From fdd3aa0b19700ab564da895a2a85bf3fdb0bedf0 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Thu, 9 Jul 2015 09:30:09 -0700 Subject: Improve bndmov encoding with zero displacement If x86-64 assembler doesn't support MPX, we encode bndmov instruction by hand. When displacement is zero, assembler generates shorter encoding. This patch improves bndmov encoding with zero displacement so that ld.so is identical when using assemblers with and without MPX support. * sysdeps/x86_64/dl-trampoline.S (_dl_runtime_resolve): Improve bndmov encoding with zero displacement. --- sysdeps/x86_64/dl-trampoline.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S index b151d3566d..678c57fc24 100644 --- a/sysdeps/x86_64/dl-trampoline.S +++ b/sysdeps/x86_64/dl-trampoline.S @@ -80,7 +80,11 @@ _dl_runtime_resolve: bndmov %bnd2, REGISTER_SAVE_BND2(%rsp) bndmov %bnd3, REGISTER_SAVE_BND3(%rsp) # else +# if REGISTER_SAVE_BND0 == 0 + .byte 0x66,0x0f,0x1b,0x04,0x24 +# else .byte 0x66,0x0f,0x1b,0x44,0x24,REGISTER_SAVE_BND0 +# endif .byte 0x66,0x0f,0x1b,0x4c,0x24,REGISTER_SAVE_BND1 .byte 0x66,0x0f,0x1b,0x54,0x24,REGISTER_SAVE_BND2 .byte 0x66,0x0f,0x1b,0x5c,0x24,REGISTER_SAVE_BND3 @@ -104,7 +108,11 @@ _dl_runtime_resolve: .byte 0x66,0x0f,0x1a,0x5c,0x24,REGISTER_SAVE_BND3 .byte 0x66,0x0f,0x1a,0x54,0x24,REGISTER_SAVE_BND2 .byte 0x66,0x0f,0x1a,0x4c,0x24,REGISTER_SAVE_BND1 +# if REGISTER_SAVE_BND0 == 0 + .byte 0x66,0x0f,0x1a,0x04,0x24 +# else .byte 0x66,0x0f,0x1a,0x44,0x24,REGISTER_SAVE_BND0 +# endif # endif #endif # Get register content back. -- cgit 1.4.1