usdt: Implement assign_to_local

src/cc/usdt.h

@@ -33,11 +33,19 @@ class Argument {
  optional<std::string> deref_ident_;
  optional<std::string> register_name_;
 
+ uint64_t get_global_address(int pid) const;
+ static const std::unordered_map<std::string, std::string> translations_;
+
  public:
  Argument();
  ~Argument();
 
+ void assign_to_local(std::ostream &stream,
+ const std::string &local_name, optional<int> pid = nullopt) const;
+
  int arg_size() const { return arg_size_.value_or(sizeof(void *)); }
+ std::string ctype() const;
+ void normalize_register_name(std::string *normalized) const;
 
  const optional<std::string> &deref_ident() const { return deref_ident_; }
  const optional<std::string> &register_name() const { return register_name_; }

src/cc/usdt_args.cc

@@ -15,12 +15,82 @@
  */
 #include "usdt.h"
 #include <unordered_map>
+#include "vendor/tinyformat.hpp"
 
 namespace USDT {
 
 Argument::Argument() {}
 Argument::~Argument() {}
 
+const std::unordered_map<std::string, std::string> Argument::translations_ = {
+ {"rax", "ax"}, {"rbx", "bx"}, {"rcx", "cx"}, {"rdx", "dx"},
+ {"rdi", "di"}, {"rsi", "si"}, {"rbp", "bp"}, {"rsp", "sp"},
+ {"rip", "ip"}, {"eax", "ax"}, {"ebx", "bx"}, {"ecx", "cx"},
+ {"edx", "dx"}, {"edi", "di"}, {"esi", "si"}, {"ebp", "bp"},
+ {"esp", "sp"}, {"eip", "ip"},
+
+ {"al", "ax"}, {"bl", "bx"}, {"cl", "cx"}, {"dl", "dx"}
+};
+
+std::string Argument::ctype() const {
+ const int s = arg_size() * 8;
+ return (s < 0) ?
+ tfm::format("int%d_t", -s) :
+ tfm::format("uint%d_t", s);
+}
+
+void Argument::normalize_register_name(std::string *normalized) const {
+ if (!register_name_)
+ return;
+
+ normalized->assign(*register_name_);
+ if ((*normalized)[0] == '%')
+ normalized->erase(0, 1);
+
+ auto it = translations_.find(*normalized);
+ if (it != translations_.end())
+ normalized->assign(it->second);
+}
+
+uint64_t Argument::get_global_address(int pid) const {
+ return 0x0;
+}
+
+void Argument::assign_to_local(std::ostream &stream,
+ const std::string &local_name, optional<int> pid) const {
+
+ std::string regname;
+ normalize_register_name(&regname);
+
+ if (constant_) {
+ tfm::format(stream, "%s = %d;", local_name, *constant_);
+ return;
+ }
+
+ if (!deref_offset_) {
+ tfm::format(stream, "%s = (%s)ctx->%s;", local_name, ctype(), regname);
+ return;
+ }
+
+ 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",
+ regname, *deref_offset_, local_name, local_name);
+ return;
+ }
+
+ tfm::format(stream,
+ "{\n"
+ " u64 __temp = 0x%xull + %d;\n"
+ " bpf_probe_read(&%s, sizeof(%s), (void *)__temp);\n"
+ "}\n",
+ get_global_address(pid.value_or(-1)),
+ *deref_offset_, local_name, local_name);
+}
+
 ssize_t ArgumentParser::parse_number(ssize_t pos, optional<int> *result) {
  char *endp;
  int number = strtol(arg_ + pos, &endp, 0);