[2211] 2009-05-13 Javier Mart?\195?\173n <address@hidden>

[Pavel Roskin]

Revision: 2211
          http://svn.sv.gnu.org/viewvc/?view=rev&root=grub&revision=2211
Author:   proski
Date:     2009-05-14 01:23:49 +0000 (Thu, 14 May 2009)
Log Message:
-----------
2009-05-13  Javier Mart?\195?\173n <address@hidden>

        * commands/i386/pc/drivemap.c: New file - implement drivemap
        command.
        * commands/i386/pc/drivemap_int13h.S: New file - int13 handler.
        * conf/i386-pc.rmk: Add drivemap.c and drivemap_int13h.S.

Modified Paths:
--------------
    trunk/grub2/ChangeLog
    trunk/grub2/conf/i386-pc.rmk

Added Paths:
-----------
    trunk/grub2/commands/i386/pc/drivemap.c
    trunk/grub2/commands/i386/pc/drivemap_int13h.S

Modified: trunk/grub2/ChangeLog
===================================================================
--- trunk/grub2/ChangeLog       2009-05-13 21:28:25 UTC (rev 2210)
+++ trunk/grub2/ChangeLog       2009-05-14 01:23:49 UTC (rev 2211)
@@ -1,3 +1,10 @@
+2009-05-13  Javier Martín <address@hidden>
+
+       * commands/i386/pc/drivemap.c: New file - implement drivemap
+       command.
+       * commands/i386/pc/drivemap_int13h.S: New file - int13 handler.
+       * conf/i386-pc.rmk: Add drivemap.c and drivemap_int13h.S.
+
 2009-05-13  Pavel Roskin  <address@hidden>
 
        * util/i386/pc/grub-setup.c (setup): Remove unused variable

Added: trunk/grub2/commands/i386/pc/drivemap.c
===================================================================
--- trunk/grub2/commands/i386/pc/drivemap.c                             (rev 0)
+++ trunk/grub2/commands/i386/pc/drivemap.c     2009-05-14 01:23:49 UTC (rev 
2211)
@@ -0,0 +1,445 @@
+/* drivemap.c - command to manage the BIOS drive mappings.  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2008, 2009  Free Software Foundation, Inc.
+ *
+ *  GRUB 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.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/extcmd.h>
+#include <grub/dl.h>
+#include <grub/mm.h>
+#include <grub/misc.h>
+#include <grub/disk.h>
+#include <grub/loader.h>
+#include <grub/machine/memory.h>
+
+
+#define MODNAME "drivemap"
+
+/* Real mode IVT slot (seg:off far pointer) for interrupt 0x13.  */
+static grub_uint32_t *const int13slot = UINT_TO_PTR (4 * 0x13);
+
+/* Remember to update enum opt_idxs accordingly.  */
+static const struct grub_arg_option options[] = {
+  {"list", 'l', 0, "show the current mappings", 0, 0},
+  {"reset", 'r', 0, "reset all mappings to the default values", 0, 0},
+  {"swap", 's', 0, "perform both direct and reverse mappings", 0, 0},
+  {0, 0, 0, 0, 0, 0}
+};
+
+/* Remember to update options[] accordingly.  */
+enum opt_idxs
+{
+  OPTIDX_LIST = 0,
+  OPTIDX_RESET,
+  OPTIDX_SWAP,
+};
+
+/* Realmode far ptr (2 * 16b) to the previous INT13h handler.  */
+extern grub_uint32_t grub_drivemap_oldhandler;
+
+/* The type "void" is used for imported assembly labels, takes no storage and
+   serves just to take the address with &label.  */
+
+/* The assembly function to replace the old INT13h handler. It does not follow
+   any C callspecs and returns with IRET.  */
+extern const void grub_drivemap_handler;
+
+/* Start of the drive mappings area (space reserved at runtime).  */
+extern const void grub_drivemap_mapstart;
+
+typedef struct drivemap_node
+{
+  struct drivemap_node *next;
+  grub_uint8_t newdrive;
+  grub_uint8_t redirto;
+} drivemap_node_t;
+
+typedef struct __attribute__ ((packed)) int13map_node
+{
+  grub_uint8_t disknum;
+  grub_uint8_t mapto;
+} int13map_node_t;
+
+#define INT13H_OFFSET(x) \
+       (((grub_uint8_t *)(x)) - ((grub_uint8_t *)&grub_drivemap_handler))
+
+static drivemap_node_t *map_head;
+static void *drivemap_hook;
+static int drivemap_mmap;
+
+/* Puts the specified mapping into the table, replacing an existing mapping
+   for newdrive or adding a new one if required.  */
+static grub_err_t
+drivemap_set (grub_uint8_t newdrive, grub_uint8_t redirto)
+{
+  drivemap_node_t *mapping = 0;
+  drivemap_node_t *search = map_head;
+  while (search)
+    {
+      if (search->newdrive == newdrive)
+       {
+         mapping = search;
+         break;
+       }
+      search = search->next;
+    }
+
+  /* Check for pre-existing mappings to modify before creating a new one.  */
+  if (mapping)
+    mapping->redirto = redirto;
+  else
+    {
+      mapping = grub_malloc (sizeof (drivemap_node_t));
+      if (! mapping)
+       return grub_error (GRUB_ERR_OUT_OF_MEMORY,
+                          "cannot allocate map entry, not enough memory");
+      mapping->newdrive = newdrive;
+      mapping->redirto = redirto;
+      mapping->next = map_head;
+      map_head = mapping;
+    }
+  return GRUB_ERR_NONE;
+}
+
+/* Removes the mapping for newdrive from the table.  If there is no mapping,
+   then this function behaves like a no-op on the map.  */
+static void
+drivemap_remove (grub_uint8_t newdrive)
+{
+  drivemap_node_t *mapping = 0;
+  drivemap_node_t *search = map_head;
+  drivemap_node_t *previous = 0;
+
+  while (search)
+    {
+      if (search->newdrive == newdrive)
+       {
+         mapping = search;
+         break;
+       }
+      previous = search;
+      search = search->next;
+    }
+
+  if (mapping)
+    {
+      if (previous)
+       previous->next = mapping->next;
+      else
+       map_head = mapping->next;
+      grub_free (mapping);
+    }
+}
+
+/* Given a device name, resolves its BIOS disk number and stores it in the
+   passed location, which should only be trusted if ERR_NONE is returned.  */
+static grub_err_t
+parse_biosdisk (const char *name, grub_uint8_t *disknum)
+{
+  grub_disk_t disk;
+  /* Skip the first ( in (hd0) - disk_open wants just the name.  */
+  if (*name == '(')
+    name++;
+
+  disk = grub_disk_open (name);
+  if (! disk)
+    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "unknown device \"%s\"",
+                      name);
+  const enum grub_disk_dev_id id = disk->dev->id;
+  /* The following assignment is only sound if the device is indeed a
+     biosdisk.  The caller must check the return value.  */
+  if (disknum)
+    *disknum = disk->id;
+  grub_disk_close (disk);
+  if (id != GRUB_DISK_DEVICE_BIOSDISK_ID)
+    return grub_error (GRUB_ERR_BAD_DEVICE, "%s is not a BIOS disk", name);
+  return GRUB_ERR_NONE;
+}
+
+/* Given a BIOS disk number, returns its GRUB device name if it exists.
+   If the call succeeds, the resulting device string must be freed.
+   For nonexisting BIOS disk numbers, this function returns
+   GRUB_ERR_UNKNOWN_DEVICE.  */
+static grub_err_t
+revparse_biosdisk (const grub_uint8_t dnum, const char **output)
+{
+  int found = 0;
+  auto int find (const char *name);
+  int find (const char *name)
+  {
+    const grub_disk_t disk = grub_disk_open (name);
+    if (! disk)
+      return 0;
+    if (disk->id == dnum && disk->dev->id == GRUB_DISK_DEVICE_BIOSDISK_ID)
+      {
+       found = 1;
+       if (output)
+         *output = grub_strdup (name);
+      }
+    grub_disk_close (disk);
+    return found;
+  }
+
+  grub_disk_dev_iterate (find);
+  if (found)
+    return GRUB_ERR_NONE;
+  return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "BIOS disk %02x not found",
+                    dnum);
+}
+
+/* Given a GRUB-like device name and a convenient location, stores the
+   related BIOS disk number.  Accepts devices like \((f|h)dN\), with
+   0 <= N < 128.  */
+static grub_err_t
+tryparse_diskstring (const char *str, grub_uint8_t *output)
+{
+  /* Skip opening paren in order to allow both (hd0) and hd0.  */
+  if (*str == '(')
+    str++;
+  if ((str[0] == 'f' || str[0] == 'h') && str[1] == 'd')
+    {
+      grub_uint8_t bios_num = (str[0] == 'h') ? 0x80 : 0x00;
+      unsigned long drivenum = grub_strtoul (str + 2, 0, 0);
+      if (grub_errno == GRUB_ERR_NONE && drivenum < 128)
+       {
+         bios_num |= drivenum;
+         if (output)
+           *output = bios_num;
+         return GRUB_ERR_NONE;
+       }
+    }
+  return grub_error (GRUB_ERR_BAD_ARGUMENT, "device format \"%s\" "
+                    "invalid: must be (f|h)dN, with 0 <= N < 128", str);
+}
+
+static grub_err_t
+list_mappings (void)
+{
+  /* Show: list mappings.  */
+  if (! map_head)
+    {
+      grub_printf ("No drives have been remapped\n");
+      return GRUB_ERR_NONE;
+    }
+
+  grub_printf ("OS disk #num ------> GRUB/BIOS device\n");
+  drivemap_node_t *curnode = map_head;
+  while (curnode)
+    {
+      const char *dname = 0;
+      grub_err_t err = revparse_biosdisk (curnode->redirto, &dname);
+      if (err != GRUB_ERR_NONE)
+       return err;
+      grub_printf ("%cD #%-3u (0x%02x)       %s\n",
+                  (curnode->newdrive & 0x80) ? 'H' : 'F',
+                  curnode->newdrive & 0x7F, curnode->newdrive, dname);
+      curnode = curnode->next;
+      grub_free ((char *) dname);
+    }
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
+grub_cmd_drivemap (struct grub_extcmd *cmd, int argc, char **args)
+{
+  if (cmd->state[OPTIDX_LIST].set)
+    {
+      return list_mappings ();
+    }
+  else if (cmd->state[OPTIDX_RESET].set)
+    {
+      /* Reset: just delete all mappings, freeing their memory.  */
+      drivemap_node_t *curnode = map_head;
+      drivemap_node_t *prevnode = 0;
+      while (curnode)
+       {
+         prevnode = curnode;
+         curnode = curnode->next;
+         grub_free (prevnode);
+       }
+      map_head = 0;
+      return GRUB_ERR_NONE;
+    }
+  else if (!cmd->state[OPTIDX_SWAP].set && argc == 0)
+    {
+      /* No arguments */
+      return list_mappings ();
+    }
+
+  /* Neither flag: put mapping.  */
+  grub_uint8_t mapfrom = 0;
+  grub_uint8_t mapto = 0xFF;
+  grub_err_t err;
+
+  if (argc != 2)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, "two arguments required");
+
+  err = parse_biosdisk (args[0], &mapfrom);
+  if (err != GRUB_ERR_NONE)
+    return err;
+
+  /* When swapping we require both devices to be BIOS disks, but when
+     performing direct mappings we only require the 2nd argument to look
+     like a BIOS disk in order to resolve it into a BIOS disk number.  */
+  if (cmd->state[OPTIDX_SWAP].set)
+    err = parse_biosdisk (args[1], &mapto);
+  else
+    err = tryparse_diskstring (args[1], &mapto);
+  if (err != GRUB_ERR_NONE)
+    return err;
+
+  if (mapto == mapfrom)
+    {
+      /* Reset to default.  */
+      grub_dprintf (MODNAME, "Removing mapping for %s (%02x)\n",
+                   args[0], mapfrom);
+      drivemap_remove (mapfrom);
+      return GRUB_ERR_NONE;
+    }
+  /* Set the mapping for the disk (overwrites any existing mapping).  */
+  grub_dprintf (MODNAME, "%s %s (%02x) = %s (%02x)\n",
+               cmd->state[OPTIDX_SWAP].set ? "Swapping" : "Mapping",
+               args[1], mapto, args[0], mapfrom);
+  err = drivemap_set (mapto, mapfrom);
+  /* If -s, perform the reverse mapping too (only if the first was OK).  */
+  if (cmd->state[OPTIDX_SWAP].set && err == GRUB_ERR_NONE)
+    err = drivemap_set (mapfrom, mapto);
+  return err;
+}
+
+/* Int13h handler installer - reserves conventional memory for the handler,
+   copies it over and sets the IVT entry for int13h.
+   This code rests on the assumption that GRUB does not activate any kind
+   of memory mapping apart from identity paging, since it accesses
+   realmode structures by their absolute addresses, like the IVT at 0;
+   and transforms a pmode pointer into a rmode seg:off far ptr.  */
+static grub_err_t
+install_int13_handler (int noret __attribute__ ((unused)))
+{
+  /* Size of the full int13 handler "bundle", including code and map.  */
+  grub_uint32_t total_size;
+  /* Base address of the space reserved for the handler bundle.  */
+  grub_uint8_t *handler_base = 0;
+  /* Address of the map within the deployed bundle.  */
+  int13map_node_t *handler_map;
+
+  int i;
+  int entries = 0;
+  drivemap_node_t *curentry = map_head;
+
+  /* Count entries to prepare a contiguous map block.  */
+  while (curentry)
+    {
+      entries++;
+      curentry = curentry->next;
+    }
+  if (entries == 0)
+    {
+      /* No need to install the int13h handler.  */
+      grub_dprintf (MODNAME, "No drives marked as remapped, not installing "
+                   "our int13h handler.\n");
+      return GRUB_ERR_NONE;
+    }
+
+  grub_dprintf (MODNAME, "Installing our int13h handler\n");
+
+  /* Save the pointer to the old handler.  */
+  grub_drivemap_oldhandler = *int13slot;
+  grub_dprintf (MODNAME, "Original int13 handler: %04x:%04x\n",
+               (grub_drivemap_oldhandler >> 16) & 0x0ffff,
+               grub_drivemap_oldhandler & 0x0ffff);
+
+  /* Find a rmode-segment-aligned zone in conventional memory big
+     enough to hold the handler and its data.  */
+  total_size = INT13H_OFFSET (&grub_drivemap_mapstart)
+    + (entries + 1) * sizeof (int13map_node_t);
+  grub_dprintf (MODNAME, "Payload is %u bytes long\n", total_size);
+  handler_base = grub_mmap_malign_and_register (16, total_size,
+                                               &drivemap_mmap,
+                                               GRUB_MACHINE_MEMORY_RESERVED,
+                                               GRUB_MMAP_MALLOC_LOW);
+  if (! handler_base)
+    return grub_error (GRUB_ERR_OUT_OF_MEMORY, "Could not reserve "
+                      "memory for the int13h handler");
+
+  /* Copy int13h handler bundle to reserved area.  */
+  grub_dprintf (MODNAME, "Reserved memory at %p, copying handler\n",
+               handler_base);
+  grub_memcpy (handler_base, &grub_drivemap_handler,
+              INT13H_OFFSET (&grub_drivemap_mapstart));
+
+  /* Copy the mappings to the reserved area.  */
+  curentry = map_head;
+  handler_map = (int13map_node_t *) (handler_base +
+                                    INT13H_OFFSET (&grub_drivemap_mapstart));
+  grub_dprintf (MODNAME, "Target map at %p, copying mappings\n", handler_map);
+  for (i = 0; i < entries; ++i, curentry = curentry->next)
+    {
+      handler_map[i].disknum = curentry->newdrive;
+      handler_map[i].mapto = curentry->redirto;
+      grub_dprintf (MODNAME, "\t#%d: 0x%02x <- 0x%02x\n", i,
+                   handler_map[i].disknum, handler_map[i].mapto);
+    }
+  /* Signal end-of-map.  */
+  handler_map[i].disknum = 0;
+  handler_map[i].mapto = 0;
+  grub_dprintf (MODNAME, "\t#%d: 0x00 <- 0x00 (end)\n", i);
+
+  /* Install our function as the int13h handler in the IVT.  */
+  *int13slot = ((grub_uint32_t) handler_base) << 12;   /* Segment address.  */
+  grub_dprintf (MODNAME, "New int13 handler: %04x:%04x\n",
+               (*int13slot >> 16) & 0x0ffff, *int13slot & 0x0ffff);
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
+uninstall_int13_handler (void)
+{
+  if (! grub_drivemap_oldhandler)
+    return GRUB_ERR_NONE;
+
+  *int13slot = grub_drivemap_oldhandler;
+  grub_mmap_free_and_unregister (drivemap_mmap);
+  grub_drivemap_oldhandler = 0;
+  grub_dprintf (MODNAME, "Restored int13 handler: %04x:%04x\n",
+               (*int13slot >> 16) & 0x0ffff, *int13slot & 0x0ffff);
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_extcmd_t cmd;
+
+GRUB_MOD_INIT (drivemap)
+{
+  cmd = grub_register_extcmd (MODNAME, grub_cmd_drivemap,
+                                       GRUB_COMMAND_FLAG_BOTH,
+                                       MODNAME
+                                       " -l | -r | [-s] grubdev osdisk",
+                                       "Manage the BIOS drive mappings",
+                                       options);
+  drivemap_hook =
+    grub_loader_register_preboot_hook (&install_int13_handler,
+                                      &uninstall_int13_handler,
+                                      GRUB_LOADER_PREBOOT_HOOK_PRIO_NORMAL);
+}
+
+GRUB_MOD_FINI (drivemap)
+{
+  grub_loader_unregister_preboot_hook (drivemap_hook);
+  drivemap_hook = 0;
+  grub_unregister_extcmd (cmd);
+}

Added: trunk/grub2/commands/i386/pc/drivemap_int13h.S
===================================================================
--- trunk/grub2/commands/i386/pc/drivemap_int13h.S                              
(rev 0)
+++ trunk/grub2/commands/i386/pc/drivemap_int13h.S      2009-05-14 01:23:49 UTC 
(rev 2211)
@@ -0,0 +1,66 @@
+/* drivemap_int13h.S - interrupt handler for the BIOS drive remapper */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2008, 2009  Free Software Foundation, Inc.
+ *
+ *  GRUB 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.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/symbol.h>
+
+#define INT13H_OFFSET(x) ((x) - grub_drivemap_handler)
+
+.code16
+
+/* Copy starts here.  When deployed, this code must be segment-aligned.  */
+
+/* The replacement int13 handler.  The code must be position independent.
+   Preserve all registers.  */
+FUNCTION(grub_drivemap_handler)
+       /* Map the drive number (always in DL).  */
+       push    %ax
+       push    %bx
+       movw    $INT13H_OFFSET(grub_drivemap_mapstart), %bx
+
+more_remaining:
+       movw    %cs:(%bx), %ax
+       cmpb    %ah, %al
+       jz      not_found /* DRV=DST => map end - drive not remapped, keep DL.  
*/
+       cmpb    %dl, %al
+       jz      found /* Found - drive remapped, modify DL.  */
+       inc     %bx
+       inc     %bx
+       jmp     more_remaining /* Not found, but more remaining, loop.  */
+
+found:
+       movb    %ah, %dl
+
+not_found:
+       pop     %bx
+       pop     %ax
+
+       /* Upon arrival to this point the stack must be exactly like at entry.
+          This long jump will transfer the caller's stack to the old INT13
+          handler, thus making it return directly to the original caller.  */
+       .byte   0xea
+
+/* Far pointer to the old handler.  Stored as a CS:IP in the style of real-mode
+   IVT entries (thus PI:SC in mem).  */
+VARIABLE(grub_drivemap_oldhandler)
+       .word 0x0, 0x0
+
+/* This label MUST be at the end of the copied block, since the installer code
+   reserves additional space for mappings at runtime and copies them over it.  
*/
+.align 2
+VARIABLE(grub_drivemap_mapstart)

Modified: trunk/grub2/conf/i386-pc.rmk
===================================================================
--- trunk/grub2/conf/i386-pc.rmk        2009-05-13 21:28:25 UTC (rev 2210)
+++ trunk/grub2/conf/i386-pc.rmk        2009-05-14 01:23:49 UTC (rev 2211)
@@ -185,8 +185,15 @@
        aout.mod bsd.mod pxe.mod pxecmd.mod datetime.mod date.mod \
        datehook.mod lsmmap.mod ata_pthru.mod hdparm.mod \
        usb.mod uhci.mod ohci.mod usbtest.mod usbms.mod usb_keyboard.mod \
-       efiemu.mod mmap.mod acpi.mod
+       efiemu.mod mmap.mod acpi.mod drivemap.mod
 
+# For drivemap.mod.
+drivemap_mod_SOURCES = commands/i386/pc/drivemap.c \
+                       commands/i386/pc/drivemap_int13h.S
+drivemap_mod_ASFLAGS = $(COMMON_ASFLAGS)
+drivemap_mod_CFLAGS = $(COMMON_CFLAGS)
+drivemap_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
 # For efiemu.mod.
 efiemu_mod_SOURCES = efiemu/main.c efiemu/i386/loadcore32.c \
                     efiemu/i386/loadcore64.c efiemu/i386/pc/cfgtables.c \