Merge branch 'master' of https://github.com/cloudius-systems/osv

README

@@ -48,3 +48,20 @@ To run OSv
     (gdb) connect
     (gdb) osv syms
     (gdb) bt
+
+
+ Tracing
+ =======
+ Uncomment the "tracing-flags =" line in build.mak, and rebuild.
+ Run the program until it aborts, then in gdb:
+
+ set pagination off
+ set print elements 0
+ set print array-indexes on
+ set print pretty on
+ set logging on
+ print trace_log
+ print trace_record_last._M_i % trace_max
+
+ gdb.txt will contain the the log, the last line contains the array index
+ of the last trace entry, read backwards from there.

arch/x64/arch.hh

@@ -2,6 +2,7 @@
 #define ARCH_HH_
 
 #include "processor.hh"
+#include "msr.hh"
 
 // namespace arch - architecture independent interface for architecture
 //                  dependent operations (e.g. irq_disable vs. cli)
@@ -33,11 +34,23 @@ public:
     void restore() {
         asm volatile("sub $128, %%rsp; pushq %0; popfq; add $128, %%rsp" : : "r"(_rflags));
     }
+    bool enabled() const {
+        return _rflags & 0x200;
+    }
 private:
     unsigned long _rflags;
 };
 
+extern bool tls_available() __attribute__((no_instrument_function));
+
+inline bool tls_available()
+{
+    unsigned a, d;
+    asm("rdmsr" : "=a"(a), "=d"(d) : "c"(msr::IA32_FS_BASE));
+    // don't call rdmsr, since we don't want function instrumentation
+    return a != 0 || d != 0;
 }
 
+}
 
 #endif /* ARCH_HH_ */

build.mak

 
 arch = x64
-#cmdline = java.so Hello
-cmdline = testrunner.so
+cmdline = java.so Hello
+#cmdline = testrunner.so
 INCLUDES = -I. -I$(src)/arch/$(arch) -I$(src) -I$(src)/external/libunwind/include -I$(src)/include
 INCLUDES += -I$(src)/external/acpica/source/include
 COMMON = $(autodepend) -g -Wall -Wno-pointer-arith -Werror -Wformat=0 \
 	-U _FORTIFY_SOURCE -fno-stack-protector $(INCLUDES) \
-	$(arch-cflags) $(cflags-$(mode)) $(acpi-defines)
+	$(arch-cflags) $(cflags-$(mode)) $(acpi-defines) $(tracing-flags)
+
+tracing-flags =
+#tracing-flags = -finstrument-functions -finstrument-functions-exclude-file-list=atomic,trace.cc
 
 CXXFLAGS = -std=gnu++11 -lstdc++ $(do-sys-includes) $(COMMON)
 CFLAGS = -std=gnu99 $(COMMON)
@@ -193,6 +196,7 @@ objects += core/sched.o
 objects += core/mmio.o
 objects += core/sglist.o
 objects += core/kprintf.o
+objects += core/trace.o
 
 unittests:= tests/tst-hub.o
 

core/trace.cc

+#include "osv/trace.hh"
+#include "sched.hh"
+#include "arch.hh"
+#include <atomic>
+
+enum class trace_record_type {
+    invalid,
+    entry,
+    exit,
+};
+
+struct trace_record {
+    trace_record_type type;
+    sched::thread* thread;
+    void* fn;
+    void* caller;
+};
+
+constexpr unsigned max_trace = 100000;
+
+trace_record trace_log[max_trace];
+std::atomic<unsigned> trace_record_last;
+bool trace_enabled;
+
+void enable_trace()
+{
+    trace_enabled = true;
+}
+
+void add_trace_record(const trace_record& tr)
+{
+    unsigned p = trace_record_last.fetch_add(1, std::memory_order_relaxed);
+    p %= max_trace;
+    trace_log[p] = tr;
+}
+
+extern "C" void __cyg_profile_func_enter(void *this_fn, void *call_site)
+{
+    if (!trace_enabled) {
+        return;
+    }
+    add_trace_record(trace_record{trace_record_type::entry, sched::thread::current(),
+        this_fn, call_site});
+}
+
+extern "C" void __cyg_profile_func_exit(void *this_fn, void *call_site)
+{
+    if (!trace_enabled || !arch::tls_available()) {
+        return;
+    }
+    add_trace_record(trace_record{trace_record_type::exit, sched::thread::current(),
+        this_fn, call_site});
+}
+

include/osv/trace.hh

+#ifndef TRACE_HH_
+#define TRACE_HH_
+
+void enable_trace();
+
+#endif /* TRACE_HH_ */

include/sched.hh

@@ -151,7 +151,7 @@ public:
     void wake();
     static void sleep_until(u64 abstime);
     static void yield();
-    static thread* current();
+    static thread* current() __attribute((no_instrument_function));
     stack_info get_stack_info();
     cpu* tcpu();
     void join();

loader.cc

@@ -22,6 +22,7 @@
 #include "barrier.hh"
 #include "tests/tst-hub.hh"
 #include "arch.hh"
+#include "osv/trace.hh"
 
 asm(".pushsection \".debug_gdb_scripts\", \"MS\",@progbits,1 \n"
     ".byte 1 \n"
@@ -93,6 +94,7 @@ int main(int ac, char **av)
 void main_cont(int ac, char** av)
 {
     smp_launch();
+    enable_trace();
     sched::init_detached_threads_reaper();
 
     vfs_init();