From 4984912eb23113a4007940cd09c8351c0623ea5f Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Mon, 12 Apr 2010 13:17:15 -0400 Subject: perf probe: Query basic types from debuginfo Query the basic type information (byte-size and signed-flag) from debuginfo and pass that to kprobe-tracer. This is especially useful for tracing the members of data structure, because each member has different byte-size on the memory. Cc: Ingo Molnar Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Frederic Weisbecker LKML-Reference: <20100412171715.3790.23730.stgit@localhost6.localdomain6> Signed-off-by: Masami Hiramatsu Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-finder.c | 78 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 70 insertions(+), 8 deletions(-) (limited to 'tools/perf/util/probe-finder.c') diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 105e95c95eeb..ebeb413ac473 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -84,6 +84,9 @@ const char *x86_64_regs_table[X86_64_MAX_REGS] = { #define arch_regs_table x86_32_regs_table #endif +/* Kprobe tracer basic type is up to u64 */ +#define MAX_BASIC_TYPE_BITS 64 + /* Return architecture dependent register string (for kprobe-tracer) */ static const char *get_arch_regstr(unsigned int n) { @@ -230,6 +233,31 @@ static Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem) return die_mem; } +static bool die_is_signed_type(Dwarf_Die *tp_die) +{ + Dwarf_Attribute attr; + Dwarf_Word ret; + + if (dwarf_attr(tp_die, DW_AT_encoding, &attr) == NULL || + dwarf_formudata(&attr, &ret) != 0) + return false; + + return (ret == DW_ATE_signed_char || ret == DW_ATE_signed || + ret == DW_ATE_signed_fixed); +} + +static int die_get_byte_size(Dwarf_Die *tp_die) +{ + Dwarf_Attribute attr; + Dwarf_Word ret; + + if (dwarf_attr(tp_die, DW_AT_byte_size, &attr) == NULL || + dwarf_formudata(&attr, &ret) != 0) + return 0; + + return (int)ret; +} + /* Return values for die_find callbacks */ enum { DIE_FIND_CB_FOUND = 0, /* End of Search */ @@ -406,13 +434,42 @@ static void convert_location(Dwarf_Op *op, struct probe_finder *pf) } } +static void convert_variable_type(Dwarf_Die *vr_die, + struct kprobe_trace_arg *targ) +{ + Dwarf_Die type; + char buf[16]; + int ret; + + if (die_get_real_type(vr_die, &type) == NULL) + die("Failed to get a type information of %s.", + dwarf_diename(vr_die)); + + ret = die_get_byte_size(&type) * 8; + if (ret) { + /* Check the bitwidth */ + if (ret > MAX_BASIC_TYPE_BITS) { + pr_warning(" Warning: %s exceeds max-bitwidth." + " Cut down to %d bits.\n", + dwarf_diename(&type), MAX_BASIC_TYPE_BITS); + ret = MAX_BASIC_TYPE_BITS; + } + + ret = snprintf(buf, 16, "%c%d", + die_is_signed_type(&type) ? 's' : 'u', ret); + if (ret < 0 || ret >= 16) + die("Failed to convert variable type."); + targ->type = xstrdup(buf); + } +} + 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_ptr, + Dwarf_Die *die_mem) { struct kprobe_trace_arg_ref *ref = *ref_ptr; Dwarf_Attribute attr; - Dwarf_Die member; Dwarf_Die type; Dwarf_Word offs; @@ -450,26 +507,27 @@ static void convert_variable_fields(Dwarf_Die *vr_die, const char *varname, die("Structure on a register is not supported yet."); } - if (die_find_member(&type, field->name, &member) == NULL) + if (die_find_member(&type, field->name, die_mem) == 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 || + if (dwarf_attr(die_mem, 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); + convert_variable_fields(die_mem, field->name, field->next, + &ref, die_mem); } /* Show a variables in kprobe event format */ static void 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; @@ -483,9 +541,13 @@ static void convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) convert_location(expr, pf); - if (pf->pvar->field) + if (pf->pvar->field) { convert_variable_fields(vr_die, pf->pvar->var, - pf->pvar->field, &pf->tvar->ref); + pf->pvar->field, &pf->tvar->ref, + &die_mem); + vr_die = &die_mem; + } + convert_variable_type(vr_die, pf->tvar); /* *expr will be cached in libdw. Don't free it. */ return ; error: -- cgit v1.2.3