linux-kernel - [PATCH v1 1/3] perf env: Track kernel 64-bit mode in environment

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Date:   Mon,  9 Aug 2021 19:27:25 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Will Deacon <will@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        John Garry <john.garry@...wei.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Riccardo Mancini <rickyman7@...il.com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Li Huafei <lihuafei1@...wei.com>, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH v1 1/3] perf env: Track kernel 64-bit mode in environment

It's useful to know that the kernel is running in 32-bit or 64-bit
mode.  E.g. We can decide if perf tool is running in compat mode
based on the info.

This patch adds an item "kernel_is_64_bit" into session's environment
structure perf_env, its value is initialized based on the architecture
string.

Suggested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 tools/perf/util/env.c | 24 +++++++++++++++++++++++-
 tools/perf/util/env.h |  3 +++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
index ab341050be46..8f7ff0035c41 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -219,13 +219,35 @@ void perf_env__exit(struct perf_env *env)
 	zfree(&env->hybrid_cpc_nodes);
 }
 
-void perf_env__init(struct perf_env *env __maybe_unused)
+void perf_env__init(struct perf_env *env)
 {
 #ifdef HAVE_LIBBPF_SUPPORT
 	env->bpf_progs.infos = RB_ROOT;
 	env->bpf_progs.btfs = RB_ROOT;
 	init_rwsem(&env->bpf_progs.lock);
 #endif
+	env->kernel_is_64_bit = -1;
+}
+
+static void perf_env__init_kernel_mode(struct perf_env *env)
+{
+	const char *arch = perf_env__raw_arch(env);
+
+	if (!strncmp(arch, "x86_64", 6) || !strncmp(arch, "aarch64", 7) ||
+	    !strncmp(arch, "arm64", 5) || !strncmp(arch, "mips64", 6) ||
+	    !strncmp(arch, "parisc64", 8) || !strncmp(arch, "riscv64", 7) ||
+	    !strncmp(arch, "s390x", 5) || !strncmp(arch, "sparc64", 7))
+		env->kernel_is_64_bit = 1;
+	else
+		env->kernel_is_64_bit = 0;
+}
+
+int perf_env__kernel_is_64_bit(struct perf_env *env)
+{
+	if (env->kernel_is_64_bit == -1)
+		perf_env__init_kernel_mode(env);
+
+	return env->kernel_is_64_bit;
 }
 
 int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[])
diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index 6824a7423a2d..1f5175820a05 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -61,6 +61,7 @@ struct perf_env {
 	unsigned long long	total_mem;
 	unsigned int		msr_pmu_type;
 	unsigned int		max_branches;
+	int			kernel_is_64_bit;
 
 	int			nr_cmdline;
 	int			nr_sibling_cores;
@@ -143,6 +144,8 @@ extern struct perf_env perf_env;
 
 void perf_env__exit(struct perf_env *env);
 
+int perf_env__kernel_is_64_bit(struct perf_env *env);
+
 int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[]);
 
 int perf_env__read_cpuid(struct perf_env *env);
-- 
2.25.1