[PATCH v2 3/3] tracing: make "string" the default type for [ku]probe event $comm
From: Omar Sandoval
Date: Thu Jun 02 2016 - 21:11:34 EST
From: Omar Sandoval <osandov@xxxxxx>
You'd only ever want $comm as a string, but the default is still u64.
Push the type parsing later so we can decide based on the actual
fetcharg and make "string" the default for $comm.
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
---
Documentation/trace/kprobetrace.txt | 6 +--
Documentation/trace/uprobetracer.txt | 6 +--
kernel/trace/trace_probe.c | 102 +++++++++++++++++++++++------------
3 files changed, 75 insertions(+), 39 deletions(-)
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 0bf746656d06..da3b437d4e5e 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -40,7 +40,7 @@ Synopsis of kprobe_events
$stackN : Fetch Nth entry of stack (N >= 0)
$stack : Fetch stack address.
$retval : Fetch return value.(*)
- $comm : Fetch current task comm.(***)
+ $comm : Fetch current task comm.
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
@@ -49,7 +49,6 @@ Synopsis of kprobe_events
(*) only for return probe.
(**) this is useful for fetching a field of data structures.
- (***) you probably want this as a string, i.e., $comm:string
Types
-----
@@ -65,7 +64,8 @@ offset, and container-size (usually 32). The syntax is;
b<bit-width>@<bit-offset>/<container-size>
-For $comm, the type must be either "string" or "string_size".
+For $comm, the type must be either "string" or "string_size". The default is
+"string".
Per-Probe Event Filtering
diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.txt
index 34754da46860..5daa61cf431a 100644
--- a/Documentation/trace/uprobetracer.txt
+++ b/Documentation/trace/uprobetracer.txt
@@ -36,7 +36,7 @@ Synopsis of uprobe_tracer
$stackN : Fetch Nth entry of stack (N >= 0)
$stack : Fetch stack address.
$retval : Fetch return value.(*)
- $comm : Fetch current task comm.(***)
+ $comm : Fetch current task comm.
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
@@ -45,7 +45,6 @@ Synopsis of uprobe_tracer
(*) only for return probe.
(**) this is useful for fetching a field of data structures.
- (***) you probably want this as a string, i.e., $comm:string
Types
-----
@@ -60,7 +59,8 @@ offset, and container-size (usually 32). The syntax is;
b<bit-width>@<bit-offset>/<container-size>
-For $comm, the type must be either "string" or "string_size".
+For $comm, the type must be either "string" or "string_size". The default is
+"string".
Event Profiling
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 3900b6e4a05d..6b0a553308f9 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -296,6 +296,26 @@ static void fetch_user_stack_address(struct pt_regs *regs, void *dummy, void *de
}
NOKPROBE_SYMBOL(fetch_user_stack_address);
+static int parse_fetch_type(const char *t, ssize_t *size,
+ const struct fetch_type **tp,
+ const struct fetch_type *ftbl,
+ const char *default_t)
+{
+ if (!t)
+ t = default_t;
+
+ *tp = find_fetch_type(t, ftbl);
+ if (!*tp) {
+ pr_info("Unsupported type: %s\n", t);
+ return -EINVAL;
+ }
+
+ if (size)
+ *size += (*tp)->size;
+
+ return 0;
+}
+
static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
fetch_func_t orig_fn,
const struct fetch_type *ftbl)
@@ -339,21 +359,28 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
-static int parse_probe_vars(char *arg, const struct fetch_type *t,
- struct fetch_param *f, bool is_return,
- bool is_kprobe)
+static int parse_probe_vars(char *arg, const char *t, ssize_t *size,
+ const struct fetch_type **tp, struct fetch_param *f,
+ bool is_return, bool is_kprobe,
+ const struct fetch_type *ftbl)
{
int ret = 0;
unsigned long param;
if (strcmp(arg, "retval") == 0) {
+ ret = parse_fetch_type(t, size, tp, ftbl, NULL);
+ if (ret)
+ return ret;
if (is_return)
- f->fn = t->fetch[FETCH_MTD_retval];
+ f->fn = (*tp)->fetch[FETCH_MTD_retval];
else
ret = -EINVAL;
} else if (strncmp(arg, "stack", 5) == 0) {
+ ret = parse_fetch_type(t, size, tp, ftbl, NULL);
+ if (ret)
+ return ret;
if (arg[5] == '\0') {
- if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
+ if (strcmp((*tp)->name, DEFAULT_FETCH_TYPE_STR))
return -EINVAL;
if (is_kprobe)
@@ -365,16 +392,19 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
if (ret || (is_kprobe && param > PARAM_MAX_STACK))
ret = -EINVAL;
else {
- f->fn = t->fetch[FETCH_MTD_stack];
+ f->fn = (*tp)->fetch[FETCH_MTD_stack];
f->data = (void *)param;
}
} else
ret = -EINVAL;
} else if (strcmp(arg, "comm") == 0) {
- if (strcmp(t->name, "string") != 0 &&
- strcmp(t->name, "string_size") != 0)
+ ret = parse_fetch_type(t, size, tp, ftbl, "string");
+ if (ret)
+ return ret;
+ if (strcmp((*tp)->name, "string") != 0 &&
+ strcmp((*tp)->name, "string_size") != 0)
return -EINVAL;
- f->fn = t->fetch[FETCH_MTD_comm];
+ f->fn = (*tp)->fetch[FETCH_MTD_comm];
} else
ret = -EINVAL;
@@ -382,9 +412,10 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
}
/* Recursive argument parser */
-static int parse_probe_arg(char *arg, const struct fetch_type *t,
- struct fetch_param *f, bool is_return, bool is_kprobe,
- const struct fetch_type *ftbl)
+static int parse_probe_arg(char *arg, const char *t, ssize_t *size,
+ const struct fetch_type **tp,
+ struct fetch_param *f, bool is_return,
+ bool is_kprobe, const struct fetch_type *ftbl)
{
unsigned long param;
long offset;
@@ -393,25 +424,32 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
switch (arg[0]) {
case '$':
- ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
+ ret = parse_probe_vars(arg + 1, t, size, tp, f, is_return,
+ is_kprobe, ftbl);
break;
case '%': /* named register */
+ ret = parse_fetch_type(t, size, tp, ftbl, NULL);
+ if (ret)
+ break;
ret = regs_query_register_offset(arg + 1);
if (ret >= 0) {
- f->fn = t->fetch[FETCH_MTD_reg];
+ f->fn = (*tp)->fetch[FETCH_MTD_reg];
f->data = (void *)(unsigned long)ret;
ret = 0;
}
break;
case '@': /* memory, file-offset or symbol */
+ ret = parse_fetch_type(t, size, tp, ftbl, NULL);
+ if (ret)
+ break;
if (isdigit(arg[1])) {
ret = kstrtoul(arg + 1, 0, ¶m);
if (ret)
break;
- f->fn = t->fetch[FETCH_MTD_memory];
+ f->fn = (*tp)->fetch[FETCH_MTD_memory];
f->data = (void *)param;
} else if (arg[1] == '+') {
/* kprobes don't support file offsets */
@@ -422,7 +460,7 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
if (ret)
break;
- f->fn = t->fetch[FETCH_MTD_file_offset];
+ f->fn = (*tp)->fetch[FETCH_MTD_file_offset];
f->data = (void *)offset;
} else {
/* uprobes don't support symbols */
@@ -435,13 +473,16 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
f->data = alloc_symbol_cache(arg + 1, offset);
if (f->data)
- f->fn = t->fetch[FETCH_MTD_symbol];
+ f->fn = (*tp)->fetch[FETCH_MTD_symbol];
}
break;
case '+': /* deref memory */
arg++; /* Skip '+', because kstrtol() rejects it. */
case '-':
+ ret = parse_fetch_type(t, size, tp, ftbl, NULL);
+ if (ret)
+ break;
tmp = strchr(arg, '(');
if (!tmp)
break;
@@ -459,7 +500,6 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
struct deref_fetch_param *dprm;
const struct fetch_type *t2;
- t2 = find_fetch_type(NULL, ftbl);
*tmp = '\0';
dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
@@ -467,22 +507,24 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
return -ENOMEM;
dprm->offset = offset;
- dprm->fetch = t->fetch[FETCH_MTD_memory];
- dprm->fetch_size = get_fetch_size_function(t,
- dprm->fetch, ftbl);
- ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
- is_kprobe, ftbl);
+ dprm->fetch = (*tp)->fetch[FETCH_MTD_memory];
+ dprm->fetch_size = get_fetch_size_function((*tp),
+ dprm->fetch,
+ ftbl);
+ ret = parse_probe_arg(arg, NULL, NULL, &t2, &dprm->orig,
+ is_return, is_kprobe, ftbl);
if (ret)
kfree(dprm);
else {
- f->fn = t->fetch[FETCH_MTD_deref];
+ f->fn = (*tp)->fetch[FETCH_MTD_deref];
f->data = (void *)dprm;
}
}
break;
}
if (!ret && !f->fn) { /* Parsed, but do not find fetch method */
- pr_info("%s type has no corresponding fetch method.\n", t->name);
+ pr_info("%s type has no corresponding fetch method.\n",
+ (*tp)->name);
ret = -EINVAL;
}
@@ -549,15 +591,9 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
arg[t - parg->comm] = '\0';
t++;
}
- parg->type = find_fetch_type(t, ftbl);
- if (!parg->type) {
- pr_info("Unsupported type: %s\n", t);
- return -EINVAL;
- }
parg->offset = *size;
- *size += parg->type->size;
- ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
- is_kprobe, ftbl);
+ ret = parse_probe_arg(arg, t, size, &parg->type, &parg->fetch,
+ is_return, is_kprobe, ftbl);
if (ret >= 0 && t != NULL)
ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
--
2.8.3