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authorH.J. Lu <hjl.tools@gmail.com>2021-08-17 19:35:48 -0700
committerH.J. Lu <hjl.tools@gmail.com>2021-09-19 13:51:35 -0700
commita93d9e03a31ec14405cb3a09aa95413b67067380 (patch)
tree532f865c7241b3cf363433272e5923c468ea2969 /include
parent885762aa31d75de8b9fea4c0e2e372b582d4c548 (diff)
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Extend struct r_debug to support multiple namespaces [BZ #15971]
Glibc does not provide an interface for debugger to access libraries
loaded in multiple namespaces via dlmopen.

The current rtld-debugger interface is described in the file:

elf/rtld-debugger-interface.txt

under the "Standard debugger interface" heading.  This interface only
provides access to the first link-map (LM_ID_BASE).

1. Bump r_version to 2 when multiple namespaces are used.  This triggers
the GDB bug:

https://sourceware.org/bugzilla/show_bug.cgi?id=28236

2. Add struct r_debug_extended to extend struct r_debug into a linked-list,
where each element correlates to an unique namespace.
3. Initialize the r_debug_extended structure.  Bump r_version to 2 for
the new namespace and add the new namespace to the namespace linked list.
4. Add _dl_debug_update to return the address of struct r_debug' of a
namespace.
5. Add a hidden symbol, _r_debug_extended, for struct r_debug_extended.
6. Provide the symbol, _r_debug, with size of struct r_debug, as an alias
of _r_debug_extended, for programs which reference _r_debug.

This fixes BZ #15971.

Reviewed-by: Florian Weimer <fweimer@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/link.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/link.h b/include/link.h
index 4af16cb596..7b8250db36 100644
--- a/include/link.h
+++ b/include/link.h
@@ -353,6 +353,10 @@ struct auditstate
 };
 
 
+/* This is the hidden instance of struct r_debug_extended used by the
+   dynamic linker.  */
+extern struct r_debug_extended _r_debug_extended attribute_hidden;
+
 #if __ELF_NATIVE_CLASS == 32
 # define symbind symbind32
 #elif __ELF_NATIVE_CLASS == 64