[PATCH v2] Add a module for retrieving SMBIOS information

* [PATCH v2] Add a module for retrieving SMBIOS information
@ 2015-02-08 18:54 David Michael
  2015-02-08 20:13 ` Prarit Bhargava
                   ` (2 more replies)
  0 siblings, 3 replies; 11+ messages in thread
From: David Michael @ 2015-02-08 18:54 UTC (permalink / raw)
  To: grub-devel
  Cc: Prarit Bhargava, Raghuraman Thirumalairajan, Andrei Borzenkov,
	Rajat Jain, Leif Lindholm, Sanjay Jain, Stu Grossman

The following are two use cases from Rajat Jain <rajatjain@juniper.net>:

1) We have a board that boots Linux and this board itself can be plugged into one of different chassis types. We need to pass different parameters to the kernel based on the "CHASSIS_TYPE" information that is passed by the bios in the DMI / SMBIOS tables.

2) We may have a USB stick that can go into multiple boards, and the exact kernel to be loaded depends on the machine information (PRODUCT_NAME etc) passed via the DMI.

* grub-core/commands/smbios.c: New file.
* grub-core/Makefile.core.def (smbios): New module.
* docs/grub.texi (smbios): New node.
(Command-line and menu entry commands): Add a menu entry for smbios.
---

Changes since v1:

* Removed formfeeds and quoted use cases in the commit messages as
  suggested by Prarit Bhargava.

* Enabled building the module on all EFI platforms as suggested by Leif
  Lindholm.

 docs/grub.texi              |  67 ++++++++
 grub-core/Makefile.core.def |   7 +
 grub-core/commands/smbios.c | 361 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 435 insertions(+)
 create mode 100644 grub-core/commands/smbios.c

diff --git a/docs/grub.texi b/docs/grub.texi
index 46b9e7f..f4e187f 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -3830,6 +3830,7 @@ you forget a command, you can run the command @command{help}
 * sha256sum::                   Compute or check SHA256 hash
 * sha512sum::                   Compute or check SHA512 hash
 * sleep::                       Wait for a specified number of seconds
+* smbios::                      Retrieve SMBIOS information
 * source::                      Read a configuration file in same context
 * test::                        Check file types and compare values
 * true::                        Do nothing, successfully
@@ -4944,6 +4945,72 @@ if timeout was interrupted by @key{ESC}.
 @end deffn
 
 
+@node smbios
+@subsection smbios
+
+@deffn Command smbios @
+ [@option{-t} @var{type}] @
+ [@option{-h} @var{handle}] @
+ [@option{-m} @var{match}] @
+ [ (@option{-b} | @option{-w} | @option{-d} | @option{-q} | @option{-s}) @
+   @var{offset} [@option{-v} @var{variable}] ]
+Retrieve SMBIOS information.  This command is only available on x86 and EFI
+systems.
+
+When run with no options, @command{smbios} will print the SMBIOS table entries
+to the console as the header values, a hex dump, and a string list.  The
+following options can filter which table entries are printed.
+
+@itemize @bullet
+@item
+Specifying @option{-t} will only print entries with a matching @var{type}.  The
+type can be any value from 0 to 255.  Specify a value outside this range to
+match entries with any type.  The default is -1.
+@item
+Specifying @option{-h} will only print entries with a matching @var{handle}.
+The handle can be any value from 0 to 65535.  Specify a value outside this
+range to match entries with any handle.  The default is -1.
+@item
+Specifying @option{-m} will only print number @var{match} in the list of all
+filtered entries; e.g. @code{smbios -m 3} will print the third entry.  The list
+is always ordered the same as the hardware's SMBIOS table.  The match number
+can be any positive value.  Specify 0 to match all entries.  The default is 0.
+@end itemize
+
+The remaining options print the value of a field in the matched SMBIOS table
+entry.  Only one of these options may be specified.  When they are used, the
+option @code{-m 0} is synonymous with @code{-m 1} to match the first entry.
+
+@itemize @bullet
+@item
+When given @option{-b}, print the value of the byte
+at @var{offset} bytes into the matched SMBIOS table entry.
+@item
+When given @option{-w}, print the value of the word (two bytes)
+at @var{offset} bytes into the matched SMBIOS table entry.
+@item
+When given @option{-d}, print the value of the dword (four bytes)
+at @var{offset} bytes into the matched SMBIOS table entry.
+@item
+When given @option{-q}, print the value of the qword (eight bytes)
+at @var{offset} bytes into the matched SMBIOS table entry.
+@item
+When given @option{-s}, print the string table entry with its index found
+at @var{offset} bytes into the matched SMBIOS table entry.
+@end itemize
+
+If any of the options in the above list were given, a variable name can be
+specified with @option{-v} to store the value instead of printing it.
+
+For example, this will store and display the system manufacturer string.
+
+@example
+smbios -t 1 -s 4 -v system_manufacturer
+echo $system_manufacturer
+@end example
+@end deffn
+
+
 @node source
 @subsection source
 
diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 42443bc..f87de70 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -1023,6 +1023,13 @@ module = {
 };
 
 module = {
+  name = smbios;
+  common = commands/smbios.c;
+  enable = efi;
+  enable = x86;
+};
+
+module = {
   name = suspend;
   ieee1275 = commands/ieee1275/suspend.c;
   enable = i386_ieee1275;
diff --git a/grub-core/commands/smbios.c b/grub-core/commands/smbios.c
new file mode 100644
index 0000000..d8edeea
--- /dev/null
+++ b/grub-core/commands/smbios.c
@@ -0,0 +1,361 @@
+/* Expose SMBIOS data to the console and configuration files */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2013,2014,2015  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/dl.h>
+#include <grub/extcmd.h>
+#include <grub/env.h>
+#include <grub/i18n.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+
+#ifdef GRUB_MACHINE_EFI
+#include <grub/efi/efi.h>
+#else
+#include <grub/acpi.h>
+#endif
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+/* Reference: DMTF Standard DSP0134 2.7.1 Table 1 */
+
+struct __attribute__ ((packed)) grub_smbios_ieps
+  {
+    grub_uint8_t  anchor[5]; /* "_DMI_" */
+    grub_uint8_t  checksum;
+    grub_uint16_t table_length;
+    grub_uint32_t table_address;
+    grub_uint16_t structures;
+    grub_uint8_t  revision;
+  };
+
+struct __attribute__ ((packed)) grub_smbios_eps
+  {
+    grub_uint8_t  anchor[4]; /* "_SM_" */
+    grub_uint8_t  checksum;
+    grub_uint8_t  length;
+    grub_uint8_t  version_major;
+    grub_uint8_t  version_minor;
+    grub_uint16_t maximum_structure_size;
+    grub_uint8_t  revision;
+    grub_uint8_t  formatted[5];
+    struct grub_smbios_ieps intermediate;
+  };
+
+static const struct grub_smbios_eps *eps = NULL;
+
+/* Reference: DMTF Standard DSP0134 2.7.1 Section 5.2.1 */
+
+/*
+ * In order for any of this module to function, it needs to find an entry point
+ * structure.  This returns a pointer to a struct that identifies the fields of
+ * the EPS, or NULL if it cannot be located.
+ */
+static const struct grub_smbios_eps *
+grub_smbios_locate_eps (void)
+{
+#ifdef GRUB_MACHINE_EFI
+  static const grub_efi_guid_t smbios_guid = GRUB_EFI_SMBIOS_TABLE_GUID;
+  const grub_efi_system_table_t *st = grub_efi_system_table;
+  const grub_efi_configuration_table_t *t = st->configuration_table;
+  unsigned int i;
+
+  for (i = 0; i < st->num_table_entries; i++)
+    if (grub_memcmp (&smbios_guid, &t->vendor_guid, sizeof (smbios_guid)) == 0)
+      {
+        grub_dprintf ("smbios", "Found entry point structure at %p\n",
+                      t->vendor_table);
+        return (const struct grub_smbios_eps *)t->vendor_table;
+      }
+    else
+      t++;
+#else
+  grub_uint8_t *ptr;
+
+  for (ptr = (grub_uint8_t *)0x000F0000;
+       ptr < (grub_uint8_t *)0x00100000;
+       ptr += 16)
+    if (grub_memcmp (ptr, "_SM_", 4) == 0
+        && grub_byte_checksum (ptr, ptr[5]) == 0)
+      {
+        grub_dprintf ("smbios", "Found entry point structure at %p\n", ptr);
+        return (const struct grub_smbios_eps *)ptr;
+      }
+#endif
+
+  grub_dprintf ("smbios", "Failed to locate entry point structure\n");
+  return NULL;
+}
+
+/* Reference: DMTF Standard DSP0134 2.7.1 Sections 6.1.2-6.1.3 */
+
+/*
+ * Given a pointer to the first bytes of an entry, print its contents in a
+ * semi-human-readable format.  Return the size of the entry printed.
+ */
+static grub_uint16_t
+grub_smbios_dump_entry (const grub_uint8_t *entry)
+{
+  const grub_uint8_t *ptr = entry;
+  grub_uint8_t newstr = 1;
+  grub_uint8_t length;
+
+  /* Write the entry's mandatory four header bytes. */
+  length = ptr[1];
+  grub_printf ("Entry: Type=0x%02x Length=0x%02x Handle=0x%04x\n",
+               ptr[0], length, *(1 + (grub_uint16_t *)ptr));
+
+  /* Dump of the formatted area (including the header) in hex. */
+  grub_printf (" Hex Dump: ");
+  while (length-- > 0)
+    grub_printf ("%02x", *ptr++);
+  grub_printf ("\n");
+
+  /* Print each string found in the appended string list. */
+  while (ptr[0] != 0 || ptr[1] != 0)
+    {
+      if (newstr)
+        grub_printf (" String: %s\n", ptr);
+      newstr = *ptr++ == 0;
+    }
+  ptr += 2;
+
+  /* Return the total number of bytes covered. */
+  return ptr - entry;
+}
+
+/* Reference: DMTF Standard DSP0134 2.7.1 Sections 6.1.2-6.1.3 */
+
+/*
+ * Return or print a matched table entry.  Multiple entries can be matched if
+ * they are being printed.
+ *
+ * This method can handle up to three criteria for selecting an entry:
+ *   - The entry's "type" field             (use outside [0,0xFF] to ignore)
+ *   - The entry's "handle" field           (use outside [0,0xFFFF] to ignore)
+ *   - The entry to return if several match (use 0 to print all matches)
+ *
+ * The parameter "print" was added for verbose debugging.  When non-zero, the
+ * matched entries are printed to the console instead of returned.
+ */
+static const grub_uint8_t *
+grub_smbios_match_entry (const struct grub_smbios_eps *ep,
+                         const grub_int16_t type,
+                         const grub_int32_t handle,
+                         const grub_uint16_t match,
+                         const grub_uint8_t print)
+{
+  grub_addr_t table_address = (grub_addr_t)ep->intermediate.table_address;
+  grub_uint16_t table_length = ep->intermediate.table_length;
+  grub_uint16_t structures = ep->intermediate.structures;
+  grub_uint16_t structure = 0;
+  grub_uint16_t matches = 0;
+  const grub_uint8_t *table = (const grub_uint8_t *)table_address;
+  const grub_uint8_t *ptr = table;
+
+  while (ptr - table < table_length && structure++ < structures)
+
+    /* Test if the current entry matches the given parameters. */
+    if ((handle < 0 || 65535 < handle || handle == *(1 + (grub_uint16_t *)ptr))
+        && (type < 0 || 255 < type || type == ptr[0])
+        && (match == 0 || match == ++matches))
+      {
+        if (print)
+          {
+            ptr += grub_smbios_dump_entry (ptr);
+            if (match > 0)
+              break;
+          }
+        else
+          return ptr;
+      }
+
+    /* If the entry didn't match, skip it (formatted area and string list). */
+    else
+      {
+        ptr += ptr[1];
+        while (*ptr++ != 0 || *ptr++ != 0);
+      }
+
+  return NULL;
+}
+
+/* Reference: DMTF Standard DSP0134 2.7.1 Section 6.1.3 */
+
+/*
+ * Given a pointer to a string list and a number, iterate over each of the
+ * strings until the desired item is reached.  (The value of 1 indicates the
+ * first string, etc.)
+ */
+static const char *
+grub_smbios_get_string (const grub_uint8_t *strings, const grub_uint8_t number)
+{
+  const char *ptr = (const char *)strings;
+  grub_uint8_t newstr = 1;
+  grub_uint8_t index = 1;
+
+  /* A string referenced with zero is interpreted as unset. */
+  if (number == 0)
+    return NULL;
+
+  /* Search the string table, incrementing the counter as each null passes. */
+  while (ptr[0] != 0 || ptr[1] != 0)
+    {
+      if (newstr && number == index++)
+        return ptr;
+      newstr = *ptr++ == 0;
+    }
+
+  /* The requested string index is greater than the number of table entries. */
+  return NULL;
+}
+
+static grub_err_t
+grub_cmd_smbios (grub_extcmd_context_t ctxt,
+                 int argc __attribute__ ((unused)),
+                 char **argv __attribute__ ((unused)))
+{
+  struct grub_arg_list *state = ctxt->state;
+
+  grub_int16_t type = -1;
+  grub_int32_t handle = -1;
+  grub_uint16_t match = 0;
+  grub_uint8_t offset = 0;
+
+  const grub_uint8_t *entry;
+  grub_uint8_t accessors;
+  grub_uint8_t i;
+  char buffer[24]; /* 64-bit number -> maximum 20 decimal digits */
+  const char *value = buffer;
+
+  if (eps == NULL)
+    return grub_error (GRUB_ERR_FILE_NOT_FOUND, N_("missing entry point"));
+
+  /* Only one value can be returned at a time; reject multiple selections. */
+  accessors = !!state[3].set + !!state[4].set + !!state[5].set +
+              !!state[6].set + !!state[7].set;
+  if (accessors > 1)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("too many -b|-w|-d|-q|-s"));
+
+  /* Reject the environment variable if no value was selected. */
+  if (accessors == 0 && state[8].set)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("-v without -b|-w|-d|-q|-s"));
+
+  /* Read the given matching parameters. */
+  if (state[0].set)
+    type = grub_strtol (state[0].arg, NULL, 0);
+  if (state[1].set)
+    handle = grub_strtol (state[1].arg, NULL, 0);
+  if (state[2].set)
+    match = grub_strtoul (state[2].arg, NULL, 0);
+
+  /* When not selecting a value, print all matching entries and quit. */
+  if (accessors == 0)
+    {
+      grub_smbios_match_entry (eps, type, handle, match, 1);
+      return GRUB_ERR_NONE;
+    }
+
+  /* Select a single entry from the matching parameters. */
+  entry = grub_smbios_match_entry (eps, type, handle, match, 0);
+  if (entry == NULL)
+    return grub_error (GRUB_ERR_FILE_NOT_FOUND, N_("no such entry"));
+
+  /* Ensure the specified offset+length is within the matched entry. */
+  for (i = 3; i <= 7; i++)
+    if (state[i].set)
+      {
+        offset = grub_strtoul (state[i].arg, NULL, 0);
+        if (offset + (1 << (i == 7 ? 0 : i - 3)) > entry[1])
+          return grub_error (GRUB_ERR_OUT_OF_RANGE, N_("value outside entry"));
+        break;
+      }
+
+  /* If a string was requested, try to find its pointer. */
+  if (state[7].set)
+    {
+      value = grub_smbios_get_string (entry + entry[1], entry[offset]);
+      if (value == NULL)
+        return grub_error (GRUB_ERR_OUT_OF_RANGE, N_("string not defined"));
+    }
+
+  /* Create a string from a numeric value suitable for printing. */
+  else if (state[3].set)
+    grub_snprintf (buffer, sizeof (buffer), "%u", entry[offset]);
+  else if (state[4].set)
+    grub_snprintf (buffer, sizeof (buffer), "%u",
+                   *(grub_uint16_t *)(entry + offset));
+  else if (state[5].set)
+    grub_snprintf (buffer, sizeof (buffer), "%" PRIuGRUB_UINT32_T,
+                   *(grub_uint32_t *)(entry + offset));
+  else if (state[6].set)
+    grub_snprintf (buffer, sizeof (buffer), "%" PRIuGRUB_UINT64_T,
+                   *(grub_uint64_t *)(entry + offset));
+
+  /* Store or print the requested value. */
+  if (state[8].set)
+    {
+      grub_env_set (state[8].arg, value);
+      grub_env_export (state[8].arg);
+    }
+  else
+    grub_printf ("%s\n", value);
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_extcmd_t cmd;
+
+static const struct grub_arg_option options[] =
+  {
+    {"type",       't', 0, N_("Match entries with the given type."),
+                           N_("byte"), ARG_TYPE_INT},
+    {"handle",     'h', 0, N_("Match entries with the given handle."),
+                           N_("word"), ARG_TYPE_INT},
+    {"match",      'm', 0, N_("Select the entry to use when several match."),
+                           N_("number"), ARG_TYPE_INT},
+    {"get-byte",   'b', 0, N_("Get the byte's value at the given offset."),
+                           N_("offset"), ARG_TYPE_INT},
+    {"get-word",   'w', 0, N_("Get two bytes' value at the given offset."),
+                           N_("offset"), ARG_TYPE_INT},
+    {"get-dword",  'd', 0, N_("Get four bytes' value at the given offset."),
+                           N_("offset"), ARG_TYPE_INT},
+    {"get-qword",  'q', 0, N_("Get eight bytes' value at the given offset."),
+                           N_("offset"), ARG_TYPE_INT},
+    {"get-string", 's', 0, N_("Get the string specified at the given offset."),
+                           N_("offset"), ARG_TYPE_INT},
+    {"variable",   'v', 0, N_("Store the value in the given variable name."),
+                           N_("name"), ARG_TYPE_STRING},
+    {0, 0, 0, 0, 0, 0}
+  };
+
+GRUB_MOD_INIT(smbios)
+{
+  /* SMBIOS data is supposed to be static, so find it only once during init. */
+  eps = grub_smbios_locate_eps ();
+
+  cmd = grub_register_extcmd ("smbios", grub_cmd_smbios, 0,
+                              N_("[-t byte] [-h word] [-m number] "
+                                 "[(-b|-w|-d|-q|-s) offset [-v name]]"),
+                              N_("Retrieve SMBIOS information."), options);
+}
+
+GRUB_MOD_FINI(smbios)
+{
+  grub_unregister_extcmd (cmd);
+}
-- 
2.1.0



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