Attempt to add bp to allow better symbol resolution for native frames.

Author: sobolron

examples/cpp/pyperf/PyPerfBPFProgram.cc

@@ -168,6 +168,7 @@ struct event {
   int32_t stack[STACK_MAX_LEN];
   uintptr_t user_ip;
   uintptr_t user_sp;
+  uintptr_t user_bp;
   uint32_t user_stack_len;
   uint8_t raw_user_stack[__USER_STACKS_PAGES__ * PAGE_SIZE];
 #define FRAME_CODE_IS_NULL 0x80000001
@@ -345,6 +346,7 @@ on_event(struct pt_regs* ctx) {
 
     event->user_sp = user_regs.sp;
     event->user_ip = user_regs.ip;
+    event->user_bp = user_regs.bp;
     event->user_stack_len = 0;
 
     // Subtract 128 from sp for x86-ABI red zone

examples/cpp/pyperf/PyPerfNativeStackTrace.cc

@@ -31,6 +31,7 @@ const uint8_t *NativeStackTrace::stack = NULL;
 size_t NativeStackTrace::stack_len = 0;
 uintptr_t NativeStackTrace::sp = 0;
 uintptr_t NativeStackTrace::ip = 0;
+uintptr_t NativeStackTrace::bp = 0;
 ProcSymbolsCache NativeStackTrace::procSymbolsCache;
 bool NativeStackTrace::insert_dso_name = false;
 const static double ProcSymbolsCacheTTL_S = 60;
@@ -43,11 +44,12 @@ static double steady_time_since_epoch() {
 }
 
 NativeStackTrace::NativeStackTrace(uint32_t pid, const unsigned char *raw_stack,
-                                   size_t stack_len, uintptr_t ip, uintptr_t sp) : error_occurred(false) {
+                                   size_t stack_len, uintptr_t ip, uintptr_t sp, uintptr_t bp) : error_occurred(false) {
   NativeStackTrace::stack = raw_stack;
   NativeStackTrace::stack_len = stack_len;
   NativeStackTrace::ip = ip;
   NativeStackTrace::sp = sp;
+  NativeStackTrace::bp = bp;
 
   if (stack_len == 0) {
     return;
@@ -157,6 +159,15 @@ NativeStackTrace::NativeStackTrace(uint32_t pid, const unsigned char *raw_stack,
 
 int NativeStackTrace::UPT_access_reg(unw_addr_space_t as, unw_regnum_t regnum,
                                      unw_word_t *valp, int write, void *arg) {
+  if (regnum == UNW_X86_64_RBP) {
+    if (write) {
+      logInfo(2, "Libunwind attempts to write to BP\n");
+      return -UNW_EINVAL;
+    }
+
+    *valp = NativeStackTrace::bp;
+    return 0;
+  }
   if (regnum == UNW_REG_SP) {
     if (write) {
       logInfo(2, "Libunwind attempts to write to SP\n");
@@ -234,7 +245,7 @@ int NativeStackTrace::UPT_access_mem(unw_addr_space_t as, unw_word_t addr,
 int NativeStackTrace::UPT_access_fpreg(unw_addr_space_t as, unw_regnum_t reg, unw_fpreg_t *val,
                                        int write, void *arg) {
   logInfo(3, "Libunwind unexpected UPT_access_fpreg() attempt\n");
-  return -UNW_EINVAL;
+  return -UNW_EINVAL; 
 }
 
 int NativeStackTrace::UPT_resume(unw_addr_space_t as, unw_cursor_t *c, void *arg) {

examples/cpp/pyperf/PyPerfNativeStackTrace.h

@@ -25,7 +25,8 @@ typedef std::map<uint32_t, ProcSymbolsCacheEntry> ProcSymbolsCache;
 class NativeStackTrace {
  public:
   explicit NativeStackTrace(uint32_t pid, const uint8_t *raw_stack,
-                            size_t stack_len, uintptr_t ip, uintptr_t sp);
+                            size_t stack_len, uintptr_t ip, uintptr_t sp,
+                            uintptr_t bp);
 
   std::vector<std::string> get_stack_symbol() const;
   bool error_occured() const;
@@ -41,6 +42,7 @@ class NativeStackTrace {
   static size_t stack_len;
   static uintptr_t ip;
   static uintptr_t sp;
+  static uintptr_t bp;
   static ProcSymbolsCache procSymbolsCache;
 
   static int UPT_access_reg(unw_addr_space_t as, unw_regnum_t regnum,

examples/cpp/pyperf/PyPerfType.h

@@ -225,6 +225,7 @@ typedef struct event {
 #define FRAME_CODE_IS_NULL ((int32_t)0x80000001)
   uintptr_t user_ip;
   uintptr_t user_sp;
+  uintptr_t user_bp;
   uint32_t user_stack_len;
   uint8_t raw_user_stack[]; // NOTICE: Field with variadic length - must be last!
 } Event;
@@ -248,7 +249,7 @@ struct PyPerfSample {
         kernelStackId(raw->kernel_stack_id),
         pyStackIds(raw->stack, raw->stack + raw->stack_len),
         nativeStack(raw->pid, raw->raw_user_stack, raw->user_stack_len,
-                    raw->user_ip, raw->user_sp) {}
+                    raw->user_ip, raw->user_sp, raw->user_bp) {}
 };
 
 }  // namespace pyperf