Re: [PATCH V1 06/19] perf tools: Fix kernel_start for PTI on x86

From: Adrian Hunter
Date: Wed May 16 2018 - 13:45:37 EST


On 05/16/2018 04:55 PM, Arnaldo Carvalho de Melo wrote:
> Em Wed, May 16, 2018 at 04:45:41PM +0300, Adrian Hunter escreveu:
>> On 16/05/18 16:00, Arnaldo Carvalho de Melo wrote:
>>> 2303 bool machine__is(struct machine *machine, const char *arch)
>>> 2304 {
>>> 2305 return machine && machine->env && !strcmp(machine->env->arch, arch);
>>> 2306 }
>>> 2307
>>> 2308 int machine__get_kernel_start(struct machine *machine)
>>> 2309 {
>>> (gdb) p machine
>>> $1 = (struct machine *) 0xc55548
>>> (gdb) p machine->env
>>> $2 = (struct perf_env *) 0xc06400 <perf_env>
>>> (gdb) p machine-env->arch
>>> No symbol "env" in current context.
>>> (gdb) p machine->env->arch
>>> $3 = 0x0
>>> (gdb)
>
>> If there is no perf_data then perf_session__new() uses perf_env but it seems
>> perf_env.arch is not initialized. Would it be OK to initialize
>> perf_env.arch and perf_env.nr_cpus_avail?
>
> I guess so, to make that always available, i.e. no perf.data? Those
> should reflect the running machine environment.
>
> So a preparatory patch that makes that the case would be good, I think.

How about this:

From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Date: Wed, 16 May 2018 19:58:19 +0300
Subject: [PATCH] perf tools: Initialize perf_env.arch and
perf_env.nr_cpus_avail

Initialize perf_env.arch and perf_env.nr_cpus_avail so that they are
available for tools to use, even for tools that are not processing a
perf.data file.

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
tools/perf/perf.c | 4 ++++
tools/perf/util/env.c | 36 ++++++++++++++++++++++++++++++++++++
tools/perf/util/env.h | 2 ++
3 files changed, 42 insertions(+)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 20a08cb32332..03ec7a3b996b 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -300,7 +300,11 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
commit_pager_choice();

perf_env__set_cmdline(&perf_env, argc, argv);
+ status = perf_env__read_common(&perf_env);
+ if (status < 0)
+ goto cleanup;
status = p->fn(argc, argv);
+cleanup:
perf_config__exit();
exit_browser(status);
perf_env__exit(&perf_env);
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
index 4c842762e3f2..0d34de3449a5 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -93,6 +93,42 @@ int perf_env__read_cpu_topology_map(struct perf_env *env)
return 0;
}

+static int perf_env__read_arch(struct perf_env *env)
+{
+ struct utsname uts;
+
+ if (env->arch)
+ return 0;
+
+ if (!uname(&uts))
+ env->arch = strdup(uts.machine);
+
+ return env->arch ? 0 : -ENOMEM;
+}
+
+static void perf_env__read_nr_cpus_avail(struct perf_env *env)
+{
+ if (env->nr_cpus_avail == 0)
+ env->nr_cpus_avail = cpu__max_present_cpu();
+}
+
+int perf_env__read_common(struct perf_env *env)
+{
+ int ret;
+
+ ret = perf_env__read_arch(env);
+ if (ret < 0)
+ goto out_err;
+
+ perf_env__read_nr_cpus_avail(env);
+
+ return 0;
+
+out_err:
+ pr_err("Failed to determine machine environment\n");
+ return ret;
+}
+
void cpu_cache_level__free(struct cpu_cache_level *cache)
{
free(cache->type);
diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index c4ef2e523367..a83ece08d6e4 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -73,6 +73,8 @@ struct perf_env {

int perf_env__read_cpu_topology_map(struct perf_env *env);

+int perf_env__read_common(struct perf_env *env);
+
void cpu_cache_level__free(struct cpu_cache_level *cache);

const char *perf_env__arch(struct perf_env *env);
--
1.9.1