elf-fdpic.c

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/* elf-fdpic.c: ELF FDPIC memory layout management
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * 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() */