Commit 5b279a26 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Ingo Molnar
Browse files

efi/x86: Clean up efi_systab_init() routine for legibility 



Clean up the efi_systab_init() routine which maps the EFI system
table and copies the relevant pieces of data out of it.

The current routine is very difficult to read, so let's clean that
up. Also, switch to a R/O mapping of the system table since that is
all we need.

Finally, use a plain u64 variable to record the physical address of
the system table instead of pointlessly stashing it in a struct efi
that is never used for anything else.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Matthew Garrett <mjg59@google.com>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20200103113953.9571-13-ardb@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 33b85447

arch/x86/platform/efi/efi.c

+82 −84
Original line number Diff line number Diff line
@@ -54,8 +54,8 @@ 
#include <asm/x86_init.h>

#include <asm/uv/uv.h>



struct efi efi_phys __initdata;

static efi_system_table_t efi_systab __initdata;

static u64 efi_systab_phys __initdata;



static efi_config_table_type_t arch_tables[] __initdata = {

#ifdef CONFIG_X86_UV
@@ -327,74 +327,70 @@ void __init efi_print_memmap(void) 
	}

}



static int __init efi_systab_init(void *phys)

static int __init efi_systab_init(u64 phys)

{

	if (efi_enabled(EFI_64BIT)) {

		efi_system_table_64_t *systab64;

		struct efi_setup_data *data = NULL;

		u64 tmp = 0;

	int size = efi_enabled(EFI_64BIT) ? sizeof(efi_system_table_64_t)

					  : sizeof(efi_system_table_32_t);

	bool over4g = false;

	void *p;



		if (efi_setup) {

			data = early_memremap(efi_setup, sizeof(*data));

			if (!data)

				return -ENOMEM;

		}

		systab64 = early_memremap((unsigned long)phys,

					 sizeof(*systab64));

		if (systab64 == NULL) {

	p = early_memremap_ro(phys, size);

	if (p == NULL) {

		pr_err("Couldn't map the system table!\n");

			if (data)

				early_memunmap(data, sizeof(*data));

		return -ENOMEM;

	}



	if (efi_enabled(EFI_64BIT)) {

		const efi_system_table_64_t *systab64 = p;



		efi_systab.hdr			= systab64->hdr;

		efi_systab.fw_vendor = data ? (unsigned long)data->fw_vendor :

					      systab64->fw_vendor;

		tmp |= data ? data->fw_vendor : systab64->fw_vendor;

		efi_systab.fw_vendor		= systab64->fw_vendor;

		efi_systab.fw_revision		= systab64->fw_revision;

		efi_systab.con_in_handle	= systab64->con_in_handle;

		tmp |= systab64->con_in_handle;

		efi_systab.con_in		= systab64->con_in;

		tmp |= systab64->con_in;

		efi_systab.con_out_handle	= systab64->con_out_handle;

		tmp |= systab64->con_out_handle;

		efi_systab.con_out		= (void *)(unsigned long)systab64->con_out;

		tmp |= systab64->con_out;

		efi_systab.stderr_handle	= systab64->stderr_handle;

		tmp |= systab64->stderr_handle;

		efi_systab.stderr		= systab64->stderr;

		tmp |= systab64->stderr;

		efi_systab.runtime = data ?

				     (void *)(unsigned long)data->runtime :

				     (void *)(unsigned long)systab64->runtime;

		tmp |= data ? data->runtime : systab64->runtime;

		efi_systab.runtime		= (void *)(unsigned long)systab64->runtime;

		efi_systab.boottime		= (void *)(unsigned long)systab64->boottime;

		tmp |= systab64->boottime;

		efi_systab.nr_tables		= systab64->nr_tables;

		efi_systab.tables = data ? (unsigned long)data->tables :

					   systab64->tables;

		tmp |= data ? data->tables : systab64->tables;

		efi_systab.tables		= systab64->tables;



		early_memunmap(systab64, sizeof(*systab64));

		if (data)

			early_memunmap(data, sizeof(*data));

#ifdef CONFIG_X86_32

		if (tmp >> 32) {

			pr_err("EFI data located above 4GB, disabling EFI.\n");

			return -EINVAL;

		}

#endif

	} else {

		efi_system_table_32_t *systab32;

		over4g = systab64->con_in_handle	> U32_MAX ||

			 systab64->con_in		> U32_MAX ||

			 systab64->con_out_handle	> U32_MAX ||

			 systab64->con_out		> U32_MAX ||

			 systab64->stderr_handle	> U32_MAX ||

			 systab64->stderr		> U32_MAX ||

			 systab64->boottime		> U32_MAX;



		systab32 = early_memremap((unsigned long)phys,

					 sizeof(*systab32));

		if (systab32 == NULL) {

			pr_err("Couldn't map the system table!\n");

		if (efi_setup) {

			struct efi_setup_data *data;



			data = early_memremap_ro(efi_setup, sizeof(*data));

			if (!data) {

				early_memunmap(p, size);

				return -ENOMEM;

			}



			efi_systab.fw_vendor	= (unsigned long)data->fw_vendor;

			efi_systab.runtime	= (void *)(unsigned long)data->runtime;

			efi_systab.tables	= (unsigned long)data->tables;



			over4g |= data->fw_vendor	> U32_MAX ||

				  data->runtime		> U32_MAX ||

				  data->tables		> U32_MAX;



			early_memunmap(data, sizeof(*data));

		} else {

			over4g |= systab64->fw_vendor	> U32_MAX ||

				  systab64->runtime	> U32_MAX ||

				  systab64->tables	> U32_MAX;

		}

	} else {

		const efi_system_table_32_t *systab32 = p;



		efi_systab.hdr			= systab32->hdr;

		efi_systab.fw_vendor		= systab32->fw_vendor;

		efi_systab.fw_revision		= systab32->fw_revision;
@@ -408,8 +404,13 @@ static int __init efi_systab_init(void *phys) 
		efi_systab.boottime		= (void *)(unsigned long)systab32->boottime;

		efi_systab.nr_tables		= systab32->nr_tables;

		efi_systab.tables		= systab32->tables;

	}



	early_memunmap(p, size);



		early_memunmap(systab32, sizeof(*systab32));

	if (IS_ENABLED(CONFIG_X86_32) && over4g) {

		pr_err("EFI data located above 4GB, disabling EFI.\n");

		return -EINVAL;

	}



	efi.systab = &efi_systab;
@@ -435,20 +436,17 @@ void __init efi_init(void) 
	char vendor[100] = "unknown";

	int i = 0;



#ifdef CONFIG_X86_32

	if (boot_params.efi_info.efi_systab_hi ||

	    boot_params.efi_info.efi_memmap_hi) {

	if (IS_ENABLED(CONFIG_X86_32) &&

	    (boot_params.efi_info.efi_systab_hi ||

	     boot_params.efi_info.efi_memmap_hi)) {

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

		return;

	}

	efi_phys.systab = (efi_system_table_t *)boot_params.efi_info.efi_systab;

#else

	efi_phys.systab = (efi_system_table_t *)

			  (boot_params.efi_info.efi_systab |

			  ((__u64)boot_params.efi_info.efi_systab_hi<<32));

#endif



	if (efi_systab_init(efi_phys.systab))

	efi_systab_phys = boot_params.efi_info.efi_systab |

			  ((__u64)boot_params.efi_info.efi_systab_hi << 32);



	if (efi_systab_init(efi_systab_phys))

		return;



	efi.config_table = (unsigned long)efi.systab->tables;
@@ -601,7 +599,7 @@ static void __init get_systab_virt_addr(efi_memory_desc_t *md) 


	size = md->num_pages << EFI_PAGE_SHIFT;

	end = md->phys_addr + size;

	systab = (u64)(unsigned long)efi_phys.systab;

	systab = efi_systab_phys;

	if (md->phys_addr <= systab && systab < end) {

		systab += md->virt_addr - md->phys_addr;

		efi.systab = (efi_system_table_t *)(unsigned long)systab;

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