gdb, gdbserver: extend RSP to support namespaces

Introduce a new qXfer:libraries-svr4:read annex key/value pair

    lmid=<namespace identifier>

to be used together with start and prev to provide the namespace of start
and prev to gdbserver.

Unknown key/value pairs are ignored by gdbserver so no new supports check
is needed.

Introduce a new library-list-svr4 library attribute

    lmid

to provide the namespace of a library entry to GDB.

This implementation uses the address of a namespace's r_debug object as
namespace identifier.

This should have incremented the minor version but since unknown XML
attributes are ignored, anyway, and since changing the version results in
a warning from GDB, the version is left at 1.0.

1 files changed, 17 insertions, 9 deletions

diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index e83ccceed83..4754366d443 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -6489,8 +6489,8 @@ static const link_map_offsets lmo_64bit_offsets =
 /* Get the loaded shared libraries from one namespace.  */
 
 static void
-read_link_map (std::string &document, CORE_ADDR lm_addr, CORE_ADDR lm_prev,
-	       int ptr_size, const link_map_offsets *lmo)
+read_link_map (std::string &document, CORE_ADDR lmid, CORE_ADDR lm_addr,
+	       CORE_ADDR lm_prev, int ptr_size, const link_map_offsets *lmo)
 {
   CORE_ADDR l_name, l_addr, l_ld, l_next, l_prev;
 
@@ -6525,9 +6525,9 @@ read_link_map (std::string &document, CORE_ADDR lm_addr, CORE_ADDR lm_prev,
 	  string_appendf (document, "<library name=\"");
 	  xml_escape_text_append (&document, (char *) libname);
 	  string_appendf (document, "\" lm=\"0x%s\" l_addr=\"0x%s\" "
-			  "l_ld=\"0x%s\"/>",
+			  "l_ld=\"0x%s\" lmid=\"0x%s\"/>",
 			  paddress (lm_addr), paddress (l_addr),
-			  paddress (l_ld));
+			  paddress (l_ld), paddress (lmid));
 	}
 
       lm_prev = lm_addr;
@@ -6547,7 +6547,7 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
   char filename[PATH_MAX];
   int pid, is_elf64;
   unsigned int machine;
-  CORE_ADDR lm_addr = 0, lm_prev = 0;
+  CORE_ADDR lmid = 0, lm_addr = 0, lm_prev = 0;
 
   if (writebuf != NULL)
     return -2;
@@ -6581,7 +6581,9 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
 	break;
 
       name_len = sep - annex;
-      if (name_len == 5 && startswith (annex, "start"))
+      if (name_len == 4 && startswith (annex, "lmid"))
+	addrp = &lmid;
+      else if (name_len == 5 && startswith (annex, "start"))
 	addrp = &lm_addr;
       else if (name_len == 4 && startswith (annex, "prev"))
 	addrp = &lm_prev;
@@ -6600,19 +6602,25 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
   std::string document = "<library-list-svr4 version=\"1.0\"";
 
   /* When the starting LM_ADDR is passed in the annex, only traverse that
-     namespace.
+     namespace, which is assumed to be identified by LMID.
 
      Otherwise, start with R_DEBUG and traverse all namespaces we find.  */
   if (lm_addr != 0)
     {
       document += ">";
-      read_link_map (document, lm_addr, lm_prev, ptr_size, lmo);
+      read_link_map (document, lmid, lm_addr, lm_prev, ptr_size, lmo);
     }
   else
     {
       if (lm_prev != 0)
 	warning ("ignoring prev=0x%s without start", paddress (lm_prev));
 
+      /* We could interpret LMID as 'provide only the libraries for this
+	 namespace' but GDB is currently only providing lmid, start, and
+	 prev, or nothing.  */
+      if (lmid != 0)
+	warning ("ignoring lmid=0x%s without start", paddress (lmid));
+
       CORE_ADDR r_debug = priv->r_debug;
       if (r_debug == 0)
 	r_debug = priv->r_debug = get_r_debug (pid, is_elf64);
@@ -6678,7 +6686,7 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
 		}
 	    }
 
-	  read_link_map (document, lm_addr, lm_prev, ptr_size, lmo);
+	  read_link_map (document, r_debug, lm_addr, lm_prev, ptr_size, lmo);
 
 	  if (r_version < 2)
 	    break;