprobe_trace_entry *entry;
> + struct ring_buffer_event *event;
> + int size, i, pc;
> + unsigned long irq_flags;
> + struct ftrace_event_call *call = &event_kretprobe;
> + if (&tp->call.name)
> + call = &tp->call;
> +
> + local_save_flags(irq_flags);
> + pc = preempt_count();
> +
> + size = sizeof(struct kretprobe_trace_entry) -
> + (sizeof(unsigned long) * (TRACE_KPROBE_ARGS - tp->nr_args));
> +
> + event = trace_current_buffer_lock_reserve(TRACE_KRETPROBE, size,
> + irq_flags, pc);
> + if (!event)
> + return 0;
> +
> + entry = ring_buffer_event_data(event);
> + entry->nargs = tp->nr_args;
> + entry->func = (unsigned long)probe_address(tp);
> + entry->ret_ip = (unsigned long)ri->ret_addr;
> + for (i = 0; i < tp->nr_args; i++)
> + entry->args[i] = call_fetch(&tp->args[i], regs);
> +
> + if (!filter_current_check_discard(call, entry, event))
> + trace_nowake_buffer_unlock_commit(event, irq_flags, pc);
> +
> + return 0;
> +}
> +
> +/* Event entry printers */
> +enum print_line_t
> +print_kprobe_event(struct trace_iterator *iter, int flags)
> +{
> + struct kprobe_trace_entry *field;
> + struct trace_seq *s = &iter->seq;
> + int i;
> +
> + trace_assign_type(field, iter->ent);
> +
> + if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
> + goto partial;
> +
> + if (!trace_seq_puts(s, ":"))
> + goto partial;
> +
> + for (i = 0; i < field->nargs; i++)
> + if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
> + goto partial;
> +
> + if (!trace_seq_puts(s, "\n"))
> + goto partial;
> +
> + return TRACE_TYPE_HANDLED;
> +partial:
> + return TRACE_TYPE_PARTIAL_LINE;
> +}
> +
> +enum print_line_t
> +print_kretprobe_event(struct trace_iterator *iter, int flags)
> +{
> + struct kretprobe_trace_entry *field;
> + struct trace_seq *s = &iter->seq;
> + int i;
> +
> + trace_assign_type(field, iter->ent);
> +
> + if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
> + goto partial;
> +
> + if (!trace_seq_puts(s, " <- "))
> + goto partial;
> +
> + if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
> + goto partial;
> +
> + if (!trace_seq_puts(s, ":"))
> + goto partial;
> +
> + for (i = 0; i < field->nargs; i++)
> + if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
> + goto partial;
> +
> + if (!trace_seq_puts(s, "\n"))
> + goto partial;
> +
> + return TRACE_TYPE_HANDLED;
> +partial:
> + return TRACE_TYPE_PARTIAL_LINE;
> +}
> +
> +static struct trace_event kprobe_trace_event = {
> + .type = TRACE_KPROBE,
> + .trace = print_kprobe_event,
> +};
> +
> +static struct trace_event kretprobe_trace_event = {
> + .type = TRACE_KRETPROBE,
> + .trace = print_kretprobe_event,
> +};
> +
> +static int probe_event_enable(struct ftrace_event_call *call)
> +{
> + struct trace_probe *tp = container_of(call, struct trace_probe, call);
> + if (probe_is_return(tp))
> + return enable_kretprobe(&tp->rp);
> + else
> + return enable_kprobe(&tp->kp);
> +}
> +
> +static void probe_event_disable(struct ftrace_event_call *call)
> +{
> + struct trace_probe *tp = container_of(call, struct trace_probe, call);
> + if (probe_is_return(tp))
> + disable_kretprobe(&tp->rp);
> + else
> + disable_kprobe(&tp->kp);
> +}
> +
> +static int probe_event_raw_init(struct ftrace_event_call *event_call)
> +{
> + INIT_LIST_HEAD(&event_call->fields);
> + init_preds(event_call);
> + return 0;
> +}
> +
> +#undef DEFINE_FIELD
> +#define DEFINE_FIELD(type, item, name, is_signed) \
> + do { \
> + ret = trace_define_field(event_call, #type, name, \
> + offsetof(typeof(field), item), \
> + sizeof(field.item), is_signed);\
> + if (ret) \
> + return ret; \
> + } while (0)
> +
> +static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
> +{
> + int ret, i;
> + struct kprobe_trace_entry field;
> + char buf[MAX_ARGSTR_LEN + 1];
> + struct trace_probe *tp = container_of(event_call,
> + struct trace_probe, call);
> +
> + __common_field(int, type, 1);
> + __common_field(unsigned char, flags, 0);
> + __common_field(unsigned char, preempt_count, 0);
> + __common_field(int, pid, 1);
> + __common_field(int, tgid, 1);
> +
> + DEFINE_FIELD(unsigned long, ip, "ip", 0);
> + DEFINE_FIELD(int, nargs, "nargs", 1);
> + for (i = 0; i < tp->nr_args; i++) {
> + /* Set argN as a field */
> + sprintf(buf, "arg%d", i);
> + DEFINE_FIELD(unsigned long, args[i], buf, 0);
> + /* Set argument string as an alias field */
> + ret = trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
> + if (ret)
> + return ret;
> + DEFINE_FIELD(unsigned long, args[i], buf, 0);
> + }
> + return 0;
> +}
> +
> +static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
> +{
> + int ret, i;
> + struct kretprobe_trace_entry field;
> + char buf[MAX_ARGSTR_LEN + 1];
> + struct trace_probe *tp = container_of(event_call,
> + struct trace_probe, call);
> +
> + __common_field(int, type, 1);
> + __common_field(unsigned char, flags, 0);
> + __common_field(unsigned char, preempt_count, 0);
> + __common_field(int, pid, 1);
> + __common_field(int, tgid, 1);
> +
> + DEFINE_FIELD(unsigned long, func, "func", 0);
> + DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
> + DEFINE_FIELD(int, nargs, "nargs", 1);
> + for (i = 0; i < tp->nr_args; i++) {
> + /* Set argN as a field */
> + sprintf(buf, "arg%d", i);
> + DEFINE_FIELD(unsigned long, args[i], buf, 0);
> + /* Set argument string as an alias field */
> + ret = trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
> + if (ret)
> + return ret;
> + DEFINE_FIELD(unsigned long, args[i], buf, 0);
> + }
> + return 0;
> +}
> +
> +static int __probe_event_show_format(struct ftrace_event_call *call,
> + struct trace_seq *s, const char *fmt,
> + const char *arg)
> +{
> + int i;
> + char buf[MAX_ARGSTR_LEN + 1];
> + struct trace_probe *tp = container_of(call, struct trace_probe, call);
> +
> + /* Show aliases */
> + for (i = 0; i < tp->nr_args; i++) {
> + if (trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]))
> + return 0;
> + if (!trace_seq_printf(s, "\talias: %s;\toriginal: arg%d;\n",
> + buf, i))
> + return 0;
> + }
> + /* Show format */
> + if (!trace_seq_printf(s, "\nprint fmt: \"%s", fmt))
> + return 0;
> +
> + for (i = 0; i < tp->nr_args; i++)
> + if (!trace_seq_puts(s, " 0x%lx"))
> + return 0;
> +
> + if (!trace_seq_printf(s, "\", %s", arg))
> + return 0;
> +
> + for (i = 0; i < tp->nr_args; i++)
> + if (!trace_seq_printf(s, ", arg%d", i))
> + return 0;
> +
> + return trace_seq_puts(s, "\n");
> +}
> +
> +#undef SHOW_FIELD
> +#define SHOW_FIELD(type, item, name) \
> + do { \
> + ret = trace_seq_printf(s, "\tfield: " #type " %s;\t" \
> + "offset:%u;tsize:%u;\n", name, \
> + (unsigned)offsetof(typeof(field), item),\
> + (unsigned)sizeof(type)); \
> + if (!ret) \
> + return 0; \
> + } while (0)
> +
> +static int kprobe_event_show_format(struct ftrace_event_call *call,
> + struct trace_seq *s)
> +{
> + struct kprobe_trace_entry field __attribute__((unused));
> + int ret, i;
> + char buf[8];
> + struct trace_probe *tp = container_of(call, struct trace_probe, call);
> +
> + SHOW_FIELD(unsigned long, ip, "ip");
> + SHOW_FIELD(int, nargs, "nargs");
> +
> + /* Show fields */
> + for (i = 0; i < tp->nr_args; i++) {
> + sprintf(buf, "arg%d", i);
> + SHOW_FIELD(unsigned long, args[i], buf);
> + }
> + trace_seq_puts(s, "\n");
> +
> + return __probe_event_show_format(call, s, "%lx:", "ip");
> +}
> +
> +static int kretprobe_event_show_format(struct ftrace_event_call *call,
> + struct trace_seq *s)
> +{
> + struct kretprobe_trace_entry field __attribute__((unused));
> + int ret, i;
> + char buf[8];
> + struct trace_probe *tp = container_of(call, struct trace_probe, call);
> +
> + SHOW_FIELD(unsigned long, func, "func");
> + SHOW_FIELD(unsigned long, ret_ip, "ret_ip");
> + SHOW_FIELD(int, nargs, "nargs");
> +
> + /* Show fields */
> + for (i = 0; i < tp->nr_args; i++) {
> + sprintf(buf, "arg%d", i);
> + SHOW_FIELD(unsigned long, args[i], buf);
> + }
> + trace_seq_puts(s, "\n");
> +
> + return __probe_event_show_format(call, s, "%lx <- %lx:",
> + "func, ret_ip");
> +}
> +
> +static int register_probe_event(struct trace_probe *tp)
> +{
> + struct ftrace_event_call *call = &tp->call;
> + int ret;
> +
> + /* Initialize ftrace_event_call */
> + call->system = "kprobes";
> + if (probe_is_return(tp)) {
> + call->event = &kretprobe_trace_event;
> + call->id = TRACE_KRETPROBE;
> + call->raw_init = probe_event_raw_init;
> + call->show_format = kretprobe_event_show_format;
> + call->define_fields = kretprobe_event_define_fields;
> + } else {
> + call->event = &kprobe_trace_event;
> + call->id = TRACE_KPROBE;
> + call->raw_init = probe_event_raw_init;
> + call->show_format = kprobe_event_show_format;
> + call->define_fields = kprobe_event_define_fields;
> + }
> + call->enabled = 1;
> + call->regfunc = probe_event_enable;
> + call->unregfunc = probe_event_disable;
> + ret = trace_add_event_call(call);
> + if (ret)
> + pr_info("Failed to register kprobe event: %s\n", call->name);
> + return ret;
> +}
> +
> +static void unregister_probe_event(struct trace_probe *tp)
> +{
> + /*
> + * Prevent to unregister event itself because the event is shared
> + * among other probes.
> + */
> + tp->call.event = NULL;
> + trace_remove_event_call(&tp->call);
> +}
> +
> +/* Make a debugfs interface for controling probe points */
> +static __init int init_kprobe_trace(void)
> +{
> + struct dentry *d_tracer;
> + struct dentry *entry;
> + int ret;
> +
> + ret = register_ftrace_event(&kprobe_trace_event);
> + if (!ret) {
> + pr_warning("Could not register kprobe_trace_event type.\n");
> + return 0;
> + }
> + ret = register_ftrace_event(&kretprobe_trace_event);
> + if (!ret) {
> + pr_warning("Could not register kretprobe_trace_event type.\n");
> + return 0;
> + }
> +
> + d_tracer = tracing_init_dentry();
> + if (!d_tracer)
> + return 0;
> +
> + entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
> + NULL, &kprobe_events_ops);
> +
> + if (!entry)
> + pr_warning("Could not create debugfs "
> + "'kprobe_events' entry\n");
> + return 0;
> +}
> +fs_initcall(init_kprobe_trace);
> +
> +
> +#ifdef CONFIG_FTRACE_STARTUP_TEST
> +
> +static int kprobe_trace_selftest_target(int a1, int a2, int a3,
> + int a4, int a5, int a6)
> +{
> + return a1 + a2 + a3 + a4 + a5 + a6;
> +}
> +
> +static __init int kprobe_trace_self_tests_init(void)
> +{
> + int ret;
> + int (*target)(int, int, int, int, int, int);
> + target = kprobe_trace_selftest_target;
> +
> + pr_info("Testing kprobe tracing: ");
> +
> + ret = command_trace_probe("p:testprobe kprobe_trace_selftest_target "
> + "a1 a2 a3 a4 a5 a6");
> + if (WARN_ON_ONCE(ret))
> + pr_warning("error enabling function entry\n");
> +
> + ret = command_trace_probe("r:testprobe2 kprobe_trace_selftest_target "
> + "ra rv");
> + if (WARN_ON_ONCE(ret))
> + pr_warning("error enabling function return\n");
> +
> + ret = target(1, 2, 3, 4, 5, 6);
> +
> + cleanup_all_probes();
> +
> + pr_cont("OK\n");
> + return 0;
> +}
> +
> +late_initcall(kprobe_trace_self_tests_init);
> +
> +#endif
>
>
> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America), Inc.
> Software Solutions Division
>
> e-mail: mhiramat@redhat.com