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tracing/kprobe: Drop function argument access syntax

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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
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) @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
$stackN : Fetch Nth entry of stack (N >= 0) $stackN : Fetch Nth entry of stack (N >= 0)
$stack : Fetch stack address. $stack : Fetch stack address.
$argN : Fetch function argument. (N >= 0)(*) $retval : Fetch return value.(*)
$retval : Fetch return value.(**) +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
NAME=FETCHARG: Set NAME as the argument name of FETCHARG. NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
(*) aN may not correct on asmlinkaged functions and at the middle of (*) only for return probe.
function body. (**) this is useful for fetching a field of data structures.
(**) only for return probe.
(***) this is useful for fetching a field of data structures.
Per-Probe Event Filtering Per-Probe Event Filtering
@@ -82,11 +79,14 @@ Usage examples
To add a probe as a new event, write a new definition to kprobe_events To add a probe as a new event, write a new definition to kprobe_events
as below. as below.
echo p:myprobe do_sys_open dfd=$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 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 1st to 4th arguments as "myprobe" event. Note, which register/stack entry is
choose more familiar names for each arguments. 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 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 SYMBOL(e.g. "sys_open+0x1b/0x1d <- do_sys_open" means kernel
returns from do_sys_open to sys_open+0x1b). 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; 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, static __kprobes unsigned long fetch_retvalue(struct pt_regs *regs,
void *dummy) void *dummy)
{ {
@@ -231,9 +226,7 @@ static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
{ {
int ret = -EINVAL; int ret = -EINVAL;
if (ff->func == fetch_argument) if (ff->func == fetch_register) {
ret = snprintf(buf, n, "$arg%lu", (unsigned long)ff->data);
else if (ff->func == fetch_register) {
const char *name; const char *name;
name = regs_query_register_name((unsigned int)((long)ff->data)); name = regs_query_register_name((unsigned int)((long)ff->data));
ret = snprintf(buf, n, "%%%s", name); 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 } else
ret = -EINVAL; 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 } else
ret = -EINVAL; ret = -EINVAL;
return ret; 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 kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
* - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS] * - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
* Fetch args: * Fetch args:
* $argN : fetch Nth of function argument. (N:0-)
* $retval : fetch return value * $retval : fetch return value
* $stack : fetch stack address * $stack : fetch stack address
* $stackN : fetch Nth of stack (N:0-) * $stackN : fetch Nth of stack (N:0-)