efi/random: use arch-independent efi_call_proto()

To handle all arch-specific peculiarities when calling an EFI protocol
function, a wrapper efi_call_proto() exists on all relevant architectures.
On arm/arm64, this is merely a plain function call. On x86, a special EFI
entry stub needs to be used, however, as the calling convention differs.
To make the efi/random stub arch-independent, use efi_call_proto()
instead of the existing non-portable calls to the EFI get_rng protocol
function. This also requires the addition of some typedefs.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c
index b4b1d1dcb5fdc0ce690af90e65b1ddfcdf898f74..53f1466f7de68d7206b5250ee891ab2731f23cec 100644 (file)
--- a/drivers/firmware/efi/libstub/random.c
+++ b/drivers/firmware/efi/libstub/random.c
@@ -9,6 +9,18 @@
 
 #include "efistub.h"
 
+typedef struct efi_rng_protocol efi_rng_protocol_t;
+
+typedef struct {
+       u32 get_info;
+       u32 get_rng;
+} efi_rng_protocol_32_t;
+
+typedef struct {
+       u64 get_info;
+       u64 get_rng;
+} efi_rng_protocol_64_t;
+
 struct efi_rng_protocol {
        efi_status_t (*get_info)(struct efi_rng_protocol *,
                                 unsigned long *, efi_guid_t *);
@@ -28,7 +40,7 @@ efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg,
        if (status != EFI_SUCCESS)
                return status;
 
-       return rng->get_rng(rng, NULL, size, out);
+       return efi_call_proto(efi_rng_protocol, get_rng, rng, NULL, size, out);
 }
 
 /*
@@ -161,15 +173,16 @@ efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg)
        if (status != EFI_SUCCESS)
                return status;
 
-       status = rng->get_rng(rng, &rng_algo_raw, EFI_RANDOM_SEED_SIZE,
-                             seed->bits);
+       status = efi_call_proto(efi_rng_protocol, get_rng, rng, &rng_algo_raw,
+                                EFI_RANDOM_SEED_SIZE, seed->bits);
+
        if (status == EFI_UNSUPPORTED)
                /*
                 * Use whatever algorithm we have available if the raw algorithm
                 * is not implemented.
                 */
-               status = rng->get_rng(rng, NULL, EFI_RANDOM_SEED_SIZE,
-                                     seed->bits);
+               status = efi_call_proto(efi_rng_protocol, get_rng, rng, NULL,
+                                        EFI_RANDOM_SEED_SIZE, seed->bits);
 
        if (status != EFI_SUCCESS)
                goto err_freepool;