Export fw_vendor, runtime and config tables physical
addresses to /sys/firmware/efi/systab becaue kexec
kernel will 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.

changelog:
Greg: add standalone sysfs files instead of add lines to systab
Document them as testing ABI
Greg: use group attrs and is_visible
Boris: align comments lines

Signed-off-by: Dave Young <dyo...@redhat.com>
---
 Documentation/ABI/testing/sysfs-firmware-efi |   26 +++++++++++++++
 arch/x86/platform/efi/efi.c                  |    4 ++
 drivers/firmware/efi/efi.c                   |   44 +++++++++++++++++++++++++++
 include/linux/efi.h                          |    3 +
 4 files changed, 77 insertions(+)

--- efi.orig/drivers/firmware/efi/efi.c
+++ efi/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 +74,54 @@ static ssize_t systab_show(struct kobjec
 static struct kobj_attribute efi_attr_systab =
                        __ATTR(systab, 0400, systab_show, NULL);
 
+static ssize_t fw_vendor_show(struct kobject *kobj,
+                               struct kobj_attribute *attr, char *buf)
+{
+       return sprintf(buf, "0x%lx\n", efi.fw_vendor);
+}
+
+static ssize_t runtime_show(struct kobject *kobj,
+                               struct kobj_attribute *attr, char *buf)
+{
+       return sprintf(buf, "0x%lx\n", efi.runtime);
+}
+
+static ssize_t config_table_show(struct kobject *kobj,
+                               struct kobj_attribute *attr, char *buf)
+{
+       return sprintf(buf, "0x%lx\n", efi.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,
+       &efi_attr_fw_vendor.attr,
+       &efi_attr_runtime.attr,
+       &efi_attr_config_table.attr,
        NULL,   /* maybe more in the future? */
 };
 
+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;
--- efi.orig/include/linux/efi.h
+++ efi/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;
--- efi.orig/arch/x86/platform/efi/efi.c
+++ efi/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
         */
--- /dev/null
+++ efi/Documentation/ABI/testing/sysfs-firmware-efi
@@ -0,0 +1,26 @@
+What:          /sys/firmware/efi/fw_vendor
+Date:          Nov 2013
+Contact:       Dave Young <dyo...@redhat.org>
+Description:
+               Shows the physical address of firmware vendor in the EFI
+               system table.
+Users:
+               Kexec Mailing List <ke...@lists.infradead.org>
+
+What:          /sys/firmware/efi/runtime
+Date:          Nov 2013
+Contact:       Dave Young <dyo...@redhat.org>
+Description:
+               Shows the physical address of runtime service table in the
+               EFI system table.
+Users:
+               Kexec Mailing List <ke...@lists.infradead.org>
+
+What:          /sys/firmware/efi/config_table
+Date:          Nov 2013
+Contact:       Dave Young <dyo...@redhat.org>
+Description:
+               Shows the physical address of config table in the EFI
+               system table.
+Users:
+               Kexec Mailing List <ke...@lists.infradead.org>

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