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Violators will be prosecuted for from ; Wed, 14 Mar 2018 15:19:28 -0000 Subject: Re: [PATCH 7/8] perf probe: Support SDT markers having reference counter (semaphore) References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com> <20180313125603.19819-8-ravi.bangoria@linux.vnet.ibm.com> <20180314230909.52963a161210294ea2fc0420@kernel.org> From: Ravi Bangoria Date: Wed, 14 Mar 2018 20:51:32 +0530 MIME-Version: 1.0 In-Reply-To: <20180314230909.52963a161210294ea2fc0420@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Message-Id: <60a29e08-c4a4-4f9e-aca1-8dafdd064956@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Masami Hiramatsu Cc: oleg@redhat.com, peterz@infradead.org, srikar@linux.vnet.ibm.com, acme@kernel.org, ananth@linux.vnet.ibm.com, akpm@linux-foundation.org, alexander.shishkin@linux.intel.com, alexis.berlemont@gmail.com, corbet@lwn.net, dan.j.williams@intel.com, gregkh@linuxfoundation.org, huawei.libin@huawei.com, hughd@google.com, jack@suse.cz, jglisse@redhat.com, jolsa@redhat.com, kan.liang@intel.com, kirill.shutemov@linux.intel.com, kjlx@templeofstupid.com, kstewart@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, pombredanne@nexb.com, rostedt@goodmis.org, tglx@linutronix.de, tmricht@linux.vnet.ibm.com, willy@infradead.org, yao.jin@linux.intel.com, fengguang.wu@intel.com, Ravi Bangoria On 03/14/2018 07:39 PM, Masami Hiramatsu wrote: > Hi Ravi, > > This code logic looks good. I just have several small comments for style. > > On Tue, 13 Mar 2018 18:26:02 +0530 > Ravi Bangoria wrote: > >> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c >> index e1dbc98..2cbe68a 100644 >> --- a/tools/perf/util/probe-event.c >> +++ b/tools/perf/util/probe-event.c >> @@ -1832,6 +1832,12 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev) >> tp->offset = strtoul(fmt2_str, NULL, 10); >> } >> >> + if (tev->uprobes) { >> + fmt2_str = strchr(p, '('); >> + if (fmt2_str) >> + tp->ref_ctr_offset = strtoul(fmt2_str + 1, NULL, 0); >> + } >> + >> tev->nargs = argc - 2; >> tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs); >> if (tev->args == NULL) { >> @@ -2054,15 +2060,22 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev) >> } >> >> /* Use the tp->address for uprobes */ >> - if (tev->uprobes) >> - err = strbuf_addf(&buf, "%s:0x%lx", tp->module, tp->address); >> - else if (!strncmp(tp->symbol, "0x", 2)) >> + if (tev->uprobes) { >> + if (tp->ref_ctr_offset) >> + err = strbuf_addf(&buf, "%s:0x%lx(0x%lx)", tp->module, >> + tp->address, tp->ref_ctr_offset); >> + else >> + err = strbuf_addf(&buf, "%s:0x%lx", tp->module, >> + tp->address); >> + } else if (!strncmp(tp->symbol, "0x", 2)) { >> /* Absolute address. See try_to_find_absolute_address() */ >> err = strbuf_addf(&buf, "%s%s0x%lx", tp->module ?: "", >> tp->module ? ":" : "", tp->address); >> - else >> + } else { >> err = strbuf_addf(&buf, "%s%s%s+%lu", tp->module ?: "", >> tp->module ? ":" : "", tp->symbol, tp->offset); >> + } > What the purpose of this {}? The starting if has multiple statements and thus it needs braces. So I added braces is all other conditions. >> + >> if (err) >> goto error; >> >> diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h >> index 45b14f0..15a98c3 100644 >> --- a/tools/perf/util/probe-event.h >> +++ b/tools/perf/util/probe-event.h >> @@ -27,6 +27,7 @@ struct probe_trace_point { >> char *symbol; /* Base symbol */ >> char *module; /* Module name */ >> unsigned long offset; /* Offset from symbol */ >> + unsigned long ref_ctr_offset; /* SDT reference counter offset */ >> unsigned long address; /* Actual address of the trace point */ >> bool retprobe; /* Return probe flag */ >> }; >> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c >> index 4ae1123..08ba3a6 100644 >> --- a/tools/perf/util/probe-file.c >> +++ b/tools/perf/util/probe-file.c >> @@ -701,6 +701,12 @@ static unsigned long long sdt_note__get_addr(struct sdt_note *note) >> : (unsigned long long)note->addr.a64[0]; >> } >> >> +static unsigned long long sdt_note__get_ref_ctr_offset(struct sdt_note *note) >> +{ >> + return note->bit32 ? (unsigned long long)note->addr.a32[2] >> + : (unsigned long long)note->addr.a64[2]; >> +} > Could you please introduce an enum for specifying the index by name? > > e.g. > enum { > SDT_NOTE_IDX_ADDR = 0, > SDT_NOTE_IDX_REFCTR = 2, > }; That will be good. Will change it. >> + >> static const char * const type_to_suffix[] = { >> ":s64", "", "", "", ":s32", "", ":s16", ":s8", >> "", ":u8", ":u16", "", ":u32", "", "", "", ":u64" >> @@ -776,14 +782,24 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note, >> { >> struct strbuf buf; >> char *ret = NULL, **args; >> - int i, args_count; >> + int i, args_count, err; >> + unsigned long long ref_ctr_offset; >> >> if (strbuf_init(&buf, 32) < 0) >> return NULL; >> >> - if (strbuf_addf(&buf, "p:%s/%s %s:0x%llx", >> + ref_ctr_offset = sdt_note__get_ref_ctr_offset(note); >> + >> + if (ref_ctr_offset) >> + err = strbuf_addf(&buf, "p:%s/%s %s:0x%llx(0x%llx)", >> sdtgrp, note->name, pathname, >> - sdt_note__get_addr(note)) < 0) >> + sdt_note__get_addr(note), ref_ctr_offset); >> + else >> + err = strbuf_addf(&buf, "p:%s/%s %s:0x%llx", >> + sdtgrp, note->name, pathname, >> + sdt_note__get_addr(note)); > This can be minimized (and avoid repeating) by using 2 strbuf_addf()s, like > > err = strbuf_addf(&buf, "p:%s/%s %s:0x%llx", > sdtgrp, note->name, pathname, > sdt_note__get_addr(note)); > if (ref_ctr_offset && !err < 0) > err = strbuf_addf("(0x%llx)", ref_ctr_offset); Sure. Will change it. > >> + >> + if (err < 0) >> goto error; >> >> if (!note->args) >> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c >> index 2de7705..76c7b54 100644 >> --- a/tools/perf/util/symbol-elf.c >> +++ b/tools/perf/util/symbol-elf.c >> @@ -1928,6 +1928,16 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len, >> } >> } >> >> + /* Adjust reference counter offset */ >> + if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_PROBES_SCN, NULL)) { >> + if (shdr.sh_offset) { >> + if (tmp->bit32) >> + tmp->addr.a32[2] -= (shdr.sh_addr - shdr.sh_offset); >> + else >> + tmp->addr.a64[2] -= (shdr.sh_addr - shdr.sh_offset); > Here we should use enum above too. Sure. Thanks for the review :) Ravi