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authorFlorian Weimer <fweimer@redhat.com>2021-12-28 22:52:56 +0100
committerFlorian Weimer <fweimer@redhat.com>2021-12-28 22:52:56 +0100
commit5d28a8962dcb6ec056b81d730e3c6fb57185a210 (patch)
tree3d714aaef575deba322fa5a1e29c76c6f96dc850 /elf/tst-dl_find_object-mod3.c
parent83b8d5027d2f80c4603cd706da95d6c9a09a4e16 (diff)
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elf: Add _dl_find_object function
It can be used to speed up the libgcc unwinder, and the internal
_dl_find_dso_for_object function (which is used for caller
identification in dlopen and related functions, and in dladdr).

_dl_find_object is in the internal namespace due to bug 28503.
If libgcc switches to _dl_find_object, this namespace issue will
be fixed.  It is located in libc for two reasons: it is necessary
to forward the call to the static libc after static dlopen, and
there is a link ordering issue with -static-libgcc and libgcc_eh.a
because libc.so is not a linker script that includes ld.so in the
glibc build tree (so that GCC's internal -lc after libgcc_eh.a does
not pick up ld.so).

It is necessary to do the i386 customization in the
sysdeps/x86/bits/dl_find_object.h header shared with x86-64 because
otherwise, multilib installations are broken.

The implementation uses software transactional memory, as suggested
by Torvald Riegel.  Two copies of the supporting data structures are
used, also achieving full async-signal-safety.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Diffstat (limited to 'elf/tst-dl_find_object-mod3.c')
-rw-r--r--elf/tst-dl_find_object-mod3.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/elf/tst-dl_find_object-mod3.c b/elf/tst-dl_find_object-mod3.c
new file mode 100644
index 0000000000..c1fc20ff9c
--- /dev/null
+++ b/elf/tst-dl_find_object-mod3.c
@@ -0,0 +1,10 @@
+char mod3_data[4096];
+
+void
+mod3_function (void (*f) (void))
+{
+  /* Make sure this is not a tail call and unwind information is
+     therefore needed.  */
+  f ();
+  f ();
+}