[PATCH] mips: pldd: support DT_MIPS_RLD_MAP and DT_MIPS_RLD_MAP_REL

[Xi Ruoyao <xry111@mengyan1223.wang>]

MIPS uses DT_MIPS_RLD_MAP and DT_MIPS_RLD_MAP_REL for accessing r_debug,
instead of DT_DEBUG.
---
 elf/pldd-xx.c | 67 ++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 53 insertions(+), 14 deletions(-)

diff --git a/elf/pldd-xx.c b/elf/pldd-xx.c
index 1cdfb49c53..ec397f00e5 100644
--- a/elf/pldd-xx.c
+++ b/elf/pldd-xx.c
@@ -22,6 +22,12 @@
 #define EW_(e, w, t) EW__(e, w, _##t)
 #define EW__(e, w, t) e##w##t
 
+#if CLASS == 32
+typedef Elf32_Word E(val_type);
+#else
+typedef Elf64_Xword E(val_type);
+#endif
+
 struct E(link_map)
 {
   EW(Addr) l_addr;
@@ -70,6 +76,35 @@ _Static_assert (offsetof (struct r_debug, r_map)
 		== offsetof (struct E(r_debug), r_map), "r_map");
 #endif
 
+static EW(Addr)
+E(r_debug_offset) (EW(Dyn) *d, int memfd, EW(Addr) d_addr)
+{
+#ifdef __mips__
+  EW(Addr) ptr;
+
+  switch (d->d_tag)
+    {
+    case DT_MIPS_RLD_MAP_REL:
+      ptr = d_addr + d->d_un.d_val;
+      break;
+    case DT_MIPS_RLD_MAP:
+      ptr = d->d_un.d_ptr;
+      break;
+    default:
+      return 0;
+    }
+
+    if (pread (memfd, &ptr, sizeof (ptr), ptr) != sizeof (ptr))
+      return 0;
+
+    return ptr;
+#else
+  if (d->d_tag == DT_DEBUG)
+    return (off_t) d->d_un.d_ptr;
+
+  return 0;
+#endif
+}
 
 static int
 
@@ -126,21 +161,25 @@ E(find_maps) (const char *exe, int memfd, pid_t pid, void *auxv,
 	    != p[i].p_filesz)
 	  error (EXIT_FAILURE, 0, gettext ("cannot read dynamic section"));
 
-	/* Search for the DT_DEBUG entry.  */
+	/* Search for the r_debug struct.  */
 	for (unsigned int j = 0; j < p[i].p_filesz / sizeof (EW(Dyn)); ++j)
-	  if (dyn[j].d_tag == DT_DEBUG && dyn[j].d_un.d_ptr != 0)
-	    {
-	      struct E(r_debug) r;
-	      if (pread (memfd, &r, sizeof (r), dyn[j].d_un.d_ptr)
-		  != sizeof (r))
-		error (EXIT_FAILURE, 0, gettext ("cannot read r_debug"));
-
-	      if (r.r_map != 0)
-		{
-		  list = r.r_map;
-		  break;
-		}
-	    }
+	  {
+	    EW(Addr) d_addr = offset + p[i].p_vaddr + sizeof (EW(Dyn)) * j;
+	    EW(Addr) off = E(r_debug_offset)(&dyn[j], memfd, d_addr);
+	    if (off != 0)
+	      {
+		struct E(r_debug) r;
+		if (pread (memfd, &r, sizeof (r), off)
+		    != sizeof (r))
+		  error (EXIT_FAILURE, 0, gettext ("cannot read r_debug"));
+
+		if (r.r_map != 0)
+		  {
+		    list = r.r_map;
+		    break;
+		  }
+	      }
+	  }
 
 	free (dyn);
 	break;
-- 
2.35.0