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 6e8fdf5ad1135c0100c8b7a5220bb79db2359ddb..28677c55113f8cea59e59c67e7cd53cfcd615b6d 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 4e8ba39eaf0fd93cbca557eaecf3efcd954ee05b..76fa1e9a2b39399b1944e4a13c68a054c9a5c386 100644 (file)
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -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,

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 86c524c504b0d97e4407e600557dbc8c84508021..0219cf2d6c7607d3aeeb0a748d1f33a889fc864b 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -809,15 +809,15 @@ 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();
@@ -890,7 +890,7 @@ void __init setup_arch(char **cmdline_p)
 
        finish_e820_parsing();
 
-       if (efi_enabled)
+       if (efi_enabled(EFI_BOOT))
                efi_init();
 
        dmi_scan_machine();
@@ -973,7 +973,7 @@ 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 */
@@ -1112,7 +1112,7 @@ 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;
@@ -1129,14 +1129,14 @@ 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
 }

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index ad4439145f858314dfe518cf7cd9336c5fe9c96d..5426e482db6e28bf00945f74f0a9ec4604fd6881 100644 (file)
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -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;
-               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;
@@ -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) &&

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 9eaf708f588553ee78b10bb6571e55859fb1db3c..251435a78aefa234e8334294af1326286e3a16dd 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 ad4c97345a6fc850f9da68ef06ca1f18abc01245..008d645983245b66e3b5530df4a37ff8a9cc16b6 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -429,7 +429,8 @@ 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 b74050b95d6af93ad5720baa39790b852a7f1413..9ac1e9dfa89caa97eb6db687429faf5f75ad2809 100644 (file)
--- a/drivers/scsi/isci/init.c
+++ b/drivers/scsi/isci/init.c
@@ -633,7 +633,7 @@ 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 8670eb1eb8cd27aea69ad00c6b08328e65b7ed79..b424f64cae4b97cece26a28910be656ee3566823 100644 (file)
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -542,18 +542,30 @@ 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 cd147a9187863b135e59a2d876a2080b62b7d3f1..857166fb9f315f5ede90e7e3ecdbccd5413bd89b 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -604,7 +604,7 @@ 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();
@@ -632,7 +632,7 @@ 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_late_init();
                efi_free_boot_services();
        }