From: Ard Biesheuvel <ardb@kernel.org>
Date: Wed, 22 Jan 2020 14:58:15 +0100
Subject: efi: Make rng_seed table handling local to efi.c
Patch-mainline: v5.7-rc1
Git-commit: 5d288dbd88606d8f215c7138b10649115d79cadd
References: jsc#SLE-16407

Move the rng_seed table address from struct efi into a static global
variable in efi.c, which is the only place we ever refer to it anyway.
This reduces the footprint of struct efi, which is a r/w data structure
that is shared with the world.

Tested-by: Tony Luck <tony.luck@intel.com> # arch/ia64
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
 drivers/firmware/efi/efi.c |   21 ++++++++++-----------
 include/linux/efi.h        |    1 -
 2 files changed, 10 insertions(+), 12 deletions(-)

--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -45,13 +45,14 @@ struct efi __read_mostly efi = {
 	.config_table		= EFI_INVALID_TABLE_ADDR,
 	.esrt			= EFI_INVALID_TABLE_ADDR,
 	.mem_attr_table		= EFI_INVALID_TABLE_ADDR,
-	.rng_seed		= EFI_INVALID_TABLE_ADDR,
 	.tpm_log		= EFI_INVALID_TABLE_ADDR,
 	.tpm_final_log		= EFI_INVALID_TABLE_ADDR,
 	.mem_reserve		= EFI_INVALID_TABLE_ADDR,
 };
 EXPORT_SYMBOL(efi);
 
+static unsigned long __ro_after_init rng_seed = EFI_INVALID_TABLE_ADDR;
+
 struct mm_struct efi_mm = {
 	.mm_rb			= RB_ROOT,
 	.mm_users		= ATOMIC_INIT(2),
@@ -524,7 +525,7 @@ static __initdata efi_config_table_type_
 	{SMBIOS3_TABLE_GUID, "SMBIOS 3.0", &efi.smbios3},
 	{EFI_SYSTEM_RESOURCE_TABLE_GUID, "ESRT", &efi.esrt},
 	{EFI_MEMORY_ATTRIBUTES_TABLE_GUID, "MEMATTR", &efi.mem_attr_table},
-	{LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &efi.rng_seed},
+	{LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &rng_seed},
 	{LINUX_EFI_TPM_EVENT_LOG_GUID, "TPMEventLog", &efi.tpm_log},
 	{LINUX_EFI_TPM_FINAL_LOG_GUID, "TPMFinalLog", &efi.tpm_final_log},
 	{LINUX_EFI_MEMRESERVE_TABLE_GUID, "MEMRESERVE", &efi.mem_reserve},
@@ -592,11 +593,11 @@ int __init efi_config_parse_tables(void
 	pr_cont("\n");
 	set_bit(EFI_CONFIG_TABLES, &efi.flags);
 
-	if (efi.rng_seed != EFI_INVALID_TABLE_ADDR) {
+	if (rng_seed != EFI_INVALID_TABLE_ADDR) {
 		struct linux_efi_random_seed *seed;
 		u32 size = 0;
 
-		seed = early_memremap(efi.rng_seed, sizeof(*seed));
+		seed = early_memremap(rng_seed, sizeof(*seed));
 		if (seed != NULL) {
 			size = READ_ONCE(seed->size);
 			early_memunmap(seed, sizeof(*seed));
@@ -604,8 +605,7 @@ int __init efi_config_parse_tables(void
 			pr_err("Could not map UEFI random seed!\n");
 		}
 		if (size > 0) {
-			seed = early_memremap(efi.rng_seed,
-					      sizeof(*seed) + size);
+			seed = early_memremap(rng_seed, sizeof(*seed) + size);
 			if (seed != NULL) {
 				pr_notice("seeding entropy pool\n");
 				add_bootloader_randomness(seed->bits, size);
@@ -1105,7 +1105,7 @@ static int update_efi_random_seed(struct
 	if (!kexec_in_progress)
 		return NOTIFY_DONE;
 
-	seed = memremap(efi.rng_seed, sizeof(*seed), MEMREMAP_WB);
+	seed = memremap(rng_seed, sizeof(*seed), MEMREMAP_WB);
 	if (seed != NULL) {
 		size = min(seed->size, EFI_RANDOM_SEED_SIZE);
 		memunmap(seed);
@@ -1113,8 +1113,7 @@ static int update_efi_random_seed(struct
 		pr_err("Could not map UEFI random seed!\n");
 	}
 	if (size > 0) {
-		seed = memremap(efi.rng_seed, sizeof(*seed) + size,
-				MEMREMAP_WB);
+		seed = memremap(rng_seed, sizeof(*seed) + size, MEMREMAP_WB);
 		if (seed != NULL) {
 			seed->size = size;
 			get_random_bytes(seed->bits, seed->size);
@@ -1130,9 +1129,9 @@ static struct notifier_block efi_random_
 	.notifier_call = update_efi_random_seed,
 };
 
-static int register_update_efi_random_seed(void)
+static int __init register_update_efi_random_seed(void)
 {
-	if (efi.rng_seed == EFI_INVALID_TABLE_ADDR)
+	if (rng_seed == EFI_INVALID_TABLE_ADDR)
 		return 0;
 	return register_reboot_notifier(&efi_random_seed_nb);
 }
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -540,7 +540,6 @@ extern struct efi {
 	unsigned long config_table;	/* config tables */
 	unsigned long esrt;		/* ESRT table */
 	unsigned long mem_attr_table;	/* memory attributes table */
-	unsigned long rng_seed;		/* UEFI firmware random seed */
 	unsigned long tpm_log;		/* TPM2 Event Log table */
 	unsigned long tpm_final_log;	/* TPM2 Final Events Log table */
 	unsigned long mem_reserve;	/* Linux EFI memreserve table */