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elf-fdpic.c

/* elf-fdpic.c: ELF FDPIC memory layout management
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/elf-fdpic.h>
#include <asm/mman.h>

/*****************************************************************************/
/*
 * lay out the userspace VM according to our grand design
 */
#ifdef CONFIG_MMU
void elf_fdpic_arch_lay_out_mm(struct elf_fdpic_params *exec_params,
                         struct elf_fdpic_params *interp_params,
                         unsigned long *start_stack,
                         unsigned long *start_brk)
{
      *start_stack = 0x02200000UL;

      /* if the only executable is a shared object, assume that it is an interpreter rather than
       * a true executable, and map it such that "ld.so --list" comes out right
       */
      if (!(interp_params->flags & ELF_FDPIC_FLAG_PRESENT) &&
          exec_params->hdr.e_type != ET_EXEC
          ) {
            exec_params->load_addr = PAGE_SIZE;

            *start_brk = 0x80000000UL;
      }
      else {
            exec_params->load_addr = 0x02200000UL;

            if ((exec_params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) ==
                ELF_FDPIC_FLAG_INDEPENDENT
                ) {
                  exec_params->flags &= ~ELF_FDPIC_FLAG_ARRANGEMENT;
                  exec_params->flags |= ELF_FDPIC_FLAG_CONSTDISP;
            }
      }

} /* end elf_fdpic_arch_lay_out_mm() */
#endif

/*****************************************************************************/
/*
 * place non-fixed mmaps firstly in the bottom part of memory, working up, and then in the top part
 * of memory, working down
 */
unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len,
                             unsigned long pgoff, unsigned long flags)
{
      struct vm_area_struct *vma;
      unsigned long limit;

      if (len > TASK_SIZE)
            return -ENOMEM;

      /* handle MAP_FIXED */
      if (flags & MAP_FIXED)
            return addr;

      /* only honour a hint if we're not going to clobber something doing so */
      if (addr) {
            addr = PAGE_ALIGN(addr);
            vma = find_vma(current->mm, addr);
            if (TASK_SIZE - len >= addr &&
                (!vma || addr + len <= vma->vm_start))
                  goto success;
      }

      /* search between the bottom of user VM and the stack grow area */
      addr = PAGE_SIZE;
      limit = (current->mm->start_stack - 0x00200000);
      if (addr + len <= limit) {
            limit -= len;

            if (addr <= limit) {
                  vma = find_vma(current->mm, PAGE_SIZE);
                  for (; vma; vma = vma->vm_next) {
                        if (addr > limit)
                              break;
                        if (addr + len <= vma->vm_start)
                              goto success;
                        addr = vma->vm_end;
                  }
            }
      }

      /* search from just above the WorkRAM area to the top of memory */
      addr = PAGE_ALIGN(0x80000000);
      limit = TASK_SIZE - len;
      if (addr <= limit) {
            vma = find_vma(current->mm, addr);
            for (; vma; vma = vma->vm_next) {
                  if (addr > limit)
                        break;
                  if (addr + len <= vma->vm_start)
                        goto success;
                  addr = vma->vm_end;
            }

            if (!vma && addr <= limit)
                  goto success;
      }

#if 0
      printk("[area] l=%lx (ENOMEM) f='%s'\n",
             len, filp ? filp->f_path.dentry->d_name.name : "");
#endif
      return -ENOMEM;

 success:
#if 0
      printk("[area] l=%lx ad=%lx f='%s'\n",
             len, addr, filp ? filp->f_path.dentry->d_name.name : "");
#endif
      return addr;
} /* end arch_get_unmapped_area() */

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