efi: Make rng_seed table handling local to efi.c

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>

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 68527fb..bbb6246 100644 (file)
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -44,13 +44,14 @@ 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),
@@ -467,7 +468,7 @@ static __initdata efi_config_table_type_t common_tables[] = {
        {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},
@@ -535,11 +536,11 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
        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 = seed->size;
                        early_memunmap(seed, sizeof(*seed));
@@ -547,8 +548,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
                        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, seed->size);
@@ -1048,7 +1048,7 @@ static int update_efi_random_seed(struct notifier_block *nb,
        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);
@@ -1056,8 +1056,7 @@ static int update_efi_random_seed(struct notifier_block *nb,
                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);
@@ -1073,9 +1072,9 @@ static struct notifier_block efi_random_seed_nb = {
        .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);
 }

diff --git a/include/linux/efi.h b/include/linux/efi.h
index e091f2a..3638054 100644 (file)
--- 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 */