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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 | |
| parent | da9f3334106ee0f98c499c54bdfe3c4fcbb348f4 (diff) | |
| download | glibc-afcd9480feca651eef436d8438b783dde5c3bbb2.zip glibc-afcd9480feca651eef436d8438b783dde5c3bbb2.tar.gz glibc-afcd9480feca651eef436d8438b783dde5c3bbb2.tar.bz2 | |
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')
| -rw-r--r-- | elf/dynamic-link.h | 9 | ||||
| -rw-r--r-- | elf/elf.h | 8 |
2 files changed, 13 insertions, 4 deletions
diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h index 6f4a773..8d428e2 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) @@ -2194,6 +2194,8 @@ enum #define R_PPC_GOT_DTPREL16_LO 92 /* half16* (sym+add)@got@dtprel@l */ #define R_PPC_GOT_DTPREL16_HI 93 /* half16* (sym+add)@got@dtprel@h */ #define R_PPC_GOT_DTPREL16_HA 94 /* half16* (sym+add)@got@dtprel@ha */ +#define R_PPC_TLSGD 95 /* none (sym+add)@tlsgd */ +#define R_PPC_TLSLD 96 /* none (sym+add)@tlsld */ /* The remaining relocs are from the Embedded ELF ABI, and are not in the SVR4 ELF ABI. */ @@ -2237,7 +2239,11 @@ enum /* PowerPC specific values for the Dyn d_tag field. */ #define DT_PPC_GOT (DT_LOPROC + 0) -#define DT_PPC_NUM 1 +#define DT_PPC_OPT (DT_LOPROC + 1) +#define DT_PPC_NUM 2 + +/* PowerPC specific values for the DT_PPC_OPT Dyn entry. */ +#define PPC_OPT_TLS 1 /* PowerPC64 relocations defined by the ABIs */ #define R_PPC64_NONE R_PPC_NONE |