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[187.26.100.98]) by smtp.gmail.com with ESMTPSA id h44sm12291549qtc.1.2019.11.06.11.57.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Nov 2019 11:57:04 -0800 (PST) From: Arnaldo Carvalho de Melo X-Google-Original-From: Arnaldo Carvalho de Melo Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id EBEC840B1D; Wed, 6 Nov 2019 16:56:59 -0300 (-03) Date: Wed, 6 Nov 2019 16:56:59 -0300 To: Masami Hiramatsu Cc: Ingo Molnar , Steven Rostedt , linux-kernel@vger.kernel.org, Tom Zanussi , Ravi Bangoria , Namhyung Kim Subject: Re: [PATCH 4/5] perf probe: Support DW_AT_const_value constant value Message-ID: <20191106195659.GD11935@kernel.org> References: <157291299825.19771.5190465639558208592.stgit@devnote2> <157291303888.19771.11876536314853955934.stgit@devnote2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <157291303888.19771.11876536314853955934.stgit@devnote2> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Tue, Nov 05, 2019 at 09:17:19AM +0900, Masami Hiramatsu escreveu: > Support DW_AT_const_value for variable assignment instead of location. > Note that this requires ftrace supporting immediate value. This one could have come before the other two, depends on the previous two being applied. - Arnaldo > Signed-off-by: Masami Hiramatsu > --- > tools/perf/util/probe-file.c | 7 +++++++ > tools/perf/util/probe-file.h | 1 + > tools/perf/util/probe-finder.c | 11 +++++++++++ > 3 files changed, 19 insertions(+) > > diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c > index a63f1a19b0e8..5003ba403345 100644 > --- a/tools/perf/util/probe-file.c > +++ b/tools/perf/util/probe-file.c > @@ -1008,6 +1008,7 @@ enum ftrace_readme { > FTRACE_README_UPROBE_REF_CTR, > FTRACE_README_USER_ACCESS, > FTRACE_README_MULTIPROBE_EVENT, > + FTRACE_README_IMMEDIATE_VALUE, > FTRACE_README_END, > }; > > @@ -1022,6 +1023,7 @@ static struct { > DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"), > DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*[u]*"), > DEFINE_TYPE(FTRACE_README_MULTIPROBE_EVENT, "*Create/append/*"), > + DEFINE_TYPE(FTRACE_README_IMMEDIATE_VALUE, "*\\imm-value,*"), > }; > > static bool scan_ftrace_readme(enum ftrace_readme type) > @@ -1092,3 +1094,8 @@ bool multiprobe_event_is_supported(void) > { > return scan_ftrace_readme(FTRACE_README_MULTIPROBE_EVENT); > } > + > +bool immediate_value_is_supported(void) > +{ > + return scan_ftrace_readme(FTRACE_README_IMMEDIATE_VALUE); > +} > diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h > index 850d1b52d60a..0dba88c0f5f0 100644 > --- a/tools/perf/util/probe-file.h > +++ b/tools/perf/util/probe-file.h > @@ -72,6 +72,7 @@ bool kretprobe_offset_is_supported(void); > bool uprobe_ref_ctr_is_supported(void); > bool user_access_is_supported(void); > bool multiprobe_event_is_supported(void); > +bool immediate_value_is_supported(void); > #else /* ! HAVE_LIBELF_SUPPORT */ > static inline struct probe_cache *probe_cache__new(const char *tgt __maybe_unused, struct nsinfo *nsi __maybe_unused) > { > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c > index 9ecea45da4ca..2e3a468c8350 100644 > --- a/tools/perf/util/probe-finder.c > +++ b/tools/perf/util/probe-finder.c > @@ -177,6 +177,17 @@ static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr, > if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL) > goto static_var; > > + /* Constant value */ > + if (dwarf_attr(vr_die, DW_AT_const_value, &attr) && > + immediate_value_is_supported()) { > + Dwarf_Sword snum; > + > + dwarf_formsdata(&attr, &snum); > + ret = asprintf(&tvar->value, "\\%ld", (long)snum); > + > + return ret < 0 ? -ENOMEM : 0; > + } > + > /* TODO: handle more than 1 exprs */ > if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL) > return -EINVAL; /* Broken DIE ? */ -- - Arnaldo