elf: Testing infrastructure for ld.so DSO sorting (BZ #17645)

This is the first of a 2-part patch set that fixes slow DSO sorting behavior in
the dynamic loader, as reported in BZ #17645. In order to facilitate such a
large modification to the dynamic loader, this first patch implements a testing
framework for validating shared object sorting behavior, to enable comparison
between old/new sorting algorithms, and any later enhancements.

This testing infrastructure consists of a Python script
scripts/dso-ordering-test.py' which takes in a description language, consisting
of strings that describe a set of link dependency relations between DSOs, and
generates testcase programs and Makefile fragments to automatically test the
described situation, for example:

  a->b->c->d          # four objects linked one after another

  a->[bc]->d;b->c     # a depends on b and c, which both depend on d,
                      # b depends on c (b,c linked to object a in fixed order)

  a->b->c;{+a;%a;-a}  # a, b, c serially dependent, main program uses
                      # dlopen/dlsym/dlclose on object a

  a->b->c;{}!->[abc]  # a, b, c serially dependent; multiple tests generated
                      # to test all permutations of a, b, c ordering linked
                      # to main program

 (Above is just a short description of what the script can do, more
  documentation is in the script comments.)

Two files containing several new tests, elf/dso-sort-tests-[12].def are added,
including test scenarios for BZ #15311 and Redhat issue #1162810 [1].

Due to the nature of dynamic loader tests, where the sorting behavior and test
output occurs before/after main(), generating testcases to use
support/test-driver.c does not suffice to control meaningful timeout for ld.so.
Therefore a new utility program 'support/test-run-command', based on
test-driver.c/support_test_main.c has been added. This does the same testcase
control, but for a program specified through a command-line rather than at the
source code level. This utility is used to run the dynamic loader testcases
generated by dso-ordering-test.py.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1162810

Signed-off-by: Chung-Lin Tang  <cltang@codesourcery.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/elf/Makefile b/elf/Makefile
index bf45d8ee24..bdcf4cb885 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -477,6 +477,21 @@ tests-special += $(objpfx)order-cmp.out $(objpfx)tst-array1-cmp.out \
 		 $(objpfx)tst-unused-dep-cmp.out
 endif
 
+# DSO sorting tests:
+# The dso-ordering-test.py script generates testcase source files in $(objpfx),
+# creating a $(objpfx)<testcase-name>-dir for each testcase, and creates a
+# Makefile fragment to be included.
+define include_dsosort_tests
+$(objpfx)$(1).generated-makefile: $(1)
+	$(PYTHON) $(..)scripts/dso-ordering-test.py \
+	--description-file $$< --objpfx $(objpfx) --output-makefile $$@
+include $(objpfx)$(1).generated-makefile
+endef
+
+# Generate from each testcase description file
+$(eval $(call include_dsosort_tests,dso-sort-tests-1.def))
+$(eval $(call include_dsosort_tests,dso-sort-tests-2.def))
+
 check-abi: $(objpfx)check-abi-ld.out
 tests-special += $(objpfx)check-abi-ld.out
 update-abi: update-abi-ld