[boot_rom] Remove references to hw_sha256.h
Signed-off-by: Miguel Young de la Sota <mcyoung@google.com>
diff --git a/sw/device/boot_rom/bootstrap.c b/sw/device/boot_rom/bootstrap.c
index 9eee13b..3607719 100644
--- a/sw/device/boot_rom/bootstrap.c
+++ b/sw/device/boot_rom/bootstrap.c
@@ -11,9 +11,10 @@
#include "sw/device/lib/base/memory.h"
#include "sw/device/lib/base/mmio.h"
#include "sw/device/lib/dif/dif_gpio.h"
+#include "sw/device/lib/dif/dif_hmac.h"
#include "sw/device/lib/dif/dif_spi_device.h"
#include "sw/device/lib/flash_ctrl.h"
-#include "sw/device/lib/hw_sha256.h"
+#include "sw/device/lib/runtime/check.h"
#include "sw/device/lib/runtime/hart.h"
#include "sw/device/lib/runtime/log.h"
#include "sw/device/lib/testing/check.h"
@@ -65,16 +66,47 @@
}
/**
+ * Computes the SHA256 of the given data.
+ */
+static void compute_sha256(const dif_hmac_t *hmac, const void *data, size_t len,
+ dif_hmac_digest_t *digest) {
+ CHECK(dif_hmac_mode_sha256_start(hmac) == kDifHmacOk);
+ const char *data8 = (const char *)data;
+ size_t data_left = len;
+ while (data_left > 0) {
+ size_t bytes_sent;
+ dif_hmac_fifo_result_t result =
+ dif_hmac_fifo_push(hmac, data8, data_left, &bytes_sent);
+ if (result == kDifHmacFifoOk) {
+ break;
+ }
+ CHECK(result == kDifHmacFifoFull, "Error while pushing to FIFO.");
+ data8 += bytes_sent;
+ data_left -= bytes_sent;
+ }
+
+ CHECK(dif_hmac_process(hmac) == kDifHmacOk);
+ dif_hmac_digest_result_t digest_result = kDifHmacDigestProcessing;
+ while (digest_result == kDifHmacDigestProcessing) {
+ digest_result = dif_hmac_digest_read(hmac, digest);
+ }
+ CHECK(digest_result == kDifHmacDigestOk, "Error reading the digest.");
+}
+
+/**
* Compares the SHA256 hash of the recieved data with the recieved hash.
*
* Returns true if the hashes match.
*/
-static bool check_frame_hash(const spiflash_frame_t *frame) {
- uint8_t hash[sizeof(frame->header.hash)];
- uint8_t *data = ((uint8_t *)frame) + sizeof(hash);
- hw_SHA256_hash(data, sizeof(spiflash_frame_t) - sizeof(hash), hash);
+static bool check_frame_hash(const dif_hmac_t *hmac,
+ const spiflash_frame_t *frame) {
+ dif_hmac_digest_t digest;
+ size_t digest_len = sizeof(digest.digest);
- return memcmp(hash, frame->header.hash, sizeof(hash)) == 0;
+ uint8_t *data = ((uint8_t *)frame) + digest_len;
+ compute_sha256(hmac, data, sizeof(spiflash_frame_t) - digest_len, &digest);
+
+ return memcmp(digest.digest, frame->header.hash.digest, digest_len) == 0;
}
/**
@@ -83,8 +115,8 @@
* This function checks that the sequence numbers and hashes of the frames are
* correct before programming them into flash.
*/
-static int bootstrap_flash(dif_spi_device_t *spi) {
- uint8_t ack[SHA256_DIGEST_SIZE] = {0};
+static int bootstrap_flash(dif_spi_device_t *spi, dif_hmac_t *hmac) {
+ dif_hmac_digest_t ack = {0};
uint32_t expected_frame_num = 0;
while (true) {
size_t bytes_available;
@@ -101,18 +133,20 @@
expected_frame_num);
if (frame_num == expected_frame_num) {
- if (!check_frame_hash(&frame)) {
+ if (!check_frame_hash(hmac, &frame)) {
LOG_ERROR("Detected hash mismatch on frame #%d", frame_num);
- CHECK(dif_spi_device_send(spi, ack, sizeof(ack),
+ CHECK(dif_spi_device_send(spi, (uint8_t *)&ack.digest,
+ sizeof(ack.digest),
/*bytes_received=*/NULL) == kDifSpiDeviceOk,
"Failed to send bytes to SPI.");
continue;
}
- hw_SHA256_hash(&frame, sizeof(spiflash_frame_t), ack);
- CHECK(dif_spi_device_send(spi, ack, sizeof(ack),
- /*bytes_received=*/NULL) == kDifSpiDeviceOk,
- "Failed to send bytes to SPI.");
+ compute_sha256(hmac, &frame, sizeof(spiflash_frame_t), &ack);
+ CHECK(
+ dif_spi_device_send(spi, (uint8_t *)&ack.digest, sizeof(ack.digest),
+ /*bytes_received=*/NULL) == kDifSpiDeviceOk,
+ "Failed to send bytes to SPI.");
if (expected_frame_num == 0) {
flash_default_region_access(/*rd_en=*/true, /*prog_en=*/true,
@@ -136,9 +170,10 @@
}
} else {
// Send previous ack if unable to verify current frame.
- CHECK(dif_spi_device_send(spi, ack, sizeof(ack),
- /*bytes_received=*/NULL) == kDifSpiDeviceOk,
- "Failed to send bytes to SPI.");
+ CHECK(
+ dif_spi_device_send(spi, (uint8_t *)&ack.digest, sizeof(ack.digest),
+ /*bytes_received=*/NULL) == kDifSpiDeviceOk,
+ "Failed to send bytes to SPI.");
}
}
}
@@ -174,8 +209,17 @@
}) == kDifSpiDeviceOk,
"Failed to configure SPI.");
+ dif_hmac_t hmac;
+ dif_hmac_config_t config = {
+ .base_addr = mmio_region_from_addr(TOP_EARLGREY_HMAC_BASE_ADDR),
+ .message_endianness = kDifHmacEndiannessBig,
+ .digest_endianness = kDifHmacEndiannessBig,
+ };
+ CHECK(dif_hmac_init(&config, &hmac) == kDifHmacOk,
+ "Failed to configure HMAC.");
+
LOG_INFO("HW initialisation completed, waiting for SPI input...");
- int error = bootstrap_flash(&spi);
+ int error = bootstrap_flash(&spi, &hmac);
if (error != 0) {
error |= erase_flash();
LOG_ERROR("Bootstrap error: 0x%x", error);
diff --git a/sw/device/boot_rom/meson.build b/sw/device/boot_rom/meson.build
index 286f1f2..9c78f11 100644
--- a/sw/device/boot_rom/meson.build
+++ b/sw/device/boot_rom/meson.build
@@ -56,7 +56,7 @@
sw_lib_pinmux,
sw_lib_dif_gpio,
sw_lib_dif_spi_device,
- sw_lib_hmac,
+ sw_lib_dif_hmac,
sw_lib_mmio,
sw_lib_runtime_log,
sw_lib_dif_uart,
diff --git a/sw/device/boot_rom/spiflash_frame.h b/sw/device/boot_rom/spiflash_frame.h
index 40d0818..de8867a 100644
--- a/sw/device/boot_rom/spiflash_frame.h
+++ b/sw/device/boot_rom/spiflash_frame.h
@@ -5,10 +5,9 @@
#ifndef OPENTITAN_SW_DEVICE_BOOT_ROM_SPIFLASH_FRAME_H_
#define OPENTITAN_SW_DEVICE_BOOT_ROM_SPIFLASH_FRAME_H_
-#include <stdalign.h>
#include <stdint.h>
-#include "sw/device/lib/hw_sha256.h"
+#include "sw/device/lib/dif/dif_hmac.h"
/**
* The total size of a spiflash frame.
@@ -45,7 +44,7 @@
/**
* SHA256 of the entire frame_t message starting at the `frame_num` offset.
*/
- uint32_t hash[SHA256_DIGEST_SIZE / sizeof(uint32_t)];
+ dif_hmac_digest_t hash;
/**
* Frame number starting at 0. The last frame should be OR'd with
* FRAME_EOF_MARKER.
