elf: Add glibc-hwcaps subdirectory support to ld.so cache processing

This recognizes the DL_CACHE_HWCAP_EXTENSION flag in cache entries,
and picks the supported cache entry with the highest priority.

The elf/tst-glibc-hwcaps-prepend-cache test documents a non-desired
aspect of the current cache implementation: If the cache selects a DSO
that does not exist on disk, _dl_map_object falls back to open_path,
which may or may not find an alternative implementation.  This is an
existing limitation that also applies to the legacy hwcaps processing
for ld.so.cache.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/elf/tst-glibc-hwcaps-cache.script b/elf/tst-glibc-hwcaps-cache.script
new file mode 100644
index 0000000000..6356d15208
--- /dev/null
+++ b/elf/tst-glibc-hwcaps-cache.script
@@ -0,0 +1,6 @@
+# test-container does not support scripts in sysdeps directories, so
+# collect everything in one file.
+
+cp $B/elf/libmarkermod2-1.so $L/libmarkermod2.so
+cp $B/elf/libmarkermod3-1.so $L/libmarkermod3.so
+cp $B/elf/libmarkermod4-1.so $L/libmarkermod4.so