Commit eb684408 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

arm64: efi: Use SMBIOS processor version to key off Ampere quirk 



Instead of using the SMBIOS type 1 record 'family' field, which is often
modified by OEMs, use the type 4 'processor ID' and 'processor version'
fields, which are set to a small set of probe-able values on all known
Ampere EFI systems in the field.

Fixes: 550b33cf ("arm64: efi: Force the use of ...")
Tested-by: default avatarAndrea Righi <andrea.righi@canonical.com>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 34343eb0

drivers/firmware/efi/libstub/arm64.c

+31 −8
Original line number Diff line number Diff line
@@ -16,22 +16,45 @@ 


static bool system_needs_vamap(void)

{

	const u8 *type1_family = efi_get_smbios_string(1, family);

	const struct efi_smbios_type4_record *record;

	const u32 __aligned(1) *socid;

	const u8 *version;



	/*

	 * Ampere eMAG, Altra, and Altra Max machines crash in SetTime() if

	 * SetVirtualAddressMap() has not been called prior.

	 * SetVirtualAddressMap() has not been called prior. Most Altra systems

	 * can be identified by the SMCCC soc ID, which is conveniently exposed

	 * via the type 4 SMBIOS records. Otherwise, test the processor version

	 * field. eMAG systems all appear to have the processor version field

	 * set to "eMAG".

	 */

	if (!type1_family || (

	    strcmp(type1_family, "eMAG") &&

	    strcmp(type1_family, "Altra") &&

	    strcmp(type1_family, "Altra Max")))

	record = (struct efi_smbios_type4_record *)efi_get_smbios_record(4);

	if (!record)

		return false;



	socid = (u32 *)record->processor_id;

	switch (*socid & 0xffff000f) {

		static char const altra[] = "Ampere(TM) Altra(TM) Processor";

		static char const emag[] = "eMAG";



	default:

		version = efi_get_smbios_string(&record->header, 4,

						processor_version);

		if (!version || (strncmp(version, altra, sizeof(altra) - 1) &&

				 strncmp(version, emag, sizeof(emag) - 1)))

			break;



		fallthrough;



	case 0x0a160001:	// Altra

	case 0x0a160002:	// Altra Max

		efi_warn("Working around broken SetVirtualAddressMap()\n");

		return true;

	}



	return false;

}



efi_status_t check_platform_features(void)

{

	u64 tg;

drivers/firmware/efi/libstub/efistub.h

+38 −3
Original line number Diff line number Diff line
@@ -1074,6 +1074,8 @@ struct efi_smbios_record { 
	u16	handle;

};



const struct efi_smbios_record *efi_get_smbios_record(u8 type);



struct efi_smbios_type1_record {

	struct efi_smbios_record	header;
@@ -1087,14 +1089,47 @@ struct efi_smbios_type1_record { 
	u8				family;

};



#define efi_get_smbios_string(__type, __name) ({			\

struct efi_smbios_type4_record {

	struct efi_smbios_record	header;



	u8				socket;

	u8				processor_type;

	u8				processor_family;

	u8				processor_manufacturer;

	u8				processor_id[8];

	u8				processor_version;

	u8				voltage;

	u16				external_clock;

	u16				max_speed;

	u16				current_speed;

	u8				status;

	u8				processor_upgrade;

	u16				l1_cache_handle;

	u16				l2_cache_handle;

	u16				l3_cache_handle;

	u8				serial_number;

	u8				asset_tag;

	u8				part_number;

	u8				core_count;

	u8				enabled_core_count;

	u8				thread_count;

	u16				processor_characteristics;

	u16				processor_family2;

	u16				core_count2;

	u16				enabled_core_count2;

	u16				thread_count2;

	u16				thread_enabled;

};



#define efi_get_smbios_string(__record, __type, __name) ({		\

	int size = sizeof(struct efi_smbios_type ## __type ## _record);	\

	int off = offsetof(struct efi_smbios_type ## __type ## _record,	\

			   __name);					\

	__efi_get_smbios_string(__type, off, size);			\

	__efi_get_smbios_string((__record), __type, off, size);		\

})



const u8 *__efi_get_smbios_string(u8 type, int offset, int recsize);

const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record,

				  u8 type, int offset, int recsize);



void efi_remap_image(unsigned long image_base, unsigned alloc_size,

		     unsigned long code_size);

drivers/firmware/efi/libstub/smbios.c

+11 −2
Original line number Diff line number Diff line
@@ -22,19 +22,28 @@ struct efi_smbios_protocol { 
	u8 minor_version;

};



const u8 *__efi_get_smbios_string(u8 type, int offset, int recsize)

const struct efi_smbios_record *efi_get_smbios_record(u8 type)

{

	struct efi_smbios_record *record;

	efi_smbios_protocol_t *smbios;

	efi_status_t status;

	u16 handle = 0xfffe;

	const u8 *strtable;



	status = efi_bs_call(locate_protocol, &EFI_SMBIOS_PROTOCOL_GUID, NULL,

			     (void **)&smbios) ?:

		 efi_call_proto(smbios, get_next, &handle, &type, &record, NULL);

	if (status != EFI_SUCCESS)

		return NULL;

	return record;

}



const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record,

				  u8 type, int offset, int recsize)

{

	const u8 *strtable;



	if (!record)

		return NULL;



	strtable = (u8 *)record + record->length;

	for (int i = 1; i < ((u8 *)record)[offset]; i++) {