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tracing/kprobe: Drop function argument access syntax 

Drop function argument access syntax, because the function
arguments depend on not only architecture but also
compile-options and function API. And now, we have perf-probe
for finding register/memory assigned to each argument.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Neuling <mikey@neuling.org>
Cc: linuxppc-dev@ozlabs.org
LKML-Reference: <20100105224648.19431.52309.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Masami Hiramatsu 2010-01-05 17:46:48 -05:00 committed by Ingo Molnar
parent ec3a903960
commit 14640106f2
2 changed files with 11 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
Documentation/trace/kprobetrace.txt
View File

@ -37,15 +37,12 @@ Synopsis of kprobe_events
@SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
$stackN : Fetch Nth entry of stack (N >= 0)
$stack : Fetch stack address.
$argN : Fetch function argument. (N >= 0)(*)
$retval : Fetch return value.(**)
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
$retval : Fetch return value.(*)
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
(*) aN may not correct on asmlinkaged functions and at the middle of
function body.
(**) only for return probe.
(***) this is useful for fetching a field of data structures.
(*) only for return probe.
(**) this is useful for fetching a field of data structures.
Per-Probe Event Filtering
@ -82,11 +79,14 @@ Usage examples
To add a probe as a new event, write a new definition to kprobe_events
as below.
echo p:myprobe do_sys_open dfd=$arg0 filename=$arg1 flags=$arg2 mode=$arg3 > /sys/kernel/debug/tracing/kprobe_events
echo p:myprobe do_sys_open dfd=%ax filename=%dx flags=%cx mode=+4($stack) > /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. As this example shows, users can
choose more familiar names for each arguments.
1st to 4th arguments as "myprobe" event. Note, which register/stack entry is
assigned to each function argument depends on arch-specific ABI. If you unsure
the ABI, please try to use probe subcommand of perf-tools (you can find it
under tools/perf/).
As this example shows, users can choose more familiar names for each arguments.
echo r:myretprobe do_sys_open $retval >> /sys/kernel/debug/tracing/kprobe_events
@ -147,4 +147,3 @@ events, you need to enable it.
returns from SYMBOL(e.g. "sys_open+0x1b/0x1d <- do_sys_open" means kernel
returns from do_sys_open to sys_open+0x1b).

18
kernel/trace/trace_kprobe.c
View File

@ -91,11 +91,6 @@ static __kprobes unsigned long fetch_memory(struct pt_regs *regs, void *addr)
return retval;
}
static __kprobes unsigned long fetch_argument(struct pt_regs *regs, void *num)
{
return regs_get_argument_nth(regs, (unsigned int)((unsigned long)num));
}
static __kprobes unsigned long fetch_retvalue(struct pt_regs *regs,
void *dummy)
{
@ -231,9 +226,7 @@ static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
{
int ret = -EINVAL;
if (ff->func == fetch_argument)
ret = snprintf(buf, n, "$arg%lu", (unsigned long)ff->data);
else if (ff->func == fetch_register) {
if (ff->func == fetch_register) {
const char *name;
name = regs_query_register_name((unsigned int)((long)ff->data));
ret = snprintf(buf, n, "%%%s", name);
@ -489,14 +482,6 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
}
} else
ret = -EINVAL;
} else if (strncmp(arg, "arg", 3) == 0 && isdigit(arg[3])) {
ret = strict_strtoul(arg + 3, 10, &param);
if (ret || param > PARAM_MAX_ARGS)
ret = -EINVAL;
else {
ff->func = fetch_argument;
ff->data = (void *)param;
}
} else
ret = -EINVAL;
return ret;
@ -611,7 +596,6 @@ static int create_trace_probe(int argc, char **argv)
* - Add kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
* - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
* Fetch args:
* $argN : fetch Nth of function argument. (N:0-)
* $retval : fetch return value
* $stack : fetch stack address
* $stackN : fetch Nth of stack (N:0-)