161 lines
4.5 KiB
Diff
161 lines
4.5 KiB
Diff
From 79d849a3a0462ab0a33cbf208e27e28d05eab213 Mon Sep 17 00:00:00 2001
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From: Viktor Malik <viktor.malik@gmail.com>
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Date: Fri, 3 Mar 2023 08:28:54 +0100
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Subject: [PATCH 1/2] Parse kernel configuration
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In future, it may (and will) be useful to have access to the running
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kernel configuration, e.g. to add config-specific compilation options to
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ClangParser.
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This adds and fills a new map BPFtrace::kconfig that maps config options
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to their values. Both the option name and the value are strings. The
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configuration is parsed from one of two sources:
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- /boot/config-$(uname -r)
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- /proc/config.gz
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For testing purposes, the config filename may be passed through the
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BPFTRACE_KCONFIG_TEST env variable.
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---
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src/bpftrace.h | 1 +
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src/utils.cpp | 50 +++++++++++++++++++++++++++++++++++++++++++++++++
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src/utils.h | 12 ++++++++++++
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tests/utils.cpp | 19 +++++++++++++++++++
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4 files changed, 82 insertions(+)
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diff --git a/src/bpftrace.h b/src/bpftrace.h
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index a6a8c00b..94587bff 100644
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--- a/src/bpftrace.h
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+++ b/src/bpftrace.h
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@@ -168,6 +168,7 @@ public:
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std::map<libbpf::bpf_func_id, location> helper_use_loc_;
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// mapping traceable functions to modules (or "vmlinux") that they appear in
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FuncsModulesMap traceable_funcs_;
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+ KConfig kconfig;
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std::vector<std::unique_ptr<AttachedProbe>> attached_probes_;
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std::map<std::string, std::unique_ptr<PCAPwriter>> pcap_writers;
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diff --git a/src/utils.cpp b/src/utils.cpp
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index 2d9c6695..54c8f054 100644
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--- a/src/utils.cpp
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+++ b/src/utils.cpp
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@@ -28,6 +28,7 @@
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#include <bcc/bcc_syms.h>
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#include <bcc/bcc_usdt.h>
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#include <elf.h>
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+#include <zlib.h>
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#include <linux/version.h>
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@@ -178,6 +179,55 @@ StdioSilencer::~StdioSilencer()
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}
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}
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+KConfig::KConfig()
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+{
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+ std::vector<std::string> config_locs;
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+
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+ // Try to get the config from BPFTRACE_KCONFIG_TEST env
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+ // If not set, use the set of default locations
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+ const char *path_env = std::getenv("BPFTRACE_KCONFIG_TEST");
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+ if (path_env)
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+ config_locs = { std::string(path_env) };
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+ else
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+ {
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+ struct utsname utsname;
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+ if (uname(&utsname) < 0)
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+ return;
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+ config_locs = {
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+ "/boot/config-" + std::string(utsname.release),
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+ "/proc/config.gz",
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+ };
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+ }
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+
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+ for (auto &path : config_locs)
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+ {
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+ // gzopen/gzgets handle both uncompressed and compressed files
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+ gzFile file = gzopen(path.c_str(), "r");
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+ if (!file)
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+ continue;
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+
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+ char buf[4096];
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+ while (gzgets(file, buf, sizeof(buf)))
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+ {
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+ std::string option(buf);
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+ if (option.find("CONFIG_") == 0)
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+ {
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+ // trim trailing '\n'
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+ if (option[option.length() - 1] == '\n')
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+ option = option.substr(0, option.length() - 1);
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+
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+ auto split = option.find("=");
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+ if (split == std::string::npos)
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+ continue;
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+
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+ config.emplace(option.substr(0, split), option.substr(split + 1));
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+ }
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+ }
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+ gzclose(file);
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+ }
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+}
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+
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+
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bool get_uint64_env_var(const std::string &str, uint64_t &dest)
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{
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if (const char* env_p = std::getenv(str.c_str()))
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diff --git a/src/utils.h b/src/utils.h
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index dccc4504..a76aa161 100644
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--- a/src/utils.h
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+++ b/src/utils.h
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@@ -130,6 +130,18 @@ struct DeprecatedName
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typedef std::unordered_map<std::string, std::unordered_set<std::string>>
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FuncsModulesMap;
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+struct KConfig
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+{
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+ KConfig();
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+ bool has_value(const std::string &name, const std::string &value) const
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+ {
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+ auto c = config.find(name);
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+ return c != config.end() && c->second == value;
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+ }
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+
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+ std::unordered_map<std::string, std::string> config;
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+};
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+
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static std::vector<DeprecatedName> DEPRECATED_LIST =
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{
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};
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diff --git a/tests/utils.cpp b/tests/utils.cpp
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index 9ca4ace5..8470745b 100644
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--- a/tests/utils.cpp
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+++ b/tests/utils.cpp
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@@ -222,6 +222,25 @@ TEST(utils, get_cgroup_path_in_hierarchy)
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}
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}
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+TEST(utils, parse_kconfig)
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+{
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+ char path[] = "/tmp/configXXXXXX";
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+ int fd = mkstemp(path);
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+ const std::string config = "# Intro comment\n"
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+ "CONFIG_YES=y\n"
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+ "CONFIG_MOD=m\n"
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+ "CONFIG_VAL=42\n"
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+ "# CONFIG_NO is not set";
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+ EXPECT_EQ(write(fd, config.c_str(), config.length()), config.length());
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+ setenv("BPFTRACE_KCONFIG_TEST", path, true);
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+
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+ KConfig kconfig;
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+ ASSERT_TRUE(kconfig.has_value("CONFIG_YES", "y"));
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+ ASSERT_TRUE(kconfig.has_value("CONFIG_MOD", "m"));
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+ ASSERT_TRUE(kconfig.has_value("CONFIG_VAL", "42"));
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+ ASSERT_EQ(kconfig.config.find("CONFIG_NO"), kconfig.config.end());
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+}
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+
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} // namespace utils
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} // namespace test
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} // namespace bpftrace
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--
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2.39.2
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