diff options
Diffstat (limited to 'tapsets.cxx')
| -rw-r--r-- | tapsets.cxx | 262 |
1 files changed, 257 insertions, 5 deletions
diff --git a/tapsets.cxx b/tapsets.cxx index 5c7d46c1..f99fbef4 100644 --- a/tapsets.cxx +++ b/tapsets.cxx @@ -6851,17 +6851,24 @@ public: struct utrace_var_expanding_visitor: public var_expanding_visitor { - utrace_var_expanding_visitor(systemtap_session& s, const string& pn, + utrace_var_expanding_visitor(systemtap_session& s, probe_point* l, + const string& pn, enum utrace_derived_probe_flags f): - sess (s), probe_name (pn), flags (f), target_symbol_seen (false) {} + sess (s), base_loc (l), probe_name (pn), flags (f), + target_symbol_seen (false), add_block(NULL), add_probe(NULL) {} systemtap_session& sess; + probe_point* base_loc; string probe_name; enum utrace_derived_probe_flags flags; bool target_symbol_seen; + block *add_block; + probe *add_probe; + std::map<std::string, symbol *> return_ts_map; void visit_target_symbol_arg (target_symbol* e); void visit_target_symbol_context (target_symbol* e); + void visit_target_symbol_cached (target_symbol* e); void visit_target_symbol (target_symbol* e); }; @@ -6876,10 +6883,23 @@ utrace_derived_probe::utrace_derived_probe (systemtap_session &s, target_symbol_seen(false) { // Expand local variables in the probe body - utrace_var_expanding_visitor v (s, name, flags); + utrace_var_expanding_visitor v (s, l, name, flags); this->body = v.require (this->body); target_symbol_seen = v.target_symbol_seen; + // If during target-variable-expanding the probe, we added a new block + // of code, add it to the start of the probe. + if (v.add_block) + this->body = new block(v.add_block, this->body); + // If when target-variable-expanding the probe, we added a new + // probe, add it in a new file to the list of files to be processed. + if (v.add_probe) + { + stapfile *f = new stapfile; + f->probes.push_back(v.add_probe); + s.files.push_back(f); + } + // Reset the sole element of the "locations" vector as a // "reverse-engineered" form of the incoming (q.base_loc) probe // point. This allows a user to see what program etc. @@ -6939,6 +6959,216 @@ utrace_derived_probe::join_group (systemtap_session& s) void +utrace_var_expanding_visitor::visit_target_symbol_cached (target_symbol* e) +{ + // Get the full name of the target symbol. + stringstream ts_name_stream; + e->print(ts_name_stream); + string ts_name = ts_name_stream.str(); + + // Check and make sure we haven't already seen this target + // variable in this return probe. If we have, just return our + // last replacement. + map<string, symbol *>::iterator i = return_ts_map.find(ts_name); + if (i != return_ts_map.end()) + { + provide (i->second); + return; + } + + // We've got to do several things here to handle target + // variables in return probes. + + // (1) Synthesize a global array which is the cache of the + // target variable value. We don't need a nesting level counter + // like the dwarf_var_expanding_visitor::visit_target_symbol() + // does since a particular thread can only be in one system + // calls at a time. The array will look like this: + // + // _utrace_tvar_{name}_{num} + string aname = (string("_utrace_tvar_") + + e->base_name.substr(1) + + "_" + lex_cast<string>(tick++)); + vardecl* vd = new vardecl; + vd->name = aname; + vd->tok = e->tok; + sess.globals.push_back (vd); + + // (2) Create a new code block we're going to insert at the + // beginning of this probe to get the cached value into a + // temporary variable. We'll replace the target variable + // reference with the temporary variable reference. The code + // will look like this: + // + // _utrace_tvar_tid = tid() + // _utrace_tvar_{name}_{num}_tmp + // = _utrace_tvar_{name}_{num}[_utrace_tvar_tid] + // delete _utrace_tvar_{name}_{num}[_utrace_tvar_tid] + + // (2a) Synthesize the tid temporary expression, which will look + // like this: + // + // _utrace_tvar_tid = tid() + symbol* tidsym = new symbol; + tidsym->name = string("_utrace_tvar_tid"); + tidsym->tok = e->tok; + + if (add_block == NULL) + { + add_block = new block; + add_block->tok = e->tok; + + // Synthesize a functioncall to grab the thread id. + functioncall* fc = new functioncall; + fc->tok = e->tok; + fc->function = string("tid"); + + // Assign the tid to '_utrace_tvar_tid'. + assignment* a = new assignment; + a->tok = e->tok; + a->op = "="; + a->left = tidsym; + a->right = fc; + + expr_statement* es = new expr_statement; + es->tok = e->tok; + es->value = a; + add_block->statements.push_back (es); + } + + // (2b) Synthesize an array reference and assign it to a + // temporary variable (that we'll use as replacement for the + // target variable reference). It will look like this: + // + // _utrace_tvar_{name}_{num}_tmp + // = _utrace_tvar_{name}_{num}[_utrace_tvar_tid] + + arrayindex* ai_tvar = new arrayindex; + ai_tvar->tok = e->tok; + + symbol* sym = new symbol; + sym->name = aname; + sym->tok = e->tok; + ai_tvar->base = sym; + + ai_tvar->indexes.push_back(tidsym); + + symbol* tmpsym = new symbol; + tmpsym->name = aname + "_tmp"; + tmpsym->tok = e->tok; + + assignment* a = new assignment; + a->tok = e->tok; + a->op = "="; + a->left = tmpsym; + a->right = ai_tvar; + + expr_statement* es = new expr_statement; + es->tok = e->tok; + es->value = a; + + add_block->statements.push_back (es); + + // (2c) Delete the array value. It will look like this: + // + // delete _utrace_tvar_{name}_{num}[_utrace_tvar_tid] + + delete_statement* ds = new delete_statement; + ds->tok = e->tok; + ds->value = ai_tvar; + add_block->statements.push_back (ds); + + // (3) We need an entry probe that saves the value for us in the + // global array we created. Create the entry probe, which will + // look like this: + // + // probe process(PATH_OR_PID).syscall { + // _utrace_tvar_tid = tid() + // _utrace_tvar_{name}_{num}[_utrace_tvar_tid] = ${param} + // } + // + // Why the temporary for tid()? If we end up caching more + // than one target variable, we can reuse the temporary instead + // of calling tid() multiple times. + + if (add_probe == NULL) + { + add_probe = new probe; + add_probe->tok = e->tok; + + // We need the name of the current probe point, minus the + // ".return". Create a new probe point, copying all the + // components, stopping when we see the ".return" + // component. + probe_point* pp = new probe_point; + for (unsigned c = 0; c < base_loc->components.size(); c++) + { + if (base_loc->components[c]->functor == "return") + break; + else + pp->components.push_back(base_loc->components[c]); + } + pp->tok = e->tok; + pp->optional = base_loc->optional; + add_probe->locations.push_back(pp); + + add_probe->body = new block; + add_probe->body->tok = e->tok; + + // Synthesize a functioncall to grab the thread id. + functioncall* fc = new functioncall; + fc->tok = e->tok; + fc->function = string("tid"); + + // Assign the tid to '_utrace_tvar_tid'. + assignment* a = new assignment; + a->tok = e->tok; + a->op = "="; + a->left = tidsym; + a->right = fc; + + expr_statement* es = new expr_statement; + es->tok = e->tok; + es->value = a; + add_probe->body = new block(add_probe->body, es); + + vardecl* vd = new vardecl; + vd->tok = e->tok; + vd->name = tidsym->name; + vd->type = pe_long; + vd->set_arity(0); + add_probe->locals.push_back(vd); + } + + // Save the value, like this: + // + // _utrace_tvar_{name}_{num}[_utrace_tvar_tid] = ${param} + a = new assignment; + a->tok = e->tok; + a->op = "="; + a->left = ai_tvar; + a->right = e; + + es = new expr_statement; + es->tok = e->tok; + es->value = a; + + add_probe->body = new block(add_probe->body, es); + + // (4) Provide the '_utrace_tvar_{name}_{num}_tmp' variable to + // our parent so it can be used as a substitute for the target + // symbol. + provide (tmpsym); + + // (5) Remember this replacement since we might be able to reuse + // it later if the same return probe references this target + // symbol again. + return_ts_map[ts_name] = tmpsym; + return; +} + + +void utrace_var_expanding_visitor::visit_target_symbol_arg (target_symbol* e) { string argnum_s = e->base_name.substr(4,e->base_name.length()-4); @@ -7026,8 +7256,30 @@ utrace_var_expanding_visitor::visit_target_symbol_context (target_symbol* e) throw semantic_error ("only \"process(PATH_OR_PID).syscall.return\" support $return.", e->tok); fname = "_utrace_syscall_return"; } + else if (sname == "$syscall") + { + // If we've got a syscall entry probe, we can just call the + // right function. + if (flags == UDPF_SYSCALL) { + fname = "_utrace_syscall_nr"; + } + // If we're in a syscal return probe, we can't really access + // $syscall. So, similar to what + // dwarf_var_expanding_visitor::visit_target_symbol() does, + // we'll create an syscall entry probe to cache $syscall, then + // we'll access the cached value in the syscall return probe. + else { + visit_target_symbol_cached (e); + + // Remember that we've seen a target variable. + target_symbol_seen = true; + return; + } + } else - fname = "_utrace_syscall_nr"; + { + throw semantic_error ("unknown target variable", e->tok); + } // Remember that we've seen a target variable. target_symbol_seen = true; @@ -7381,7 +7633,7 @@ utrace_derived_probe_group::emit_module_decls (systemtap_session& s) s.op->indent(1); s.op->newline() << "switch (p->flags) {"; s.op->indent(1); - // For death probes, go ahead and call the probe directly. + // For end probes, go ahead and call the probe directly. if (flags_seen[UDPF_END]) { s.op->newline() << "case UDPF_END:"; |