On Fri, 17 Jun, at 02:52:14PM, Octavian Purdila wrote:
> This patch allows SSDTs to be loaded from EFI variables. It works by
> specifying the EFI variable name containing the SSDT to be loaded. All
> variables with the same name (regardless of the vendor GUID) will be
> loaded.
>
> Note that we can't use acpi_install_table and we must rely on the
> dynamic ACPI table loading and bus re-scanning mechanisms. That is
> because I2C/SPI controllers are initialized earlier then the EFI
> subsystems and all I2C/SPI ACPI devices are enumerated when the
> I2C/SPI controllers are initialized.
>
> Signed-off-by: Octavian Purdila <[email protected]>
> ---
> Documentation/acpi/ssdt-overlays.txt | 67 ++++++++++++++++++++++
> Documentation/kernel-parameters.txt | 7 +++
> drivers/firmware/efi/efi.c | 106
> +++++++++++++++++++++++++++++++++++
> 3 files changed, 180 insertions(+)
[...]
> @@ -195,6 +197,107 @@ static void generic_ops_unregister(void)
> efivars_unregister(&generic_efivars);
> }
>
> +#if IS_ENABLED(CONFIG_ACPI)
> +#define EFIVAR_SSDT_NAME_MAX 16
> +static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX];
> +static int __init efivar_ssdt_setup(char *str)
> +{
> + if (strlen(str) < sizeof(efivar_ssdt))
> + memcpy(efivar_ssdt, str, strlen(str));
> + else
> + pr_warn("efivar_ssdt: name too long: %s\n", str);
> + return 0;
> +}
> +__setup("efivar_ssdt=", efivar_ssdt_setup);
> +
> +static LIST_HEAD(efivar_ssdts);
> +
> +static inline void pr_efivar_name(efi_char16_t *name16)
> +{
> + char name[EFIVAR_SSDT_NAME_MAX];
> + int i;
> +
> + for (i = 0; i < EFIVAR_SSDT_NAME_MAX - 1; i++)
> + name[i] = name16[i] & 0xFF;
> + name[i] = 0;
> + pr_cont("%s", name);
> +}
Please use the various ucs2_* functions we already have in lib/.
> +static __init int efivar_acpi_iter(efi_char16_t *name, efi_guid_t vendor,
> + unsigned long name_size, void *data)
> +{
> + int i;
> + int str_len = name_size / sizeof(efi_char16_t);
> + struct efivar_entry *entry;
> +
> + if (str_len != strlen(efivar_ssdt) + 1)
> + return 0;
> +
> + for (i = 0; i < str_len; i++)
> + if ((name[i] & 0xFF) != efivar_ssdt[i])
> + return 0;
> +
> + entry = kzalloc(sizeof(*entry), GFP_KERNEL);
> + if (!entry)
> + return -ENOMEM;
> +
> + memcpy(entry->var.VariableName, name, name_size);
> + memcpy(&entry->var.VendorGuid, &vendor, sizeof(efi_guid_t));
> +
> + efivar_entry_add(entry, &efivar_ssdts);
> +
> + return 0;
> +}
> +
> +static __init int efivar_ssdt_load(void)
> +{
> + struct efivar_entry *i;
> + int err;
> +
> + err = efivar_init(efivar_acpi_iter, NULL, true, &efivar_ssdts);
> + if (err) {
> + pr_err("%s: efivar_init failed: %d\n", __func__, err);
> + return err;
> + }
> +
> + list_for_each_entry(i, &efivar_ssdts, list) {
> + void *data;
> + unsigned long size;
> +
> + pr_info("loading SSDT from EFI variable ");
> + pr_efivar_name(i->var.VariableName); pr_cont("\n");
> +
> + err = efivar_entry_size(i, &size);
> + if (err) {
> + pr_err("failed to get size\n");
> + continue;
> + }
> +
> + data = kmalloc(size, GFP_KERNEL);
> + if (!data)
> + continue;
> +
> + err = efivar_entry_get(i, NULL, &size, data);
> + if (err) {
> + pr_err("failed to get data\n");
> + kfree(data);
> + continue;
> + }
> +
> + err = acpi_load_table(data);
> + if (err) {
> + pr_err("failed to load table: %d\n", err);
> + kfree(data);
> + continue;
> + }
> + }
> +
Since 'efivar_ssdts' isn't exported to userspace and is never
traversed again after its built in efivar_acpi_iter(), can't you just
fold the code from the above list_for_each_entry() loop into
efivar_acpi_iter()?
You should be able to call efivar_entry_get() without 'entry' actually
being on any list since the list is only used for duplicate variable
detection in this case.
