drivers/firmware/efi/libstub/x86-stub.c

Source file repositories/reference/linux-study-clean/drivers/firmware/efi/libstub/x86-stub.c

File Facts

System
Linux kernel
Corpus path
drivers/firmware/efi/libstub/x86-stub.c
Extension
.c
Size
27650 bytes
Lines
1071
Domain
Driver Families
Bucket
drivers/firmware
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct smbios_entry_point {
	u8	anchor[4];
	u8	ep_checksum;
	u8	ep_length;
	u8	major_version;
	u8	minor_version;
	u16	max_size_entry;
	u8	ep_rev;
	u8	reserved[5];

	struct __packed {
		u8	anchor[5];
		u8	checksum;
		u16	st_length;
		u32	st_address;
		u16	number_of_entries;
		u8	bcd_rev;
	} intm;
};

static bool verify_ep_checksum(const void *ptr, int length)
{
	u8 sum = 0;

	for (int i = 0; i < length; i++)
		sum += ((u8 *)ptr)[i];

	return sum == 0;
}

static bool verify_ep_integrity(const struct smbios_entry_point *ep)
{
	if (memcmp(ep->anchor, "_SM_", sizeof(ep->anchor)) != 0)
		return false;

	if (memcmp(ep->intm.anchor, "_DMI_", sizeof(ep->intm.anchor)) != 0)
		return false;

	if (!verify_ep_checksum(ep, ep->ep_length) ||
	    !verify_ep_checksum(&ep->intm, sizeof(ep->intm)))
		return false;

	return true;
}

static const struct efi_smbios_record *search_record(void *table, u32 length,
						     u8 type)
{
	const u8 *p, *end;

	p = (u8 *)table;
	end = p + length;

	while (p + sizeof(struct efi_smbios_record) < end) {
		const struct efi_smbios_record *hdr =
			(struct efi_smbios_record *)p;
		const u8 *next;

		if (hdr->type == type)
			return hdr;

		/* Type 127 = End-of-Table */
		if (hdr->type == 0x7F)
			return NULL;

		/* Jumping to the unformed section */
		next = p + hdr->length;

		/* Unformed section ends with 0000h */
		while ((next[0] != 0 || next[1] != 0) && next + 1 < end)
			next++;

		next += 2;
		p = next;
	}

	return NULL;
}

static const struct efi_smbios_record *get_table_record(u8 type)
{
	const struct smbios_entry_point *ep;

	/*
	 * Locate the legacy 32-bit SMBIOS entrypoint in memory, and parse it
	 * directly. Needed by some Macs that do not implement the EFI protocol.
	 */
	ep = get_efi_config_table(SMBIOS_TABLE_GUID);
	if (!ep)
		return NULL;

Annotation

Implementation Notes