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perf probe: Support static and global variables 

Add static and global variables support to perf probe.
This allows user to trace non-local variables (and
structure members) at probe points.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100519195749.2885.17451.stgit@localhost6.localdomain6>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Masami Hiramatsu 2010-05-19 15:57:49 -04:00 committed by Arnaldo Carvalho de Melo
parent b2a3c12b74
commit b7dcb857cc
2 changed files with 74 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
tools/perf/util/probe-event.c
View File

@ -926,6 +926,7 @@ static int __synthesize_kprobe_trace_arg_ref(struct kprobe_trace_arg_ref *ref,
static int synthesize_kprobe_trace_arg(struct kprobe_trace_arg *arg,
char *buf, size_t buflen)
{
struct kprobe_trace_arg_ref *ref = arg->ref;
int ret, depth = 0;
char *tmp = buf;
@ -939,16 +940,24 @@ static int synthesize_kprobe_trace_arg(struct kprobe_trace_arg *arg,
buf += ret;
buflen -= ret;
/* Special case: @XXX */
if (arg->value[0] == '@' && arg->ref)
ref = ref->next;
/* Dereferencing arguments */
if (arg->ref) {
depth = __synthesize_kprobe_trace_arg_ref(arg->ref, &buf,
if (ref) {
depth = __synthesize_kprobe_trace_arg_ref(ref, &buf,
&buflen, 1);
if (depth < 0)
return depth;
}
/* Print argument value */
ret = e_snprintf(buf, buflen, "%s", arg->value);
if (arg->value[0] == '@' && arg->ref)
ret = e_snprintf(buf, buflen, "%s%+ld", arg->value,
arg->ref->offset);
else
ret = e_snprintf(buf, buflen, "%s", arg->value);
if (ret < 0)
return ret;
buf += ret;

87
tools/perf/util/probe-finder.c
View File

@ -406,14 +406,50 @@ static Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
* Probe finder related functions
*/
/* Show a location */
static int convert_location(Dwarf_Op *op, struct probe_finder *pf)
static struct kprobe_trace_arg_ref *alloc_trace_arg_ref(long offs)
{
struct kprobe_trace_arg_ref *ref;
ref = zalloc(sizeof(struct kprobe_trace_arg_ref));
if (ref != NULL)
ref->offset = offs;
return ref;
}
/* Show a location */
static int convert_variable_location(Dwarf_Die *vr_die, struct probe_finder *pf)
{
Dwarf_Attribute attr;
Dwarf_Op *op;
size_t nops;
unsigned int regn;
Dwarf_Word offs = 0;
bool ref = false;
const char *regs;
struct kprobe_trace_arg *tvar = pf->tvar;
int ret;
/* TODO: handle more than 1 exprs */
if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL ||
dwarf_getlocation_addr(&attr, pf->addr, &op, &nops, 1) <= 0 ||
nops == 0) {
/* TODO: Support const_value */
pr_err("Failed to find the location of %s at this address.\n"
" Perhaps, it has been optimized out.\n", pf->pvar->var);
return -ENOENT;
}
if (op->atom == DW_OP_addr) {
/* Static variables on memory (not stack), make @varname */
ret = strlen(dwarf_diename(vr_die));
tvar->value = zalloc(ret + 2);
if (tvar->value == NULL)
return -ENOMEM;
snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
tvar->ref = alloc_trace_arg_ref((long)offs);
if (tvar->ref == NULL)
return -ENOMEM;
return 0;
}
/* If this is based on frame buffer, set the offset */
if (op->atom == DW_OP_fbreg) {
@ -455,10 +491,9 @@ static int convert_location(Dwarf_Op *op, struct probe_finder *pf)
return -ENOMEM;
if (ref) {
tvar->ref = zalloc(sizeof(struct kprobe_trace_arg_ref));
tvar->ref = alloc_trace_arg_ref((long)offs);
if (tvar->ref == NULL)
return -ENOMEM;
tvar->ref->offset = (long)offs;
}
return 0;
}
@ -666,20 +701,13 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
/* Show a variables in kprobe event format */
static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
{
Dwarf_Attribute attr;
Dwarf_Die die_mem;
Dwarf_Op *expr;
size_t nexpr;
int ret;
if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
goto error;
/* TODO: handle more than 1 exprs */
ret = dwarf_getlocation_addr(&attr, pf->addr, &expr, &nexpr, 1);
if (ret <= 0 || nexpr == 0)
goto error;
pr_debug("Converting variable %s into trace event.\n",
dwarf_diename(vr_die));
ret = convert_location(expr, pf);
ret = convert_variable_location(vr_die, pf);
if (ret == 0 && pf->pvar->field) {
ret = convert_variable_fields(vr_die, pf->pvar->var,
pf->pvar->field, &pf->tvar->ref,
@ -690,19 +718,14 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type);
/* *expr will be cached in libdw. Don't free it. */
return ret;
error:
/* TODO: Support const_value */
pr_err("Failed to find the location of %s at this address.\n"
" Perhaps, it has been optimized out.\n", pf->pvar->var);
return -ENOENT;
}
/* Find a variable in a subprogram die */
static int find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
{
Dwarf_Die vr_die;
Dwarf_Die vr_die, *scopes;
char buf[32], *ptr;
int ret;
int ret, nscopes;
if (pf->pvar->name)
pf->tvar->name = strdup(pf->pvar->name);
@ -730,12 +753,26 @@ static int find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
pr_debug("Searching '%s' variable in context.\n",
pf->pvar->var);
/* Search child die for local variables and parameters. */
if (!die_find_variable(sp_die, pf->pvar->var, &vr_die)) {
if (die_find_variable(sp_die, pf->pvar->var, &vr_die))
ret = convert_variable(&vr_die, pf);
else {
/* Search upper class */
nscopes = dwarf_getscopes_die(sp_die, &scopes);
if (nscopes > 0) {
ret = dwarf_getscopevar(scopes, nscopes, pf->pvar->var,
0, NULL, 0, 0, &vr_die);
if (ret >= 0)
ret = convert_variable(&vr_die, pf);
else
ret = -ENOENT;
free(scopes);
} else
ret = -ENOENT;
}
if (ret < 0)
pr_warning("Failed to find '%s' in this function.\n",
pf->pvar->var);
return -ENOENT;
}
return convert_variable(&vr_die, pf);
return ret;
}
/* Show a probe point to output buffer */