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| author | Alan Modra <amodra@gmail.com> | 2015-03-25 15:53:47 +1030 |
|---|---|---|
| committer | Alan Modra <amodra@gmail.com> | 2015-03-25 15:53:47 +1030 |
| commit | afcd9480feca651eef436d8438b783dde5c3bbb2 (patch) | |
| tree | 97bd1be08268c51e674154d3bf98af3a2256c6f8 /elf/dynamic-link.h | |
| parent | da9f3334106ee0f98c499c54bdfe3c4fcbb348f4 (diff) | |
| download | glibc-afcd9480feca651eef436d8438b783dde5c3bbb2.tar.gz glibc-afcd9480feca651eef436d8438b783dde5c3bbb2.tar.xz glibc-afcd9480feca651eef436d8438b783dde5c3bbb2.zip | |
powerpc __tls_get_addr call optimization
This patch is glibc support for a PowerPC TLS optimization, inspired by Alexandre Oliva's TLS optimization for other processors, http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt In essence, this optimization uses a zero module id in the tls_index GOT entry to indicate that a TLS variable is allocated space in the static TLS area. A special plt call linker stub for __tls_get_addr checks for such a tls_index and if found, returns the offset immediately. The linker communicates the fact that the special __tls_get_addr stub is used by setting a bit in the dynamic tag DT_PPC64_OPT/DT_PPC_OPT. glibc communicates to the linker that this optimization is available by the presence of __tls_get_addr_opt. tst-tlsmod2.so is built with -Wl,--no-tls-get-addr-optimize for tst-tls-dlinfo, which otherwise would fail since it tests that no static tls is allocated. The ld option --no-tls-get-addr-optimize has been available since binutils-2.20 so doesn't need a configure test. * NEWS: Advertise TLS optimization. * elf/elf.h (R_PPC_TLSGD, R_PPC_TLSLD, DT_PPC_OPT, PPC_OPT_TLS): Define. (DT_PPC_NUM): Increment. * elf/dynamic-link.h (HAVE_STATIC_TLS): Define. (CHECK_STATIC_TLS): Use here. * sysdeps/powerpc/powerpc32/dl-machine.h (elf_machine_rela): Optimize TLS descriptors. * sysdeps/powerpc/powerpc64/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/powerpc/dl-tls.c: New file. * sysdeps/powerpc/Versions: Add __tls_get_addr_opt. * sysdeps/powerpc/tst-tlsopt-powerpc.c: New tls test. * sysdeps/unix/sysv/linux/powerpc/Makefile: Add new test. Build tst-tlsmod2.so with --no-tls-get-addr-optimize. * sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist: Update. * sysdeps/unix/sysv/linux/powerpc/powerpc64/ld.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/ld-le.abilist: Likewise.
Diffstat (limited to 'elf/dynamic-link.h')
| -rw-r--r-- | elf/dynamic-link.h | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h index 6f4a773d5a..8d428e20d3 100644 --- a/elf/dynamic-link.h +++ b/elf/dynamic-link.h @@ -25,11 +25,14 @@ an attempt to allocate it in surplus space on the fly. If that can't be done, we fall back to the error that DF_STATIC_TLS is intended to produce. */ +#define HAVE_STATIC_TLS(map, sym_map) \ + (__builtin_expect ((sym_map)->l_tls_offset != NO_TLS_OFFSET \ + && ((sym_map)->l_tls_offset \ + != FORCED_DYNAMIC_TLS_OFFSET), 1)) + #define CHECK_STATIC_TLS(map, sym_map) \ do { \ - if (__builtin_expect ((sym_map)->l_tls_offset == NO_TLS_OFFSET \ - || ((sym_map)->l_tls_offset \ - == FORCED_DYNAMIC_TLS_OFFSET), 0)) \ + if (!HAVE_STATIC_TLS (map, sym_map)) \ _dl_allocate_static_tls (sym_map); \ } while (0) |