[PATCH] elf: Remove Intel MPX support (lazy PLT, ld.so profile, and LD_AUDIT)
H.J. Lu
hjl.tools@gmail.com
Mon Oct 11 01:07:26 GMT 2021
On Sun, Oct 10, 2021 at 5:59 PM Fangrui Song <maskray@google.com> wrote:
>
> Intel MPX failed to gain wide adoption and has been deprecated for a
> while. GCC 9.1 removed Intel MPX support. Linux kernel removed MPX in
> 2019.
>
> This patch removes the support code from the dynamic loader.
> ---
> NEWS | 2 ++
> config.h.in | 3 --
> sysdeps/i386/configure | 27 -----------------
> sysdeps/i386/configure.ac | 15 ---------
> sysdeps/i386/dl-trampoline.S | 21 -------------
> sysdeps/i386/link-defines.sym | 2 --
> sysdeps/x86_64/configure | 27 -----------------
> sysdeps/x86_64/configure.ac | 15 ---------
> sysdeps/x86_64/dl-trampoline.S | 9 ------
> sysdeps/x86_64/dl-trampoline.h | 54 ---------------------------------
> sysdeps/x86_64/link-defines.sym | 3 --
> 11 files changed, 2 insertions(+), 176 deletions(-)
>
> diff --git a/NEWS b/NEWS
> index 2e3804e4d8..220d327071 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -61,6 +61,8 @@ Deprecated and removed features, and other changes affecting compatibility:
>
> when audit modules or dlmopen are used.
>
> +* Intel MPX support (lazy PLT, ld.so profile, and LD_AUDIT) has been removed.
> +
> Changes to build and runtime requirements:
>
> [Add changes to build and runtime requirements here]
> diff --git a/config.h.in b/config.h.in
> index 964873f27e..0a6f57b006 100644
> --- a/config.h.in
> +++ b/config.h.in
> @@ -84,9 +84,6 @@
> /* Define if assembler supports arch13 instructions on S390. */
> #undef HAVE_S390_ARCH13_ASM_SUPPORT
>
> -/* Define if assembler supports Intel MPX. */
> -#undef HAVE_MPX_SUPPORT
> -
> /* Define if the compiler\'s exception support is based on libunwind. */
> #undef HAVE_CC_WITH_LIBUNWIND
>
> diff --git a/sysdeps/i386/configure b/sysdeps/i386/configure
> index bb482ca16c..ed46d53314 100644
> --- a/sysdeps/i386/configure
> +++ b/sysdeps/i386/configure
> @@ -83,33 +83,6 @@ $as_echo "$libc_cv_ld_static_pie" >&6; }
> fi
> fi
>
> -{ $as_echo "$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 :
> - $as_echo_n "(cached) " >&6
> -else
> - cat > conftest.s <<\EOF
> - bndmov %bnd0,(%esp)
> -EOF
> -if { ac_try='${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
> -
> $as_echo "#define PI_STATIC_AND_HIDDEN 1" >>confdefs.h
>
>
> diff --git a/sysdeps/i386/configure.ac b/sysdeps/i386/configure.ac
> index 5e43eb0adf..a6a0672835 100644
> --- a/sysdeps/i386/configure.ac
> +++ b/sysdeps/i386/configure.ac
> @@ -53,21 +53,6 @@ rm -f conftest*])
> fi
> fi
>
> -dnl Check whether asm supports Intel MPX
> -AC_CACHE_CHECK(for Intel MPX support, libc_cv_asm_mpx, [dnl
> -cat > conftest.s <<\EOF
> - bndmov %bnd0,(%esp)
> -EOF
> -if AC_TRY_COMMAND(${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)
> diff --git a/sysdeps/i386/dl-trampoline.S b/sysdeps/i386/dl-trampoline.S
> index b5ec0326df..5669ab18f5 100644
> --- a/sysdeps/i386/dl-trampoline.S
> +++ b/sysdeps/i386/dl-trampoline.S
> @@ -19,12 +19,6 @@
> #include <sysdep.h>
> #include <link-defines.h>
>
> -#ifdef HAVE_MPX_SUPPORT
> -# define PRESERVE_BND_REGS_PREFIX bnd
> -#else
> -# define PRESERVE_BND_REGS_PREFIX .byte 0xf2
> -#endif
> -
> .text
> .globl _dl_runtime_resolve
> .type _dl_runtime_resolve, @function
> @@ -250,13 +244,6 @@ _dl_runtime_profile:
> movl %edx, LRV_EDX_OFFSET(%esp)
> fstpt LRV_ST0_OFFSET(%esp)
> fstpt LRV_ST1_OFFSET(%esp)
> -#ifdef HAVE_MPX_SUPPORT
> - bndmov %bnd0, LRV_BND0_OFFSET(%esp)
> - bndmov %bnd1, LRV_BND1_OFFSET(%esp)
> -#else
> - .byte 0x66,0x0f,0x1b,0x44,0x24,LRV_BND0_OFFSET
> - .byte 0x66,0x0f,0x1b,0x4c,0x24,LRV_BND1_OFFSET
> -#endif
> pushl %esp
> cfi_adjust_cfa_offset (4)
> # Address of La_i86_regs area.
> @@ -270,17 +257,9 @@ _dl_runtime_profile:
> movl LRV_EDX_OFFSET(%esp), %edx
> fldt LRV_ST1_OFFSET(%esp)
> fldt LRV_ST0_OFFSET(%esp)
> -#ifdef HAVE_MPX_SUPPORT
> - bndmov LRV_BND0_OFFSET(%esp), %bnd0
> - bndmov LRV_BND1_OFFSET(%esp), %bnd1
> -#else
> - .byte 0x66,0x0f,0x1a,0x44,0x24,LRV_BND0_OFFSET
> - .byte 0x66,0x0f,0x1a,0x4c,0x24,LRV_BND1_OFFSET
> -#endif
> # Restore stack before return.
> addl $(LRV_SIZE + 4 + LR_SIZE + 4), %esp
> cfi_adjust_cfa_offset (-(LRV_SIZE + 4 + LR_SIZE + 4))
> - PRESERVE_BND_REGS_PREFIX
> ret
> cfi_endproc
> .size _dl_runtime_profile, .-_dl_runtime_profile
> diff --git a/sysdeps/i386/link-defines.sym b/sysdeps/i386/link-defines.sym
> index 0995adb37f..a63dcb9218 100644
> --- a/sysdeps/i386/link-defines.sym
> +++ b/sysdeps/i386/link-defines.sym
> @@ -16,5 +16,3 @@ LRV_EAX_OFFSET offsetof (struct La_i86_retval, lrv_eax)
> LRV_EDX_OFFSET offsetof (struct La_i86_retval, lrv_edx)
> LRV_ST0_OFFSET offsetof (struct La_i86_retval, lrv_st0)
> LRV_ST1_OFFSET offsetof (struct La_i86_retval, lrv_st1)
> -LRV_BND0_OFFSET offsetof (struct La_i86_retval, lrv_bnd0)
> -LRV_BND1_OFFSET offsetof (struct La_i86_retval, lrv_bnd1)
> diff --git a/sysdeps/x86_64/configure b/sysdeps/x86_64/configure
> index 585279f83d..d4dd0aa7df 100755
> --- a/sysdeps/x86_64/configure
> +++ b/sysdeps/x86_64/configure
> @@ -23,33 +23,6 @@ $as_echo "$libc_cv_cc_mprefer_vector_width" >&6; }
> config_vars="$config_vars
> config-cflags-mprefer-vector-width = $libc_cv_cc_mprefer_vector_width"
>
> -{ $as_echo "$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
> - $as_echo "#define HAVE_MPX_SUPPORT 1" >>confdefs.h
> -
> -fi
> -
> if test x"$build_mathvec" = xnotset; then
> build_mathvec=yes
> fi
> diff --git a/sysdeps/x86_64/configure.ac b/sysdeps/x86_64/configure.ac
> index 29e14033c0..c4c748c1d0 100644
> --- a/sysdeps/x86_64/configure.ac
> +++ b/sysdeps/x86_64/configure.ac
> @@ -10,21 +10,6 @@ LIBC_TRY_CC_OPTION([-mprefer-vector-width=128],
> LIBC_CONFIG_VAR([config-cflags-mprefer-vector-width],
> [$libc_cv_cc_mprefer_vector_width])
>
> -dnl Check whether asm supports Intel MPX
> -AC_CACHE_CHECK(for Intel MPX support, libc_cv_asm_mpx, [dnl
> -cat > conftest.s <<\EOF
> - bndmov %bnd0,(%rsp)
> -EOF
> -if AC_TRY_COMMAND(${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 $libc_cv_asm_mpx = yes; then
> - AC_DEFINE(HAVE_MPX_SUPPORT)
> -fi
> -
> if test x"$build_mathvec" = xnotset; then
> build_mathvec=yes
> fi
> diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
> index 90b2a6ce56..fa71330be2 100644
> --- a/sysdeps/x86_64/dl-trampoline.S
> +++ b/sysdeps/x86_64/dl-trampoline.S
> @@ -42,15 +42,6 @@
>
> /* Area on stack to save and restore registers used for parameter
> passing when calling _dl_fixup. */
> -#ifdef __ILP32__
> -# define PRESERVE_BND_REGS_PREFIX
> -#else
> -# ifdef HAVE_MPX_SUPPORT
> -# define PRESERVE_BND_REGS_PREFIX bnd
> -# else
> -# define PRESERVE_BND_REGS_PREFIX .byte 0xf2
> -# endif
> -#endif
> #define REGISTER_SAVE_RAX 0
> #define REGISTER_SAVE_RCX (REGISTER_SAVE_RAX + 8)
> #define REGISTER_SAVE_RDX (REGISTER_SAVE_RCX + 8)
> diff --git a/sysdeps/x86_64/dl-trampoline.h b/sysdeps/x86_64/dl-trampoline.h
> index b9a12970cd..dfbfefbd4a 100644
> --- a/sysdeps/x86_64/dl-trampoline.h
> +++ b/sysdeps/x86_64/dl-trampoline.h
> @@ -149,8 +149,6 @@ _dl_runtime_resolve:
> # Adjust stack(PLT did 2 pushes)
> add $(LOCAL_STORAGE_AREA + 16), %RSP_LP
> cfi_adjust_cfa_offset(-(LOCAL_STORAGE_AREA + 16))
> - # Preserve bound registers.
> - PRESERVE_BND_REGS_PREFIX
> jmp *%r11 # Jump to function address.
> cfi_endproc
> .size _dl_runtime_resolve, .-_dl_runtime_resolve
> @@ -230,20 +228,6 @@ _dl_runtime_profile:
> movaps %xmm6, (LR_XMM_OFFSET + XMM_SIZE*6)(%rsp)
> movaps %xmm7, (LR_XMM_OFFSET + XMM_SIZE*7)(%rsp)
>
> -# ifndef __ILP32__
> -# ifdef HAVE_MPX_SUPPORT
> - bndmov %bnd0, (LR_BND_OFFSET)(%rsp) # Preserve bound
> - bndmov %bnd1, (LR_BND_OFFSET + BND_SIZE)(%rsp) # registers. Nops if
> - bndmov %bnd2, (LR_BND_OFFSET + BND_SIZE*2)(%rsp) # MPX not available
> - bndmov %bnd3, (LR_BND_OFFSET + BND_SIZE*3)(%rsp) # or disabled.
> -# else
> - .byte 0x66,0x0f,0x1b,0x84,0x24;.long (LR_BND_OFFSET)
> - .byte 0x66,0x0f,0x1b,0x8c,0x24;.long (LR_BND_OFFSET + BND_SIZE)
> - .byte 0x66,0x0f,0x1b,0x94,0x24;.long (LR_BND_OFFSET + BND_SIZE*2)
> - .byte 0x66,0x0f,0x1b,0x9c,0x24;.long (LR_BND_OFFSET + BND_SIZE*3)
> -# endif
> -# endif
> -
> # ifdef RESTORE_AVX
> /* This is to support AVX audit modules. */
> VMOVA %VEC(0), (LR_VECTOR_OFFSET)(%rsp)
> @@ -366,25 +350,10 @@ _dl_runtime_profile:
> vmovdqa %xmm7, (LR_XMM_OFFSET + XMM_SIZE*7)(%rsp)
>
> 1:
> -# endif
> -
> -# ifndef __ILP32__
> -# ifdef HAVE_MPX_SUPPORT
> - bndmov (LR_BND_OFFSET)(%rsp), %bnd0 # Restore bound
> - bndmov (LR_BND_OFFSET + BND_SIZE)(%rsp), %bnd1 # registers.
> - bndmov (LR_BND_OFFSET + BND_SIZE*2)(%rsp), %bnd2
> - bndmov (LR_BND_OFFSET + BND_SIZE*3)(%rsp), %bnd3
> -# else
> - .byte 0x66,0x0f,0x1a,0x84,0x24;.long (LR_BND_OFFSET)
> - .byte 0x66,0x0f,0x1a,0x8c,0x24;.long (LR_BND_OFFSET + BND_SIZE)
> - .byte 0x66,0x0f,0x1a,0x94,0x24;.long (LR_BND_OFFSET + BND_SIZE*2)
> - .byte 0x66,0x0f,0x1a,0x9c,0x24;.long (LR_BND_OFFSET + BND_SIZE*3)
> -# endif
> # endif
>
> mov 16(%rbx), %R10_LP # Anything in framesize?
> test %R10_LP, %R10_LP
> - PRESERVE_BND_REGS_PREFIX
> jns 3f
>
> /* There's nothing in the frame size, so there
> @@ -403,7 +372,6 @@ _dl_runtime_profile:
> add $48, %RSP_LP # Adjust the stack to the return value
> # (eats the reloc index and link_map)
> cfi_adjust_cfa_offset(-48)
> - PRESERVE_BND_REGS_PREFIX
> jmp *%r11 # Jump to function address.
>
> 3:
> @@ -430,7 +398,6 @@ _dl_runtime_profile:
> movq 32(%rdi), %rsi
> movq 40(%rdi), %rdi
>
> - PRESERVE_BND_REGS_PREFIX
> call *%r11
>
> mov 24(%rbx), %RSP_LP # Drop the copied stack content
> @@ -475,16 +442,6 @@ _dl_runtime_profile:
> vmovdqa %xmm1, (LRV_SIZE + XMM_SIZE)(%rcx)
> # endif
>
> -# ifndef __ILP32__
> -# ifdef HAVE_MPX_SUPPORT
> - bndmov %bnd0, LRV_BND0_OFFSET(%rcx) # Preserve returned bounds.
> - bndmov %bnd1, LRV_BND1_OFFSET(%rcx)
> -# else
> - .byte 0x66,0x0f,0x1b,0x81;.long (LRV_BND0_OFFSET)
> - .byte 0x66,0x0f,0x1b,0x89;.long (LRV_BND1_OFFSET)
> -# endif
> -# endif
> -
> fstpt LRV_ST0_OFFSET(%rcx)
> fstpt LRV_ST1_OFFSET(%rcx)
>
> @@ -515,16 +472,6 @@ _dl_runtime_profile:
> VMOVA LRV_VECTOR1_OFFSET(%rsp), %VEC(1)
>
> 1:
> -# endif
> -
> -# ifndef __ILP32__
> -# ifdef HAVE_MPX_SUPPORT
> - bndmov LRV_BND0_OFFSET(%rsp), %bnd0 # Restore bound registers.
> - bndmov LRV_BND1_OFFSET(%rsp), %bnd1
> -# else
> - .byte 0x66,0x0f,0x1a,0x84,0x24;.long (LRV_BND0_OFFSET)
> - .byte 0x66,0x0f,0x1a,0x8c,0x24;.long (LRV_BND1_OFFSET)
> -# endif
> # endif
>
> fldt LRV_ST1_OFFSET(%rsp)
> @@ -538,7 +485,6 @@ _dl_runtime_profile:
> add $48, %RSP_LP # Adjust the stack to the return value
> # (eats the reloc index and link_map)
> cfi_adjust_cfa_offset(-48)
> - PRESERVE_BND_REGS_PREFIX
> retq
>
> cfi_endproc
> diff --git a/sysdeps/x86_64/link-defines.sym b/sysdeps/x86_64/link-defines.sym
> index 963c69b320..eb9431f101 100644
> --- a/sysdeps/x86_64/link-defines.sym
> +++ b/sysdeps/x86_64/link-defines.sym
> @@ -19,9 +19,6 @@ LR_RBP_OFFSET offsetof (struct La_x86_64_regs, lr_rbp)
> LR_RSP_OFFSET offsetof (struct La_x86_64_regs, lr_rsp)
> LR_XMM_OFFSET offsetof (struct La_x86_64_regs, lr_xmm)
> LR_VECTOR_OFFSET offsetof (struct La_x86_64_regs, lr_vector)
> -#ifndef __ILP32__
> -LR_BND_OFFSET offsetof (struct La_x86_64_regs, lr_bnd)
> -#endif
>
> LRV_SIZE sizeof (struct La_x86_64_retval)
> LRV_RAX_OFFSET offsetof (struct La_x86_64_retval, lrv_rax)
> --
> 2.33.0.882.g93a45727a2-goog
>
LGTM.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Thanks.
--
H.J.
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