From f6cca76ee3c93091daf72f8351913f6b58f1a34c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophile=20Bastian?= <contact@tobast.fr>
Date: Sun, 9 Jun 2019 19:02:24 +0200
Subject: [PATCH] Enhance debug messages

---
 src/eh_elf/eh_elf.c | 12 ++++++++++--
 src/x86_64/Gstep.c  | 13 ++++++++++---
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/eh_elf/eh_elf.c b/src/eh_elf/eh_elf.c
index 0bdc543b..b48af9a2 100644
--- a/src/eh_elf/eh_elf.c
+++ b/src/eh_elf/eh_elf.c
@@ -97,6 +97,12 @@ int set_dwarf_loc_ifdef(
 
 int eh_elf_step_cursor(struct cursor *cursor) {
     uintptr_t ip = cursor->dwarf.ip;
+    {
+        uintptr_t dbp;
+        dwarf_get(&cursor->dwarf, cursor->dwarf.loc[UNW_TDEP_BP], &dbp);
+        Debug (4, "AT ENTER bp=%016lx%s sp=%016lx ip=%016lx\n", dbp,
+                DWARF_IS_NULL_LOC(cursor->dwarf.loc[UNW_TDEP_BP])?" [NULL]":"",
+                cursor->dwarf.cfa, cursor->dwarf.ip);
     }
 
     // Retrieve memory map entry
@@ -134,10 +140,12 @@ int eh_elf_step_cursor(struct cursor *cursor) {
     _fetch_state.last_rc = 0;
     _fetch_state.cur_rsp = cursor->dwarf.cfa;
 
-    Debug(4, "Unwinding in mmap entry %s at position 0x%lx (sp=%016lx)\n",
+    Debug(4, "Unwinding in mmap entry %s at position 0x%lx (sp=%016lx, bp=%016lx)\n",
             mmap_entry->object_name,
             ip - mmap_entry->offset,
-            eh_elf_context.rsp);
+            eh_elf_context.rsp,
+            eh_elf_context.rbp
+            );
 
     eh_elf_context.flags = 0;
     // Call fde_func
diff --git a/src/x86_64/Gstep.c b/src/x86_64/Gstep.c
index 39cc473b..d4e48090 100644
--- a/src/x86_64/Gstep.c
+++ b/src/x86_64/Gstep.c
@@ -80,6 +80,13 @@ unw_step (unw_cursor_t *cursor)
   _step_id_data.orig_cfa = c->dwarf.cfa;
 
   UnwDebug(3, "unw_step called\n");
+  {
+      uintptr_t dbp;
+      dwarf_get(&c->dwarf, c->dwarf.loc[RBP], &dbp);
+      UnwDebug (4, "unw_step context:  bp=%016lx%s sp=%016lx ip=%016lx\n", dbp,
+              DWARF_IS_NULL_LOC(c->dwarf.loc[RBP])? " [NULL]": "",
+              c->dwarf.cfa, c->dwarf.ip);
+  }
   struct timespec _timer_start = chrono_start();
   int ret, i;
 
@@ -114,11 +121,10 @@ unw_step (unw_cursor_t *cursor)
 
   if (ret < 0 && ret != -UNW_ENOINFO)
     {
-      UnwDebug (3, "dwarf_step also failed?\n", ret);
+      UnwDebug (3, "dwarf_step also failed [%d]?\n", ret);
       UnwDebug (2, "returning %d\n", ret);
       return ret;
     }
-  UnwDebug(4, "UNW_ENOINFO=%d\n", UNW_ENOINFO);
   UnwDebug(3, "fallback continuing\n");
 
   if (likely (ret >= 0))
@@ -135,6 +141,7 @@ unw_step (unw_cursor_t *cursor)
         uintptr_t dbp;
         dwarf_get(&c->dwarf, c->dwarf.loc[RBP], &dbp);
         UnwDebug (3, "     DWARF:  bp=%016lx sp=%016lx ip=%016lx\n", dbp, c->dwarf.cfa, c->dwarf.ip);
+        UnwDebug(3, "fallback with actual dwarf\n");
     }
   else
     {
@@ -157,7 +164,7 @@ unw_step (unw_cursor_t *cursor)
          Validate all addresses before dereferencing. */
       c->validate = 1;
 
-      UnwDebug (13, "dwarf_step() failed (ret=%d), trying frame-chain\n", ret);
+      UnwDebug (4, "dwarf_step() failed (ret=%d), trying frame-chain\n", ret);
 
       if (unw_is_signal_frame (cursor))
         {