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Commit 83e68189 authored by Matt Fleming's avatar Matt Fleming Committed by H. Peter Anvin
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efi: Make 'efi_enabled' a function to query EFI facilities 

Originally 'efi_enabled' indicated whether a kernel was booted from
EFI firmware. Over time its semantics have changed, and it now
indicates whether or not we are booted on an EFI machine with
bit-native firmware, e.g. 64-bit kernel with 64-bit firmware.

The immediate motivation for this patch is the bug report at,

    https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557

which details how running a platform driver on an EFI machine that is
designed to run under BIOS can cause the machine to become
bricked. Also, the following report,

    https://bugzilla.kernel.org/show_bug.cgi?id=47121



details how running said driver can also cause Machine Check
Exceptions. Drivers need a new means of detecting whether they're
running on an EFI machine, as sadly the expression,

    if (!efi_enabled)

hasn't been a sufficient condition for quite some time.

Users actually want to query 'efi_enabled' for different reasons -
what they really want access to is the list of available EFI
facilities.

For instance, the x86 reboot code needs to know whether it can invoke
the ResetSystem() function provided by the EFI runtime services, while
the ACPI OSL code wants to know whether the EFI config tables were
mapped successfully. There are also checks in some of the platform
driver code to simply see if they're running on an EFI machine (which
would make it a bad idea to do BIOS-y things).

This patch is a prereq for the samsung-laptop fix patch.

Cc: David Airlie <airlied@linux.ie>
Cc: Corentin Chary <corentincj@iksaif.net>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Peter Jones <pjones@redhat.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Steve Langasek <steve.langasek@canonical.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad@kernel.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent f44310b9

arch/x86/include/asm/efi.h

+1 −0
Original line number Diff line number Diff line
@@ -94,6 +94,7 @@ extern void __iomem *efi_ioremap(unsigned long addr, unsigned long size, 
#endif /* CONFIG_X86_32 */



extern int add_efi_memmap;

extern unsigned long x86_efi_facility;

extern void efi_set_executable(efi_memory_desc_t *md, bool executable);

extern int efi_memblock_x86_reserve_range(void);

extern void efi_call_phys_prelog(void);

arch/x86/kernel/reboot.c

+1 −1
Original line number Diff line number Diff line
@@ -584,7 +584,7 @@ static void native_machine_emergency_restart(void) 
			break;



		case BOOT_EFI:

			if (efi_enabled)

			if (efi_enabled(EFI_RUNTIME_SERVICES))

				efi.reset_system(reboot_mode ?

						 EFI_RESET_WARM :

						 EFI_RESET_COLD,

arch/x86/kernel/setup.c

+14 −14
Original line number Diff line number Diff line
@@ -807,15 +807,15 @@ void __init setup_arch(char **cmdline_p) 
#ifdef CONFIG_EFI

	if (!strncmp((char *)&boot_params.efi_info.efi_loader_signature,

		     "EL32", 4)) {

		efi_enabled = 1;

		efi_64bit = false;

		set_bit(EFI_BOOT, &x86_efi_facility);

	} else if (!strncmp((char *)&boot_params.efi_info.efi_loader_signature,

		     "EL64", 4)) {

		efi_enabled = 1;

		efi_64bit = true;

		set_bit(EFI_BOOT, &x86_efi_facility);

		set_bit(EFI_64BIT, &x86_efi_facility);

	}

	if (efi_enabled && efi_memblock_x86_reserve_range())

		efi_enabled = 0;



	if (efi_enabled(EFI_BOOT))

		efi_memblock_x86_reserve_range();

#endif



	x86_init.oem.arch_setup();
@@ -888,7 +888,7 @@ void __init setup_arch(char **cmdline_p) 


	finish_e820_parsing();



	if (efi_enabled)

	if (efi_enabled(EFI_BOOT))

		efi_init();



	dmi_scan_machine();
@@ -971,7 +971,7 @@ void __init setup_arch(char **cmdline_p) 
	 * The EFI specification says that boot service code won't be called

	 * after ExitBootServices(). This is, in fact, a lie.

	 */

	if (efi_enabled)

	if (efi_enabled(EFI_MEMMAP))

		efi_reserve_boot_services();



	/* preallocate 4k for mptable mpc */
@@ -1114,7 +1114,7 @@ void __init setup_arch(char **cmdline_p) 


#ifdef CONFIG_VT

#if defined(CONFIG_VGA_CONSOLE)

	if (!efi_enabled || (efi_mem_type(0xa0000) != EFI_CONVENTIONAL_MEMORY))

	if (!efi_enabled(EFI_BOOT) || (efi_mem_type(0xa0000) != EFI_CONVENTIONAL_MEMORY))

		conswitchp = &vga_con;

#elif defined(CONFIG_DUMMY_CONSOLE)

	conswitchp = &dummy_con;
@@ -1131,14 +1131,14 @@ void __init setup_arch(char **cmdline_p) 
	register_refined_jiffies(CLOCK_TICK_RATE);



#ifdef CONFIG_EFI

	/* Once setup is done above, disable efi_enabled on mismatched

	 * firmware/kernel archtectures since there is no support for

	 * runtime services.

	/* Once setup is done above, unmap the EFI memory map on

	 * mismatched firmware/kernel archtectures since there is no

	 * support for runtime services.

	 */

	if (efi_enabled && IS_ENABLED(CONFIG_X86_64) != efi_64bit) {

	if (efi_enabled(EFI_BOOT) &&

	    IS_ENABLED(CONFIG_X86_64) != efi_enabled(EFI_64BIT)) {

		pr_info("efi: Setup done, disabling due to 32/64-bit mismatch\n");

		efi_unmap_memmap();

		efi_enabled = 0;

	}

#endif

}

arch/x86/platform/efi/efi.c

+34 −23
Original line number Diff line number Diff line
@@ -51,9 +51,6 @@ 


#define EFI_DEBUG	1



int efi_enabled;

EXPORT_SYMBOL(efi_enabled);



struct efi __read_mostly efi = {

	.mps        = EFI_INVALID_TABLE_ADDR,

	.acpi       = EFI_INVALID_TABLE_ADDR,
@@ -69,19 +66,28 @@ EXPORT_SYMBOL(efi); 


struct efi_memory_map memmap;



bool efi_64bit;



static struct efi efi_phys __initdata;

static efi_system_table_t efi_systab __initdata;



static inline bool efi_is_native(void)

{

	return IS_ENABLED(CONFIG_X86_64) == efi_64bit;

	return IS_ENABLED(CONFIG_X86_64) == efi_enabled(EFI_64BIT);

}



unsigned long x86_efi_facility;



/*

 * Returns 1 if 'facility' is enabled, 0 otherwise.

 */

int efi_enabled(int facility)

{

	return test_bit(facility, &x86_efi_facility) != 0;

}

EXPORT_SYMBOL(efi_enabled);



static int __init setup_noefi(char *arg)

{

	efi_enabled = 0;

	clear_bit(EFI_BOOT, &x86_efi_facility);

	return 0;

}

early_param("noefi", setup_noefi);
@@ -426,6 +432,7 @@ void __init efi_reserve_boot_services(void) 


void __init efi_unmap_memmap(void)

{

	clear_bit(EFI_MEMMAP, &x86_efi_facility);

	if (memmap.map) {

		early_iounmap(memmap.map, memmap.nr_map * memmap.desc_size);

		memmap.map = NULL;
@@ -460,7 +467,7 @@ void __init efi_free_boot_services(void) 


static int __init efi_systab_init(void *phys)

{

	if (efi_64bit) {

	if (efi_enabled(EFI_64BIT)) {

		efi_system_table_64_t *systab64;

		u64 tmp = 0;
@@ -552,7 +559,7 @@ static int __init efi_config_init(u64 tables, int nr_tables) 
	void *config_tables, *tablep;

	int i, sz;



	if (efi_64bit)

	if (efi_enabled(EFI_64BIT))

		sz = sizeof(efi_config_table_64_t);

	else

		sz = sizeof(efi_config_table_32_t);
@@ -572,7 +579,7 @@ static int __init efi_config_init(u64 tables, int nr_tables) 
		efi_guid_t guid;

		unsigned long table;



		if (efi_64bit) {

		if (efi_enabled(EFI_64BIT)) {

			u64 table64;

			guid = ((efi_config_table_64_t *)tablep)->guid;

			table64 = ((efi_config_table_64_t *)tablep)->table;
@@ -684,7 +691,6 @@ void __init efi_init(void) 
	if (boot_params.efi_info.efi_systab_hi ||

	    boot_params.efi_info.efi_memmap_hi) {

		pr_info("Table located above 4GB, disabling EFI.\n");

		efi_enabled = 0;

		return;

	}

	efi_phys.systab = (efi_system_table_t *)boot_params.efi_info.efi_systab;
@@ -694,10 +700,10 @@ void __init efi_init(void) 
			  ((__u64)boot_params.efi_info.efi_systab_hi<<32));

#endif



	if (efi_systab_init(efi_phys.systab)) {

		efi_enabled = 0;

	if (efi_systab_init(efi_phys.systab))

		return;

	}



	set_bit(EFI_SYSTEM_TABLES, &x86_efi_facility);



	/*

	 * Show what we know for posterity
@@ -715,10 +721,10 @@ void __init efi_init(void) 
		efi.systab->hdr.revision >> 16,

		efi.systab->hdr.revision & 0xffff, vendor);



	if (efi_config_init(efi.systab->tables, efi.systab->nr_tables)) {

		efi_enabled = 0;

	if (efi_config_init(efi.systab->tables, efi.systab->nr_tables))

		return;

	}



	set_bit(EFI_CONFIG_TABLES, &x86_efi_facility);



	/*

	 * Note: We currently don't support runtime services on an EFI
@@ -727,15 +733,17 @@ void __init efi_init(void) 


	if (!efi_is_native())

		pr_info("No EFI runtime due to 32/64-bit mismatch with kernel\n");

	else if (efi_runtime_init()) {

		efi_enabled = 0;

	else {

		if (efi_runtime_init())

			return;

		set_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);

	}



	if (efi_memmap_init()) {

		efi_enabled = 0;

	if (efi_memmap_init())

		return;

	}



	set_bit(EFI_MEMMAP, &x86_efi_facility);



#ifdef CONFIG_X86_32

	if (efi_is_native()) {

		x86_platform.get_wallclock = efi_get_time;
@@ -969,6 +977,9 @@ u32 efi_mem_type(unsigned long phys_addr) 
	efi_memory_desc_t *md;

	void *p;



	if (!efi_enabled(EFI_MEMMAP))

		return 0;



	for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {

		md = p;

		if ((md->phys_addr <= phys_addr) &&

drivers/acpi/osl.c

+1 −1
Original line number Diff line number Diff line
@@ -250,7 +250,7 @@ acpi_physical_address __init acpi_os_get_root_pointer(void) 
		return acpi_rsdp;

#endif



	if (efi_enabled) {

	if (efi_enabled(EFI_CONFIG_TABLES)) {

		if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)

			return efi.acpi20;

		else if (efi.acpi != EFI_INVALID_TABLE_ADDR)