Revert 98909 - Use chain-loading for Linux nacl_helper

chrome/nacl/nacl_helper_bootstrap_linux.x

Index: chrome/nacl/nacl_helper_bootstrap_linux.x
===================================================================
--- chrome/nacl/nacl_helper_bootstrap_linux.x	(revision 98909)
+++ chrome/nacl/nacl_helper_bootstrap_linux.x	(working copy)
@@ -1,93 +0,0 @@
-/* Copyright (c) 2011 The Chromium Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- *
- * This is a custom linker script used to build nacl_helper_bootstrap.
- * It has a very special layout.  This script will only work with input
- * that is kept extremely minimal.  If there are unexpected input sections
- * not named here, the result will not be correct.
- *
- * We need to use a standalone loader program rather than just using a
- * dynamically-linked program here because its entire address space will be
- * taken over for the NaCl untrusted address space.  A normal program would
- * cause dynamic linker data structures to point to its .dynamic section,
- * which is no longer available after startup.
- *
- * We need this special layout (and the nacl_helper_bootstrap_munge_phdr
- * step) because simply having bss space large enough to reserve the
- * address space would cause the kernel loader to think we're using that
- * much anonymous memory and refuse to execute the program on a machine
- * with not much memory available.
- */
-
-/*
- * Set the entry point to the symbol called _start, which we define in assembly.
- */
-ENTRY(_start)
-
-/*
- * This is the address where the program text starts.
- * We set this as low as we think we can get away with.
- * The common settings for sysctl vm.mmap_min_addr range from 4k to 64k.
- */
-TEXT_START = 0x10000;
-
-/*
- * This is the top of the range we are trying to reserve, which is 1G
- * for x86-32 and ARM.  For an x86-64 zero-based sandbox, this really
- * needs to be 36G.
- */
-RESERVE_TOP = 1 << 30;
-
-/*
- * We specify the program headers we want explicitly, to get the layout
- * exactly right and to give the "reserve" segment p_flags of zero, so
- * that it gets mapped as PROT_NONE.
- */
-PHDRS {
-  text PT_LOAD FILEHDR PHDRS;
-  reserve PT_LOAD FLAGS(0);
-  stack PT_GNU_STACK FLAGS(6);	/* RW, no E */
-}
-
-/*
- * Now we lay out the sections across those segments.
- */
-SECTIONS {
-  /*
-   * Here is the program itself.
-   */
-  .text TEXT_START + SIZEOF_HEADERS : {
-    *(.note.gnu.build-id)
-    *(.text*)
-    *(.rodata*)
-    *(.eh_frame*)
-  } :text
-  etext = .;
-
-  /*
-   * Now we move up to the next p_align increment, and place the dummy
-   * segment there.  The linker emits this segment with the p_vaddr and
-   * p_memsz we want, which reserves the address space.  But the linker
-   * gives it a p_filesz of zero.  We have to edit the phdr after link
-   * time to give it a p_filesz matching its p_memsz.  That way, the
-   * kernel doesn't think we are preallocating a huge amount of memory.
-   * It just maps it from the file, i.e. way off the end of the file,
-   * which is perfect for reserving the address space.
-   */
-  . = ALIGN(CONSTANT(COMMONPAGESIZE));
-  RESERVE_START = .;
-  .reserve : {
-    . = RESERVE_TOP - RESERVE_START;
-  } :reserve
-
-  /*
-   * These are empty input sections the linker generates.
-   * If we don't discard them, they pollute the flags in the output segment.
-   */
-  /DISCARD/ : {
-    *(.iplt)
-    *(.rel*)
-    *(.igot.plt)
-  }
-}