From 88c6ca0bef20fa9fb71355fac3da526a138dd724 Mon Sep 17 00:00:00 2001
From: Igor Zamyatin <igor.zamyatin@intel.com>
Date: Tue, 1 Apr 2014 10:16:04 -0700
Subject: [PATCH] Save/restore bound registers in _dl_runtime_resolve
This patch saves and restores bound registers in symbol lookup for x86-64:
1. Branches without BND prefix clear bound registers.
2. x86-64 pass bounds in bound registers as specified in MPX psABI
extension on hjl/mpx/master branch at
https://github.com/hjl-tools/x86-64-psABI
https://groups.google.com/forum/#!topic/x86-64-abi/KFsB0XTgWYc
Binutils has been updated to create an alternate PLT to add BND prefix
when branching to ld.so.
* config.h.in (HAVE_MPX_SUPPORT): New #undef.
* sysdeps/x86_64/configure.ac: Set HAVE_MPX_SUPPORT.
* sysdeps/x86_64/configure: Regenerated.
* sysdeps/x86_64/dl-trampoline.S (REGISTER_SAVE_AREA): New
macro.
(_dl_runtime_resolve): Use it. Save and restore Intel MPX
bound registers when calling _dl_fixup.
---
ChangeLog | 11 +++++++++
config.h.in | 3 +++
sysdeps/x86_64/configure | 27 ++++++++++++++++++++++
sysdeps/x86_64/configure.ac | 15 +++++++++++++
sysdeps/x86_64/dl-trampoline.S | 51 +++++++++++++++++++++++++++++++++++++-----
5 files changed, 101 insertions(+), 6 deletions(-)
@@ -1,3 +1,14 @@
+2014-04-01 Igor Zamyatin <igor.zamyatin@intel.com>
+ H.J. Lu <hongjiu.lu@intel.com>
+
+ * config.h.in (HAVE_MPX_SUPPORT): New #undef.
+ * sysdeps/x86_64/configure.ac: Set HAVE_MPX_SUPPORT.
+ * sysdeps/x86_64/configure: Regenerated.
+ * sysdeps/x86_64/dl-trampoline.S (REGISTER_SAVE_AREA): New
+ macro.
+ (_dl_runtime_resolve): Use it. Save and restore Intel MPX
+ bound registers when calling _dl_fixup.
+
2014-04-01 Will Newton <will.newton@linaro.org>
* benchtests/Makefile (CFLAGS-bench-ffs.c): Add
@@ -104,6 +104,9 @@
/* Define if assembler supports AVX512. */
#undef HAVE_AVX512_ASM_SUPPORT
+/* Define if assembler supports Intel MPX. */
+#undef HAVE_MPX_SUPPORT
+
/* Define if gcc supports FMA4. */
#undef HAVE_FMA4_SUPPORT
@@ -222,6 +222,33 @@ $as_echo "$libc_cv_cc_novzeroupper" >&6; }
config_vars="$config_vars
config-cflags-novzeroupper = $libc_cv_cc_novzeroupper"
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for Intel MPX support" >&5
+$as_echo_n "checking for Intel MPX support... " >&6; }
+if ${libc_cv_asm_mpx+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ cat > conftest.s <<\EOF
+ bndmov %bnd0,(%rsp)
+EOF
+if { ac_try='${CC-cc} -c $ASFLAGS conftest.s 1>&5'
+ { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+ test $ac_status = 0; }; }; then
+ libc_cv_asm_mpx=yes
+else
+ libc_cv_asm_mpx=no
+fi
+rm -f conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_asm_mpx" >&5
+$as_echo "$libc_cv_asm_mpx" >&6; }
+if test $libc_cv_asm_mpx == yes; then
+ $as_echo "#define HAVE_MPX_SUPPORT 1" >>confdefs.h
+
+fi
+
$as_echo "#define PI_STATIC_AND_HIDDEN 1" >>confdefs.h
# work around problem with autoconf and empty lines at the end of files
@@ -75,6 +75,21 @@ LIBC_TRY_CC_OPTION([-mno-vzeroupper],
])
LIBC_CONFIG_VAR([config-cflags-novzeroupper], [$libc_cv_cc_novzeroupper])
+dnl Check whether asm supports Intel MPX
+AC_CACHE_CHECK(for Intel MPX support, libc_cv_asm_mpx, [dnl
+cat > conftest.s <<\EOF
+ bndmov %bnd0,(%rsp)
+EOF
+if AC_TRY_COMMAND(${CC-cc} -c $ASFLAGS conftest.s 1>&AS_MESSAGE_LOG_FD); then
+ libc_cv_asm_mpx=yes
+else
+ libc_cv_asm_mpx=no
+fi
+rm -f conftest*])
+if test $libc_cv_asm_mpx == yes; then
+ AC_DEFINE(HAVE_MPX_SUPPORT)
+fi
+
dnl It is always possible to access static and hidden symbols in an
dnl position independent way.
AC_DEFINE(PI_STATIC_AND_HIDDEN)
@@ -24,6 +24,16 @@
# error RTLD_SAVESPACE_SSE must be aligned to 32 bytes
#endif
+/* Area on stack to save and restore registers used for parameter
+ passing when calling _dl_fixup. */
+#ifdef __ILP32__
+/* X32 saves RCX, RDX, RSI, RDI, R8 and R9 plus RAX. */
+# define REGISTER_SAVE_AREA (8 * 7)
+#else
+/* X86-64 saves RCX, RDX, RSI, RDI, R8 and R9 plus RAX as well as BND0,
+ BND1, BND2, BND3. */
+# define REGISTER_SAVE_AREA (8 * 7 + 16 * 4)
+#endif
.text
.globl _dl_runtime_resolve
.type _dl_runtime_resolve, @function
@@ -31,8 +41,8 @@
cfi_startproc
_dl_runtime_resolve:
cfi_adjust_cfa_offset(16) # Incorporate PLT
- subq $56,%rsp
- cfi_adjust_cfa_offset(56)
+ subq $REGISTER_SAVE_AREA,%rsp
+ cfi_adjust_cfa_offset(REGISTER_SAVE_AREA)
movq %rax,(%rsp) # Preserve registers otherwise clobbered.
movq %rcx, 8(%rsp)
movq %rdx, 16(%rsp)
@@ -40,10 +50,38 @@ _dl_runtime_resolve:
movq %rdi, 32(%rsp)
movq %r8, 40(%rsp)
movq %r9, 48(%rsp)
- movq 64(%rsp), %rsi # Copy args pushed by PLT in register.
- movq 56(%rsp), %rdi # %rdi: link_map, %rsi: reloc_index
+#ifndef __ILP32__
+# ifdef HAVE_MPX_SUPPORT
+ bndmov %bnd0, 56(%rsp) # We also have to preserve bound registers.
+ bndmov %bnd1, 72(%rsp) # These are nops if Intel MPX isn't available
+ bndmov %bnd2, 88(%rsp) # or disabled.
+ bndmov %bnd3, 104(%rsp)
+# else
+ .byte 0x66,0x0f,0x1b,0x44,0x24,0x38
+ .byte 0x66,0x0f,0x1b,0x4c,0x24,0x48
+ .byte 0x66,0x0f,0x1b,0x54,0x24,0x58
+ .byte 0x66,0x0f,0x1b,0x5c,0x24,0x68
+# endif
+#endif
+ # Copy args pushed by PLT in register.
+ # %rdi: link_map, %rsi: reloc_index
+ movq (REGISTER_SAVE_AREA + 8)(%rsp), %rsi
+ movq REGISTER_SAVE_AREA(%rsp), %rdi
call _dl_fixup # Call resolver.
movq %rax, %r11 # Save return value
+#ifndef __ILP32__
+# ifdef HAVE_MPX_SUPPORT
+ bndmov 104(%rsp), %bnd3 # Restore bound registers back.
+ bndmov 88(%rsp), %bnd2 # These are nops if Intel MPX isn't avaiable
+ bndmov 72(%rsp), %bnd1 # or disabled.
+ bndmov 56(%rsp), %bnd0
+# else
+ .byte 0x66,0x0f,0x1a,0x5c,0x24,0x68
+ .byte 0x66,0x0f,0x1a,0x54,0x24,0x58
+ .byte 0x66,0x0f,0x1a,0x4c,0x24,0x48
+ .byte 0x66,0x0f,0x1a,0x44,0x24,0x38
+# endif
+#endif
movq 48(%rsp), %r9 # Get register content back.
movq 40(%rsp), %r8
movq 32(%rsp), %rdi
@@ -51,8 +89,9 @@ _dl_runtime_resolve:
movq 16(%rsp), %rdx
movq 8(%rsp), %rcx
movq (%rsp), %rax
- addq $72, %rsp # Adjust stack(PLT did 2 pushes)
- cfi_adjust_cfa_offset(-72)
+ # Adjust stack(PLT did 2 pushes)
+ addq $(REGISTER_SAVE_AREA + 16), %rsp
+ cfi_adjust_cfa_offset(-(REGISTER_SAVE_AREA + 16))
jmp *%r11 # Jump to function address.
cfi_endproc
.size _dl_runtime_resolve, .-_dl_runtime_resolve
--
1.8.5.3