efi: Export more EFI table variables to sysfs

Export fw_vendor, runtime and config table physical addresses to
/sys/firmware/efi/{fw_vendor,runtime,config_table} because kexec kernels
need them.

From EFI spec these 3 variables will be updated to virtual address after
entering virtual mode. But kernel startup code will need the physical
address.

Signed-off-by: Dave Young <dyoung@redhat.com>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --git a/Documentation/ABI/testing/sysfs-firmware-efi b/Documentation/ABI/testing/sysfs-firmware-efi
new file mode 100644 (file)
index 0000000..05874da
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-efi
@@ -0,0 +1,20 @@
+What:          /sys/firmware/efi/fw_vendor
+Date:          December 2013
+Contact:       Dave Young <dyoung@redhat.com>
+Description:   It shows the physical address of firmware vendor field in the
+               EFI system table.
+Users:         Kexec
+
+What:          /sys/firmware/efi/runtime
+Date:          December 2013
+Contact:       Dave Young <dyoung@redhat.com>
+Description:   It shows the physical address of runtime service table entry in
+               the EFI system table.
+Users:         Kexec
+
+What:          /sys/firmware/efi/config_table
+Date:          December 2013
+Contact:       Dave Young <dyoung@redhat.com>
+Description:   It shows the physical address of config table entry in the EFI
+               system table.
+Users:         Kexec

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 4694632..2859107 100644 (file)
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -653,6 +653,10 @@ void __init efi_init(void)
 
        set_bit(EFI_SYSTEM_TABLES, &x86_efi_facility);
 
+       efi.config_table = (unsigned long)efi.systab->tables;
+       efi.fw_vendor    = (unsigned long)efi.systab->fw_vendor;
+       efi.runtime      = (unsigned long)efi.systab->runtime;
+
        /*
         * Show what we know for posterity
         */

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 2e2fbde..72533af 100644 (file)
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -32,6 +32,9 @@ struct efi __read_mostly efi = {
        .hcdp       = EFI_INVALID_TABLE_ADDR,
        .uga        = EFI_INVALID_TABLE_ADDR,
        .uv_systab  = EFI_INVALID_TABLE_ADDR,
+       .fw_vendor  = EFI_INVALID_TABLE_ADDR,
+       .runtime    = EFI_INVALID_TABLE_ADDR,
+       .config_table  = EFI_INVALID_TABLE_ADDR,
 };
 EXPORT_SYMBOL(efi);
 
@@ -71,13 +74,49 @@ static ssize_t systab_show(struct kobject *kobj,
 static struct kobj_attribute efi_attr_systab =
                        __ATTR(systab, 0400, systab_show, NULL);
 
+#define EFI_FIELD(var) efi.var
+
+#define EFI_ATTR_SHOW(name) \
+static ssize_t name##_show(struct kobject *kobj, \
+                               struct kobj_attribute *attr, char *buf) \
+{ \
+       return sprintf(buf, "0x%lx\n", EFI_FIELD(name)); \
+}
+
+EFI_ATTR_SHOW(fw_vendor);
+EFI_ATTR_SHOW(runtime);
+EFI_ATTR_SHOW(config_table);
+
+static struct kobj_attribute efi_attr_fw_vendor = __ATTR_RO(fw_vendor);
+static struct kobj_attribute efi_attr_runtime = __ATTR_RO(runtime);
+static struct kobj_attribute efi_attr_config_table = __ATTR_RO(config_table);
+
 static struct attribute *efi_subsys_attrs[] = {
        &efi_attr_systab.attr,
-       NULL,   /* maybe more in the future? */
+       &efi_attr_fw_vendor.attr,
+       &efi_attr_runtime.attr,
+       &efi_attr_config_table.attr,
+       NULL,
 };
 
+static umode_t efi_attr_is_visible(struct kobject *kobj,
+                                  struct attribute *attr, int n)
+{
+       umode_t mode = attr->mode;
+
+       if (attr == &efi_attr_fw_vendor.attr)
+               return (efi.fw_vendor == EFI_INVALID_TABLE_ADDR) ? 0 : mode;
+       else if (attr == &efi_attr_runtime.attr)
+               return (efi.runtime == EFI_INVALID_TABLE_ADDR) ? 0 : mode;
+       else if (attr == &efi_attr_config_table.attr)
+               return (efi.config_table == EFI_INVALID_TABLE_ADDR) ? 0 : mode;
+
+       return mode;
+}
+
 static struct attribute_group efi_subsys_attr_group = {
        .attrs = efi_subsys_attrs,
+       .is_visible = efi_attr_is_visible,
 };
 
 static struct efivars generic_efivars;

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 6c0ca52..fb60b10 100644 (file)
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -556,6 +556,9 @@ extern struct efi {
        unsigned long hcdp;             /* HCDP table */
        unsigned long uga;              /* UGA table */
        unsigned long uv_systab;        /* UV system table */
+       unsigned long fw_vendor;        /* fw_vendor */
+       unsigned long runtime;          /* runtime table */
+       unsigned long config_table;     /* config tables */
        efi_get_time_t *get_time;
        efi_set_time_t *set_time;
        efi_get_wakeup_time_t *get_wakeup_time;