1/* elf-fdpic.c: ELF FDPIC memory layout management
  2 *
  3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
  4 * Written by David Howells (dhowells@redhat.com)
  5 *
  6 * This program is free software; you can redistribute it and/or
  7 * modify it under the terms of the GNU General Public License
  8 * as published by the Free Software Foundation; either version
  9 * 2 of the License, or (at your option) any later version.
 10 */
 11
 12#include <linux/sched.h>
 13#include <linux/mm.h>
 14#include <linux/fs.h>
 15#include <linux/elf-fdpic.h>
 16#include <asm/mman.h>
 17
 18/*****************************************************************************/
 19/*
 20 * lay out the userspace VM according to our grand design
 21 */
 22#ifdef CONFIG_MMU
 23void elf_fdpic_arch_lay_out_mm(struct elf_fdpic_params *exec_params,
 24			       struct elf_fdpic_params *interp_params,
 25			       unsigned long *start_stack,
 26			       unsigned long *start_brk)
 27{
 28	*start_stack = 0x02200000UL;
 29
 30	/* if the only executable is a shared object, assume that it is an interpreter rather than
 31	 * a true executable, and map it such that "ld.so --list" comes out right
 32	 */
 33	if (!(interp_params->flags & ELF_FDPIC_FLAG_PRESENT) &&
 34	    exec_params->hdr.e_type != ET_EXEC
 35	    ) {
 36		exec_params->load_addr = PAGE_SIZE;
 37
 38		*start_brk = 0x80000000UL;
 39	}
 40	else {
 41		exec_params->load_addr = 0x02200000UL;
 42
 43		if ((exec_params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) ==
 44		    ELF_FDPIC_FLAG_INDEPENDENT
 45		    ) {
 46			exec_params->flags &= ~ELF_FDPIC_FLAG_ARRANGEMENT;
 47			exec_params->flags |= ELF_FDPIC_FLAG_CONSTDISP;
 48		}
 49	}
 50
 51} /* end elf_fdpic_arch_lay_out_mm() */
 52#endif
 53
 54/*****************************************************************************/
 55/*
 56 * place non-fixed mmaps firstly in the bottom part of memory, working up, and then in the top part
 57 * of memory, working down
 58 */
 59unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len,
 60				     unsigned long pgoff, unsigned long flags)
 61{
 62	struct vm_area_struct *vma;
 63	unsigned long limit;
 64
 65	if (len > TASK_SIZE)
 66		return -ENOMEM;
 67
 68	/* handle MAP_FIXED */
 69	if (flags & MAP_FIXED)
 70		return addr;
 71
 72	/* only honour a hint if we're not going to clobber something doing so */
 73	if (addr) {
 74		addr = PAGE_ALIGN(addr);
 75		vma = find_vma(current->mm, addr);
 76		if (TASK_SIZE - len >= addr &&
 77		    (!vma || addr + len <= vma->vm_start))
 78			goto success;
 79	}
 80
 81	/* search between the bottom of user VM and the stack grow area */
 82	addr = PAGE_SIZE;
 83	limit = (current->mm->start_stack - 0x00200000);
 84	if (addr + len <= limit) {
 85		limit -= len;
 86
 87		if (addr <= limit) {
 88			vma = find_vma(current->mm, PAGE_SIZE);
 89			for (; vma; vma = vma->vm_next) {
 90				if (addr > limit)
 91					break;
 92				if (addr + len <= vma->vm_start)
 93					goto success;
 94				addr = vma->vm_end;
 95			}
 96		}
 97	}
 98
 99	/* search from just above the WorkRAM area to the top of memory */
100	addr = PAGE_ALIGN(0x80000000);
101	limit = TASK_SIZE - len;
102	if (addr <= limit) {
103		vma = find_vma(current->mm, addr);
104		for (; vma; vma = vma->vm_next) {
105			if (addr > limit)
106				break;
107			if (addr + len <= vma->vm_start)
108				goto success;
109			addr = vma->vm_end;
110		}
111
112		if (!vma && addr <= limit)
113			goto success;
114	}
115
116#if 0
117	printk("[area] l=%lx (ENOMEM) f='%s'\n",
118	       len, filp ? filp->f_path.dentry->d_name.name : "");
119#endif
120	return -ENOMEM;
121
122 success:
123#if 0
124	printk("[area] l=%lx ad=%lx f='%s'\n",
125	       len, addr, filp ? filp->f_path.dentry->d_name.name : "");
126#endif
127	return addr;
128} /* end arch_get_unmapped_area() */