efi: Make 'efi_enabled' a function to query EFI facilities

commit 83e68189745ad931c2afd45d8ee3303929233e7f upstream.

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.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
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>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 029189db84dedbe7e81180198ab7b1a10faf9026..da37433e36288407ca589f621aad8317861c6894 100644 (file)
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -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);

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 3034ee5afb0f6c45b09ce3207e8f45f4fc9f0089..df1b604c0c1fdbf90aef4effe1625f8c33ec1c2e 100644 (file)
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -619,7 +619,7 @@ 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,

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b71e4a533ccd980ecc211c7b3e128a37742406f4..537dc033868d57bee3324aca885d312f5574076c 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -818,15 +818,15 @@ 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();
@@ -899,7 +899,7 @@ void __init setup_arch(char **cmdline_p)
 
        finish_e820_parsing();
 
-       if (efi_enabled)
+       if (efi_enabled(EFI_BOOT))
                efi_init();
 
        dmi_scan_machine();
@@ -982,7 +982,7 @@ 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 */
@@ -1119,7 +1119,7 @@ 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;
@@ -1136,14 +1136,14 @@ void __init setup_arch(char **cmdline_p)
        arch_init_ideal_nops();
 
 #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
 }

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 6825327d00a703529574eb147e75a47afdf8c5e2..6fcd4ad9bb62275a96602a34df81da22ca2ab243 100644 (file)
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -50,9 +50,6 @@
 
 #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,
@@ -68,19 +65,28 @@ 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);
@@ -425,6 +431,7 @@ 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;
@@ -459,7 +466,7 @@ 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;
 
@@ -551,7 +558,7 @@ 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);
@@ -571,7 +578,7 @@ 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;
@@ -683,7 +690,6 @@ 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;
@@ -693,10 +699,10 @@ 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
@@ -714,10 +720,10 @@ 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
@@ -726,15 +732,17 @@ 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;
-               return;
+       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;
@@ -943,6 +951,9 @@ u64 efi_mem_attributes(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) &&

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index c3881b2eb8b2c5a0ac9b353aa7d7bdd699001ba0..f48720cf96fffa89dedfbf7eb3de1668e09d1de4 100644 (file)
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -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)

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index fd3ae6290d71ecfd927cc4447a942c099bd223ea..982f1f5f5742f21da9206f62fa622ce17adefe9f 100644 (file)
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -471,7 +471,7 @@ void __init dmi_scan_machine(void)
        char __iomem *p, *q;
        int rc;
 
-       if (efi_enabled) {
+       if (efi_enabled(EFI_CONFIG_TABLES)) {
                if (efi.smbios == EFI_INVALID_TABLE_ADDR)
                        goto error;
 

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index d10c9873dd9a8684d7137e49245afc9b40d13d60..bfd8f4392492a442bab14f76aef7ab12c49d3ce7 100644 (file)
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -1224,7 +1224,7 @@ efivars_init(void)
        printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
               EFIVARS_DATE);
 
-       if (!efi_enabled)
+       if (!efi_enabled(EFI_RUNTIME_SERVICES))
                return 0;
 
        /* For now we'll register the efi directory at /sys/firmware/efi */
@@ -1262,7 +1262,7 @@ err_put:
 static void __exit
 efivars_exit(void)
 {
-       if (efi_enabled) {
+       if (efi_enabled(EFI_RUNTIME_SERVICES)) {
                unregister_efivars(&__efivars);
                kobject_put(efi_kobj);
        }

diff --git a/drivers/firmware/iscsi_ibft_find.c b/drivers/firmware/iscsi_ibft_find.c
index 4da4eb9ae92604c35349ebaeb39b4a612bac3ed6..2224f1dc074b1329d7ce9c80b78bef4fffc6e98b 100644 (file)
--- a/drivers/firmware/iscsi_ibft_find.c
+++ b/drivers/firmware/iscsi_ibft_find.c
@@ -99,7 +99,7 @@ unsigned long __init find_ibft_region(unsigned long *sizep)
        /* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
         * only use ACPI for this */
 
-       if (!efi_enabled)
+       if (!efi_enabled(EFI_BOOT))
                find_ibft_in_mem();
 
        if (ibft_addr) {

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index de5e0b51dc63af93dc62fc455f51e610990ec6d7..68c89dbfd976211d239df916767035bbdd7dc657 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -358,7 +358,8 @@ bool radeon_card_posted(struct radeon_device *rdev)
 {
        uint32_t reg;
 
-       if (efi_enabled && rdev->pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE)
+       if (efi_enabled(EFI_BOOT) &&
+           rdev->pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE)
                return false;
 
        /* first check CRTCs */

diff --git a/drivers/platform/x86/ibm_rtl.c b/drivers/platform/x86/ibm_rtl.c
index 7481146a5b473c1cab6745a7d6ac1ae76e66257e..97c2be195efc36eeb76bd848f2c1327be7f168c2 100644 (file)
--- a/drivers/platform/x86/ibm_rtl.c
+++ b/drivers/platform/x86/ibm_rtl.c
@@ -244,7 +244,7 @@ static int __init ibm_rtl_init(void) {
        if (force)
                pr_warn("module loaded by force\n");
        /* first ensure that we are running on IBM HW */
-       else if (efi_enabled || !dmi_check_system(ibm_rtl_dmi_table))
+       else if (efi_enabled(EFI_BOOT) || !dmi_check_system(ibm_rtl_dmi_table))
                return -ENODEV;
 
        /* Get the address for the Extended BIOS Data Area */

diff --git a/drivers/scsi/isci/init.c b/drivers/scsi/isci/init.c
index 4c150dffb1abf8f38774a656d5f0e3ccc8f76533..5a1bd0ca2bb90b4130975bfe81b374c56d584de2 100644 (file)
--- a/drivers/scsi/isci/init.c
+++ b/drivers/scsi/isci/init.c
@@ -470,7 +470,7 @@ static int __devinit isci_pci_probe(struct pci_dev *pdev, const struct pci_devic
                return -ENOMEM;
        pci_set_drvdata(pdev, pci_info);
 
-       if (efi_enabled)
+       if (efi_enabled(EFI_RUNTIME_SERVICES))
                orom = isci_get_efi_var(pdev);
 
        if (!orom)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 5782114f4838658fc75802ba5e26e68e64ff2ed7..eee8b0b190ea0b92bf7aeb4e5edf756a272ed6ea 100644 (file)
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -539,18 +539,30 @@ extern int __init efi_setup_pcdp_console(char *);
 #endif
 
 /*
- * We play games with efi_enabled so that the compiler will, if possible, remove
- * EFI-related code altogether.
+ * We play games with efi_enabled so that the compiler will, if
+ * possible, remove EFI-related code altogether.
  */
+#define EFI_BOOT               0       /* Were we booted from EFI? */
+#define EFI_SYSTEM_TABLES      1       /* Can we use EFI system tables? */
+#define EFI_CONFIG_TABLES      2       /* Can we use EFI config tables? */
+#define EFI_RUNTIME_SERVICES   3       /* Can we use runtime services? */
+#define EFI_MEMMAP             4       /* Can we use EFI memory map? */
+#define EFI_64BIT              5       /* Is the firmware 64-bit? */
+
 #ifdef CONFIG_EFI
 # ifdef CONFIG_X86
-   extern int efi_enabled;
-   extern bool efi_64bit;
+extern int efi_enabled(int facility);
 # else
-#  define efi_enabled 1
+static inline int efi_enabled(int facility)
+{
+       return 1;
+}
 # endif
 #else
-# define efi_enabled 0
+static inline int efi_enabled(int facility)
+{
+       return 0;
+}
 #endif
 
 /*

diff --git a/init/main.c b/init/main.c
index c2178d267c1ae8e7948832cdeba0c96b76b9b35d..02c1384657808b9676d56a6fe9a09c8b490d3c29 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -602,7 +602,7 @@ asmlinkage void __init start_kernel(void)
        pidmap_init();
        anon_vma_init();
 #ifdef CONFIG_X86
-       if (efi_enabled)
+       if (efi_enabled(EFI_RUNTIME_SERVICES))
                efi_enter_virtual_mode();
 #endif
        thread_info_cache_init();
@@ -630,7 +630,7 @@ asmlinkage void __init start_kernel(void)
        acpi_early_init(); /* before LAPIC and SMP init */
        sfi_init_late();
 
-       if (efi_enabled)
+       if (efi_enabled(EFI_RUNTIME_SERVICES))
                efi_free_boot_services();
 
        ftrace_init();