linux_dsm_epyc7002/arch/x86/entry/vdso/vdso-layout.lds.S
H.J. Lu 4caffe6a28 x86/vdso: Discard .note.gnu.property sections in vDSO
With the command-line option -mx86-used-note=yes which can also be
enabled at binutils build time with:

  --enable-x86-used-note  generate GNU x86 used ISA and feature properties

the x86 assembler in binutils 2.32 and above generates a program property
note in a note section, .note.gnu.property, to encode used x86 ISAs and
features.  But kernel linker script only contains a single NOTE segment:

  PHDRS
  {
   text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
   dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
   note PT_NOTE FLAGS(4); /* PF_R */
   eh_frame_hdr 0x6474e550;
  }

The NOTE segment generated by the vDSO linker script is aligned to 4 bytes.
But the .note.gnu.property section must be aligned to 8 bytes on x86-64:

  [hjl@gnu-skx-1 vdso]$ readelf -n vdso64.so

  Displaying notes found in: .note
    Owner                Data size 	Description
    Linux                0x00000004	Unknown note type: (0x00000000)
     description data: 06 00 00 00
  readelf: Warning: note with invalid namesz and/or descsz found at offset 0x20
  readelf: Warning:  type: 0x78, namesize: 0x00000100, descsize: 0x756e694c, alignment: 8

Since the note.gnu.property section in the vDSO is not checked by the
dynamic linker, discard the .note.gnu.property sections in the vDSO.

 [ bp: Massage. ]

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200326174314.254662-1-hjl.tools@gmail.com
2020-03-27 15:53:05 +01:00

106 lines
2.5 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0 */
#include <asm/vdso.h>
/*
* Linker script for vDSO. This is an ELF shared object prelinked to
* its virtual address, and with only one read-only segment.
* This script controls its layout.
*/
SECTIONS
{
/*
* User/kernel shared data is before the vDSO. This may be a little
* uglier than putting it after the vDSO, but it avoids issues with
* non-allocatable things that dangle past the end of the PT_LOAD
* segment.
*/
vvar_start = . - 4 * PAGE_SIZE;
vvar_page = vvar_start;
/* Place all vvars at the offsets in asm/vvar.h. */
#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
#include <asm/vvar.h>
#undef EMIT_VVAR
pvclock_page = vvar_start + PAGE_SIZE;
hvclock_page = vvar_start + 2 * PAGE_SIZE;
timens_page = vvar_start + 3 * PAGE_SIZE;
#undef _ASM_X86_VVAR_H
/* Place all vvars in timens too at the offsets in asm/vvar.h. */
#define EMIT_VVAR(name, offset) timens_ ## name = timens_page + offset;
#include <asm/vvar.h>
#undef EMIT_VVAR
. = SIZEOF_HEADERS;
.hash : { *(.hash) } :text
.gnu.hash : { *(.gnu.hash) }
.dynsym : { *(.dynsym) }
.dynstr : { *(.dynstr) }
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
.dynamic : { *(.dynamic) } :text :dynamic
.rodata : {
*(.rodata*)
*(.data*)
*(.sdata*)
*(.got.plt) *(.got)
*(.gnu.linkonce.d.*)
*(.bss*)
*(.dynbss*)
*(.gnu.linkonce.b.*)
} :text
/*
* Discard .note.gnu.property sections which are unused and have
* different alignment requirement from vDSO note sections.
*/
/DISCARD/ : {
*(.note.gnu.property)
}
.note : { *(.note.*) } :text :note
.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
.eh_frame : { KEEP (*(.eh_frame)) } :text
/*
* Text is well-separated from actual data: there's plenty of
* stuff that isn't used at runtime in between.
*/
.text : { *(.text*) } :text =0x90909090,
.altinstructions : { *(.altinstructions) } :text
.altinstr_replacement : { *(.altinstr_replacement) } :text
/DISCARD/ : {
*(.discard)
*(.discard.*)
*(__bug_table)
}
}
/*
* Very old versions of ld do not recognize this name token; use the constant.
*/
#define PT_GNU_EH_FRAME 0x6474e550
/*
* We must supply the ELF program headers explicitly to get just one
* PT_LOAD segment, and set the flags explicitly to make segments read-only.
*/
PHDRS
{
text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
note PT_NOTE FLAGS(4); /* PF_R */
eh_frame_hdr PT_GNU_EH_FRAME;
}