[PATCH v7 07/12] efi: export more efi table variable to sysfs

Dave Young
2013-12-20T10:04:36Z

Export fw_vendor, runtime and config table physical addresses to
/sys/firmware/efi/{fw_vendor,runtime,config_table} because kexec kernel
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
Boris: add macros for _show functions, documentation fixes.
Matt: Documentation fixes.

Signed-off-by: Dave Young <dyoung@redhat.com>
---
Documentation/ABI/testing/sysfs-firmware-efi | 20 ++++++++++++++
arch/x86/platform/efi/efi.c | 4 +++
drivers/firmware/efi/efi.c | 41 +++++++++++++++++++++++++++-
include/linux/efi.h | 3 ++
4 files changed, 67 insertions(+), 1 deletion(-)
create mode 100644 Documentation/ABI/testing/sysfs-firmware-efi

diff --git a/Documentation/ABI/testing/sysfs-firmware-efi b/Documentation/ABI/testing/sysfs-firmware-efi
new file mode 100644
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 fd49100..d12d145 100644
--- 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 b716a66..6d0bc52 100644
--- 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 49ece2c..988af61 100644
--- 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;
--
1.8.3.1