path: root/drivers/firmware/dmi_scan.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/types.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/dmi.h>
#include <linux/efi.h>
#include <linux/memblock.h>
#include <linux/random.h>
#include <asm/dmi.h>
#include <asm/unaligned.h>

#ifndef SMBIOS_ENTRY_POINT_SCAN_START
#define SMBIOS_ENTRY_POINT_SCAN_START 0xF0000
#endif

struct kobject *dmi_kobj;
EXPORT_SYMBOL_GPL(dmi_kobj);

/*
 * DMI stands for "Desktop Management Interface".  It is part
 * of and an antecedent to, SMBIOS, which stands for System
 * Management BIOS.  See further: https://www.dmtf.org/standards
 */
static const char dmi_empty_string[] = "";

static u32 dmi_ver __initdata;
static u32 dmi_len;
static u16 dmi_num;
static u8 smbios_entry_point[32];
static int smbios_entry_point_size;

/* DMI system identification string used during boot */
static char dmi_ids_string[128] __initdata;

static struct dmi_memdev_info {
	const char *device;
	const char *bank;
	u64 size;		/* bytes */
	u16 handle;
	u8 type;		/* DDR2, DDR3, DDR4 etc */
} *dmi_memdev;
static int dmi_memdev_nr;

static const char * __init dmi_string_nosave(const struct dmi_header *dm, u8 s)
{
	const u8 *bp = ((u8 *) dm) + dm->length;
	const u8 *nsp;

	if (s) {
		while (--s > 0 && *bp)
			bp += strlen(bp) + 1;

		/* Strings containing only spaces are considered empty */
		nsp = bp;
		while (*nsp == ' ')
			nsp++;
		if (*nsp != '\0')
			return bp;
	}

	return dmi_empty_string;
}

static const char * __init dmi_string(const struct dmi_header *dm, u8 s)
{
	const char *bp = dmi_string_nosave(dm, s);
	char *str;
	size_t len;

	if (bp == dmi_empty_string)
		return dmi_empty_string;

	len = strlen(bp) + 1;
	str = dmi_alloc(len);
	if (str != NULL)
		strcpy(str, bp);

	return str;
}

/*
 *	We have to be cautious here. We have seen BIOSes with DMI pointers
 *	pointing to completely the wrong place for example
 */
static void dmi_decode_table(u8 *buf,
			     void (*decode)(const struct dmi_header *, void *),
			     void *private_data)
{
	u8 *data = buf;
	int i = 0;

	/*
	 * Stop when we have seen all the items the table claimed to have
	 * (SMBIOS < 3.0 only) OR we reach an end-of-table marker (SMBIOS
	 * >= 3.0 only) OR we run off the end of the table (should never
	 * happen but sometimes does on bogus implementations.)
	 */
	while ((!dmi_num || i < dmi_num) &&
	       (data - buf + sizeof(struct dmi_header)) <= dmi_len) {
		const struct dmi_header *dm = (const struct dmi_header *)data;

		/*
		 *  We want to know the total length (formatted area and
		 *  strings) before decoding to make sure we won't run off the
		 *  table in dmi_decode or dmi_string
		 */
		data += dm->length;
		while ((data - buf < dmi_len - 1) && (data[0] || data[1]))
			data++;
		if (data - buf < dmi_len - 1)
			decode(dm, private_data);

		data += 2;
		i++;

		/*
		 * 7.45 End-of-Table (Type 127) [SMBIOS reference spec v3.0.0]
		 * For tables behind a 64-bit entry point, we have no item
		 * count and no exact table length, so stop on end-of-table
		 * marker. For tables behind a 32-bit entry point, we have
		 * seen OEM structures behind the end-of-table marker on
		 * some systems, so don't trust it.
		 */
		if (!dmi_num && dm->type == DMI_ENTRY_END_OF_TABLE)
			break;
	}

	/* Trim DMI table length if needed */
	if (dmi_len > data - buf)
		dmi_len = data - buf;
}

static phys_addr_t dmi_base;

static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,
		void *))
{
	u8 *buf;
	u32 orig_dmi_len = dmi_len;

	buf = dmi_early_remap(dmi_base, orig_dmi_len);
	if <