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

2021-10-21T14:23:53Z

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 Reviewed-by: Adhemerval Zanella

glibc/support/Depend, branch master

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