Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753804AbbEKOTi (ORCPT ); Mon, 11 May 2015 10:19:38 -0400 Received: from sender1.zohomail.com ([74.201.84.155]:22379 "EHLO sender1.zohomail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752646AbbEKOTg (ORCPT ); Mon, 11 May 2015 10:19:36 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=zapps768; d=zoho.com; h=message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type; b=vWR2tRF3jgtNk91jI9Kotav6Iv7PiSdY91C7ZrwrOA3ZNd7OlXYooq+zBOuBeX2zz8fkRQ9dT8NB IiMlC2k/bz5ioAksM1tMM/fHzG6nBGKRq1p/VTeUOb0ilYsrt8Lz Message-ID: <5550BA77.9060209@zoho.com> Date: Mon, 11 May 2015 22:19:35 +0800 From: hekuang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Arnaldo Carvalho de Melo , He Kuang CC: masami.hiramatsu.pt@hitachi.com, a.p.zijlstra@chello.nl, jolsa@kernel.org, mingo@redhat.com, wangnan0@huawei.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 2/3] perf probe: Add --range option to show variable location range References: <1431349804-31849-1-git-send-email-hekuang@huawei.com> <1431349804-31849-2-git-send-email-hekuang@huawei.com> <20150511135825.GF28183@kernel.org> In-Reply-To: <20150511135825.GF28183@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 12697 Lines: 371 hi, Arnaldo On 05/11/2015 09:58 PM, Arnaldo Carvalho de Melo wrote: > Em Mon, May 11, 2015 at 01:10:03PM +0000, He Kuang escreveu: >> It is not easy for users to get the accurate byte offset or the line >> number where a local variable can be probed. With '--range' option, >> local variables in scope of the probe point are showed with byte offset >> range, and can be added according to this range information. > Please, when you send a V4 patch like this, state what changed with > regards to the previous version, as I already applied this patch :-\ > > - Arnaldo > I will check next time. Thanks. >> For example, there are some variables in function >> generic_perform_write(): >> >> >> 0 ssize_t generic_perform_write(struct file *file, >> 1 struct iov_iter *i, loff_t pos) >> 2 { >> 3 struct address_space *mapping = file->f_mapping; >> 4 const struct address_space_operations *a_ops = mapping->a_ops; >> ... >> 42 status = a_ops->write_begin(file, mapping, pos, bytes, flags, >> &page, &fsdata); >> 44 if (unlikely(status < 0)) >> >> But we got failed when we try to probe the variable 'a_ops' at line 42 >> or 44. >> >> $ perf probe --add 'generic_perform_write:42 a_ops' >> Failed to find the location of a_ops at this address. >> Perhaps, it has been optimized out. >> >> This is because source code do not match assembly, so a variable may not >> be available in the sourcecode line where it presents. After this patch, >> we can lookup the accurate byte offset range of a variable, 'INV' >> indicates that this variable is not valid at the given point, but >> available in scope: >> >> $ perf probe --vars 'generic_perform_write:42' --range >> Available variables at generic_perform_write:42 >> @ >> [INV] ssize_t written @ >> [INV] struct address_space_operations* a_ops @ >> [VAL] (unknown_type) fsdata @ >> [VAL] loff_t pos @ >> [VAL] long int status @ >> [VAL] long unsigned int bytes @ >> [VAL] struct address_space* mapping @ >> [VAL] struct iov_iter* i @ >> [VAL] struct page* page @ >> >> Then it is more clearly for us to do the probe with this variable: >> >> $ perf probe --add 'generic_perform_write+170 a_ops' >> Added new event: >> probe:generic_perform_write (on generic_perform_write+170 with a_ops) >> >> Signed-off-by: He Kuang >> Acked-by: Masami Hiramatsu >> --- >> tools/perf/builtin-probe.c | 2 + >> tools/perf/util/dwarf-aux.c | 121 +++++++++++++++++++++++++++++++++++++++++ >> tools/perf/util/dwarf-aux.h | 2 + >> tools/perf/util/probe-event.h | 1 + >> tools/perf/util/probe-finder.c | 57 ++++++++++++++----- >> 5 files changed, 170 insertions(+), 13 deletions(-) >> >> diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c >> index 7fa2c7a..1272559 100644 >> --- a/tools/perf/builtin-probe.c >> +++ b/tools/perf/builtin-probe.c >> @@ -372,6 +372,8 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused) >> "Show accessible variables on PROBEDEF", opt_show_vars), >> OPT_BOOLEAN('\0', "externs", &probe_conf.show_ext_vars, >> "Show external variables too (with --vars only)"), >> + OPT_BOOLEAN('\0', "range", &probe_conf.show_location_range, >> + "Show variables location range in scope (with --vars only)"), >> OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name, >> "file", "vmlinux pathname"), >> OPT_STRING('s', "source", &symbol_conf.source_prefix, >> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c >> index 737c9db..afa0971 100644 >> --- a/tools/perf/util/dwarf-aux.c >> +++ b/tools/perf/util/dwarf-aux.c >> @@ -913,3 +913,124 @@ int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf) >> return 0; >> } >> >> +/** >> + * die_get_var_innermost_scope - Get innermost scope range of given variable DIE >> + * @sp_die: a subprogram DIE >> + * @vr_die: a variable DIE >> + * @buf: a strbuf for variable byte offset range >> + * >> + * Get the innermost scope range of @vr_die and stores it in @buf as >> + * "@". >> + */ >> +static int die_get_var_innermost_scope(Dwarf_Die *sp_die, Dwarf_Die *vr_die, >> + struct strbuf *buf) >> +{ >> + Dwarf_Die *scopes; >> + int count; >> + size_t offset = 0; >> + Dwarf_Addr base; >> + Dwarf_Addr start, end; >> + Dwarf_Addr entry; >> + int ret; >> + bool first = true; >> + const char *name; >> + >> + ret = dwarf_entrypc(sp_die, &entry); >> + if (ret) >> + return ret; >> + >> + name = dwarf_diename(sp_die); >> + if (!name) >> + return -ENOENT; >> + >> + count = dwarf_getscopes_die(vr_die, &scopes); >> + >> + /* (*SCOPES)[1] is the DIE for the scope containing that scope */ >> + if (count <= 1) { >> + ret = -EINVAL; >> + goto out; >> + } >> + >> + while ((offset = dwarf_ranges(&scopes[1], offset, &base, >> + &start, &end)) > 0) { >> + start -= entry; >> + end -= entry; >> + >> + if (first) { >> + strbuf_addf(buf, "@<%s+[%lu-%lu", >> + name, start, end); >> + first = false; >> + } else { >> + strbuf_addf(buf, ",%lu-%lu", >> + start, end); >> + } >> + } >> + >> + if (!first) >> + strbuf_addf(buf, "]>"); >> + >> +out: >> + free(scopes); >> + return ret; >> +} >> + >> +/** >> + * die_get_var_range - Get byte offset range of given variable DIE >> + * @sp_die: a subprogram DIE >> + * @vr_die: a variable DIE >> + * @buf: a strbuf for type and variable name and byte offset range >> + * >> + * Get the byte offset range of @vr_die and stores it in @buf as >> + * "@". >> + */ >> +int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf) >> +{ >> + int ret = 0; >> + Dwarf_Addr base; >> + Dwarf_Addr start, end; >> + Dwarf_Addr entry; >> + Dwarf_Op *op; >> + size_t nops; >> + size_t offset = 0; >> + Dwarf_Attribute attr; >> + bool first = true; >> + const char *name; >> + >> + ret = dwarf_entrypc(sp_die, &entry); >> + if (ret) >> + return ret; >> + >> + name = dwarf_diename(sp_die); >> + if (!name) >> + return -ENOENT; >> + >> + if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL) >> + return -EINVAL; >> + >> + while ((offset = dwarf_getlocations( >> + &attr, offset, &base, >> + &start, &end, &op, &nops)) > 0) { >> + if (start == 0) { >> + /* Single Location Descriptions */ >> + ret = die_get_var_innermost_scope(sp_die, vr_die, buf); >> + return ret; >> + } >> + >> + /* Location Lists */ >> + start -= entry; >> + end -= entry; >> + if (first) { >> + strbuf_addf(buf, "@<%s+[%lu-%lu", >> + name, start, end); >> + first = false; >> + } else { >> + strbuf_addf(buf, ",%lu-%lu", >> + start, end); >> + } >> + } >> + >> + if (!first) >> + strbuf_addf(buf, "]>"); >> + >> + return ret; >> +} >> diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h >> index 60676fd..c154c0b8 100644 >> --- a/tools/perf/util/dwarf-aux.h >> +++ b/tools/perf/util/dwarf-aux.h >> @@ -121,4 +121,6 @@ extern int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf); >> >> /* Get the name and type of given variable DIE, stored as "type\tname" */ >> extern int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf); >> +extern int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, >> + struct strbuf *buf); >> #endif >> diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h >> index 1e2faa3..537eb32 100644 >> --- a/tools/perf/util/probe-event.h >> +++ b/tools/perf/util/probe-event.h >> @@ -9,6 +9,7 @@ >> /* Probe related configurations */ >> struct probe_conf { >> bool show_ext_vars; >> + bool show_location_range; >> bool force_add; >> bool no_inlines; >> int max_probes; >> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c >> index dcca551..f032329 100644 >> --- a/tools/perf/util/probe-finder.c >> +++ b/tools/perf/util/probe-finder.c >> @@ -177,7 +177,7 @@ static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr, >> Dwarf_Word offs = 0; >> bool ref = false; >> const char *regs; >> - int ret; >> + int ret, ret2 = 0; >> >> if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL) >> goto static_var; >> @@ -187,9 +187,19 @@ static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr, >> return -EINVAL; /* Broken DIE ? */ >> if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) { >> ret = dwarf_entrypc(sp_die, &tmp); >> - if (ret || addr != tmp || >> - dwarf_tag(vr_die) != DW_TAG_formal_parameter || >> - dwarf_highpc(sp_die, &tmp)) >> + if (ret) >> + return -ENOENT; >> + >> + if (probe_conf.show_location_range && >> + (dwarf_tag(vr_die) == DW_TAG_variable)) { >> + ret2 = -ERANGE; >> + } else if (addr != tmp || >> + dwarf_tag(vr_die) != DW_TAG_formal_parameter) { >> + return -ENOENT; >> + } >> + >> + ret = dwarf_highpc(sp_die, &tmp); >> + if (ret) >> return -ENOENT; >> /* >> * This is fuzzed by fentry mcount. We try to find the >> @@ -210,7 +220,7 @@ found: >> if (op->atom == DW_OP_addr) { >> static_var: >> if (!tvar) >> - return 0; >> + return ret2; >> /* Static variables on memory (not stack), make @varname */ >> ret = strlen(dwarf_diename(vr_die)); >> tvar->value = zalloc(ret + 2); >> @@ -220,7 +230,7 @@ static_var: >> tvar->ref = alloc_trace_arg_ref((long)offs); >> if (tvar->ref == NULL) >> return -ENOMEM; >> - return 0; >> + return ret2; >> } >> >> /* If this is based on frame buffer, set the offset */ >> @@ -250,14 +260,14 @@ static_var: >> } >> >> if (!tvar) >> - return 0; >> + return ret2; >> >> regs = get_arch_regstr(regn); >> if (!regs) { >> /* This should be a bug in DWARF or this tool */ >> pr_warning("Mapping for the register number %u " >> "missing on this architecture.\n", regn); >> - return -ERANGE; >> + return -ENOTSUP; >> } >> >> tvar->value = strdup(regs); >> @@ -269,7 +279,7 @@ static_var: >> if (tvar->ref == NULL) >> return -ENOMEM; >> } >> - return 0; >> + return ret2; >> } >> >> #define BYTES_TO_BITS(nb) ((nb) * BITS_PER_LONG / sizeof(long)) >> @@ -1268,13 +1278,34 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data) >> ret = convert_variable_location(die_mem, af->pf.addr, >> af->pf.fb_ops, &af->pf.sp_die, >> NULL); >> - if (ret == 0) { >> + if (ret == 0 || ret == -ERANGE) { >> + int ret2; >> + bool externs = !af->child; >> struct strbuf buf; >> >> strbuf_init(&buf, 64); >> - ret = die_get_varname(die_mem, &buf); >> - pr_debug2("Add new var: %s\n", buf.buf); >> - if (ret == 0) { >> + >> + if (probe_conf.show_location_range) { >> + if (!externs) { >> + if (ret) >> + strbuf_addf(&buf, "[INV]\t"); >> + else >> + strbuf_addf(&buf, "[VAL]\t"); >> + } else >> + strbuf_addf(&buf, "[EXT]\t"); >> + } >> + >> + ret2 = die_get_varname(die_mem, &buf); >> + >> + if (!ret2 && probe_conf.show_location_range && >> + !externs) { >> + strbuf_addf(&buf, "\t"); >> + ret2 = die_get_var_range(&af->pf.sp_die, >> + die_mem, &buf); >> + } >> + >> + pr_debug("Add new var: %s\n", buf.buf); >> + if (ret2 == 0) { >> strlist__add(vl->vars, >> strbuf_detach(&buf, NULL)); >> } >> -- >> 1.8.5.2 > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/