arch/tile/mm/elf.c

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  */
  14
  15 #include <linux/mm.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/binfmts.h>
  18 #include <linux/compat.h>
  19 #include <linux/mman.h>
  20 #include <linux/elf.h>
  21 #include <asm/pgtable.h>
  22 #include <asm/pgalloc.h>
  23 #include <asm/sections.h>
  24
  25 /* Notify a running simulator, if any, that an exec just occurred. */
  26 static void sim_notify_exec(const char *binary_name)
  27 {
  28         unsigned char c;
  29         do {
  30                 c = *binary_name++;
  31                 __insn_mtspr(SPR_SIM_CONTROL,
  32                              (SIM_CONTROL_OS_EXEC
  33                               | (c << _SIM_CONTROL_OPERATOR_BITS)));
  34
  35         } while (c);
  36 }
  37
  38 static int notify_exec(void)
  39 {
  40         int retval = 0;  /* failure */
  41         struct vm_area_struct *vma = current->mm->mmap;
  42         while (vma) {
  43                 if ((vma->vm_flags & VM_EXECUTABLE) && vma->vm_file)
  44                         break;
  45                 vma = vma->vm_next;
  46         }
  47         if (vma) {
  48                 char *buf = (char *) __get_free_page(GFP_KERNEL);
  49                 if (buf) {
  50                         char *path = d_path(&vma->vm_file->f_path,
  51                                             buf, PAGE_SIZE);
  52                         if (!IS_ERR(path)) {
  53                                 sim_notify_exec(path);
  54                                 retval = 1;
  55                         }
  56                         free_page((unsigned long)buf);
  57                 }
  58         }
  59         return retval;
  60 }
  61
  62 /* Notify a running simulator, if any, that we loaded an interpreter. */
  63 static void sim_notify_interp(unsigned long load_addr)
  64 {
  65         size_t i;
  66         for (i = 0; i < sizeof(load_addr); i++) {
  67                 unsigned char c = load_addr >> (i * 8);
  68                 __insn_mtspr(SPR_SIM_CONTROL,
  69                              (SIM_CONTROL_OS_INTERP
  70                               | (c << _SIM_CONTROL_OPERATOR_BITS)));
  71         }
  72 }
  73
  74
  75 /* Kernel address of page used to map read-only kernel data into userspace. */
  76 static void *vdso_page;
  77
  78 /* One-entry array used for install_special_mapping. */
  79 static struct page *vdso_pages[1];
  80
  81 static int __init vdso_setup(void)
  82 {
  83         vdso_page = (void *)get_zeroed_page(GFP_ATOMIC);
  84         memcpy(vdso_page, __rt_sigreturn, __rt_sigreturn_end - __rt_sigreturn);
  85         vdso_pages[0] = virt_to_page(vdso_page);
  86         return 0;
  87 }
  88 device_initcall(vdso_setup);
  89
  90 const char *arch_vma_name(struct vm_area_struct *vma)
  91 {
  92         if (vma->vm_private_data == vdso_pages)
  93                 return "[vdso]";
  94 #ifndef __tilegx__
  95         if (vma->vm_start == MEM_USER_INTRPT)
  96                 return "[intrpt]";
  97 #endif
  98         return NULL;
  99 }
 100
 101 int arch_setup_additional_pages(struct linux_binprm *bprm,
 102                                 int executable_stack)
 103 {
 104         struct mm_struct *mm = current->mm;
 105         unsigned long vdso_base;
 106         int retval = 0;
 107
 108         /*
 109          * Notify the simulator that an exec just occurred.
 110          * If we can't find the filename of the mapping, just use
 111          * whatever was passed as the linux_binprm filename.
 112          */
 113         if (!notify_exec())
 114                 sim_notify_exec(bprm->filename);
 115
 116         down_write(&mm->mmap_sem);
 117
 118         /*
 119          * MAYWRITE to allow gdb to COW and set breakpoints
 120          *
 121          * Make sure the vDSO gets into every core dump.  Dumping its
 122          * contents makes post-mortem fully interpretable later
 123          * without matching up the same kernel and hardware config to
 124          * see what PC values meant.
 125          */
 126         vdso_base = VDSO_BASE;
 127         retval = install_special_mapping(mm, vdso_base, PAGE_SIZE,
 128                                          VM_READ|VM_EXEC|
 129                                          VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
 130                                          VM_ALWAYSDUMP,
 131                                          vdso_pages);
 132
 133 #ifndef __tilegx__
 134         /*
 135          * Set up a user-interrupt mapping here; the user can't
 136          * create one themselves since it is above TASK_SIZE.
 137          * We make it unwritable by default, so the model for adding
 138          * interrupt vectors always involves an mprotect.
 139          */
 140         if (!retval) {
 141                 unsigned long addr = MEM_USER_INTRPT;
 142                 addr = mmap_region(NULL, addr, INTRPT_SIZE,
 143                                    MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE,
 144                                    VM_READ|VM_EXEC|
 145                                    VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 0);
 146                 if (addr > (unsigned long) -PAGE_SIZE)
 147                         retval = (int) addr;
 148         }
 149 #endif
 150
 151         up_write(&mm->mmap_sem);
 152
 153         return retval;
 154 }
 155
 156
 157 void elf_plat_init(struct pt_regs *regs, unsigned long load_addr)
 158 {
 159         /* Zero all registers. */
 160         memset(regs, 0, sizeof(*regs));
 161
 162         /* Report the interpreter's load address. */
 163         sim_notify_interp(load_addr);
 164 }