From b7dcb857cc3eb89136111fefe89780129c1af1d7 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Wed, 19 May 2010 15:57:49 -0400 Subject: 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 Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Frederic Weisbecker LKML-Reference: <20100519195749.2885.17451.stgit@localhost6.localdomain6> Signed-off-by: Masami Hiramatsu Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-event.c | 15 ++++++-- tools/perf/util/probe-finder.c | 85 ++++++++++++++++++++++++++++++------------ 2 files changed, 73 insertions(+), 27 deletions(-) (limited to 'tools') diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 351baa9a369..09cf5465e10 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -926,6 +926,7 @@ out: 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; diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 308664deb85..3e64e1fa105 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -406,14 +406,50 @@ static Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name, * Probe finder related functions */ +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_location(Dwarf_Op *op, struct probe_finder *pf) +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 @@ next: /* 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 */ -- cgit v1.2.3-18-g5258