arch/x86/vdso/vdso-layout.lds.S

   1 #include <asm/vdso.h>
   2
   3 /*
   4  * Linker script for vDSO.  This is an ELF shared object prelinked to
   5  * its virtual address, and with only one read-only segment.
   6  * This script controls its layout.
   7  */
   8
   9 #if defined(BUILD_VDSO64)
  10 # define SHDR_SIZE 64
  11 #elif defined(BUILD_VDSO32) || defined(BUILD_VDSOX32)
  12 # define SHDR_SIZE 40
  13 #else
  14 # error unknown VDSO target
  15 #endif
  16
  17 #define NUM_FAKE_SHDRS 13
  18
  19 SECTIONS
  20 {
  21         /*
  22          * User/kernel shared data is before the vDSO.  This may be a little
  23          * uglier than putting it after the vDSO, but it avoids issues with
  24          * non-allocatable things that dangle past the end of the PT_LOAD
  25          * segment.
  26          */
  27
  28         vvar_start = . - 2 * PAGE_SIZE;
  29         vvar_page = vvar_start;
  30
  31         /* Place all vvars at the offsets in asm/vvar.h. */
  32 #define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
  33 #define __VVAR_KERNEL_LDS
  34 #include <asm/vvar.h>
  35 #undef __VVAR_KERNEL_LDS
  36 #undef EMIT_VVAR
  37
  38         hpet_page = vvar_start + PAGE_SIZE;
  39
  40         . = SIZEOF_HEADERS;
  41
  42         .hash           : { *(.hash) }                  :text
  43         .gnu.hash       : { *(.gnu.hash) }
  44         .dynsym         : { *(.dynsym) }
  45         .dynstr         : { *(.dynstr) }
  46         .gnu.version    : { *(.gnu.version) }
  47         .gnu.version_d  : { *(.gnu.version_d) }
  48         .gnu.version_r  : { *(.gnu.version_r) }
  49
  50         .dynamic        : { *(.dynamic) }               :text   :dynamic
  51
  52         .rodata         : {
  53                 *(.rodata*)
  54                 *(.data*)
  55                 *(.sdata*)
  56                 *(.got.plt) *(.got)
  57                 *(.gnu.linkonce.d.*)
  58                 *(.bss*)
  59                 *(.dynbss*)
  60                 *(.gnu.linkonce.b.*)
  61
  62                 /*
  63                  * Ideally this would live in a C file, but that won't
  64                  * work cleanly for x32 until we start building the x32
  65                  * C code using an x32 toolchain.
  66                  */
  67                 VDSO_FAKE_SECTION_TABLE_START = .;
  68                 . = . + NUM_FAKE_SHDRS * SHDR_SIZE;
  69                 VDSO_FAKE_SECTION_TABLE_END = .;
  70         }                                               :text
  71
  72         .fake_shstrtab  : { *(.fake_shstrtab) }         :text
  73
  74
  75         .note           : { *(.note.*) }                :text   :note
  76
  77         .eh_frame_hdr   : { *(.eh_frame_hdr) }          :text   :eh_frame_hdr
  78         .eh_frame       : { KEEP (*(.eh_frame)) }       :text
  79
  80
  81         /*
  82          * Text is well-separated from actual data: there's plenty of
  83          * stuff that isn't used at runtime in between.
  84          */
  85
  86         .text           : { *(.text*) }                 :text   =0x90909090,
  87
  88         /*
  89          * At the end so that eu-elflint stays happy when vdso2c strips
  90          * these.  A better implementation would avoid allocating space
  91          * for these.
  92          */
  93         .altinstructions        : { *(.altinstructions) }       :text
  94         .altinstr_replacement   : { *(.altinstr_replacement) }  :text
  95
  96         /DISCARD/ : {
  97                 *(.discard)
  98                 *(.discard.*)
  99                 *(__bug_table)
 100         }
 101 }
 102
 103 /*
 104  * Very old versions of ld do not recognize this name token; use the constant.
 105  */
 106 #define PT_GNU_EH_FRAME 0x6474e550
 107
 108 /*
 109  * We must supply the ELF program headers explicitly to get just one
 110  * PT_LOAD segment, and set the flags explicitly to make segments read-only.
 111  */
 112 PHDRS
 113 {
 114         text            PT_LOAD         FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
 115         dynamic         PT_DYNAMIC      FLAGS(4);               /* PF_R */
 116         note            PT_NOTE         FLAGS(4);               /* PF_R */
 117         eh_frame_hdr    PT_GNU_EH_FRAME;
 118 }