linux-kernel - [PATCH 2/4] efi/random: use arch-independent efi_call

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Date:   Thu,  7 Nov 2019 16:10:34 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-kernel@...r.kernel.org,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Xinwei Kong <kong.kongxinwei@...ilicon.com>,
        Zou Cao <zoucao@...ux.alibaba.com>
Subject: [PATCH 2/4] efi/random: use arch-independent efi_call_proto()

From: Dominik Brodowski <linux@...inikbrodowski.net>

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@...inikbrodowski.net>
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 drivers/firmware/efi/libstub/random.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c
index b4b1d1dcb5fd..53f1466f7de6 100644
--- 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;
-- 
2.17.1