From 221d061182b8ff5507d5768aeeecbc74f01c5dfa Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 11 Aug 2011 20:02:59 +0900 Subject: perf probe: Fix to search local variables in appropriate scope Fix perf probe to search local variables in appropriate local inlined function scope. For example, pre_schedule() has only 2 local variables, as below; $ perf probe -L pre_schedule 0 static inline void pre_schedule(struct rq *rq, struct task_struct *prev) { 2 if (prev->sched_class->pre_schedule) 3 prev->sched_class->pre_schedule(rq, prev); } However, current perf probe shows 4 local variables on pre_schedule(), because it searches variables in the caller(schedule()) scope. $ perf probe -V pre_schedule Available variables at pre_schedule @ int cpu long unsigned int* switch_count struct rq* rq struct task_struct* prev This patch fixes this issue by searching variables in the local scope of the instance of inlined function. Here is the result. $ perf probe -V pre_schedule Available variables at pre_schedule @ struct rq* rq struct task_struct* prev Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Paul Mackerras Cc: Pekka Enberg Cc: Peter Zijlstra Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20110811110259.19900.85664.stgit@fedora15 Signed-off-by: Masami Hiramatsu Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/dwarf-aux.c | 33 +++++++++++ tools/perf/util/dwarf-aux.h | 4 ++ tools/perf/util/probe-finder.c | 132 +++++++++++++++++++++++++++++++++-------- tools/perf/util/probe-finder.h | 2 +- 4 files changed, 144 insertions(+), 27 deletions(-) (limited to 'tools') diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index d9b8ad098498..425703a58638 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -96,6 +96,39 @@ int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr, return *lineno ?: -ENOENT; } +static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data); + +/** + * cu_walk_functions_at - Walk on function DIEs at given address + * @cu_die: A CU DIE + * @addr: An address + * @callback: A callback which called with found DIEs + * @data: A user data + * + * Walk on function DIEs at given @addr in @cu_die. Passed DIEs + * should be subprogram or inlined-subroutines. + */ +int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr, + int (*callback)(Dwarf_Die *, void *), void *data) +{ + Dwarf_Die die_mem; + Dwarf_Die *sc_die; + int ret = -ENOENT; + + /* Inlined function could be recursive. Trace it until fail */ + for (sc_die = die_find_realfunc(cu_die, addr, &die_mem); + sc_die != NULL; + sc_die = die_find_child(sc_die, __die_find_inline_cb, &addr, + &die_mem)) { + ret = callback(sc_die, data); + if (ret) + break; + } + + return ret; + +} + /** * die_compare_name - Compare diename and tname * @dw_die: a DIE diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h index c8e491bc133f..6f46106fd1d5 100644 --- a/tools/perf/util/dwarf-aux.h +++ b/tools/perf/util/dwarf-aux.h @@ -34,6 +34,10 @@ extern const char *cu_get_comp_dir(Dwarf_Die *cu_die); extern int cu_find_lineinfo(Dwarf_Die *cudie, unsigned long addr, const char **fname, int *lineno); +/* Walk on funcitons at given address */ +extern int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr, + int (*callback)(Dwarf_Die *, void *), void *data); + /* Compare diename and tname */ extern bool die_compare_name(Dwarf_Die *dw_die, const char *tname); diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index d6d57682473a..5c83b7d3d8ef 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -612,8 +612,8 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) return ret; } -/* Find a variable in a subprogram die */ -static int find_variable(Dwarf_Die *sp_die, struct probe_finder *pf) +/* Find a variable in a scope DIE */ +static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf) { Dwarf_Die vr_die, *scopes; char buf[32], *ptr; @@ -655,11 +655,11 @@ 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_at(sp_die, pf->pvar->var, pf->addr, &vr_die)) + if (die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) ret = convert_variable(&vr_die, pf); else { /* Search upper class */ - nscopes = dwarf_getscopes_die(sp_die, &scopes); + nscopes = dwarf_getscopes_die(sc_die, &scopes); ret = -ENOENT; while (nscopes-- > 1) { pr_debug("Searching variables in %s\n", @@ -717,26 +717,30 @@ static int convert_to_trace_point(Dwarf_Die *sp_die, Dwarf_Addr paddr, return 0; } -/* Call probe_finder callback with real subprogram DIE */ -static int call_probe_finder(Dwarf_Die *sp_die, struct probe_finder *pf) +/* Call probe_finder callback with scope DIE */ +static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf) { - Dwarf_Die die_mem; Dwarf_Attribute fb_attr; size_t nops; int ret; - /* If no real subprogram, find a real one */ - if (!sp_die || dwarf_tag(sp_die) != DW_TAG_subprogram) { - sp_die = die_find_realfunc(&pf->cu_die, pf->addr, &die_mem); - if (!sp_die) { + if (!sc_die) { + pr_err("Caller must pass a scope DIE. Program error.\n"); + return -EINVAL; + } + + /* If not a real subprogram, find a real one */ + if (dwarf_tag(sc_die) != DW_TAG_subprogram) { + if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) { pr_warning("Failed to find probe point in any " "functions.\n"); return -ENOENT; } - } + } else + memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die)); - /* Get the frame base attribute/ops */ - dwarf_attr(sp_die, DW_AT_frame_base, &fb_attr); + /* Get the frame base attribute/ops from subprogram */ + dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr); ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1); if (ret <= 0 || nops == 0) { pf->fb_ops = NULL; @@ -754,7 +758,7 @@ static int call_probe_finder(Dwarf_Die *sp_die, struct probe_finder *pf) } /* Call finder's callback handler */ - ret = pf->callback(sp_die, pf); + ret = pf->callback(sc_die, pf); /* *pf->fb_ops will be cached in libdw. Don't free it. */ pf->fb_ops = NULL; @@ -762,17 +766,82 @@ static int call_probe_finder(Dwarf_Die *sp_die, struct probe_finder *pf) return ret; } +struct find_scope_param { + const char *function; + const char *file; + int line; + int diff; + Dwarf_Die *die_mem; + bool found; +}; + +static int find_best_scope_cb(Dwarf_Die *fn_die, void *data) +{ + struct find_scope_param *fsp = data; + const char *file; + int lno; + + /* Skip if declared file name does not match */ + if (fsp->file) { + file = dwarf_decl_file(fn_die); + if (!file || strcmp(fsp->file, file) != 0) + return 0; + } + /* If the function name is given, that's what user expects */ + if (fsp->function) { + if (die_compare_name(fn_die, fsp->function)) { + memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die)); + fsp->found = true; + return 1; + } + } else { + /* With the line number, find the nearest declared DIE */ + dwarf_decl_line(fn_die, &lno); + if (lno < fsp->line && fsp->diff > fsp->line - lno) { + /* Keep a candidate and continue */ + fsp->diff = fsp->line - lno; + memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die)); + fsp->found = true; + } + } + return 0; +} + +/* Find an appropriate scope fits to given conditions */ +static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem) +{ + struct find_scope_param fsp = { + .function = pf->pev->point.function, + .file = pf->fname, + .line = pf->lno, + .diff = INT_MAX, + .die_mem = die_mem, + .found = false, + }; + + cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb, &fsp); + + return fsp.found ? die_mem : NULL; +} + static int probe_point_line_walker(const char *fname, int lineno, Dwarf_Addr addr, void *data) { struct probe_finder *pf = data; + Dwarf_Die *sc_die, die_mem; int ret; if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0) return 0; pf->addr = addr; - ret = call_probe_finder(NULL, pf); + sc_die = find_best_scope(pf, &die_mem); + if (!sc_die) { + pr_warning("Failed to find scope of probe point.\n"); + return -ENOENT; + } + + ret = call_probe_finder(sc_die, pf); /* Continue if no error, because the line will be in inline function */ return ret < 0 ? ret : 0; @@ -826,6 +895,7 @@ static int probe_point_lazy_walker(const char *fname, int lineno, Dwarf_Addr addr, void *data) { struct probe_finder *pf = data; + Dwarf_Die *sc_die, die_mem; int ret; if (!line_list__has_line(&pf->lcache, lineno) || @@ -835,7 +905,14 @@ static int probe_point_lazy_walker(const char *fname, int lineno, pr_debug("Probe line found: line:%d addr:0x%llx\n", lineno, (unsigned long long)addr); pf->addr = addr; - ret = call_probe_finder(NULL, pf); + pf->lno = lineno; + sc_die = find_best_scope(pf, &die_mem); + if (!sc_die) { + pr_warning("Failed to find scope of probe point.\n"); + return -ENOENT; + } + + ret = call_probe_finder(sc_die, pf); /* * Continue if no error, because the lazy pattern will match @@ -1059,7 +1136,7 @@ found: } /* Add a found probe point into trace event list */ -static int add_probe_trace_event(Dwarf_Die *sp_die, struct probe_finder *pf) +static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf) { struct trace_event_finder *tf = container_of(pf, struct trace_event_finder, pf); @@ -1074,8 +1151,9 @@ static int add_probe_trace_event(Dwarf_Die *sp_die, struct probe_finder *pf) } tev = &tf->tevs[tf->ntevs++]; - ret = convert_to_trace_point(sp_die, pf->addr, pf->pev->point.retprobe, - &tev->point); + /* Trace point should be converted from subprogram DIE */ + ret = convert_to_trace_point(&pf->sp_die, pf->addr, + pf->pev->point.retprobe, &tev->point); if (ret < 0) return ret; @@ -1090,7 +1168,8 @@ static int add_probe_trace_event(Dwarf_Die *sp_die, struct probe_finder *pf) for (i = 0; i < pf->pev->nargs; i++) { pf->pvar = &pf->pev->args[i]; pf->tvar = &tev->args[i]; - ret = find_variable(sp_die, pf); + /* Variable should be found from scope DIE */ + ret = find_variable(sc_die, pf); if (ret != 0) return ret; } @@ -1158,7 +1237,7 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data) } /* Add a found vars into available variables list */ -static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf) +static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf) { struct available_var_finder *af = container_of(pf, struct available_var_finder, pf); @@ -1173,8 +1252,9 @@ static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf) } vl = &af->vls[af->nvls++]; - ret = convert_to_trace_point(sp_die, pf->addr, pf->pev->point.retprobe, - &vl->point); + /* Trace point should be converted from subprogram DIE */ + ret = convert_to_trace_point(&pf->sp_die, pf->addr, + pf->pev->point.retprobe, &vl->point); if (ret < 0) return ret; @@ -1186,14 +1266,14 @@ static int add_available_vars(Dwarf_Die *sp_die, struct probe_finder *pf) if (vl->vars == NULL) return -ENOMEM; af->child = true; - die_find_child(sp_die, collect_variables_cb, (void *)af, &die_mem); + die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem); /* Find external variables */ if (!af->externs) goto out; /* Don't need to search child DIE for externs. */ af->child = false; - nscopes = dwarf_getscopes_die(sp_die, &scopes); + nscopes = dwarf_getscopes_die(sc_die, &scopes); while (nscopes-- > 1) die_find_child(&scopes[nscopes], collect_variables_cb, (void *)af, &die_mem); diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h index c478b42a2473..1132c8f0ce89 100644 --- a/tools/perf/util/probe-finder.h +++ b/tools/perf/util/probe-finder.h @@ -57,7 +57,7 @@ struct probe_finder { struct perf_probe_event *pev; /* Target probe event */ /* Callback when a probe point is found */ - int (*callback)(Dwarf_Die *sp_die, struct probe_finder *pf); + int (*callback)(Dwarf_Die *sc_die, struct probe_finder *pf); /* For function searching */ int lno; /* Line number */ -- cgit v1.2.3