linux-kernel - Re: [PATCH 11/11] perf tools: Stop fallbacking to kallsyms for vdso symbols lookup

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Message-ID: <20181027110541.GA25072@krava>
Date:   Sat, 27 Oct 2018 13:05:41 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Vinicius Costa Gomes <vinicius.gomes@...el.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Wang Nan <wangnan0@...wei.com>
Subject: Re: [PATCH 11/11] perf tools: Stop fallbacking to kallsyms for vdso
 symbols lookup

On Fri, Oct 26, 2018 at 04:19:52PM -0700, Vinicius Costa Gomes wrote:
> Hi,
> 
> Adrian Hunter <adrian.hunter@...el.com> writes:
> 
> > On 18/10/18 1:55 AM, Arnaldo Carvalho de Melo wrote:
> >> From: Arnaldo Carvalho de Melo <acme@...hat.com>
> >> 
> >> David reports that:
> >> 
> >> <quote>
> >> Perf has this hack where it uses the kernel symbol map as a backup when
> >> a symbol can't be found in the user's symbol table(s).
> >
> > I don't think this is a complete fix because it exposes new problems.
> 
> This commit broke function name resolution for 'perf record -g' for me.
> 
> What I mean is, with this commit applied:
> 
> $ ./tools/perf/perf record -g -- sleep 1
> 
> $ ./tools/perf/perf report
> 
> 'perf report' doesn't seem to be able to show the function names of the
> trace.
> 
> If I revert this commit, function names are resolved fine.

that commit just showed up some places where we have the
ip resolve wrong.. would attached patch fix it for you?

jirka


---
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 111ae858cbcb..72a5b803c797 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1824,7 +1824,7 @@ static void ip__resolve_ams(struct thread *thread,
 	 * Thus, we have to try consecutively until we find a match
 	 * or else, the symbol is unknown
 	 */
-	thread__find_cpumode_addr_location(thread, ip, &al);
+	thread__find_cpumode_addr_location(thread, ip, &al, NULL);
 
 	ams->addr = ip;
 	ams->al_addr = al.addr;
@@ -1909,8 +1909,8 @@ static int add_callchain_ip(struct thread *thread,
 
 	al.filtered = 0;
 	al.sym = NULL;
-	if (!cpumode) {
-		thread__find_cpumode_addr_location(thread, ip, &al);
+	if (!cpumode || *cpumode == PERF_RECORD_MISC_CPUMODE_UNKNOWN) {
+		thread__find_cpumode_addr_location(thread, ip, &al, cpumode);
 	} else {
 		if (ip >= PERF_CONTEXT_MAX) {
 			switch (ip) {
@@ -2151,7 +2151,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
 	struct branch_stack *branch = sample->branch_stack;
 	struct ip_callchain *chain = sample->callchain;
 	int chain_nr = 0;
-	u8 cpumode = PERF_RECORD_MISC_USER;
+	u8 cpumode = PERF_RECORD_MISC_CPUMODE_UNKNOWN;
 	int i, j, err, nr_entries;
 	int skip_idx = -1;
 	int first_call = 0;
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 2048d393ece6..1cd83ecde501 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -366,7 +366,7 @@ int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp)
 }
 
 void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
-					struct addr_location *al)
+					struct addr_location *al, u8 *cpumode)
 {
 	size_t i;
 	const u8 cpumodes[] = {
@@ -378,8 +378,11 @@ void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
 
 	for (i = 0; i < ARRAY_SIZE(cpumodes); i++) {
 		thread__find_symbol(thread, cpumodes[i], addr, al);
-		if (al->map)
+		if (al->map) {
+			if (cpumode)
+				*cpumode = cpumodes[i];
 			break;
+		}
 	}
 }
 
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 07606aa6998d..9aad9a71c943 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -99,7 +99,7 @@ struct symbol *thread__find_symbol(struct thread *thread, u8 cpumode,
 				   u64 addr, struct addr_location *al);
 
 void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
-					struct addr_location *al);
+					struct addr_location *al, u8 *cpumode);
 
 static inline void *thread__priv(struct thread *thread)
 {