[PATCH] elf: Compile _dl_debug_state separately (bug 33224)

[Florian Weimer]

This ensures that the compiler will not inline it, so that
debuggers which do not use the Systemtap probes can reliably
set a breakpoint on it.

Regression-tested on powerpc64le-linux-gnu and x86_64-linux-gnu.

---
 elf/Makefile         |  1 +
 elf/dl-debug.c       | 11 -----------
 elf/dl-debug_state.c | 30 ++++++++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/elf/Makefile b/elf/Makefile
index 44b9f192f2..48aa0b57e5 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -57,6 +57,7 @@ dl-routines = \
   dl-close \
   dl-debug \
   dl-debug-symbols \
+  dl-debug_state \
   dl-deps \
   dl-exception \
   dl-execstack \
diff --git a/elf/dl-debug.c b/elf/dl-debug.c
index 38a5b9a718..7052f4a3c1 100644
--- a/elf/dl-debug.c
+++ b/elf/dl-debug.c
@@ -167,14 +167,3 @@ _dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
 
   return &r->base;
 }
-
-
-/* This function exists solely to have a breakpoint set on it by the
-   debugger.  The debugger is supposed to find this function's address by
-   examining the r_brk member of struct r_debug, but GDB 4.15 in fact looks
-   for this particular symbol name in the PT_INTERP file.  */
-void
-_dl_debug_state (void)
-{
-}
-rtld_hidden_def (_dl_debug_state)
diff --git a/elf/dl-debug_state.c b/elf/dl-debug_state.c
new file mode 100644
index 0000000000..40c134a49e
--- /dev/null
+++ b/elf/dl-debug_state.c
@@ -0,0 +1,30 @@
+/* Debugger hook called after dynamic linker updates.
+   Copyright (C) 1996-2025 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/>.  */
+
+#include <ldsodefs.h>
+
+/* This function exists solely to have a breakpoint set on it by the
+   debugger.  The debugger is supposed to find this function's address by
+   examining the r_brk member of struct r_debug, but GDB 4.15 in fact looks
+   for this particular symbol name in the PT_INTERP file.  Therefore,
+   this function must not be inlined.  */
+void
+_dl_debug_state (void)
+{
+}
+rtld_hidden_def (_dl_debug_state)

base-commit: 0def17238661b47fd8557aafaa1bb4805e6b28e8