Re: [patch 5/9 v3] efi: export more efi table variable to sysfs

Greg KH
2013-11-21T16:42:27Z

On Thu, Nov 21, 2013 at 02:17:09PM +0800, dyoung@redhat.com wrote:
> 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
>
> Signed-off-by: Dave Young <dyoung@redhat.com>
> ---
> Documentation/ABI/testing/sysfs-firmware-efi | 26 +++++++++
> arch/x86/platform/efi/efi.c | 4 +
> drivers/firmware/efi/efi.c | 71 +++++++++++++++++++++++++--
> include/linux/efi.h | 3 +
> 4 files changed, 101 insertions(+), 3 deletions(-)
>
> --- 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);
>
> @@ -71,6 +74,31 @@ 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(fw_vendor, 0400, fw_vendor_show, NULL);
> +static struct kobj_attribute efi_attr_runtime =
> + __ATTR(runtime, 0400, runtime_show, NULL);
> +static struct kobj_attribute efi_attr_config_table =
> + __ATTR(config_table, 0400, config_table_show, NULL);
> +
> static struct attribute *efi_subsys_attrs[] = {
> &efi_attr_systab.attr,
> NULL, /* maybe more in the future? */
> @@ -123,21 +151,58 @@ static int __init efisubsys_init(void)
>
> error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
> if (error) {
> - pr_err("efi: Sysfs attribute export failed with error %d.\n",
> - error);
> + pr_err("efi: Sysfs attribute %s export failed with error %d.\n",
> + efi_attr_systab.attr.name, error);
> goto err_unregister;
> }
>
> + if (efi.fw_vendor != EFI_INVALID_TABLE_ADDR) {
> + error = sysfs_create_file(efi_kobj, &efi_attr_fw_vendor.attr);
> + if (error) {
> + pr_err("efi: Sysfs attribute %s export failed with error %d.\n",
> + efi_attr_fw_vendor.attr.name, error);
> + goto err_remove_group;
> + }
> + }
> +
> + if (efi.runtime != EFI_INVALID_TABLE_ADDR) {
> + error = sysfs_create_file(efi_kobj, &efi_attr_runtime.attr);
> + if (error) {
> + pr_err("efi: Sysfs attribute %s export failed with error %d.\n",
> + efi_attr_runtime.attr.name, error);
> + goto err_remove_fw_vendor;
> + }
> + }
> +
> + if (efi.config_table != EFI_INVALID_TABLE_ADDR) {
> + error = sysfs_create_file(efi_kobj,
> + &efi_attr_config_table.attr);
> + if (error) {
> + pr_err("efi: Sysfs attribute %s export failed with error %d.\n",
> + efi_attr_config_table.attr.name, error);
> + goto err_remove_runtime;
> + }
> + }

You don't need to do this "if SOMETHING then create the file", just use
the "is_visible" attribute in the group to do this as a callback to
determine this when the group is registered.

That should clean up this logic a bunch.

thanks,

greg k-h