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elf: Fix glibc-hwcaps priorities with cache flags mismatches [BZ #27046]
If lib->flags (in the cache) did not match GLRO (dl_correct_cache_id), searching for further glibc-hwcaps entries did not happen, and it was possible that the best glibc-hwcaps was not found. By accident, this causes a test failure for elf/tst-glibc-hwcaps-prepend-cache on armv7l. This commit changes the cache lookup logic to continue searching if (a) no match has been found, (b) a named glibc-hwcaps match has been found(), or (c) non-glibc-hwcaps match has been found and the entry flags and cache default flags do not match. _DL_CACHE_DEFAULT_ID is used instead of GLRO (dl_correct_cache_id) because the latter is only written once on i386 if loading of libc.so.5 libraries is selected, so GLRO (dl_correct_cache_id) should probably removed in a future change. Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
This commit is contained in:
Florian Weimer
parent
ac3babc394
commit
66db95b6e8
126
elf/dl-cache.c
126
elf/dl-cache.c
@ -269,81 +269,77 @@ search_cache (const char *string_table, uint32_t string_table_size,
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if (_dl_cache_check_flags (flags)
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&& _dl_cache_verify_ptr (lib->value, string_table_size))
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{
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if (best == NULL || flags == GLRO (dl_correct_cache_id))
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{
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/* Named/extension hwcaps get slightly different
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treatment: We keep searching for a better
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match. */
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bool named_hwcap = false;
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/* Named/extension hwcaps get slightly different
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treatment: We keep searching for a better
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match. */
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bool named_hwcap = false;
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if (entry_size >= sizeof (struct file_entry_new))
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{
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/* The entry is large enough to include
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HWCAP data. Check it. */
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struct file_entry_new *libnew
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= (struct file_entry_new *) lib;
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if (entry_size >= sizeof (struct file_entry_new))
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{
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/* The entry is large enough to include
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HWCAP data. Check it. */
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struct file_entry_new *libnew
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= (struct file_entry_new *) lib;
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#ifdef SHARED
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named_hwcap = dl_cache_hwcap_extension (libnew);
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if (named_hwcap
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&& !dl_cache_hwcap_isa_level_compatible (libnew))
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continue;
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named_hwcap = dl_cache_hwcap_extension (libnew);
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if (named_hwcap
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&& !dl_cache_hwcap_isa_level_compatible (libnew))
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continue;
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#endif
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/* The entries with named/extension hwcaps
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have been exhausted. Return the best
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match encountered so far if there is
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one. */
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if (!named_hwcap && best != NULL)
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break;
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/* The entries with named/extension hwcaps have
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been exhausted (they are listed before all
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other entries). Return the best match
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encountered so far if there is one. */
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if (!named_hwcap && best != NULL)
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break;
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if ((libnew->hwcap & hwcap_exclude) && !named_hwcap)
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continue;
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if (GLRO (dl_osversion)
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&& libnew->osversion > GLRO (dl_osversion))
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continue;
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if (_DL_PLATFORMS_COUNT
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&& (libnew->hwcap & _DL_HWCAP_PLATFORM) != 0
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&& ((libnew->hwcap & _DL_HWCAP_PLATFORM)
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!= platform))
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continue;
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if ((libnew->hwcap & hwcap_exclude) && !named_hwcap)
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continue;
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if (GLRO (dl_osversion)
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&& libnew->osversion > GLRO (dl_osversion))
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continue;
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if (_DL_PLATFORMS_COUNT
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&& (libnew->hwcap & _DL_HWCAP_PLATFORM) != 0
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&& ((libnew->hwcap & _DL_HWCAP_PLATFORM)
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!= platform))
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continue;
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#ifdef SHARED
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/* For named hwcaps, determine the priority
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and see if beats what has been found so
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far. */
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if (named_hwcap)
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{
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uint32_t entry_priority
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= glibc_hwcaps_priority (libnew->hwcap);
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if (entry_priority == 0)
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/* Not usable at all. Skip. */
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continue;
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else if (best == NULL
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|| entry_priority < best_priority)
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/* This entry is of higher priority
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than the previous one, or it is the
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first entry. */
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best_priority = entry_priority;
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else
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/* An entry has already been found,
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but it is a better match. */
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continue;
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}
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#endif /* SHARED */
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/* For named hwcaps, determine the priority and
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see if beats what has been found so far. */
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if (named_hwcap)
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{
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uint32_t entry_priority
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= glibc_hwcaps_priority (libnew->hwcap);
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if (entry_priority == 0)
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/* Not usable at all. Skip. */
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continue;
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else if (best == NULL
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|| entry_priority < best_priority)
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/* This entry is of higher priority
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than the previous one, or it is the
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first entry. */
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best_priority = entry_priority;
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else
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/* An entry has already been found,
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but it is a better match. */
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continue;
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}
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best = string_table + lib->value;
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if (flags == GLRO (dl_correct_cache_id)
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&& !named_hwcap)
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/* We've found an exact match for the shared
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object and no general `ELF' release. Stop
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searching, but not if a named (extension)
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hwcap is used. In this case, an entry with
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a higher priority may come up later. */
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break;
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#endif /* SHARED */
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}
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best = string_table + lib->value;
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if (!named_hwcap && flags == _DL_CACHE_DEFAULT_ID)
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/* With named hwcaps, we need to keep searching to
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see if we find a better match. A better match
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is also possible if the flags of the current
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entry do not match the expected cache flags.
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But if the flags match, no better entry will be
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found. */
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break;
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}
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}
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while (++middle <= right);
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