From: H.J. Lu Date: Thu, 9 Jul 2015 16:30:09 +0000 (-0700) Subject: Improve bndmov encoding with zero displacement X-Git-Tag: glibc-2.22~87 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2eb9ef29b698bb7706833236b4b9041f0c23ceef;p=thirdparty%2Fglibc.git 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. --- diff --git a/ChangeLog b/ChangeLog index f8765bb6b72..c48416b0e53 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2015-07-09 H.J. Lu + + * sysdeps/x86_64/dl-trampoline.S (_dl_runtime_resolve): Improve + bndmov encoding with zero displacement. + 2015-07-09 Igor Zamyatin H.J. Lu diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S index b151d3566da..678c57fc247 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.