From b52b0d793dcb226ecb0ecca1e672ca265973233c Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 20 Oct 2017 11:00:08 -0700 Subject: x86-64: Use fxsave/xsave/xsavec in _dl_runtime_resolve [BZ #21265] In _dl_runtime_resolve, use fxsave/xsave/xsavec to preserve all vector, mask and bound registers. It simplifies _dl_runtime_resolve and supports different calling conventions. ld.so code size is reduced by more than 1 KB. However, use fxsave/xsave/xsavec takes a little bit more cycles than saving and restoring vector and bound registers individually. Latency for _dl_runtime_resolve to lookup the function, foo, from one shared library plus libc.so: Before After Change Westmere (SSE)/fxsave 345 866 151% IvyBridge (AVX)/xsave 420 643 53% Haswell (AVX)/xsave 713 1252 75% Skylake (AVX+MPX)/xsavec 559 719 28% Skylake (AVX512+MPX)/xsavec 145 272 87% Ryzen (AVX)/xsavec 280 553 97% This is the worst case where portion of time spent for saving and restoring registers is bigger than majority of cases. With smaller _dl_runtime_resolve code size, overall performance impact is negligible. On IvyBridge, differences in build and test time of binutils with lazy binding GCC and binutils are noises. On Westmere, differences in bootstrap and "makc check" time of GCC 7 with lazy binding GCC and binutils are also noises. [BZ #21265] * sysdeps/x86/cpu-features-offsets.sym (XSAVE_STATE_SIZE_OFFSET): New. * sysdeps/x86/cpu-features.c: Include . (get_common_indeces): Set xsave_state_size, xsave_state_full_size and bit_arch_XSAVEC_Usable if needed. (init_cpu_features): Remove bit_arch_Use_dl_runtime_resolve_slow and bit_arch_Use_dl_runtime_resolve_opt. * sysdeps/x86/cpu-features.h (bit_arch_Use_dl_runtime_resolve_opt): Removed. (bit_arch_Use_dl_runtime_resolve_slow): Likewise. (bit_arch_Prefer_No_AVX512): Updated. (bit_arch_MathVec_Prefer_No_AVX512): Likewise. (bit_arch_XSAVEC_Usable): New. (STATE_SAVE_OFFSET): Likewise. (STATE_SAVE_MASK): Likewise. [__ASSEMBLER__]: Include . (cpu_features): Add xsave_state_size and xsave_state_full_size. (index_arch_Use_dl_runtime_resolve_opt): Removed. (index_arch_Use_dl_runtime_resolve_slow): Likewise. (index_arch_XSAVEC_Usable): New. * sysdeps/x86/cpu-tunables.c (TUNABLE_CALLBACK (set_hwcaps)): Support XSAVEC_Usable. Remove Use_dl_runtime_resolve_slow. * sysdeps/x86_64/Makefile (tst-x86_64-1-ENV): New if tunables is enabled. * sysdeps/x86_64/dl-machine.h (elf_machine_runtime_setup): Replace _dl_runtime_resolve_sse, _dl_runtime_resolve_avx, _dl_runtime_resolve_avx_slow, _dl_runtime_resolve_avx_opt, _dl_runtime_resolve_avx512 and _dl_runtime_resolve_avx512_opt with _dl_runtime_resolve_fxsave, _dl_runtime_resolve_xsave and _dl_runtime_resolve_xsavec. * sysdeps/x86_64/dl-trampoline.S (DL_RUNTIME_UNALIGNED_VEC_SIZE): Removed. (DL_RUNTIME_RESOLVE_REALIGN_STACK): Check STATE_SAVE_ALIGNMENT instead of VEC_SIZE. (REGISTER_SAVE_BND0): Removed. (REGISTER_SAVE_BND1): Likewise. (REGISTER_SAVE_BND3): Likewise. (REGISTER_SAVE_RAX): Always defined to 0. (VMOV): Removed. (_dl_runtime_resolve_avx): Likewise. (_dl_runtime_resolve_avx_slow): Likewise. (_dl_runtime_resolve_avx_opt): Likewise. (_dl_runtime_resolve_avx512): Likewise. (_dl_runtime_resolve_avx512_opt): Likewise. (_dl_runtime_resolve_sse): Likewise. (_dl_runtime_resolve_sse_vex): Likewise. (USE_FXSAVE): New. (_dl_runtime_resolve_fxsave): Likewise. (USE_XSAVE): Likewise. (_dl_runtime_resolve_xsave): Likewise. (USE_XSAVEC): Likewise. (_dl_runtime_resolve_xsavec): Likewise. * sysdeps/x86_64/dl-trampoline.h (_dl_runtime_resolve_avx512): Removed. (_dl_runtime_resolve_avx512_opt): Likewise. (_dl_runtime_resolve_avx): Likewise. (_dl_runtime_resolve_avx_opt): Likewise. (_dl_runtime_resolve_sse): Likewise. (_dl_runtime_resolve_sse_vex): Likewise. (_dl_runtime_resolve_fxsave): New. (_dl_runtime_resolve_xsave): Likewise. (_dl_runtime_resolve_xsavec): Likewise. --- sysdeps/x86_64/dl-machine.h | 38 ++++++++++---------------------------- 1 file changed, 10 insertions(+), 28 deletions(-) (limited to 'sysdeps/x86_64/dl-machine.h') diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index 6a04cbc..905a37a 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -66,12 +66,9 @@ static inline int __attribute__ ((unused, always_inline)) elf_machine_runtime_setup (struct link_map *l, int lazy, int profile) { Elf64_Addr *got; - extern void _dl_runtime_resolve_sse (ElfW(Word)) attribute_hidden; - extern void _dl_runtime_resolve_avx (ElfW(Word)) attribute_hidden; - extern void _dl_runtime_resolve_avx_slow (ElfW(Word)) attribute_hidden; - extern void _dl_runtime_resolve_avx_opt (ElfW(Word)) attribute_hidden; - extern void _dl_runtime_resolve_avx512 (ElfW(Word)) attribute_hidden; - extern void _dl_runtime_resolve_avx512_opt (ElfW(Word)) attribute_hidden; + extern void _dl_runtime_resolve_fxsave (ElfW(Word)) attribute_hidden; + extern void _dl_runtime_resolve_xsave (ElfW(Word)) attribute_hidden; + extern void _dl_runtime_resolve_xsavec (ElfW(Word)) attribute_hidden; extern void _dl_runtime_profile_sse (ElfW(Word)) attribute_hidden; extern void _dl_runtime_profile_avx (ElfW(Word)) attribute_hidden; extern void _dl_runtime_profile_avx512 (ElfW(Word)) attribute_hidden; @@ -120,29 +117,14 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile) /* This function will get called to fix up the GOT entry indicated by the offset on the stack, and then jump to the resolved address. */ - if (HAS_ARCH_FEATURE (AVX512F_Usable)) - { - if (HAS_ARCH_FEATURE (Use_dl_runtime_resolve_opt)) - *(ElfW(Addr) *) (got + 2) - = (ElfW(Addr)) &_dl_runtime_resolve_avx512_opt; - else - *(ElfW(Addr) *) (got + 2) - = (ElfW(Addr)) &_dl_runtime_resolve_avx512; - } - else if (HAS_ARCH_FEATURE (AVX_Usable)) - { - if (HAS_ARCH_FEATURE (Use_dl_runtime_resolve_opt)) - *(ElfW(Addr) *) (got + 2) - = (ElfW(Addr)) &_dl_runtime_resolve_avx_opt; - else if (HAS_ARCH_FEATURE (Use_dl_runtime_resolve_slow)) - *(ElfW(Addr) *) (got + 2) - = (ElfW(Addr)) &_dl_runtime_resolve_avx_slow; - else - *(ElfW(Addr) *) (got + 2) - = (ElfW(Addr)) &_dl_runtime_resolve_avx; - } + if (GLRO(dl_x86_cpu_features).xsave_state_size != 0) + *(ElfW(Addr) *) (got + 2) + = (HAS_ARCH_FEATURE (XSAVEC_Usable) + ? (ElfW(Addr)) &_dl_runtime_resolve_xsavec + : (ElfW(Addr)) &_dl_runtime_resolve_xsave); else - *(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_resolve_sse; + *(ElfW(Addr) *) (got + 2) + = (ElfW(Addr)) &_dl_runtime_resolve_fxsave; } } -- cgit v1.1