/* linux.c - boot Linux zImage or bzImage */
/*
 *  VAS_EBOOT  --  GRand Unified Bootloader
 *  Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2007,2008,2009,2010  Free Software Foundation, Inc.
 *
 *  VAS_EBOOT 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  VAS_EBOOT is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with VAS_EBOOT.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <VasEBoot/loader.h>
#include <VasEBoot/file.h>
#include <VasEBoot/err.h>
#include <VasEBoot/device.h>
#include <VasEBoot/disk.h>
#include <VasEBoot/misc.h>
#include <VasEBoot/types.h>
#include <VasEBoot/memory.h>
#include <VasEBoot/dl.h>
#include <VasEBoot/cpu/linux.h>
#include <VasEBoot/command.h>
#include <VasEBoot/i18n.h>
#include <VasEBoot/mm.h>
#include <VasEBoot/cpu/relocator.h>
#include <VasEBoot/video.h>
#include <VasEBoot/i386/floppy.h>
#include <VasEBoot/lib/cmdline.h>
#include <VasEBoot/linux.h>
#include <VasEBoot/safemath.h>

VAS_EBOOT_MOD_LICENSE ("GPLv3+");

#define VAS_EBOOT_LINUX_CL_OFFSET		0x9000

static VasEBoot_dl_t my_mod;

static VasEBoot_size_t linux_mem_size;
static int loaded;
static struct VasEBoot_relocator *relocator = NULL;
static VasEBoot_addr_t VasEBoot_linux_real_target;
static char *VasEBoot_linux_real_chunk;
static VasEBoot_size_t VasEBoot_linux16_prot_size;
static VasEBoot_size_t maximal_cmdline_size;

static VasEBoot_err_t
VasEBoot_linux16_boot (void)
{
  VasEBoot_uint16_t segment;
  struct VasEBoot_relocator16_state state = {0};

  segment = VasEBoot_linux_real_target >> 4;
  state.gs = state.fs = state.es = state.ds = state.ss = segment;
  state.sp = VAS_EBOOT_LINUX_SETUP_STACK;
  state.cs = segment + 0x20;
  state.ip = 0;
  state.a20 = 1;

  VasEBoot_video_set_mode ("text", 0, 0);

  VasEBoot_stop_floppy ();

  return VasEBoot_relocator16_boot (relocator, state);
}

static VasEBoot_err_t
VasEBoot_linux_unload (void)
{
  VasEBoot_dl_unref (my_mod);
  loaded = 0;
  VasEBoot_relocator_unload (relocator);
  relocator = NULL;
  return VAS_EBOOT_ERR_NONE;
}

static int
target_hook (VasEBoot_uint64_t addr, VasEBoot_uint64_t size, VasEBoot_memory_type_t type,
	    void *data)
{
  VasEBoot_uint64_t *result = data;
  VasEBoot_uint64_t candidate;

  if (type != VAS_EBOOT_MEMORY_AVAILABLE)
    return 0;
  if (addr >= 0xa0000)
    return 0;
  if (addr + size >= 0xa0000)
    size = 0xa0000 - addr;

  /* Put the real mode part at as a high location as possible.  */
  candidate = addr + size - (VAS_EBOOT_LINUX_CL_OFFSET + maximal_cmdline_size);
  /* But it must not exceed the traditional area.  */
  if (candidate > VAS_EBOOT_LINUX_OLD_REAL_MODE_ADDR)
    candidate = VAS_EBOOT_LINUX_OLD_REAL_MODE_ADDR;
  if (candidate < addr)
    return 0;

  if (candidate > *result || *result == (VasEBoot_uint64_t) -1)
    *result = candidate;
  return 0;
}

static VasEBoot_addr_t
VasEBoot_find_real_target (void)
{
  VasEBoot_uint64_t result = (VasEBoot_uint64_t) -1;

  VasEBoot_mmap_iterate (target_hook, &result);
  return result;
}

static VasEBoot_err_t
VasEBoot_cmd_linux (VasEBoot_command_t cmd __attribute__ ((unused)),
		int argc, char *argv[])
{
  VasEBoot_file_t file = 0;
  struct linux_i386_kernel_header lh;
  VasEBoot_uint8_t setup_sects;
  VasEBoot_size_t real_size;
  VasEBoot_ssize_t len;
  int i;
  char *VasEBoot_linux_prot_chunk;
  int VasEBoot_linux_is_bzimage;
  VasEBoot_addr_t VasEBoot_linux_prot_target;
  VasEBoot_err_t err;

  VasEBoot_dl_ref (my_mod);

  if (argc == 0)
    {
      VasEBoot_error (VAS_EBOOT_ERR_BAD_ARGUMENT, N_("filename expected"));
      goto fail;
    }

  file = VasEBoot_file_open (argv[0], VAS_EBOOT_FILE_TYPE_LINUX_KERNEL);
  if (! file)
    goto fail;

  if (VasEBoot_file_read (file, &lh, sizeof (lh)) != sizeof (lh))
    {
      if (!VasEBoot_errno)
	VasEBoot_error (VAS_EBOOT_ERR_BAD_OS, N_("premature end of file %s"),
		    argv[0]);
      goto fail;
    }

  if (lh.boot_flag != VasEBoot_cpu_to_le16_compile_time (0xaa55))
    {
      VasEBoot_error (VAS_EBOOT_ERR_BAD_OS, "invalid magic number");
      goto fail;
    }

  if (lh.setup_sects > VAS_EBOOT_LINUX_MAX_SETUP_SECTS)
    {
      VasEBoot_error (VAS_EBOOT_ERR_BAD_OS, "too many setup sectors");
      goto fail;
    }

  VasEBoot_linux_is_bzimage = 0;
  setup_sects = lh.setup_sects;
  linux_mem_size = 0;

  maximal_cmdline_size = 256;

  if (lh.header == VasEBoot_cpu_to_le32_compile_time (VAS_EBOOT_LINUX_I386_MAGIC_SIGNATURE)
      && VasEBoot_le_to_cpu16 (lh.version) >= 0x0200)
    {
      VasEBoot_linux_is_bzimage = (lh.loadflags & VAS_EBOOT_LINUX_FLAG_BIG_KERNEL);
      lh.type_of_loader = VAS_EBOOT_LINUX_BOOT_LOADER_TYPE;

      if (VasEBoot_le_to_cpu16 (lh.version) >= 0x0206)
	maximal_cmdline_size = VasEBoot_le_to_cpu32 (lh.cmdline_size) + 1;

      VasEBoot_linux_real_target = VasEBoot_find_real_target ();
      if (VasEBoot_linux_real_target == (VasEBoot_addr_t)-1)
	{
	  VasEBoot_error (VAS_EBOOT_ERR_OUT_OF_RANGE,
		      "no appropriate low memory found");
	  goto fail;
	}

      if (VasEBoot_le_to_cpu16 (lh.version) >= 0x0201)
	{
	  lh.heap_end_ptr = VasEBoot_cpu_to_le16_compile_time (VAS_EBOOT_LINUX_HEAP_END_OFFSET);
	  lh.loadflags |= VAS_EBOOT_LINUX_FLAG_CAN_USE_HEAP;
	}

      if (VasEBoot_le_to_cpu16 (lh.version) >= 0x0202)
	lh.cmd_line_ptr = VasEBoot_linux_real_target + VAS_EBOOT_LINUX_CL_OFFSET;
      else
	{
	  lh.cl_magic = VasEBoot_cpu_to_le16_compile_time (VAS_EBOOT_LINUX_CL_MAGIC);
	  lh.cl_offset = VasEBoot_cpu_to_le16_compile_time (VAS_EBOOT_LINUX_CL_OFFSET);
	  lh.setup_move_size = VasEBoot_cpu_to_le16_compile_time (VAS_EBOOT_LINUX_CL_OFFSET
						 + maximal_cmdline_size);
	}
    }
  else
    {
      /* Your kernel is quite old...  */
      lh.cl_magic = VasEBoot_cpu_to_le16_compile_time (VAS_EBOOT_LINUX_CL_MAGIC);
      lh.cl_offset = VasEBoot_cpu_to_le16_compile_time (VAS_EBOOT_LINUX_CL_OFFSET);

      setup_sects = VAS_EBOOT_LINUX_DEFAULT_SETUP_SECTS;

      VasEBoot_linux_real_target = VAS_EBOOT_LINUX_OLD_REAL_MODE_ADDR;
    }

  /* If SETUP_SECTS is not set, set it to the default (4).  */
  if (! setup_sects)
    setup_sects = VAS_EBOOT_LINUX_DEFAULT_SETUP_SECTS;

  real_size = setup_sects << VAS_EBOOT_DISK_SECTOR_BITS;
  if (VasEBoot_sub (VasEBoot_file_size (file), real_size, &VasEBoot_linux16_prot_size) ||
      VasEBoot_sub (VasEBoot_linux16_prot_size, VAS_EBOOT_DISK_SECTOR_SIZE, &VasEBoot_linux16_prot_size))
    {
      VasEBoot_error (VAS_EBOOT_ERR_OUT_OF_RANGE, N_("overflow is detected"));
      goto fail;
    }

  if (! VasEBoot_linux_is_bzimage
      && VAS_EBOOT_LINUX_ZIMAGE_ADDR + VasEBoot_linux16_prot_size
      > VasEBoot_linux_real_target)
    {
      VasEBoot_error (VAS_EBOOT_ERR_BAD_OS, "too big zImage (0x%" PRIxVAS_EBOOT_SIZE
		  " > 0x%" PRIxVAS_EBOOT_ADDR "), use bzImage instead",
		  VAS_EBOOT_LINUX_ZIMAGE_ADDR + VasEBoot_linux16_prot_size,
		  VasEBoot_linux_real_target);
      goto fail;
    }

  VasEBoot_dprintf ("linux", "[Linux-%s, setup=0x%x, size=0x%x]\n",
		VasEBoot_linux_is_bzimage ? "bzImage" : "zImage",
		(unsigned) real_size,
		(unsigned) VasEBoot_linux16_prot_size);

  for (i = 1; i < argc; i++)
    if (VasEBoot_memcmp (argv[i], "vga=", 4) == 0)
      {
	/* Video mode selection support.  */
	VasEBoot_uint16_t vid_mode;
	char *val = argv[i] + 4;

	if (VasEBoot_strcmp (val, "normal") == 0)
	  vid_mode = VAS_EBOOT_LINUX_VID_MODE_NORMAL;
	else if (VasEBoot_strcmp (val, "ext") == 0)
	  vid_mode = VAS_EBOOT_LINUX_VID_MODE_EXTENDED;
	else if (VasEBoot_strcmp (val, "ask") == 0)
	  vid_mode = VAS_EBOOT_LINUX_VID_MODE_ASK;
	else
	  vid_mode = (VasEBoot_uint16_t) VasEBoot_strtoul (val, 0, 0);

	if (VasEBoot_errno)
	  goto fail;

	lh.vid_mode = VasEBoot_cpu_to_le16 (vid_mode);
      }
    else if (VasEBoot_memcmp (argv[i], "mem=", 4) == 0)
      {
	const char *val = argv[i] + 4;

	linux_mem_size = VasEBoot_strtoul (val, &val, 0);

	if (VasEBoot_errno)
	  {
	    VasEBoot_errno = VAS_EBOOT_ERR_NONE;
	    linux_mem_size = 0;
	  }
	else
	  {
	    int shift = 0;

	    switch (VasEBoot_tolower (val[0]))
	      {
	      case 'g':
		shift += 10;
		/* Fallthrough.  */
	      case 'm':
		shift += 10;
		/* Fallthrough.  */
	      case 'k':
		shift += 10;
		/* Fallthrough.  */
	      default:
		break;
	      }

	    /* Check an overflow.  */
	    if (linux_mem_size > (~0UL >> shift))
	      linux_mem_size = 0;
	    else
	      linux_mem_size <<= shift;
	  }
      }

  relocator = VasEBoot_relocator_new ();
  if (!relocator)
    goto fail;

  {
    VasEBoot_relocator_chunk_t ch;
    err = VasEBoot_relocator_alloc_chunk_addr (relocator, &ch,
					   VasEBoot_linux_real_target,
					   VAS_EBOOT_LINUX_CL_OFFSET
					   + maximal_cmdline_size);
    if (err)
      return err;
    VasEBoot_linux_real_chunk = get_virtual_current_address (ch);
  }

  /* Put the real mode code at the temporary address.  */
  VasEBoot_memmove (VasEBoot_linux_real_chunk, &lh, sizeof (lh));

  len = real_size + VAS_EBOOT_DISK_SECTOR_SIZE - sizeof (lh);
  if (VasEBoot_file_read (file, VasEBoot_linux_real_chunk + sizeof (lh), len) != len)
    {
      if (!VasEBoot_errno)
	VasEBoot_error (VAS_EBOOT_ERR_BAD_OS, N_("premature end of file %s"),
		    argv[0]);
      goto fail;
    }

  if (lh.header != VasEBoot_cpu_to_le32_compile_time (VAS_EBOOT_LINUX_I386_MAGIC_SIGNATURE)
      || VasEBoot_le_to_cpu16 (lh.version) < 0x0200)
    /* Clear the heap space.  */
    VasEBoot_memset (VasEBoot_linux_real_chunk
		 + ((setup_sects + 1) << VAS_EBOOT_DISK_SECTOR_BITS),
		 0,
		 ((VAS_EBOOT_LINUX_MAX_SETUP_SECTS - setup_sects - 1)
		  << VAS_EBOOT_DISK_SECTOR_BITS));

  /* Create kernel command line.  */
  VasEBoot_memcpy ((char *)VasEBoot_linux_real_chunk + VAS_EBOOT_LINUX_CL_OFFSET,
		LINUX_IMAGE, sizeof (LINUX_IMAGE));
  err = VasEBoot_create_loader_cmdline (argc, argv,
				    (char *)VasEBoot_linux_real_chunk
				    + VAS_EBOOT_LINUX_CL_OFFSET + sizeof (LINUX_IMAGE) - 1,
				    maximal_cmdline_size
				    - (sizeof (LINUX_IMAGE) - 1),
				    VAS_EBOOT_VERIFY_KERNEL_CMDLINE);
  if (err)
    goto fail;

  if (VasEBoot_linux_is_bzimage)
    VasEBoot_linux_prot_target = VAS_EBOOT_LINUX_BZIMAGE_ADDR;
  else
    VasEBoot_linux_prot_target = VAS_EBOOT_LINUX_ZIMAGE_ADDR;
  {
    VasEBoot_relocator_chunk_t ch;
    err = VasEBoot_relocator_alloc_chunk_addr (relocator, &ch,
					   VasEBoot_linux_prot_target,
					   VasEBoot_linux16_prot_size);
    if (err)
      return err;
    VasEBoot_linux_prot_chunk = get_virtual_current_address (ch);
  }

  len = VasEBoot_linux16_prot_size;
  if (VasEBoot_file_read (file, VasEBoot_linux_prot_chunk, len) != len && !VasEBoot_errno)
    VasEBoot_error (VAS_EBOOT_ERR_BAD_OS, N_("premature end of file %s"),
		argv[0]);

  if (VasEBoot_errno == VAS_EBOOT_ERR_NONE)
    {
      VasEBoot_loader_set (VasEBoot_linux16_boot, VasEBoot_linux_unload, 0);
      loaded = 1;
    }

 fail:

  if (file)
    VasEBoot_file_close (file);

  if (VasEBoot_errno != VAS_EBOOT_ERR_NONE)
    {
      VasEBoot_dl_unref (my_mod);
      loaded = 0;
      VasEBoot_relocator_unload (relocator);
    }

  return VasEBoot_errno;
}

static VasEBoot_err_t
VasEBoot_cmd_initrd (VasEBoot_command_t cmd __attribute__ ((unused)),
		 int argc, char *argv[])
{
  VasEBoot_size_t size = 0;
  VasEBoot_addr_t addr_max, addr_min;
  struct linux_i386_kernel_header *lh;
  VasEBoot_uint8_t *initrd_chunk;
  VasEBoot_addr_t initrd_addr;
  VasEBoot_err_t err;
  struct VasEBoot_linux_initrd_context initrd_ctx = { 0, 0, 0 };

  if (argc == 0)
    {
      VasEBoot_error (VAS_EBOOT_ERR_BAD_ARGUMENT, N_("filename expected"));
      goto fail;
    }

  if (!loaded)
    {
      VasEBoot_error (VAS_EBOOT_ERR_BAD_ARGUMENT, N_("you need to load the kernel first"));
      goto fail;
    }

  lh = (struct linux_i386_kernel_header *) VasEBoot_linux_real_chunk;

  if (!(lh->header == VasEBoot_cpu_to_le32_compile_time (VAS_EBOOT_LINUX_I386_MAGIC_SIGNATURE)
	&& VasEBoot_le_to_cpu16 (lh->version) >= 0x0200))
    {
      VasEBoot_error (VAS_EBOOT_ERR_BAD_OS, "the kernel is too old for initrd");
      goto fail;
    }

  /* Get the highest address available for the initrd.  */
  if (VasEBoot_le_to_cpu16 (lh->version) >= 0x0203)
    {
      addr_max = VasEBoot_cpu_to_le32 (lh->initrd_addr_max);

      /* XXX in reality, Linux specifies a bogus value, so
	 it is necessary to make sure that ADDR_MAX does not exceed
	 0x3fffffff.  */
      if (addr_max > VAS_EBOOT_LINUX_INITRD_MAX_ADDRESS)
	addr_max = VAS_EBOOT_LINUX_INITRD_MAX_ADDRESS;
    }
  else
    addr_max = VAS_EBOOT_LINUX_INITRD_MAX_ADDRESS;

  if (linux_mem_size != 0 && linux_mem_size < addr_max)
    addr_max = linux_mem_size;

  /* Linux 2.3.xx has a bug in the memory range check, so avoid
     the last page.
     Linux 2.2.xx has a bug in the memory range check, which is
     worse than that of Linux 2.3.xx, so avoid the last 64kb.  */
  addr_max -= 0x10000;

  addr_min = VAS_EBOOT_LINUX_BZIMAGE_ADDR + VasEBoot_linux16_prot_size;

  if (VasEBoot_initrd_init (argc, argv, &initrd_ctx))
    goto fail;

  size = VasEBoot_get_initrd_size (&initrd_ctx);

  {
    VasEBoot_relocator_chunk_t ch;
    err = VasEBoot_relocator_alloc_chunk_align_safe (relocator, &ch, addr_min, addr_max, size,
						 0x1000, VAS_EBOOT_RELOCATOR_PREFERENCE_HIGH, 0);
    if (err)
      goto fail;
    initrd_chunk = get_virtual_current_address (ch);
    initrd_addr = get_physical_target_address (ch);
  }

  if (VasEBoot_initrd_load (&initrd_ctx, initrd_chunk))
    goto fail;

  lh->ramdisk_image = initrd_addr;
  lh->ramdisk_size = size;

 fail:
  VasEBoot_initrd_close (&initrd_ctx);

  return VasEBoot_errno;
}

static VasEBoot_command_t cmd_linux, cmd_initrd;

VAS_EBOOT_MOD_INIT(linux16)
{
  cmd_linux =
    VasEBoot_register_command ("linux16", VasEBoot_cmd_linux,
			   0, N_("Load Linux."));
  cmd_initrd =
    VasEBoot_register_command ("initrd16", VasEBoot_cmd_initrd,
			   0, N_("Load initrd."));
  my_mod = mod;
}

VAS_EBOOT_MOD_FINI(linux16)
{
  VasEBoot_unregister_command (cmd_linux);
  VasEBoot_unregister_command (cmd_initrd);
}