[PATCH v2] mips: pldd: support DT_MIPS_RLD_MAP and DT_MIPS_RLD_MAP_REL

[Xi Ruoyao]

[v2: remove useless typedef, seperate E(r_debug_offset) into a header.]

MIPS uses DT_MIPS_RLD_MAP and DT_MIPS_RLD_MAP_REL for accessing r_debug,
instead of DT_DEBUG.

Signed-off-by: Xi Ruoyao <xry111@mengyan1223.wang>
---
 elf/pldd-xx.c                     | 34 +++++++++++++++-----------
 sysdeps/generic/elf-pldd-rdebug.h | 26 ++++++++++++++++++++
 sysdeps/mips/elf-pldd-rdebug.h    | 40 +++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 14 deletions(-)
 create mode 100644 sysdeps/generic/elf-pldd-rdebug.h
 create mode 100644 sysdeps/mips/elf-pldd-rdebug.h

diff --git a/elf/pldd-xx.c b/elf/pldd-xx.c
index 1cdfb49c53..368528371d 100644
--- a/elf/pldd-xx.c
+++ b/elf/pldd-xx.c
@@ -22,6 +22,8 @@
 #define EW_(e, w, t) EW__(e, w, _##t)
 #define EW__(e, w, t) e##w##t
 
+#include <elf-pldd-rdebug.h>
+
 struct E(link_map)
 {
   EW(Addr) l_addr;
@@ -126,21 +128,25 @@ 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;
diff --git a/sysdeps/generic/elf-pldd-rdebug.h b/sysdeps/generic/elf-pldd-rdebug.h
new file mode 100644
index 0000000000..6df651cd55
--- /dev/null
+++ b/sysdeps/generic/elf-pldd-rdebug.h
@@ -0,0 +1,26 @@
+/* Function to access r_debug structure for pldd.
+   Copyright (C) 2020-2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+static EW(Addr)
+E(r_debug_offset) (EW(Dyn) *d, int, EW(Addr))
+{
+  if (d->d_tag == DT_DEBUG)
+    return (EW(Addr)) d->d_un.d_ptr;
+
+  return 0;
+}
diff --git a/sysdeps/mips/elf-pldd-rdebug.h b/sysdeps/mips/elf-pldd-rdebug.h
new file mode 100644
index 0000000000..89a20c191a
--- /dev/null
+++ b/sysdeps/mips/elf-pldd-rdebug.h
@@ -0,0 +1,40 @@
+/* Function to access r_debug structure for pldd, MIPS specific version.
+   Copyright (C) 2020-2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+static EW(Addr)
+E(r_debug_offset) (EW(Dyn) *d, int memfd, EW(Addr) d_addr)
+{
+  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;
+}
-- 
2.35.0