x86-64: Use fxsave/xsave/xsavec in _dl_runtime_resolve [BZ #21265]hjl/pr21265/2.24

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 <libc-internal.h>.
	(get_common_indeces): Set xsave_state_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-offsets.h>.
	(cpu_features): Add xsave_state_size.
	(index_arch_Use_dl_runtime_resolve_opt): Removed.
	(index_arch_Use_dl_runtime_resolve_slow): Likewise.
	(index_arch_XSAVEC_Usable): New.
	* 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.

(cherry picked from commit b52b0d793dcb226ecb0ecca1e672ca265973233c)

1 files changed, 10 insertions, 28 deletions

diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index c0f0fa16a2..8355432dfc 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;
 	}
     }