[RFC 06/13] Force sign-extend statement addresses on mips64 -msym32

[Crestez Dan Leonard <cdleonard at gmail dot com>]

Signed-off-by: Crestez Dan Leonard <cdleonard@gmail.com>
---
 dwflpp.cxx  | 34 ++++++++++++++++++++++++++++++++++
 dwflpp.h    |  1 +
 tapsets.cxx | 14 ++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/dwflpp.cxx b/dwflpp.cxx
index e53d5f2..dea81b9 100644
--- a/dwflpp.cxx
+++ b/dwflpp.cxx
@@ -3054,6 +3054,31 @@ dwflpp::die_location_as_function_string(Dwarf_Addr pc, Dwarf_Die *die)
   return locstr;
 }
 
+static bool
+is_elf_mips64(Elf *elf)
+{
+  GElf_Ehdr ehdr_mem;
+  GElf_Ehdr* ehdr = gelf_getehdr (elf, &ehdr_mem);
+  return ehdr->e_machine == EM_MIPS &&
+      ehdr->e_ident[EI_CLASS] == ELFCLASS64;
+}
+
+bool
+dwflpp::is_mips64_msym32(Dwarf_Die *die)
+{
+  Dwarf_Addr bias;
+  Elf* elf = (dwarf_getelf (module_dwarf)
+              ?: dwfl_module_getelf (this->module, &bias));
+  if (!::is_elf_mips64(elf)) {
+      return false;
+  }
+
+  Dwarf_Die cu_mem;
+  uint8_t address_size;
+  dwarf_diecu (die, &cu_mem, &address_size, NULL);
+  return (address_size == 4);
+}
+
 struct location *
 dwflpp::translate_location(struct obstack *pool,
                            Dwarf_Attribute *attr, Dwarf_Die *die,
@@ -3084,6 +3109,15 @@ dwflpp::translate_location(struct obstack *pool,
      to be passed in, but instead should now be zero for the same reason. */
 
  retry:
+  if (is_mips64_msym32(die))
+    {
+      /* Force sign extension */
+      if (sess.verbose > 2)
+        clog << "query_statement truncate pc=" << hex << pc
+          << " to " << hex << (uint32_t)pc
+          << " for lookup on mips64 with 32bit symbols" << endl;
+      pc = (uint32_t)pc;
+    }
   switch (dwarf_getlocation_addr (attr, pc /*+ module_bias*/, &expr, &len, 1))
     {
     case 1:			/* Should always happen.  */
diff --git a/dwflpp.h b/dwflpp.h
index 2546acf..a411ed4 100644
--- a/dwflpp.h
+++ b/dwflpp.h
@@ -649,6 +649,7 @@ private:
 
 public:
   Dwarf_Addr pr15123_retry_addr (Dwarf_Addr pc, Dwarf_Die* var);
+  bool is_mips64_msym32(Dwarf_Die *die);
 };
 
 // Template <void> specializations for iterate_over_* functions
diff --git a/tapsets.cxx b/tapsets.cxx
index 3724a96..97d4b7e 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -1610,6 +1610,20 @@ query_statement (string const & func,
 		 Dwarf_Addr stmt_addr,
 		 dwarf_query * q)
 {
+  if (1)
+  {
+    if (q->dw.is_mips64_msym32(scope_die))
+      {
+        /* Force sign extension */
+        if (q->sess.verbose > 2)
+          clog << "query_statement " << func << "@" << file << ":" << line
+            << " sign-extend stmt_addr " << hex << stmt_addr
+            << " to " << hex << ((int64_t)((int32_t)stmt_addr))
+            << " because were on mips64 with 32bit symbols" << endl;
+        stmt_addr = (int32_t)stmt_addr;
+      }
+  }
+
   try
     {
       q->add_probe_point(func, file ? file : "",