[efi] Generalise EFI entropy generation to non-x86 CPUs

Signed-off-by: Michael Brown <mcb30@ipxe.org>

2 files changed, 0 insertions, 224 deletions

diff --git a/src/arch/x86/include/bits/errfile.h b/src/arch/x86/include/bits/errfile.h
index 9eb4b548..42792242 100644
--- a/src/arch/x86/include/bits/errfile.h
+++ b/src/arch/x86/include/bits/errfile.h
@@ -53,7 +53,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #define ERRFILE_cpuid_cmd      ( ERRFILE_ARCH | ERRFILE_OTHER | 0x00000000 )
 #define ERRFILE_cpuid_settings ( ERRFILE_ARCH | ERRFILE_OTHER | 0x00010000 )
-#define ERRFILE_efi_entropy    ( ERRFILE_ARCH | ERRFILE_OTHER | 0x00020000 )
 
 /** @} */
 
diff --git a/src/arch/x86/interface/efi/efi_entropy.c b/src/arch/x86/interface/efi/efi_entropy.c
deleted file mode 100644
index a54bd12e..00000000
--- a/src/arch/x86/interface/efi/efi_entropy.c
+++ /dev/null
@@ -1,223 +0,0 @@
-/*
- * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
- * 02110-1301, USA.
- *
- * You can also choose to distribute this program under the terms of
- * the Unmodified Binary Distribution Licence (as given in the file
- * COPYING.UBDL), provided that you have satisfied its requirements.
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#include <errno.h>
-#include <ipxe/entropy.h>
-#include <ipxe/crc32.h>
-#include <ipxe/efi/efi.h>
-#include <ipxe/efi/Protocol/Rng.h>
-
-/** @file
- *
- * EFI entropy source
- *
- */
-
-/** Random number generator protocol */
-static EFI_RNG_PROTOCOL *efirng;
-EFI_REQUEST_PROTOCOL ( EFI_RNG_PROTOCOL, &efirng );
-
-/** Minimum number of bytes to request from RNG
- *
- * The UEFI spec states (for no apparently good reason) that "When a
- * Deterministic Random Bit Generator (DRBG) is used on the output of
- * a (raw) entropy source, its security level must be at least 256
- * bits."  The EDK2 codebase (mis)interprets this to mean that the
- * call to GetRNG() should fail if given a buffer less than 32 bytes.
- *
- * Incidentally, nothing in the EFI RNG protocol provides any way to
- * report the actual amount of entropy returned by GetRNG().
- */
-#define EFI_ENTROPY_RNG_LEN 32
-
-/** Time (in 100ns units) to delay waiting for timer tick
- *
- * In theory, UEFI allows us to specify a trigger time of zero to
- * simply wait for the next timer tick.  In practice, specifying zero
- * seems to often return immediately, which produces almost no
- * entropy.  Specify a delay of 1000ns to try to force an existent
- * delay.
- */
-#define EFI_ENTROPY_TRIGGER_TIME 10
-
-/** Event used to wait for timer tick */
-static EFI_EVENT tick;
-
-/**
- * Enable entropy gathering
- *
- * @ret rc		Return status code
- */
-static int efi_entropy_enable ( void ) {
-	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
-	EFI_STATUS efirc;
-	int rc;
-
-	DBGC ( &tick, "ENTROPY %s RNG protocol\n",
-	       ( efirng ? "has" : "has no" ) );
-
-	/* Create timer tick event */
-	if ( ( efirc = bs->CreateEvent ( EVT_TIMER, TPL_NOTIFY, NULL, NULL,
-					 &tick ) ) != 0 ) {
-		rc = -EEFI ( efirc );
-		DBGC ( &tick, "ENTROPY could not create event: %s\n",
-		       strerror ( rc ) );
-		return rc;
-	}
-
-	return 0;
-}
-
-/**
- * Disable entropy gathering
- *
- */
-static void efi_entropy_disable ( void ) {
-	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
-
-	/* Close timer tick event */
-	bs->CloseEvent ( tick );
-}
-
-/**
- * Wait for a timer tick
- *
- * @ret low		TSC low-order bits, or negative error
- */
-static int efi_entropy_tick ( void ) {
-	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
-	UINTN index;
-	uint16_t low;
-	uint32_t discard_d;
-	EFI_STATUS efirc;
-	int rc;
-
-	/* Wait for next timer tick */
-	if ( ( efirc = bs->SetTimer ( tick, TimerRelative,
-				      EFI_ENTROPY_TRIGGER_TIME ) ) != 0 ) {
-		rc = -EEFI ( efirc );
-		DBGC ( &tick, "ENTROPY could not set timer: %s\n",
-		       strerror ( rc ) );
-		return rc;
-	}
-	if ( ( efirc = bs->WaitForEvent ( 1, &tick, &index ) ) != 0 ) {
-		rc = -EEFI ( efirc );
-		DBGC ( &tick, "ENTROPY could not wait for timer tick: %s\n",
-		       strerror ( rc ) );
-		return rc;
-	}
-
-	/* Get current TSC low-order bits */
-	__asm__ __volatile__ ( "rdtsc" : "=a" ( low ), "=d" ( discard_d ) );
-
-	return low;
-}
-
-/**
- * Get noise sample from timer ticks
- *
- * @ret noise		Noise sample
- * @ret rc		Return status code
- */
-static int efi_get_noise_ticks ( noise_sample_t *noise ) {
-	int before;
-	int after;
-	int rc;
-
-	/* Wait for a timer tick */
-	before = efi_entropy_tick();
-	if ( before < 0 ) {
-		rc = before;
-		return rc;
-	}
-
-	/* Wait for another timer tick */
-	after = efi_entropy_tick();
-	if ( after < 0 ) {
-		rc = after;
-		return rc;
-	}
-
-	/* Use TSC delta as noise sample */
-	*noise = ( after - before );
-
-	return 0;
-}
-
-/**
- * Get noise sample from RNG protocol
- *
- * @ret noise		Noise sample
- * @ret rc		Return status code
- */
-static int efi_get_noise_rng ( noise_sample_t *noise ) {
-	uint8_t buf[EFI_ENTROPY_RNG_LEN];
-	EFI_STATUS efirc;
-	int rc;
-
-	/* Fail if we have no EFI RNG protocol */
-	if ( ! efirng )
-		return -ENOTSUP;
-
-	/* Get the minimum allowed number of random bytes */
-	if ( ( efirc = efirng->GetRNG ( efirng, NULL, EFI_ENTROPY_RNG_LEN,
-					buf ) ) != 0 ) {
-		rc = -EEFI ( efirc );
-		DBGC ( &tick, "ENTROPY could not read from RNG: %s\n",
-		       strerror ( rc ) );
-		return rc;
-	}
-
-	/* Reduce random bytes to a single noise sample.  This seems
-	 * like overkill, but we have no way of knowing how much
-	 * entropy is actually present in the bytes returned by the
-	 * RNG protocol.
-	 */
-	*noise = crc32_le ( 0, buf, sizeof ( buf ) );
-
-	return 0;
-}
-
-/**
- * Get noise sample
- *
- * @ret noise		Noise sample
- * @ret rc		Return status code
- */
-static int efi_get_noise ( noise_sample_t *noise ) {
-	int rc;
-
-	/* Try RNG first, falling back to timer ticks */
-	if ( ( ( rc = efi_get_noise_rng ( noise ) ) != 0 ) &&
-	     ( ( rc = efi_get_noise_ticks ( noise ) ) != 0 ) )
-		return rc;
-
-	return 0;
-}
-
-PROVIDE_ENTROPY_INLINE ( efi, min_entropy_per_sample );
-PROVIDE_ENTROPY ( efi, entropy_enable, efi_entropy_enable );
-PROVIDE_ENTROPY ( efi, entropy_disable, efi_entropy_disable );
-PROVIDE_ENTROPY ( efi, get_noise, efi_get_noise );