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Commit eca4783e authored by Vicent Marti's avatar Vicent Marti
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cc: Wrap the USDT probe context in a C API

parent a597f7c9
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Showing with 251 additions and 45 deletions
src/cc/bcc_usdt.h 0 → 100644
View file @ eca4783e
/*
* Copyright (c) 2016 GitHub, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef LIBBCC_USDT_H
#define LIBBCC_USDT_H
#ifdef __cplusplus
extern "C" {
#endif
#include <stdint.h>
void *bcc_usdt_new_frompid(int pid);
void *bcc_usdt_new_frompath(const char *path);
void bcc_usdt_close(void *usdt);
int bcc_usdt_enable_probe(void *, const char *, const char *);
char *bcc_usdt_genargs(void *);
typedef void (*bcc_usdt_uprobe_cb)(const char *, const char *, uint64_t, int);
void bcc_usdt_foreach_uprobe(void *usdt, bcc_usdt_uprobe_cb callback);
#ifdef __cplusplus
}
#endif
#endif
src/cc/export/helpers.h
View file @ eca4783e
......@@ -434,5 +434,10 @@ int bpf_num_cpus() asm("llvm.bpf.extra");
#error "bcc does not support this platform yet"
#endif
#define bpf_usdt_readarg(probearg, ctx) _bpf_readarg_##probearg(ctx)
#define bpf_usdt_readarg_p(probearg, ctx, buf, len) {\
u64 __addr = bpf_usdt_readarg(probearg, ctx); \
bpf_probe_read(buf, len, (void *)__addr); }
#endif
)********"
src/cc/usdt.cc
View file @ eca4783e
......@@ -14,6 +14,7 @@
* limitations under the License.
*/
#include <sstream>
#include <cstring>
#include <fcntl.h>
#include <sys/types.h>
......@@ -29,12 +30,10 @@ namespace USDT {
Probe::Location::Location(uint64_t addr, const char *arg_fmt) : address_(addr) {
ArgumentParser_x64 parser(arg_fmt);
while (!parser.done()) {
Argument *arg = new Argument();
if (!parser.parse(arg)) {
delete arg; // TODO: report error
Argument arg;
if (!parser.parse(&arg))
continue;
}
arguments_.push_back(arg);
arguments_.push_back(std::move(arg));
}
}
......@@ -51,6 +50,16 @@ bool Probe::in_shared_object() {
return in_shared_object_.value();
}
bool Probe::resolve_global_address(uint64_t *global, const uint64_t addr, optional<int> pid) {
if (in_shared_object()) {
return (pid &&
bcc_resolve_global_addr(*pid, bin_path_.c_str(), addr, global) == 0);
}
*global = addr;
return true;
}
bool Probe::lookup_semaphore_addr(uint64_t *address, int pid) {
auto it = semaphores_.find(pid);
if (it != semaphores_.end()) {
......@@ -58,12 +67,8 @@ bool Probe::lookup_semaphore_addr(uint64_t *address, int pid) {
return true;
}
if (in_shared_object()) {
uint64_t load_address = 0x0; // TODO
*address = load_address + semaphore_;
} else {
*address = semaphore_;
}
if (!resolve_global_address(address, semaphore_, pid))
return false;
semaphores_[pid] = *address;
return true;
......@@ -100,10 +105,12 @@ bool Probe::add_to_semaphore(int pid, int16_t val) {
}
bool Probe::enable(int pid) {
if (enabled_semaphores_.find(pid) != enabled_semaphores_.end())
return true;
if (!add_to_semaphore(pid, +1))
return false;
// TODO: what happens if we enable this twice?
enabled_semaphores_.emplace(pid, std::move(ProcStat(pid)));
return true;
}
......@@ -137,15 +144,8 @@ bool Probe::usdt_cases(std::ostream &stream, const optional<int> &pid) {
const size_t arg_count = locations_[0].arguments_.size();
for (size_t arg_n = 0; arg_n < arg_count; ++arg_n) {
Argument *largest = nullptr;
for (Location &location : locations_) {
Argument *candidate = location.arguments_[arg_n];
if (!largest ||
std::abs(candidate->arg_size()) > std::abs(largest->arg_size()))
largest = candidate;
}
tfm::format(stream, "%s arg%d = 0;\n", largest->ctype(), arg_n + 1);
tfm::format(stream, "%s arg%d = 0;\n",
largest_arg_type(arg_n), arg_n + 1);
}
for (size_t loc_n = 0; loc_n < locations_.size(); ++loc_n) {
......@@ -153,8 +153,8 @@ bool Probe::usdt_cases(std::ostream &stream, const optional<int> &pid) {
tfm::format(stream, "if (__loc_id == %d) {\n", loc_n);
for (size_t arg_n = 0; arg_n < location.arguments_.size(); ++arg_n) {
Argument *arg = location.arguments_[arg_n];
if (!arg->assign_to_local(stream, tfm::format("arg%d", arg_n + 1),
Argument &arg = location.arguments_[arg_n];
if (!arg.assign_to_local(stream, tfm::format("arg%d", arg_n + 1),
bin_path_, pid))
return false;
}
......@@ -163,6 +163,61 @@ bool Probe::usdt_cases(std::ostream &stream, const optional<int> &pid) {
return true;
}
std::string Probe::largest_arg_type(size_t arg_n) {
Argument *largest = nullptr;
for (Location &location : locations_) {
Argument *candidate = &location.arguments_[arg_n];
if (!largest ||
std::abs(candidate->arg_size()) > std::abs(largest->arg_size()))
largest = candidate;
}
assert(largest);
return largest->ctype();
}
bool Probe::usdt_getarg(std::ostream &stream, const optional<int> &pid) {
const size_t arg_count = locations_[0].arguments_.size();
if (arg_count == 0)
return true;
for (size_t arg_n = 0; arg_n < arg_count; ++arg_n) {
std::string ctype = largest_arg_type(arg_n);
tfm::format(stream,
"static inline %s _bpf_readarg_%s_%d(struct pt_regs *ctx) {\n"
" %s result = 0x0;\n",
ctype, name_, arg_n + 1, ctype);
if (locations_.size() == 1) {
Location &location = locations_.front();
stream << " ";
if (!location.arguments_[arg_n].assign_to_local(
stream, "result", bin_path_, pid))
return false;
stream << "\n";
} else {
stream << " switch(ctx->ip) {\n";
for (Location &location : locations_) {
uint64_t global_address;
if (!resolve_global_address(&global_address, location.address_, pid))
return false;
tfm::format(stream, " case 0x%xULL: ", global_address);
if (!location.arguments_[arg_n].assign_to_local(
stream, "result", bin_path_, pid))
return false;
stream << " break;\n";
}
stream << " }\n";
}
stream << " return result;\n}\n";
}
return true;
}
void Probe::add_location(uint64_t addr, const char *fmt) {
locations_.emplace_back(addr, fmt);
}
......@@ -210,7 +265,7 @@ std::string Context::resolve_bin_path(const std::string &bin_path) {
return result;
}
Probe *Context::find_probe(const std::string &probe_name) {
Probe *Context::get(const std::string &probe_name) const {
for (Probe *p : probes_) {
if (p->name_ == probe_name)
return p;
......@@ -218,6 +273,41 @@ Probe *Context::find_probe(const std::string &probe_name) {
return nullptr;
}
bool Context::generate_usdt_args(std::ostream &stream) {
stream << "#include <uapi/linux/ptrace.h>\n";
for (auto &p : uprobes_) {
if (!p.first->usdt_getarg(stream, pid_))
return false;
}
return true;
}
bool Context::enable_probe(const std::string &probe_name, const std::string &fn_name) {
Probe *p = get(probe_name);
if (!p)
return false;
if (p->need_enable()) {
if (!pid_ || !p->enable(pid_.value()))
return false;
}
uprobes_.emplace_back(p, fn_name);
return true;
}
void Context::each_uprobe(each_uprobe_cb callback) {
for (auto &p : uprobes_) {
for (Probe::Location &loc : p.first->locations_) {
callback(
p.first->bin_path_.c_str(),
p.second.c_str(),
loc.address_,
pid_.value_or(-1));
}
}
}
Context::Context(const std::string &bin_path) : loaded_(false) {
std::string full_path = resolve_bin_path(bin_path);
if (!full_path.empty()) {
......@@ -226,8 +316,63 @@ Context::Context(const std::string &bin_path) : loaded_(false) {
}
}
Context::Context(int pid) : loaded_(false) {
Context::Context(int pid) : pid_(pid), loaded_(false) {
if (bcc_procutils_each_module(pid, _each_module, this) == 0)
loaded_ = true;
}
Context::~Context() {
for (Probe *p : probes_) {
if (pid_ && p->enabled())
p->disable(pid_.value());
delete p;
}
}
}
extern "C" {
#include "bcc_usdt.h"
void *bcc_usdt_new_frompid(int pid) {
USDT::Context *ctx = new USDT::Context(pid);
if (!ctx->loaded()) {
delete ctx;
return nullptr;
}
return static_cast<void *>(ctx);
}
void *bcc_usdt_new_frompath(const char *path) {
USDT::Context *ctx = new USDT::Context(path);
if (!ctx->loaded()) {
delete ctx;
return nullptr;
}
return static_cast<void *>(ctx);
}
void bcc_usdt_close(void *usdt) {
USDT::Context *ctx = static_cast<USDT::Context *>(usdt);
delete ctx;
}
int bcc_usdt_enable_probe(void *usdt, const char *probe_name, const char *fn_name) {
USDT::Context *ctx = static_cast<USDT::Context *>(usdt);
return ctx->enable_probe(probe_name, fn_name) ? 0 : -1;
}
char *bcc_usdt_genargs(void *usdt) {
USDT::Context *ctx = static_cast<USDT::Context *>(usdt);
std::ostringstream stream;
if (!ctx->generate_usdt_args(stream))
return nullptr;
return strdup(stream.str().c_str());
}
void bcc_usdt_foreach_uprobe(void *usdt, bcc_usdt_uprobe_cb callback) {
USDT::Context *ctx = static_cast<USDT::Context *>(usdt);
ctx->each_uprobe(callback);
}
}
src/cc/usdt.h
View file @ eca4783e
......@@ -122,7 +122,7 @@ class Probe {
struct Location {
uint64_t address_;
std::vector<Argument *> arguments_;
std::vector<Argument> arguments_;
Location(uint64_t addr, const char *arg_fmt);
};
......@@ -131,7 +131,10 @@ class Probe {
std::unordered_map<int, ProcStat> enabled_semaphores_;
optional<bool> in_shared_object_;
std::string largest_arg_type(size_t arg_n);
bool add_to_semaphore(int pid, int16_t val);
bool resolve_global_address(uint64_t *global, const uint64_t addr, optional<int> pid);
bool lookup_semaphore_addr(uint64_t *address, int pid);
void add_location(uint64_t addr, const char *fmt);
......@@ -142,12 +145,17 @@ public:
size_t num_locations() const { return locations_.size(); }
size_t num_arguments() const { return locations_.front().arguments_.size(); }
uint64_t address(size_t n = 0) const { return locations_[n].address_; }
bool usdt_thunks(std::ostream &stream, const std::string &prefix);
bool usdt_cases(std::ostream &stream, const optional<int> &pid = nullopt);
bool usdt_getarg(std::ostream &stream, const optional<int> &pid = nullopt);
bool need_enable() const { return semaphore_ != 0x0; }
bool enable(int pid);
bool disable(int pid);
bool enabled() const { return !enabled_semaphores_.empty(); }
bool in_shared_object();
const std::string &name() { return name_; }
......@@ -159,6 +167,8 @@ public:
class Context {
std::vector<Probe *> probes_;
std::vector<std::pair<Probe *, std::string>> uprobes_;
optional<int> pid_;
bool loaded_;
static void _each_probe(const char *binpath, const struct bcc_elf_usdt *probe,
......@@ -171,9 +181,19 @@ class Context {
public:
Context(const std::string &bin_path);
Context(int pid);
~Context();
optional<int> pid() const { return pid_; }
bool loaded() const { return loaded_; }
size_t num_probes() const { return probes_.size(); }
Probe *find_probe(const std::string &probe_name);
Probe *get(const std::string &probe_name) const;
Probe *get(int pos) const { return probes_[pos]; }
bool enable_probe(const std::string &probe_name, const std::string &fn_name);
bool generate_usdt_args(std::ostream &stream);
typedef void (*each_uprobe_cb)(const char *, const char *, uint64_t, int);
void each_uprobe(each_uprobe_cb callback);
};
}
src/cc/usdt_args.cc
View file @ eca4783e
......@@ -55,37 +55,35 @@ bool Argument::assign_to_local(std::ostream &stream,
const std::string &binpath,
const optional<int> &pid) const {
if (constant_) {
tfm::format(stream, "%s = %d;\n", local_name, *constant_);
tfm::format(stream, "%s = %d;", local_name, *constant_);
return true;
}
if (!deref_offset_) {
tfm::format(stream, "%s = (%s)ctx->%s;\n", local_name, ctype(),
tfm::format(stream, "%s = (%s)ctx->%s;", local_name, ctype(),
*register_name_);
return true;
}
if (deref_offset_ && !deref_ident_) {
tfm::format(stream,
"{\n"
" u64 __temp = ctx->%s + (%d);\n"
" bpf_probe_read(&%s, sizeof(%s), (void *)__temp);\n"
"}\n",
*register_name_, *deref_offset_, local_name, local_name);
"{ u64 __addr = ctx->%s + (%d); %s __res = 0x0; "
"bpf_probe_read(&__res, sizeof(__res), (void *)__addr); "
"%s = __res; }",
*register_name_, *deref_offset_, ctype(), local_name);
return true;
}
if (deref_offset_ && deref_ident_) {
if (deref_offset_ && deref_ident_ && *register_name_ == "ip") {
uint64_t global_address;
if (!get_global_address(&global_address, binpath, pid))
return false;
tfm::format(stream,
"{\n"
" u64 __temp = 0x%xull + %d;\n"
" bpf_probe_read(&%s, sizeof(%s), (void *)__temp);\n"
"}\n",
global_address, *deref_offset_, local_name, local_name);
"{ u64 __addr = 0x%xull + %d; %s __res = 0x0; "
"bpf_probe_read(&__res, sizeof(__res), (void *)__addr); "
"%s = __res; }",
global_address, *deref_offset_, ctype(), local_name);
return true;
}
......
tests/cc/test_usdt_probes.cc
View file @ eca4783e
......@@ -39,7 +39,7 @@ TEST_CASE("test finding a probe in our own process", "[usdt]") {
REQUIRE(ctx.num_probes() >= 1);
SECTION("our test probe") {
USDT::Probe *probe = ctx.find_probe("sample_probe_1");
USDT::Probe *probe = ctx.get("sample_probe_1");
REQUIRE(probe != nullptr);
REQUIRE(probe->in_shared_object() == false);
......@@ -115,7 +115,7 @@ TEST_CASE("test listing all USDT probes in Ruby/MRI", "[usdt]") {
mri_probe_count = ctx.num_probes();
SECTION("GC static probe") {
USDT::Probe *probe = ctx.find_probe("gc__mark__begin");
USDT::Probe *probe = ctx.get("gc__mark__begin");
REQUIRE(probe != nullptr);
REQUIRE(probe->in_shared_object() == true);
......@@ -129,7 +129,7 @@ TEST_CASE("test listing all USDT probes in Ruby/MRI", "[usdt]") {
}
SECTION("object creation probe") {
USDT::Probe *probe = ctx.find_probe("object__create");
USDT::Probe *probe = ctx.get("object__create");
REQUIRE(probe != nullptr);
REQUIRE(probe->in_shared_object() == true);
......@@ -161,7 +161,7 @@ TEST_CASE("test listing all USDT probes in Ruby/MRI", "[usdt]") {
}
SECTION("array creation probe") {
USDT::Probe *probe = ctx.find_probe("array__create");
USDT::Probe *probe = ctx.get("array__create");
REQUIRE(probe != nullptr);
REQUIRE(probe->name() == "array__create");
......@@ -203,7 +203,7 @@ TEST_CASE("test listing all USDT probes in Ruby/MRI", "[usdt]") {
REQUIRE(ctx.num_probes() >= mri_probe_count);
SECTION("get probe in running process") {
USDT::Probe *probe = ctx.find_probe("gc__mark__begin");
USDT::Probe *probe = ctx.get("gc__mark__begin");
REQUIRE(probe != nullptr);
REQUIRE(probe->in_shared_object() == true);
......
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