Menu
▾
▴
[Dle-develop] [tip:perf/core] perf probe: Add data structure member access support
|
From: tip-bot f. M. H. <mhi...@re...> - 2010-03-17 11:30:42
|
Commit-ID: 7df2f32956cf0f1a45df38cd0e0fe0c3467580e8 Gitweb: http://git.kernel.org/tip/7df2f32956cf0f1a45df38cd0e0fe0c3467580e8 Author: Masami Hiramatsu <mhi...@re...> AuthorDate: Tue, 16 Mar 2010 18:06:26 -0400 Committer: Ingo Molnar <mi...@el...> CommitDate: Wed, 17 Mar 2010 12:11:15 +0100 perf probe: Add data structure member access support Support accessing members in the data structures. With this, perf-probe accepts data-structure members(IOW, it now accepts dot '.' and arrow '->' operators) as probe arguemnts. e.g. ./perf probe --add 'schedule:44 rq->curr' ./perf probe --add 'vfs_read file->f_op->read file->f_path.dentry' Note that '>' can be interpreted as redirection in command-line. Signed-off-by: Masami Hiramatsu <mhi...@re...> Cc: systemtap <sys...@so...> Cc: DLE <dle...@li...> Cc: Frederic Weisbecker <fwe...@gm...> Cc: Arnaldo Carvalho de Melo <ac...@re...> Cc: Paul Mackerras <pa...@sa...> Cc: Mike Galbraith <ef...@gm...> Cc: Peter Zijlstra <a.p...@ch...> LKML-Reference: <20100316220626.32050.57552.stgit@localhost6.localdomain6> Signed-off-by: Ingo Molnar <mi...@el...> --- tools/perf/util/probe-event.c | 90 ++++++++++++++++++++++++++++++++-- tools/perf/util/probe-event.h | 12 ++++- tools/perf/util/probe-finder.c | 105 +++++++++++++++++++++++++++++++++++++++- 3 files changed, 201 insertions(+), 6 deletions(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 4e3c1ae..64dea6c 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -262,6 +262,49 @@ static void parse_perf_probe_point(char *arg, struct perf_probe_event *pev) pp->lazy_line); } +/* Parse perf-probe event argument */ +static void parse_perf_probe_arg(const char *str, struct perf_probe_arg *arg) +{ + const char *tmp; + struct perf_probe_arg_field **fieldp; + + pr_debug("parsing arg: %s into ", str); + + tmp = strpbrk(str, "-."); + if (!is_c_varname(str) || !tmp) { + /* A variable, register, symbol or special value */ + arg->name = xstrdup(str); + pr_debug("%s\n", arg->name); + return; + } + + /* Structure fields */ + arg->name = xstrndup(str, tmp - str); + pr_debug("%s, ", arg->name); + fieldp = &arg->field; + + do { + *fieldp = xzalloc(sizeof(struct perf_probe_arg_field)); + if (*tmp == '.') { + str = tmp + 1; + (*fieldp)->ref = false; + } else if (tmp[1] == '>') { + str = tmp + 2; + (*fieldp)->ref = true; + } else + semantic_error("Argument parse error: %s", str); + + tmp = strpbrk(str, "-."); + if (tmp) { + (*fieldp)->name = xstrndup(str, tmp - str); + pr_debug("%s(%d), ", (*fieldp)->name, (*fieldp)->ref); + fieldp = &(*fieldp)->next; + } + } while (tmp); + (*fieldp)->name = xstrdup(str); + pr_debug("%s(%d)\n", (*fieldp)->name, (*fieldp)->ref); +} + /* Parse perf-probe event command */ void parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev) { @@ -281,7 +324,7 @@ void parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev) pev->nargs = argc - 1; pev->args = xzalloc(sizeof(struct perf_probe_arg) * pev->nargs); for (i = 0; i < pev->nargs; i++) { - pev->args[i].name = xstrdup(argv[i + 1]); + parse_perf_probe_arg(argv[i + 1], &pev->args[i]); if (is_c_varname(pev->args[i].name) && pev->point.retprobe) semantic_error("You can't specify local variable for" " kretprobe"); @@ -353,6 +396,33 @@ void parse_kprobe_trace_command(const char *cmd, struct kprobe_trace_event *tev) argv_free(argv); } +/* Compose only probe arg */ +int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, size_t len) +{ + struct perf_probe_arg_field *field = pa->field; + int ret; + char *tmp = buf; + + ret = e_snprintf(tmp, len, "%s", pa->name); + if (ret <= 0) + goto error; + tmp += ret; + len -= ret; + + while (field) { + ret = e_snprintf(tmp, len, "%s%s", field->ref ? "->" : ".", + field->name); + if (ret <= 0) + goto error; + tmp += ret; + len -= ret; + field = field->next; + } + return tmp - buf; +error: + die("Failed to synthesize perf probe argument: %s", strerror(-ret)); +} + /* Compose only probe point (not argument) */ static char *synthesize_perf_probe_point(struct perf_probe_point *pp) { @@ -563,6 +633,7 @@ void convert_to_perf_probe_event(struct kprobe_trace_event *tev, void clear_perf_probe_event(struct perf_probe_event *pev) { struct perf_probe_point *pp = &pev->point; + struct perf_probe_arg_field *field, *next; int i; if (pev->event) @@ -575,9 +646,18 @@ void clear_perf_probe_event(struct perf_probe_event *pev) free(pp->function); if (pp->lazy_line) free(pp->lazy_line); - for (i = 0; i < pev->nargs; i++) + for (i = 0; i < pev->nargs; i++) { if (pev->args[i].name) free(pev->args[i].name); + field = pev->args[i].field; + while (field) { + next = field->next; + if (field->name) + free(field->name); + free(field); + field = next; + } + } if (pev->args) free(pev->args); memset(pev, 0, sizeof(*pev)); @@ -682,8 +762,10 @@ static void show_perf_probe_event(struct perf_probe_event *pev) if (pev->nargs > 0) { printf(" with"); - for (i = 0; i < pev->nargs; i++) - printf(" %s", pev->args[i].name); + for (i = 0; i < pev->nargs; i++) { + synthesize_perf_probe_arg(&pev->args[i], buf, 128); + printf(" %s", buf); + } } printf(")\n"); free(place); diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h index 2a2f0a2..cd308b0 100644 --- a/tools/perf/util/probe-event.h +++ b/tools/perf/util/probe-event.h @@ -45,9 +45,17 @@ struct perf_probe_point { bool retprobe; /* Return probe flag */ }; +/* Perf probe probing argument field chain */ +struct perf_probe_arg_field { + struct perf_probe_arg_field *next; /* Next field */ + char *name; /* Name of the field */ + bool ref; /* Referencing flag */ +}; + /* Perf probe probing argument */ struct perf_probe_arg { - char *name; /* Argument name */ + char *name; /* Argument name */ + struct perf_probe_arg_field *field; /* Structure fields */ }; /* Perf probe probing event (point + arg) */ @@ -86,6 +94,8 @@ extern void parse_kprobe_trace_command(const char *cmd, /* Events to command string */ extern char *synthesize_perf_probe_command(struct perf_probe_event *pev); extern char *synthesize_kprobe_trace_command(struct kprobe_trace_event *tev); +extern int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf, + size_t len); /* Check the perf_probe_event needs debuginfo */ extern bool perf_probe_event_need_dwarf(struct perf_probe_event *pev); diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index e02b607..db52ec2 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -206,6 +206,28 @@ static Dwarf_Addr die_get_entrypc(Dwarf_Die *dw_die) return epc; } +/* Get type die, but skip qualifiers and typedef */ +static Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem) +{ + Dwarf_Attribute attr; + int tag; + + do { + if (dwarf_attr(vr_die, DW_AT_type, &attr) == NULL || + dwarf_formref_die(&attr, die_mem) == NULL) + return NULL; + + tag = dwarf_tag(die_mem); + vr_die = die_mem; + } while (tag == DW_TAG_const_type || + tag == DW_TAG_restrict_type || + tag == DW_TAG_volatile_type || + tag == DW_TAG_shared_type || + tag == DW_TAG_typedef); + + return die_mem; +} + /* Return values for die_find callbacks */ enum { DIE_FIND_CB_FOUND = 0, /* End of Search */ @@ -314,6 +336,25 @@ static Dwarf_Die *die_find_variable(Dwarf_Die *sp_die, const char *name, die_mem); } +static int __die_find_member_cb(Dwarf_Die *die_mem, void *data) +{ + const char *name = data; + + if ((dwarf_tag(die_mem) == DW_TAG_member) && + (die_compare_name(die_mem, name) == 0)) + return DIE_FIND_CB_FOUND; + + return DIE_FIND_CB_SIBLING; +} + +/* Find a member called 'name' */ +static Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name, + Dwarf_Die *die_mem) +{ + return die_find_child(st_die, __die_find_member_cb, (void *)name, + die_mem); +} + /* * Probe finder related functions */ @@ -363,6 +404,62 @@ static void convert_location(Dwarf_Op *op, struct probe_finder *pf) } } +static void convert_variable_fields(Dwarf_Die *vr_die, const char *varname, + struct perf_probe_arg_field *field, + struct kprobe_trace_arg_ref **ref_ptr) +{ + struct kprobe_trace_arg_ref *ref = *ref_ptr; + Dwarf_Attribute attr; + Dwarf_Die member; + Dwarf_Die type; + Dwarf_Word offs; + + pr_debug("converting %s in %s\n", field->name, varname); + if (die_get_real_type(vr_die, &type) == NULL) + die("Failed to get a type information of %s.", varname); + + /* Check the pointer and dereference */ + if (dwarf_tag(&type) == DW_TAG_pointer_type) { + if (!field->ref) + die("Semantic error: %s must be referred by '->'", + field->name); + /* Get the type pointed by this pointer */ + if (die_get_real_type(&type, &type) == NULL) + die("Failed to get a type information of %s.", varname); + + ref = xzalloc(sizeof(struct kprobe_trace_arg_ref)); + if (*ref_ptr) + (*ref_ptr)->next = ref; + else + *ref_ptr = ref; + } else { + if (field->ref) + die("Semantic error: %s must be referred by '.'", + field->name); + if (!ref) + die("Structure on a register is not supported yet."); + } + + /* Verify it is a data structure */ + if (dwarf_tag(&type) != DW_TAG_structure_type) + die("%s is not a data structure.", varname); + + if (die_find_member(&type, field->name, &member) == NULL) + die("%s(tyep:%s) has no member %s.", varname, + dwarf_diename(&type), field->name); + + /* Get the offset of the field */ + if (dwarf_attr(&member, DW_AT_data_member_location, &attr) == NULL || + dwarf_formudata(&attr, &offs) != 0) + die("Failed to get the offset of %s.", field->name); + ref->offset += (long)offs; + + /* Converting next field */ + if (field->next) + convert_variable_fields(&member, field->name, field->next, + &ref); +} + /* Show a variables in kprobe event format */ static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) { @@ -379,6 +476,10 @@ static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) goto error; convert_location(expr, pf); + + if (pf->pvar->field) + convert_variable_fields(vr_die, pf->pvar->name, + pf->pvar->field, &pf->tvar->ref); /* *expr will be cached in libdw. Don't free it. */ return ; error: @@ -391,13 +492,15 @@ error: static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf) { Dwarf_Die vr_die; + char buf[128]; /* TODO: Support struct members and arrays */ if (!is_c_varname(pf->pvar->name)) { /* Copy raw parameters */ pf->tvar->value = xstrdup(pf->pvar->name); } else { - pf->tvar->name = xstrdup(pf->pvar->name); + synthesize_perf_probe_arg(pf->pvar, buf, 128); + pf->tvar->name = xstrdup(buf); pr_debug("Searching '%s' variable in context.\n", pf->pvar->name); /* Search child die for local variables and parameters. */ |
