1 files changed, 29 insertions, 18 deletions

diff --git a/gdb/nat/linux-procfs.c b/gdb/nat/linux-procfs.c
index 5efc86c..d4f9af3 100644
--- a/gdb/nat/linux-procfs.c
+++ b/gdb/nat/linux-procfs.c
@@ -1,5 +1,5 @@
 /* Linux-specific PROCFS manipulation routines.
-   Copyright (C) 2009-2024 Free Software Foundation, Inc.
+   Copyright (C) 2009-2025 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -18,9 +18,9 @@
 
 #include "linux-procfs.h"
 #include "gdbsupport/filestuff.h"
+#include "gdbsupport/unordered_set.h"
 #include <dirent.h>
 #include <sys/stat.h>
-#include <unordered_set>
 #include <utility>
 
 /* Return the TGID of LWPID from /proc/pid/status.  Returns -1 if not
@@ -358,20 +358,9 @@ linux_proc_attach_tgid_threads (pid_t pid,
       return;
     }
 
-  /* Callable object to hash elements in visited_lpws.  */
-  struct pair_hash
-  {
-    std::size_t operator() (const std::pair<unsigned long, ULONGEST> &v) const
-    {
-      return (std::hash<unsigned long>() (v.first)
-	      ^ std::hash<ULONGEST>() (v.second));
-    }
-  };
-
   /* Keeps track of the LWPs we have already visited in /proc,
      identified by their PID and starttime to detect PID reuse.  */
-  std::unordered_set<std::pair<unsigned long, ULONGEST>,
-		     pair_hash> visited_lwps;
+  gdb::unordered_set<std::pair<unsigned long, ULONGEST>> visited_lwps;
 
   /* Scan the task list for existing threads.  While we go through the
      threads, new threads may be spawned.  Cycle through the list of
@@ -435,7 +424,7 @@ linux_proc_task_list_dir_exists (pid_t pid)
 /* See linux-procfs.h.  */
 
 const char *
-linux_proc_pid_to_exec_file (int pid)
+linux_proc_pid_to_exec_file (int pid, bool is_local_fs)
 {
   static char buf[PATH_MAX];
   char name[PATH_MAX];
@@ -448,9 +437,31 @@ linux_proc_pid_to_exec_file (int pid)
   else
     buf[len] = '\0';
 
-  /* Use /proc/PID/exe if the actual file can't be read, but /proc/PID/exe
-     can be.  */
-  if (access (buf, R_OK) != 0 && access (name, R_OK) == 0)
+  /* If the inferior and GDB can see the same filesystem, and NAME
+     cannot be read, maybe the file has been deleted, then we can
+     potentially use /proc/PID/exe instead.
+
+     GDB always interprets the results of this function within the
+     current sysroot (which is 'target:' by default).  This means
+     that, if we return /proc/PID/exe, GDB will try to find this file
+     within the sysroot.
+
+     This doesn't make sense if GDB is using a sysroot like:
+     '/some/random/directory/', not only is it possible that NAME
+     could be found within the sysroot, it is unlikely that
+     /proc/PID/exe will exist within the sysroot.
+
+     Similarly, if the sysroot is 'target:', but the inferior is
+     running within a separate MNT namespace, then it is more than
+     likely that the inferior will also be running in a separate PID
+     namespace, in this case PID is the pid on the host system,
+     /proc/PID/exe will not be correct within the inferiors MNT/PID
+     namespace.
+
+     So, we can fallback to use /proc/PID/exe only if IS_LOCAL_FS is
+     true, this indicates that GDB and the inferior are using the same
+     MNT namespace, and GDB's sysroot is either empty, or 'target:'.  */
+  if (is_local_fs && access (buf, R_OK) != 0 && access (name, R_OK) == 0)
     strcpy (buf, name);
 
   return buf;