| Message ID | 87sg8p1cdh.fsf@oldenburg2.str.redhat.com |
|---|---|
| State | Committed |
| Headers | show |
| Series | None | expand |
On 01/12/2020 17:48, Florian Weimer via Libc-alpha wrote: > 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. > LGTM, with just a couple of mispelling below. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> > --- > v5: Split glibc_hwcaps_priority into multiple functions. Add a DSO > deletion test that shows non-optimal behavior. > > elf/Makefile | 18 ++ > elf/dl-cache.c | 194 ++++++++++++++++++++- > elf/dl-hwcaps.c | 78 +++++++++ > elf/dl-hwcaps.h | 19 ++ > elf/tst-glibc-hwcaps-cache.c | 45 +++++ > elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf | 2 + > elf/tst-glibc-hwcaps-cache.root/postclean.req | 0 > elf/tst-glibc-hwcaps-cache.script | 6 + > elf/tst-glibc-hwcaps-prepend-cache.c | 150 ++++++++++++++++ > .../postclean.req | 0 > 10 files changed, 509 insertions(+), 3 deletions(-) > > diff --git a/elf/Makefile b/elf/Makefile > index b28930432d..95cbf66c25 100644 > --- a/elf/Makefile > +++ b/elf/Makefile > @@ -173,6 +173,12 @@ tests-container := \ > tst-ldconfig-bad-aux-cache \ > tst-ldconfig-ld_so_conf-update > > +ifeq (no,$(build-hardcoded-path-in-tests)) > +# This is an ld.so.cache test, and RPATH/RUNPATH in the executable > +# interferes with its test objectives. > +tests-container += tst-glibc-hwcaps-prepend-cache > +endif > + > tests := tst-tls9 tst-leaks1 \ > tst-array1 tst-array2 tst-array3 tst-array4 tst-array5 \ > tst-auxv tst-stringtable Ok. > @@ -1865,6 +1871,14 @@ $(objpfx)tst-glibc-hwcaps-prepend.out: \ > $< > $@; \ > $(evaluate-test) > > +# Like tst-glibc-hwcaps-prepend, but uses a container and loads the > +# library via ld.so.cache. Test setup is contained in the test > +# itself. > +$(objpfx)tst-glibc-hwcaps-prepend-cache: $(libdl) > +$(objpfx)tst-glibc-hwcaps-prepend-cache.out: \ > + $(objpfx)tst-glibc-hwcaps-prepend-cache $(objpfx)libmarkermod1-1.so \ > + $(objpfx)libmarkermod1-2.so $(objpfx)libmarkermod1-3.so > + > # tst-glibc-hwcaps-mask checks that --glibc-hwcaps-mask can be used to > # suppress all auto-detected subdirectories. > $(objpfx)tst-glibc-hwcaps-mask: $(objpfx)libmarkermod1-1.so > @@ -1876,3 +1890,7 @@ $(objpfx)tst-glibc-hwcaps-mask.out: \ > --glibc-hwcaps-mask does-not-exist \ > $< > $@; \ > $(evaluate-test) > + > +# Generic dependency for sysdeps implementation of > +# tst-glibc-hwcaps-cache. > +$(objpfx)tst-glibc-hwcaps-cache.out: $(objpfx)tst-glibc-hwcaps Ok. > diff --git a/elf/dl-cache.c b/elf/dl-cache.c > index 02c46ffb0c..e32688c0c9 100644 > --- a/elf/dl-cache.c > +++ b/elf/dl-cache.c > @@ -35,6 +35,144 @@ static struct cache_file *cache; > static struct cache_file_new *cache_new; > static size_t cachesize; > > +#ifdef SHARED > +/* This is used to cache the priorities of glibc-hwcaps > + subdirectories. The elements of _dl_cache_priorities correspond to > + the strings in the cache_extension_tag_glibc_hwcaps section. */ > +static uint32_t *glibc_hwcaps_priorities; > +static uint32_t glibc_hwcaps_priorities_length; > +static uint32_t glibc_hwcaps_priorities_allocated; > + > +/* True if the full malloc was used to allocated the array. */ > +static bool glibc_hwcaps_priorities_malloced; > + > +/* Deallocate the glibc_hwcaps_priorities array. */ > +static void > +glibc_hwcaps_priorities_free (void) > +{ > + /* When the minimal malloc is in use, free does not do anything, > + so it does not make sense to call it. */ > + if (glibc_hwcaps_priorities_malloced) > + free (glibc_hwcaps_priorities); > + glibc_hwcaps_priorities = NULL; > + glibc_hwcaps_priorities_allocated = 0; > +} > + > +/* Ordered comparision of a hwcaps string from the cache on the left s/comparision/comparison > + (identified by its string table index) and a _dl_hwcaps_priorities > + element on the right. */ > +static int > +glibc_hwcaps_compare (uint32_t left_index, struct dl_hwcaps_priority *right) > +{ > + const char *left_name = (const char *) cache + left_index; > + uint32_t left_name_length = strlen (left_name); > + uint32_t to_compare; > + if (left_name_length < right->name_length) > + to_compare = left_name_length; > + else > + to_compare = right->name_length; > + int cmp = memcmp (left_name, right->name, to_compare); > + if (cmp != 0) > + return cmp; > + if (left_name_length < right->name_length) > + return -1; > + else if (left_name_length > right->name_length) > + return 1; > + else > + return 0; > +} > + Ok. > +/* Initialize the glibc_hwcaps_priorities array and its length, > + glibc_hwcaps_priorities_length. */ > +static void > +glibc_hwcaps_priorities_init (void) > +{ > + struct cache_extension_all_loaded ext; > + if (!cache_extension_load (cache_new, cache, cachesize, &ext)) > + return; > + > + uint32_t length = (ext.sections[cache_extension_tag_glibc_hwcaps].size > + / sizeof (uint32_t)); > + if (length > glibc_hwcaps_priorities_allocated) > + { > + glibc_hwcaps_priorities_free (); > + > + uint32_t *new_allocation = malloc (length * sizeof (uint32_t)); > + if (new_allocation == NULL) > + /* This effectively disables hwcaps on memory allocation > + errors. */ > + return; > + > + glibc_hwcaps_priorities = new_allocation; > + glibc_hwcaps_priorities_allocated = length; > + glibc_hwcaps_priorities_malloced = __rtld_malloc_is_complete (); > + } > + Ok. > + /* Compute the priorities for the subdirectories by merging the > + array in the cache with the dl_hwcaps_priorities array. */ > + const uint32_t *left = ext.sections[cache_extension_tag_glibc_hwcaps].base; > + const uint32_t *left_end = left + length; > + struct dl_hwcaps_priority *right = _dl_hwcaps_priorities; > + struct dl_hwcaps_priority *right_end = right + _dl_hwcaps_priorities_length; > + uint32_t *result = glibc_hwcaps_priorities; > + > + while (left < left_end && right < right_end) > + { > + if (*left < cachesize) > + { > + int cmp = glibc_hwcaps_compare (*left, right); > + if (cmp == 0) > + { > + *result = right->priority; > + ++result; > + ++left; > + ++right; > + } > + else if (cmp < 0) > + { > + *result = 0; > + ++result; > + ++left; > + } > + else > + ++right; > + } > + else > + { > + *result = 0; > + ++result; > + } > + } > + while (left < left_end) > + { > + *result = 0; > + ++result; > + ++left; > + } > + > + glibc_hwcaps_priorities_length = length; > +} > + Ok. > +/* Return the priority of the cache_extension_tag_glibc_hwcaps section > + entry at INDEX. Zero means do not use. Otherwise, lower values > + indicate greater preference. */ > +static uint32_t > +glibc_hwcaps_priority (uint32_t index) > +{ > + /* This does not need to repeated initialization attempts because > + this function is only called if there is glibc-hwcaps data in the > + cache, so the first call initializes the glibc_hwcaps_priorities > + array. */ > + if (glibc_hwcaps_priorities_length == 0) > + glibc_hwcaps_priorities_init (); > + > + if (index < glibc_hwcaps_priorities_length) > + return glibc_hwcaps_priorities[index]; > + else > + return 0; > +} Ok. > +#endif /* SHARED */ > + > /* True if PTR is a valid string table index. */ > static inline bool > _dl_cache_verify_ptr (uint32_t ptr, size_t string_table_size) > @@ -74,6 +212,9 @@ search_cache (const char *string_table, uint32_t string_table_size, > int left = 0; > int right = nlibs - 1; > const char *best = NULL; > +#ifdef SHARED > + uint32_t best_priority = 0; > +#endif > > while (left <= right) > { > @@ -129,6 +270,11 @@ search_cache (const char *string_table, uint32_t string_table_size, > { > if (best == NULL || flags == GLRO (dl_correct_cache_id)) > { > + /* Named/extension hwcaps get slightly different > + treatment: We keep searching for a better > + match. */ > + bool named_hwcap = false; > + > if (entry_size >= sizeof (struct file_entry_new)) > { > /* The entry is large enough to include Ok. > @@ -136,7 +282,18 @@ search_cache (const char *string_table, uint32_t string_table_size, > struct file_entry_new *libnew > = (struct file_entry_new *) lib; > > - if (libnew->hwcap & hwcap_exclude) > +#ifdef SHARED > + named_hwcap = dl_cache_hwcap_extension (libnew); > +#endif > + > + /* The entries with named/extension hwcaps > + have been exhausted. Return the best > + match encountered so far if there is > + one. */ > + if (!named_hwcap && best != NULL) > + break; > + > + if ((libnew->hwcap & hwcap_exclude) && !named_hwcap) > continue; > if (GLRO (dl_osversion) > && libnew->osversion > GLRO (dl_osversion)) Ok. > @@ -146,14 +303,41 @@ search_cache (const char *string_table, uint32_t string_table_size, > && ((libnew->hwcap & _DL_HWCAP_PLATFORM) > != platform)) > continue; > + > +#ifdef SHARED > + /* For named hwcaps, determine the priority > + and see if beats what has been found so > + far. */ > + if (named_hwcap) > + { > + uint32_t entry_priority > + = glibc_hwcaps_priority (libnew->hwcap); > + if (entry_priority == 0) > + /* Not usable at all. Skip. */ > + continue; > + else if (best == NULL > + || entry_priority < best_priority) > + /* This entry is of higher priority > + than the previous one, or it is the > + first entry. */ > + best_priority = entry_priority; > + else > + /* An entry has already been found, > + but it is a better match. */ > + continue; > + } > +#endif /* SHARED */ Ok. > } > > best = string_table + lib->value; > > - if (flags == GLRO (dl_correct_cache_id)) > + if (flags == GLRO (dl_correct_cache_id) > + && !named_hwcap) > /* We've found an exact match for the shared > object and no general `ELF' release. Stop > - searching. */ > + searching, but not if a named (extension) > + hwcap is used. In this case, an entry with > + a higher priority may come up later. */ > break; > } > } > @@ -346,5 +530,9 @@ _dl_unload_cache (void) > __munmap (cache, cachesize); > cache = NULL; > } > +#ifdef SHARED > + /* This marks the glibc_hwcaps_priorities array as out-of-date. */ > + glibc_hwcaps_priorities_length = 0; > +#endif > } > #endif Ok. > diff --git a/elf/dl-hwcaps.c b/elf/dl-hwcaps.c > index f611f3a1a6..5a71f80154 100644 > --- a/elf/dl-hwcaps.c > +++ b/elf/dl-hwcaps.c > @@ -89,6 +89,81 @@ copy_hwcaps (struct copy_hwcaps *target, const char *hwcaps, > } > } > > +struct dl_hwcaps_priority *_dl_hwcaps_priorities; > +uint32_t _dl_hwcaps_priorities_length; > + > +/* Allocate _dl_hwcaps_priorities and fill it with data. */ > +static void > +compute_priorities (size_t total_count, const char *prepend, > + uint32_t bitmask, const char *mask) > +{ > + _dl_hwcaps_priorities = malloc (total_count > + * sizeof (*_dl_hwcaps_priorities)); > + if (_dl_hwcaps_priorities == NULL) > + _dl_signal_error (ENOMEM, NULL, NULL, > + N_("cannot create HWCAP priorities")); > + _dl_hwcaps_priorities_length = total_count; > + > + /* First the prepended subdirectories. */ > + size_t i = 0; > + { > + struct dl_hwcaps_split sp; > + _dl_hwcaps_split_init (&sp, prepend); > + while (_dl_hwcaps_split (&sp)) > + { > + _dl_hwcaps_priorities[i].name = sp.segment; > + _dl_hwcaps_priorities[i].name_length = sp.length; > + _dl_hwcaps_priorities[i].priority = i + 1; > + ++i; > + } > + } > + > + /* Then the built-in subdirectories that are actually active. */ > + { > + struct dl_hwcaps_split_masked sp; > + _dl_hwcaps_split_masked_init (&sp, _dl_hwcaps_subdirs, bitmask, mask); > + while (_dl_hwcaps_split_masked (&sp)) > + { > + _dl_hwcaps_priorities[i].name = sp.split.segment; > + _dl_hwcaps_priorities[i].name_length = sp.split.length; > + _dl_hwcaps_priorities[i].priority = i + 1; > + ++i; > + } > + } > + assert (i == total_count); > +} > + Ok. > +/* Sort the _dl_hwcaps_priorities array by name. */ > +static void > +sort_priorities_by_name (void) > +{ > + /* Insertion sort. There is no need to link qsort into the dynamic > + loader for such a short array. */ > + for (size_t i = 1; i < _dl_hwcaps_priorities_length; ++i) > + for (size_t j = i; j > 0; --j) > + { > + struct dl_hwcaps_priority *previous = _dl_hwcaps_priorities + j - 1; > + struct dl_hwcaps_priority *current = _dl_hwcaps_priorities + j; > + > + /* Bail out if current is greater or equal to the previous > + value. */ > + uint32_t to_compare; > + if (current->name_length < previous->name_length) > + to_compare = current->name_length; > + else > + to_compare = previous->name_length; > + int cmp = memcmp (current->name, previous->name, to_compare); > + if (cmp >= 0 > + || (cmp == 0 && current->name_length >= previous->name_length)) > + break; > + > + /* Swap *previous and *current. */ > + struct dl_hwcaps_priority tmp = *previous; > + *previous = *current; > + *current = tmp; > + } > +} > + Ok. > /* Return an array of useful/necessary hardware capability names. */ > const struct r_strlenpair * > _dl_important_hwcaps (const char *glibc_hwcaps_prepend, > @@ -111,6 +186,9 @@ _dl_important_hwcaps (const char *glibc_hwcaps_prepend, > update_hwcaps_counts (&hwcaps_counts, glibc_hwcaps_prepend, -1, NULL); > update_hwcaps_counts (&hwcaps_counts, _dl_hwcaps_subdirs, > hwcaps_subdirs_active, glibc_hwcaps_mask); > + compute_priorities (hwcaps_counts.count, glibc_hwcaps_prepend, > + hwcaps_subdirs_active, glibc_hwcaps_mask); > + sort_priorities_by_name (); > > /* Each hwcaps subdirectory has a GLIBC_HWCAPS_PREFIX string prefix > and a "/" suffix once stored in the result. */ Ok. > diff --git a/elf/dl-hwcaps.h b/elf/dl-hwcaps.h > index ab39d8a46d..ddfdde278e 100644 > --- a/elf/dl-hwcaps.h > +++ b/elf/dl-hwcaps.h > @@ -132,4 +132,23 @@ _dl_hwcaps_subdirs_build_bitmask (int subdirs, int active) > return mask ^ ((1U << inactive) - 1); > } > > +/* Pre-computed glibc-hwcaps subdirectory priorities. Used in > + dl-cache.c to quickly find the proprities for the stored HWCAP s/proprities/proprieties > + names. */ > +struct dl_hwcaps_priority > +{ > + /* The name consists of name_length bytes at name (not necessarily > + null-terminated). */ > + const char *name; > + uint32_t name_length; > + > + /* Priority of this name. A positive number. */ > + uint32_t priority; > +}; > + > +/* Pre-computed hwcaps priorities. Set up by > + _dl_important_hwcaps. */ > +extern struct dl_hwcaps_priority *_dl_hwcaps_priorities attribute_hidden; > +extern uint32_t _dl_hwcaps_priorities_length attribute_hidden; > + > #endif /* _DL_HWCAPS_H */ Ok. > diff --git a/elf/tst-glibc-hwcaps-cache.c b/elf/tst-glibc-hwcaps-cache.c > new file mode 100644 > index 0000000000..4bad56afc0 > --- /dev/null > +++ b/elf/tst-glibc-hwcaps-cache.c > @@ -0,0 +1,45 @@ > +/* Wrapper to invoke tst-glibc-hwcaps in a container, to test ld.so.cache. > + Copyright (C) 2020 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/>. */ > + > +/* This program is just a wrapper that runs ldconfig followed by > + tst-glibc-hwcaps. The actual test is provided via an > + implementation in a sysdeps subdirectory. */ > + > +#include <stdio.h> > +#include <stdlib.h> > +#include <support/support.h> > +#include <unistd.h> > + > +int > +main (int argc, char **argv) > +{ > + /* Run ldconfig to populate the cache. */ > + { > + char *command = xasprintf ("%s/ldconfig", support_install_rootsbindir); > + if (system (command) != 0) > + return 1; > + free (command); > + } > + > + /* Reuse tst-glibc-hwcaps. Since this code is running in a > + container, we can launch it directly. */ > + char *path = xasprintf ("%s/elf/tst-glibc-hwcaps", support_objdir_root); > + execv (path, argv); > + printf ("error: execv of %s failed: %m\n", path); > + return 1; > +} Ok. > diff --git a/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf b/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf > new file mode 100644 > index 0000000000..e1e74dbda2 > --- /dev/null > +++ b/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf > @@ -0,0 +1,2 @@ > +# This file was created to suppress a warning from ldconfig: > +# /sbin/ldconfig: Warning: ignoring configuration file that cannot be opened: /etc/ld.so.conf: No such file or directory Should we wrap this as well? > diff --git a/elf/tst-glibc-hwcaps-cache.root/postclean.req b/elf/tst-glibc-hwcaps-cache.root/postclean.req > new file mode 100644 > index 0000000000..e69de29bb2 Ok. > 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 Ok. > diff --git a/elf/tst-glibc-hwcaps-prepend-cache.c b/elf/tst-glibc-hwcaps-prepend-cache.c > new file mode 100644 > index 0000000000..0c1b99b14f > --- /dev/null > +++ b/elf/tst-glibc-hwcaps-prepend-cache.c > @@ -0,0 +1,150 @@ > +/* Test that --glibc-hwcaps-prepend works, using dlopen and /etc/ld.so.cache. > + Copyright (C) 2020 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 <dlfcn.h> > +#include <stddef.h> > +#include <stdio.h> > +#include <stdlib.h> > +#include <string.h> > +#include <support/check.h> > +#include <support/support.h> > +#include <support/xdlfcn.h> > +#include <support/xunistd.h> > + > +/* Invoke /sbin/ldconfig with some error checking. */ > +static void > +run_ldconfig (void) > +{ > + char *command = xasprintf ("%s/ldconfig", support_install_rootsbindir); > + TEST_COMPARE (system (command), 0); > + free (command); > +} > + > +/* The library under test. */ > +#define SONAME "libmarkermod1.so" > + > +static int > +do_test (void) > +{ > + if (dlopen (SONAME, RTLD_NOW) != NULL) > + FAIL_EXIT1 (SONAME " is already on the search path"); > + > + /* Install the default implementation of libmarkermod1.so. */ > + xmkdirp ("/etc", 0777); > + support_write_file_string ("/etc/ld.so.conf", "/glibc-test/lib\n"); > + xmkdirp ("/glibc-test/lib/glibc-hwcaps/prepend2", 0777); > + xmkdirp ("/glibc-test/lib/glibc-hwcaps/prepend3", 0777); > + { > + char *src = xasprintf ("%s/elf/libmarkermod1-1.so", support_objdir_root); > + support_copy_file (src, "/glibc-test/lib/" SONAME); > + free (src); > + } > + run_ldconfig (); > + { > + /* The default implementation can now be loaded. */ > + void *handle = xdlopen (SONAME, RTLD_NOW); > + int (*marker1) (void) = xdlsym (handle, "marker1"); > + TEST_COMPARE (marker1 (), 1); > + xdlclose (handle); > + } > + > + /* Add the first override to the directory that is searched last. */ > + { > + char *src = xasprintf ("%s/elf/libmarkermod1-2.so", support_objdir_root); > + support_copy_file (src, "/glibc-test/lib/glibc-hwcaps/prepend2/" > + SONAME); > + free (src); > + } > + { > + /* This is still the first implementation. The cache has not been > + updated. */ > + void *handle = xdlopen (SONAME, RTLD_NOW); > + int (*marker1) (void) = xdlsym (handle, "marker1"); > + TEST_COMPARE (marker1 (), 1); > + xdlclose (handle); > + } > + run_ldconfig (); > + { > + /* After running ldconfig, it is the second implementation. */ > + void *handle = xdlopen (SONAME, RTLD_NOW); > + int (*marker1) (void) = xdlsym (handle, "marker1"); > + TEST_COMPARE (marker1 (), 2); > + xdlclose (handle); > + } > + > + /* Add the second override to the directory that is searched first. */ > + { > + char *src = xasprintf ("%s/elf/libmarkermod1-3.so", support_objdir_root); > + support_copy_file (src, "/glibc-test/lib/glibc-hwcaps/prepend3/" > + SONAME); > + free (src); > + } > + { > + /* This is still the second implementation. */ > + void *handle = xdlopen (SONAME, RTLD_NOW); > + int (*marker1) (void) = xdlsym (handle, "marker1"); > + TEST_COMPARE (marker1 (), 2); > + xdlclose (handle); > + } > + run_ldconfig (); > + { > + /* After running ldconfig, it is the third implementation. */ > + void *handle = xdlopen (SONAME, RTLD_NOW); > + int (*marker1) (void) = xdlsym (handle, "marker1"); > + TEST_COMPARE (marker1 (), 3); > + xdlclose (handle); > + } > + > + /* Remove the second override again, without running ldconfig. > + Ideally, this would revert to implementation 2. However, in the > + current implementation, the cache returns exactly one file name > + which does not exist after unlinking, so the dlopen fails. */ > + xunlink ("/glibc-test/lib/glibc-hwcaps/prepend3/" SONAME); > + TEST_VERIFY (dlopen (SONAME, RTLD_NOW) == NULL); > + run_ldconfig (); > + system("/sbin/ldconfig -p"); > + { > + /* After running ldconfig, the second implementation is available > + once more. */ > + void *handle = xdlopen (SONAME, RTLD_NOW); > + int (*marker1) (void) = xdlsym (handle, "marker1"); > + TEST_COMPARE (marker1 (), 2); > + xdlclose (handle); > + } > + > + return 0; > +} > + > +static void > +prepare (int argc, char **argv) > +{ > + const char *no_restart = "no-restart"; > + if (argc == 2 && strcmp (argv[1], no_restart) == 0) > + return; > + /* Re-execute the test with an explicit loader invocation. */ > + execl (support_objdir_elf_ldso, > + support_objdir_elf_ldso, > + "--glibc-hwcaps-prepend", "prepend3:prepend2", > + argv[0], no_restart, > + NULL); > + printf ("error: execv of %s failed: %m\n", argv[0]); > + _exit (1); > +} > + > +#define PREPARE prepare > +#include <support/test-driver.c> > diff --git a/elf/tst-glibc-hwcaps-prepend-cache.root/postclean.req b/elf/tst-glibc-hwcaps-prepend-cache.root/postclean.req > new file mode 100644 > index 0000000000..e69de29bb2 > Ok.
* Adhemerval Zanella via Libc-alpha: > On 01/12/2020 17:48, Florian Weimer via Libc-alpha wrote: >> 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. >> > > LGTM, with just a couple of mispelling below. > > Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Thanks. >> diff --git a/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf b/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf >> new file mode 100644 >> index 0000000000..e1e74dbda2 >> --- /dev/null >> +++ b/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf >> @@ -0,0 +1,2 @@ >> +# This file was created to suppress a warning from ldconfig: >> +# /sbin/ldconfig: Warning: ignoring configuration file that cannot be opened: /etc/ld.so.conf: No such file or directory > > Should we wrap this as well? The error message is on one line, and that is what the other file of this kind uses (elf/tst-ldconfig-bad-aux-cache.root/etc/ld.so.conf). Maybe we should get rid of the error message instead if /etc/ld.so.conf is missing. Florian
The 12/01/2020 21:48, Florian Weimer via Libc-alpha wrote: > 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. > > --- > v5: Split glibc_hwcaps_priority into multiple functions. Add a DSO > deletion test that shows non-optimal behavior. > > elf/Makefile | 18 ++ > elf/dl-cache.c | 194 ++++++++++++++++++++- > elf/dl-hwcaps.c | 78 +++++++++ > elf/dl-hwcaps.h | 19 ++ > elf/tst-glibc-hwcaps-cache.c | 45 +++++ > elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf | 2 + > elf/tst-glibc-hwcaps-cache.root/postclean.req | 0 > elf/tst-glibc-hwcaps-cache.script | 6 + > elf/tst-glibc-hwcaps-prepend-cache.c | 150 ++++++++++++++++ > .../postclean.req | 0 > 10 files changed, 509 insertions(+), 3 deletions(-) i see stack corruption sometimes with this test: $ elf/ld.so --library-path ./.:elf --glibc-hwcaps-prepend prepend-markermod1 elf/tst-glibc-hwcaps-prepend --direct works, but $ elf/ld.so --library-path ./././././.:elf --glibc-hwcaps-prepend prepend-markermod1 elf/tst-glibc-hwcaps-prepend --direct crashes because of stack corruption in open_path at elf/dl-load.c:1901 1874 buf = alloca (max_dirnamelen + max_capstrlen + namelen); ... 1901 buflen = 1902 ((char *) __mempcpy (__mempcpy (edp, capstr[cnt].str, 1903 capstr[cnt].len), 1904 name, namelen) 1905 - buf); max_dirnamelen = 11 max_capstrlen = 18 namelen = 17 i think max_capstrlen is wrong as the string is "./././././" + "glibc-hwcaps/prepend-markermod1/" + "libmarkermod1.so" (== 10 + 32 + 17) but i don't know how this is supposed to work.
* Szabolcs Nagy: > i see stack corruption sometimes with this test: > > $ elf/ld.so --library-path ./.:elf --glibc-hwcaps-prepend prepend-markermod1 elf/tst-glibc-hwcaps-prepend --direct > > works, but > > $ elf/ld.so --library-path ./././././.:elf --glibc-hwcaps-prepend prepend-markermod1 elf/tst-glibc-hwcaps-prepend --direct > > crashes because of stack corruption in open_path > at elf/dl-load.c:1901 > > 1874 buf = alloca (max_dirnamelen + max_capstrlen + namelen); > ... > 1901 buflen = > 1902 ((char *) __mempcpy (__mempcpy (edp, capstr[cnt].str, > 1903 capstr[cnt].len), > 1904 name, namelen) > 1905 - buf); > > max_dirnamelen = 11 > max_capstrlen = 18 > namelen = 17 > > i think max_capstrlen is wrong as the string is > > "./././././" + "glibc-hwcaps/prepend-markermod1/" + "libmarkermod1.so" > > (== 10 + 32 + 17) > > but i don't know how this is supposed to work. Sorry, I can't reproduce the crash. But I think I have found the underyling issue and I'm now regression-testing a patch. Thanks, Florian
diff --git a/elf/Makefile b/elf/Makefile index b28930432d..95cbf66c25 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -173,6 +173,12 @@ tests-container := \ tst-ldconfig-bad-aux-cache \ tst-ldconfig-ld_so_conf-update +ifeq (no,$(build-hardcoded-path-in-tests)) +# This is an ld.so.cache test, and RPATH/RUNPATH in the executable +# interferes with its test objectives. +tests-container += tst-glibc-hwcaps-prepend-cache +endif + tests := tst-tls9 tst-leaks1 \ tst-array1 tst-array2 tst-array3 tst-array4 tst-array5 \ tst-auxv tst-stringtable @@ -1865,6 +1871,14 @@ $(objpfx)tst-glibc-hwcaps-prepend.out: \ $< > $@; \ $(evaluate-test) +# Like tst-glibc-hwcaps-prepend, but uses a container and loads the +# library via ld.so.cache. Test setup is contained in the test +# itself. +$(objpfx)tst-glibc-hwcaps-prepend-cache: $(libdl) +$(objpfx)tst-glibc-hwcaps-prepend-cache.out: \ + $(objpfx)tst-glibc-hwcaps-prepend-cache $(objpfx)libmarkermod1-1.so \ + $(objpfx)libmarkermod1-2.so $(objpfx)libmarkermod1-3.so + # tst-glibc-hwcaps-mask checks that --glibc-hwcaps-mask can be used to # suppress all auto-detected subdirectories. $(objpfx)tst-glibc-hwcaps-mask: $(objpfx)libmarkermod1-1.so @@ -1876,3 +1890,7 @@ $(objpfx)tst-glibc-hwcaps-mask.out: \ --glibc-hwcaps-mask does-not-exist \ $< > $@; \ $(evaluate-test) + +# Generic dependency for sysdeps implementation of +# tst-glibc-hwcaps-cache. +$(objpfx)tst-glibc-hwcaps-cache.out: $(objpfx)tst-glibc-hwcaps diff --git a/elf/dl-cache.c b/elf/dl-cache.c index 02c46ffb0c..e32688c0c9 100644 --- a/elf/dl-cache.c +++ b/elf/dl-cache.c @@ -35,6 +35,144 @@ static struct cache_file *cache; static struct cache_file_new *cache_new; static size_t cachesize; +#ifdef SHARED +/* This is used to cache the priorities of glibc-hwcaps + subdirectories. The elements of _dl_cache_priorities correspond to + the strings in the cache_extension_tag_glibc_hwcaps section. */ +static uint32_t *glibc_hwcaps_priorities; +static uint32_t glibc_hwcaps_priorities_length; +static uint32_t glibc_hwcaps_priorities_allocated; + +/* True if the full malloc was used to allocated the array. */ +static bool glibc_hwcaps_priorities_malloced; + +/* Deallocate the glibc_hwcaps_priorities array. */ +static void +glibc_hwcaps_priorities_free (void) +{ + /* When the minimal malloc is in use, free does not do anything, + so it does not make sense to call it. */ + if (glibc_hwcaps_priorities_malloced) + free (glibc_hwcaps_priorities); + glibc_hwcaps_priorities = NULL; + glibc_hwcaps_priorities_allocated = 0; +} + +/* Ordered comparision of a hwcaps string from the cache on the left + (identified by its string table index) and a _dl_hwcaps_priorities + element on the right. */ +static int +glibc_hwcaps_compare (uint32_t left_index, struct dl_hwcaps_priority *right) +{ + const char *left_name = (const char *) cache + left_index; + uint32_t left_name_length = strlen (left_name); + uint32_t to_compare; + if (left_name_length < right->name_length) + to_compare = left_name_length; + else + to_compare = right->name_length; + int cmp = memcmp (left_name, right->name, to_compare); + if (cmp != 0) + return cmp; + if (left_name_length < right->name_length) + return -1; + else if (left_name_length > right->name_length) + return 1; + else + return 0; +} + +/* Initialize the glibc_hwcaps_priorities array and its length, + glibc_hwcaps_priorities_length. */ +static void +glibc_hwcaps_priorities_init (void) +{ + struct cache_extension_all_loaded ext; + if (!cache_extension_load (cache_new, cache, cachesize, &ext)) + return; + + uint32_t length = (ext.sections[cache_extension_tag_glibc_hwcaps].size + / sizeof (uint32_t)); + if (length > glibc_hwcaps_priorities_allocated) + { + glibc_hwcaps_priorities_free (); + + uint32_t *new_allocation = malloc (length * sizeof (uint32_t)); + if (new_allocation == NULL) + /* This effectively disables hwcaps on memory allocation + errors. */ + return; + + glibc_hwcaps_priorities = new_allocation; + glibc_hwcaps_priorities_allocated = length; + glibc_hwcaps_priorities_malloced = __rtld_malloc_is_complete (); + } + + /* Compute the priorities for the subdirectories by merging the + array in the cache with the dl_hwcaps_priorities array. */ + const uint32_t *left = ext.sections[cache_extension_tag_glibc_hwcaps].base; + const uint32_t *left_end = left + length; + struct dl_hwcaps_priority *right = _dl_hwcaps_priorities; + struct dl_hwcaps_priority *right_end = right + _dl_hwcaps_priorities_length; + uint32_t *result = glibc_hwcaps_priorities; + + while (left < left_end && right < right_end) + { + if (*left < cachesize) + { + int cmp = glibc_hwcaps_compare (*left, right); + if (cmp == 0) + { + *result = right->priority; + ++result; + ++left; + ++right; + } + else if (cmp < 0) + { + *result = 0; + ++result; + ++left; + } + else + ++right; + } + else + { + *result = 0; + ++result; + } + } + while (left < left_end) + { + *result = 0; + ++result; + ++left; + } + + glibc_hwcaps_priorities_length = length; +} + +/* Return the priority of the cache_extension_tag_glibc_hwcaps section + entry at INDEX. Zero means do not use. Otherwise, lower values + indicate greater preference. */ +static uint32_t +glibc_hwcaps_priority (uint32_t index) +{ + /* This does not need to repeated initialization attempts because + this function is only called if there is glibc-hwcaps data in the + cache, so the first call initializes the glibc_hwcaps_priorities + array. */ + if (glibc_hwcaps_priorities_length == 0) + glibc_hwcaps_priorities_init (); + + if (index < glibc_hwcaps_priorities_length) + return glibc_hwcaps_priorities[index]; + else + return 0; +} +#endif /* SHARED */ + /* True if PTR is a valid string table index. */ static inline bool _dl_cache_verify_ptr (uint32_t ptr, size_t string_table_size) @@ -74,6 +212,9 @@ search_cache (const char *string_table, uint32_t string_table_size, int left = 0; int right = nlibs - 1; const char *best = NULL; +#ifdef SHARED + uint32_t best_priority = 0; +#endif while (left <= right) { @@ -129,6 +270,11 @@ search_cache (const char *string_table, uint32_t string_table_size, { if (best == NULL || flags == GLRO (dl_correct_cache_id)) { + /* Named/extension hwcaps get slightly different + treatment: We keep searching for a better + match. */ + bool named_hwcap = false; + if (entry_size >= sizeof (struct file_entry_new)) { /* The entry is large enough to include @@ -136,7 +282,18 @@ search_cache (const char *string_table, uint32_t string_table_size, struct file_entry_new *libnew = (struct file_entry_new *) lib; - if (libnew->hwcap & hwcap_exclude) +#ifdef SHARED + named_hwcap = dl_cache_hwcap_extension (libnew); +#endif + + /* The entries with named/extension hwcaps + have been exhausted. Return the best + match encountered so far if there is + one. */ + if (!named_hwcap && best != NULL) + break; + + if ((libnew->hwcap & hwcap_exclude) && !named_hwcap) continue; if (GLRO (dl_osversion) && libnew->osversion > GLRO (dl_osversion)) @@ -146,14 +303,41 @@ search_cache (const char *string_table, uint32_t string_table_size, && ((libnew->hwcap & _DL_HWCAP_PLATFORM) != platform)) continue; + +#ifdef SHARED + /* For named hwcaps, determine the priority + and see if beats what has been found so + far. */ + if (named_hwcap) + { + uint32_t entry_priority + = glibc_hwcaps_priority (libnew->hwcap); + if (entry_priority == 0) + /* Not usable at all. Skip. */ + continue; + else if (best == NULL + || entry_priority < best_priority) + /* This entry is of higher priority + than the previous one, or it is the + first entry. */ + best_priority = entry_priority; + else + /* An entry has already been found, + but it is a better match. */ + continue; + } +#endif /* SHARED */ } best = string_table + lib->value; - if (flags == GLRO (dl_correct_cache_id)) + if (flags == GLRO (dl_correct_cache_id) + && !named_hwcap) /* We've found an exact match for the shared object and no general `ELF' release. Stop - searching. */ + searching, but not if a named (extension) + hwcap is used. In this case, an entry with + a higher priority may come up later. */ break; } } @@ -346,5 +530,9 @@ _dl_unload_cache (void) __munmap (cache, cachesize); cache = NULL; } +#ifdef SHARED + /* This marks the glibc_hwcaps_priorities array as out-of-date. */ + glibc_hwcaps_priorities_length = 0; +#endif } #endif diff --git a/elf/dl-hwcaps.c b/elf/dl-hwcaps.c index f611f3a1a6..5a71f80154 100644 --- a/elf/dl-hwcaps.c +++ b/elf/dl-hwcaps.c @@ -89,6 +89,81 @@ copy_hwcaps (struct copy_hwcaps *target, const char *hwcaps, } } +struct dl_hwcaps_priority *_dl_hwcaps_priorities; +uint32_t _dl_hwcaps_priorities_length; + +/* Allocate _dl_hwcaps_priorities and fill it with data. */ +static void +compute_priorities (size_t total_count, const char *prepend, + uint32_t bitmask, const char *mask) +{ + _dl_hwcaps_priorities = malloc (total_count + * sizeof (*_dl_hwcaps_priorities)); + if (_dl_hwcaps_priorities == NULL) + _dl_signal_error (ENOMEM, NULL, NULL, + N_("cannot create HWCAP priorities")); + _dl_hwcaps_priorities_length = total_count; + + /* First the prepended subdirectories. */ + size_t i = 0; + { + struct dl_hwcaps_split sp; + _dl_hwcaps_split_init (&sp, prepend); + while (_dl_hwcaps_split (&sp)) + { + _dl_hwcaps_priorities[i].name = sp.segment; + _dl_hwcaps_priorities[i].name_length = sp.length; + _dl_hwcaps_priorities[i].priority = i + 1; + ++i; + } + } + + /* Then the built-in subdirectories that are actually active. */ + { + struct dl_hwcaps_split_masked sp; + _dl_hwcaps_split_masked_init (&sp, _dl_hwcaps_subdirs, bitmask, mask); + while (_dl_hwcaps_split_masked (&sp)) + { + _dl_hwcaps_priorities[i].name = sp.split.segment; + _dl_hwcaps_priorities[i].name_length = sp.split.length; + _dl_hwcaps_priorities[i].priority = i + 1; + ++i; + } + } + assert (i == total_count); +} + +/* Sort the _dl_hwcaps_priorities array by name. */ +static void +sort_priorities_by_name (void) +{ + /* Insertion sort. There is no need to link qsort into the dynamic + loader for such a short array. */ + for (size_t i = 1; i < _dl_hwcaps_priorities_length; ++i) + for (size_t j = i; j > 0; --j) + { + struct dl_hwcaps_priority *previous = _dl_hwcaps_priorities + j - 1; + struct dl_hwcaps_priority *current = _dl_hwcaps_priorities + j; + + /* Bail out if current is greater or equal to the previous + value. */ + uint32_t to_compare; + if (current->name_length < previous->name_length) + to_compare = current->name_length; + else + to_compare = previous->name_length; + int cmp = memcmp (current->name, previous->name, to_compare); + if (cmp >= 0 + || (cmp == 0 && current->name_length >= previous->name_length)) + break; + + /* Swap *previous and *current. */ + struct dl_hwcaps_priority tmp = *previous; + *previous = *current; + *current = tmp; + } +} + /* Return an array of useful/necessary hardware capability names. */ const struct r_strlenpair * _dl_important_hwcaps (const char *glibc_hwcaps_prepend, @@ -111,6 +186,9 @@ _dl_important_hwcaps (const char *glibc_hwcaps_prepend, update_hwcaps_counts (&hwcaps_counts, glibc_hwcaps_prepend, -1, NULL); update_hwcaps_counts (&hwcaps_counts, _dl_hwcaps_subdirs, hwcaps_subdirs_active, glibc_hwcaps_mask); + compute_priorities (hwcaps_counts.count, glibc_hwcaps_prepend, + hwcaps_subdirs_active, glibc_hwcaps_mask); + sort_priorities_by_name (); /* Each hwcaps subdirectory has a GLIBC_HWCAPS_PREFIX string prefix and a "/" suffix once stored in the result. */ diff --git a/elf/dl-hwcaps.h b/elf/dl-hwcaps.h index ab39d8a46d..ddfdde278e 100644 --- a/elf/dl-hwcaps.h +++ b/elf/dl-hwcaps.h @@ -132,4 +132,23 @@ _dl_hwcaps_subdirs_build_bitmask (int subdirs, int active) return mask ^ ((1U << inactive) - 1); } +/* Pre-computed glibc-hwcaps subdirectory priorities. Used in + dl-cache.c to quickly find the proprities for the stored HWCAP + names. */ +struct dl_hwcaps_priority +{ + /* The name consists of name_length bytes at name (not necessarily + null-terminated). */ + const char *name; + uint32_t name_length; + + /* Priority of this name. A positive number. */ + uint32_t priority; +}; + +/* Pre-computed hwcaps priorities. Set up by + _dl_important_hwcaps. */ +extern struct dl_hwcaps_priority *_dl_hwcaps_priorities attribute_hidden; +extern uint32_t _dl_hwcaps_priorities_length attribute_hidden; + #endif /* _DL_HWCAPS_H */ diff --git a/elf/tst-glibc-hwcaps-cache.c b/elf/tst-glibc-hwcaps-cache.c new file mode 100644 index 0000000000..4bad56afc0 --- /dev/null +++ b/elf/tst-glibc-hwcaps-cache.c @@ -0,0 +1,45 @@ +/* Wrapper to invoke tst-glibc-hwcaps in a container, to test ld.so.cache. + Copyright (C) 2020 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/>. */ + +/* This program is just a wrapper that runs ldconfig followed by + tst-glibc-hwcaps. The actual test is provided via an + implementation in a sysdeps subdirectory. */ + +#include <stdio.h> +#include <stdlib.h> +#include <support/support.h> +#include <unistd.h> + +int +main (int argc, char **argv) +{ + /* Run ldconfig to populate the cache. */ + { + char *command = xasprintf ("%s/ldconfig", support_install_rootsbindir); + if (system (command) != 0) + return 1; + free (command); + } + + /* Reuse tst-glibc-hwcaps. Since this code is running in a + container, we can launch it directly. */ + char *path = xasprintf ("%s/elf/tst-glibc-hwcaps", support_objdir_root); + execv (path, argv); + printf ("error: execv of %s failed: %m\n", path); + return 1; +} diff --git a/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf b/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf new file mode 100644 index 0000000000..e1e74dbda2 --- /dev/null +++ b/elf/tst-glibc-hwcaps-cache.root/etc/ld.so.conf @@ -0,0 +1,2 @@ +# This file was created to suppress a warning from ldconfig: +# /sbin/ldconfig: Warning: ignoring configuration file that cannot be opened: /etc/ld.so.conf: No such file or directory diff --git a/elf/tst-glibc-hwcaps-cache.root/postclean.req b/elf/tst-glibc-hwcaps-cache.root/postclean.req new file mode 100644 index 0000000000..e69de29bb2 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 diff --git a/elf/tst-glibc-hwcaps-prepend-cache.c b/elf/tst-glibc-hwcaps-prepend-cache.c new file mode 100644 index 0000000000..0c1b99b14f --- /dev/null +++ b/elf/tst-glibc-hwcaps-prepend-cache.c @@ -0,0 +1,150 @@ +/* Test that --glibc-hwcaps-prepend works, using dlopen and /etc/ld.so.cache. + Copyright (C) 2020 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 <dlfcn.h> +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <support/check.h> +#include <support/support.h> +#include <support/xdlfcn.h> +#include <support/xunistd.h> + +/* Invoke /sbin/ldconfig with some error checking. */ +static void +run_ldconfig (void) +{ + char *command = xasprintf ("%s/ldconfig", support_install_rootsbindir); + TEST_COMPARE (system (command), 0); + free (command); +} + +/* The library under test. */ +#define SONAME "libmarkermod1.so" + +static int +do_test (void) +{ + if (dlopen (SONAME, RTLD_NOW) != NULL) + FAIL_EXIT1 (SONAME " is already on the search path"); + + /* Install the default implementation of libmarkermod1.so. */ + xmkdirp ("/etc", 0777); + support_write_file_string ("/etc/ld.so.conf", "/glibc-test/lib\n"); + xmkdirp ("/glibc-test/lib/glibc-hwcaps/prepend2", 0777); + xmkdirp ("/glibc-test/lib/glibc-hwcaps/prepend3", 0777); + { + char *src = xasprintf ("%s/elf/libmarkermod1-1.so", support_objdir_root); + support_copy_file (src, "/glibc-test/lib/" SONAME); + free (src); + } + run_ldconfig (); + { + /* The default implementation can now be loaded. */ + void *handle = xdlopen (SONAME, RTLD_NOW); + int (*marker1) (void) = xdlsym (handle, "marker1"); + TEST_COMPARE (marker1 (), 1); + xdlclose (handle); + } + + /* Add the first override to the directory that is searched last. */ + { + char *src = xasprintf ("%s/elf/libmarkermod1-2.so", support_objdir_root); + support_copy_file (src, "/glibc-test/lib/glibc-hwcaps/prepend2/" + SONAME); + free (src); + } + { + /* This is still the first implementation. The cache has not been + updated. */ + void *handle = xdlopen (SONAME, RTLD_NOW); + int (*marker1) (void) = xdlsym (handle, "marker1"); + TEST_COMPARE (marker1 (), 1); + xdlclose (handle); + } + run_ldconfig (); + { + /* After running ldconfig, it is the second implementation. */ + void *handle = xdlopen (SONAME, RTLD_NOW); + int (*marker1) (void) = xdlsym (handle, "marker1"); + TEST_COMPARE (marker1 (), 2); + xdlclose (handle); + } + + /* Add the second override to the directory that is searched first. */ + { + char *src = xasprintf ("%s/elf/libmarkermod1-3.so", support_objdir_root); + support_copy_file (src, "/glibc-test/lib/glibc-hwcaps/prepend3/" + SONAME); + free (src); + } + { + /* This is still the second implementation. */ + void *handle = xdlopen (SONAME, RTLD_NOW); + int (*marker1) (void) = xdlsym (handle, "marker1"); + TEST_COMPARE (marker1 (), 2); + xdlclose (handle); + } + run_ldconfig (); + { + /* After running ldconfig, it is the third implementation. */ + void *handle = xdlopen (SONAME, RTLD_NOW); + int (*marker1) (void) = xdlsym (handle, "marker1"); + TEST_COMPARE (marker1 (), 3); + xdlclose (handle); + } + + /* Remove the second override again, without running ldconfig. + Ideally, this would revert to implementation 2. However, in the + current implementation, the cache returns exactly one file name + which does not exist after unlinking, so the dlopen fails. */ + xunlink ("/glibc-test/lib/glibc-hwcaps/prepend3/" SONAME); + TEST_VERIFY (dlopen (SONAME, RTLD_NOW) == NULL); + run_ldconfig (); + system("/sbin/ldconfig -p"); + { + /* After running ldconfig, the second implementation is available + once more. */ + void *handle = xdlopen (SONAME, RTLD_NOW); + int (*marker1) (void) = xdlsym (handle, "marker1"); + TEST_COMPARE (marker1 (), 2); + xdlclose (handle); + } + + return 0; +} + +static void +prepare (int argc, char **argv) +{ + const char *no_restart = "no-restart"; + if (argc == 2 && strcmp (argv[1], no_restart) == 0) + return; + /* Re-execute the test with an explicit loader invocation. */ + execl (support_objdir_elf_ldso, + support_objdir_elf_ldso, + "--glibc-hwcaps-prepend", "prepend3:prepend2", + argv[0], no_restart, + NULL); + printf ("error: execv of %s failed: %m\n", argv[0]); + _exit (1); +} + +#define PREPARE prepare +#include <support/test-driver.c> diff --git a/elf/tst-glibc-hwcaps-prepend-cache.root/postclean.req b/elf/tst-glibc-hwcaps-prepend-cache.root/postclean.req new file mode 100644 index 0000000000..e69de29bb2