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Adhemerval Zanella
5d89e7c47c
The 'unwind-link' facility allows glibc to support thread cancellation
and exit (pthread_cancel, pthread_exiti, backtrace) by dynamically
loading the unwind library at runtime, preventing a hard dependency on
libgcc_s within libc.so.
When building with libunwind (for clang/LLVM toolchains [1]), two
assumptions in the existing code break:
1. The runtime library is libunwind.so instead of libgcc_s.so.
2. libgcc relies on __gcc_personality_v0 to handle unwinding mechanics.
libunwind exposes the standard '_Unwind_*' accessors directly.
This patch adapts `unwind-link` to handle both environments based on
the HAVE_CC_WITH_LIBUNWIND configuration:
* The UNWIND_SONAME macro now selects between LIBGCC_S_SO and
LIBUNWIND_SO.
* For libgcc, it continues to resolve `__gcc_personality_v0`.
* For libunwind, it instead resolves the standard
_Unwind_GetLanguageSpecificData, _Unwind_SetGR, _Unwind_SetIP,
and _Unwind_GetRegionStart helpers.
* unwind-resume.c is updated to implement wrappers for these
accessors that forward calls to the dynamically loaded function
pointers, effectively shimming the unwinder.
Tests and Makefiles are updated to link against `$(libunwind)` where
appropriate.
Reviewed-by: Sam James <sam@gentoo.org>
[1] https://github.com/libunwind/libunwind
73 lines
2.2 KiB
Plaintext
73 lines
2.2 KiB
Plaintext
# This file (and shlib-versions files in sysdeps directories) defines
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# the shared library version numbers we will install.
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# The following lines list the associated versions to use for various
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# libraries. The entire list is processed, with earlier entries
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# taking precedence over later entries (and the files from sysdeps
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# directories coming before those from other subdirectories, which
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# come before this file).
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# This file can use cpp-style conditionals starting with % instead of #
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# to test the symbols defined in config.h by configure.
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# In the optional second column, there can one or more symbol set names
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# listed, which must be in ascending version order reading left to right
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# and must appear in this same order in the Versions.def file. Each listed
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# version subsumes all prior versions back to the previous listed version.
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#
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# An entry with DEFAULT in the first column gives a default second
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# column to apply when the matching entry for a particular library has
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# no second column. The defaults must precede the entries they apply
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# to.
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# Library=version Earliest symbol set (optional)
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# --------------- ------------------------------
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# We use the ELF ABI standard name for the default.
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ld=ld.so.1
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# The -ldl interface (see <dlfcn.h>) is the same on all platforms.
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libdl=2
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# So far the -lutil interface is the same on all platforms, except for the
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# `struct utmp' format, which depends on libc.
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libutil=1
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# Version number 2 is used on other systems for the BIND 4.9.5 resolver
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# interface.
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libresolv=2
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# Interface revision of nss_* modules. This must match NSS_SHLIB_REVISION
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# in nss/nsswitch.h, which determines the library names used for service
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# names given in /etc/nsswitch.conf.
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libnss_files=2
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libnss_dns=2
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libnss_compat=2
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libnss_ldap=2
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libnss_hesiod=2
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libnss_db=2
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# Version for libnsl with YP and NIS+ functions.
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libnsl=1
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# The gross patch for programs assuming broken locale implementations.
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libBrokenLocale=1
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# The real-time library from POSIX.1b.
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librt=1
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# The asynchronous name lookup library.
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libanl=1
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# This defines the libgcc soname version this glibc is to load for
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# asynchronous cancellation to work correctly.
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libgcc_s=1
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# The vector math library
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libmvec=1
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# The malloc debug library
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libc_malloc_debug=0
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libunwind=1
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