[sw/entropy] Various clean-up to entropy_testutil

- remove testutil's direct access to entropy complex registers - added dis_entropy_src_stop to emulate the function in edn / csrng - sever the dependency between entropy_testutil_boot_mode and auto_mode - edn1 is currently set to reseed once every 4 generates, this is because if it were set to 1, artificial test conditions could end up significantly stalling entropy distribution due to lowRISC#14505. Signed-off-by: Timothy Chen <[email protected]>
tjaychen · Aug 23, 2022 · 73a921c · 73a921c
1 parent 6b7834c
commit 73a921c
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Showing 7 changed files with 106 additions and 75 deletions.
diff --git a/sw/device/lib/dif/dif_edn.c b/sw/device/lib/dif/dif_edn.c
@@ -47,6 +47,16 @@ dif_result_t dif_edn_is_locked(const dif_edn_t *edn, bool *is_locked) {
   return kDifOk;
 }
 
+dif_result_t dif_edn_reset_config(const dif_edn_t *edn) {
+  if (edn == NULL) {
+    return kDifBadArg;
+  }
+  DIF_RETURN_IF_ERROR(check_locked(edn));
+  mmio_region_write32(edn->base_addr, EDN_CTRL_REG_OFFSET, EDN_CTRL_REG_RESVAL);
+
+  return kDifOk;
+}
+
 dif_result_t dif_edn_set_boot_mode(const dif_edn_t *edn) {
   if (edn == NULL) {
     return kDifBadArg;

diff --git a/sw/device/lib/dif/dif_edn.h b/sw/device/lib/dif/dif_edn.h
@@ -223,6 +223,18 @@ dif_result_t dif_edn_lock(const dif_edn_t *edn);
 OT_WARN_UNUSED_RESULT
 dif_result_t dif_edn_is_locked(const dif_edn_t *edn, bool *is_locked);
 
+/**
+ * Reset EDN configuration to default.
+ *
+ * Each call to this function should be sequenced with a call to
+ * `dif_edn_stop()`.
+ *
+ * @param edn An EDN handle.
+ * @return The result of the operation.
+ */
+OT_WARN_UNUSED_RESULT
+dif_result_t dif_edn_reset_config(const dif_edn_t *edn);
+
 /**
  * Enables the EDN in boot-time mode.
  *

diff --git a/sw/device/lib/dif/dif_entropy_src.c b/sw/device/lib/dif/dif_entropy_src.c
@@ -14,12 +14,46 @@
 
 #include "entropy_src_regs.h"  // Generated.
 
+dif_result_t dif_entropy_src_stop(const dif_entropy_src_t *entropy_src) {
+  if (entropy_src == NULL) {
+    return kDifBadArg;
+  }
+
+  mmio_region_write32(entropy_src->base_addr,
+                      ENTROPY_SRC_MODULE_ENABLE_REG_OFFSET,
+                      ENTROPY_SRC_MODULE_ENABLE_REG_RESVAL);
+
+  // once disabled, the entropy_src regwen is released
+  if (!mmio_region_read32(entropy_src->base_addr,
+                          ENTROPY_SRC_REGWEN_REG_OFFSET)) {
+    return kDifLocked;
+  }
+
+  // set back to default value
+  mmio_region_write32(entropy_src->base_addr,
+                      ENTROPY_SRC_ENTROPY_CONTROL_REG_OFFSET,
+                      ENTROPY_SRC_ENTROPY_CONTROL_REG_RESVAL);
+
+  mmio_region_write32(entropy_src->base_addr, ENTROPY_SRC_CONF_REG_OFFSET,
+                      ENTROPY_SRC_CONF_REG_RESVAL);
+
+  mmio_region_write32(entropy_src->base_addr,
+                      ENTROPY_SRC_HEALTH_TEST_WINDOWS_REG_OFFSET,
+                      ENTROPY_SRC_HEALTH_TEST_WINDOWS_REG_RESVAL);
+
+  mmio_region_write32(entropy_src->base_addr,
+                      ENTROPY_SRC_ALERT_THRESHOLD_REG_OFFSET,
+                      ENTROPY_SRC_ALERT_THRESHOLD_REG_RESVAL);
+
+  return kDifOk;
+}
+
 dif_result_t dif_entropy_src_configure(const dif_entropy_src_t *entropy_src,
                                        dif_entropy_src_config_t config,
                                        dif_toggle_t enabled) {
   if (entropy_src == NULL ||
       config.single_bit_mode > kDifEntropySrcSingleBitModeDisabled ||
-      !dif_is_valid_toggle(enabled)) {
+      !dif_is_valid_toggle(enabled) || config.health_test_window_size == 0) {
     return kDifBadArg;
   }
 

diff --git a/sw/device/lib/dif/dif_entropy_src.h b/sw/device/lib/dif/dif_entropy_src.h
@@ -468,6 +468,16 @@ typedef enum dif_entropy_src_error {
   kDifEntropySrcErrorHardenedCounter = 1U << 11,
 } dif_entropy_src_error_t;
 
+/**
+ * Stops the current mode of operation and disables the entropy_src module
+ *
+ *
+ * @param entropy_src An entropy source handle.
+ * @return The result of the operation.
+ */
+OT_WARN_UNUSED_RESULT
+dif_result_t dif_entropy_src_stop(const dif_entropy_src_t *entropy_src);
+
 /**
  * Configures entropy source with runtime information.
  *

diff --git a/sw/device/lib/dif/dif_entropy_src_unittest.cc b/sw/device/lib/dif/dif_entropy_src_unittest.cc
@@ -27,6 +27,7 @@ class ConfigTest : public EntropySrcTest {
       .fips_enable = false,
       .route_to_firmware = false,
       .single_bit_mode = kDifEntropySrcSingleBitModeDisabled,
+      .health_test_window_size = 1
   };
 };
 
@@ -154,10 +155,10 @@ INSTANTIATE_TEST_SUITE_P(
         ConfigParams{false, false, kDifEntropySrcSingleBitMode3, false, 64, 2,
                      kDifToggleEnabled},
         // Test alerts disabled.
-        ConfigParams{false, false, kDifEntropySrcSingleBitMode0, false, 0, 0,
+        ConfigParams{false, false, kDifEntropySrcSingleBitMode0, false, 1, 0,
                      kDifToggleDisabled},
         // Test all disabled.
-        ConfigParams{false, false, kDifEntropySrcSingleBitMode0, false, 0, 2,
+        ConfigParams{false, false, kDifEntropySrcSingleBitMode0, false, 1, 2,
                      kDifToggleDisabled},
         // Test all enabled.
         ConfigParams{true, true, kDifEntropySrcSingleBitMode0, true, 32, 2,

diff --git a/sw/device/lib/testing/entropy_testutils.c b/sw/device/lib/testing/entropy_testutils.c
@@ -8,27 +8,38 @@
 #include "sw/device/lib/dif/dif_entropy_src.h"
 #include "sw/device/lib/testing/test_framework/check.h"
 
-#include "edn_regs.h"          // Generated
-#include "entropy_src_regs.h"  // Generated
 #include "hw/top_earlgrey/sw/autogen/top_earlgrey.h"
 
+static void setup_entropy_src(const dif_entropy_src_t *entropy_src) {
+  const dif_entropy_src_config_t config = {
+      .fips_enable = true,
+      .route_to_firmware = false,
+      .single_bit_mode = kDifEntropySrcSingleBitModeDisabled,
+      .health_test_window_size = 0x0200, /*default*/
+      .alert_threshold = 2,              /*default*/
+  };
+  CHECK_DIF_OK(
+      dif_entropy_src_configure(entropy_src, config, kDifToggleEnabled));
+}
+
 void entropy_testutils_auto_mode_init(void) {
+  const dif_entropy_src_t entropy_src = {
+      .base_addr = mmio_region_from_addr(TOP_EARLGREY_ENTROPY_SRC_BASE_ADDR)};
   const dif_csrng_t csrng = {
       .base_addr = mmio_region_from_addr(TOP_EARLGREY_CSRNG_BASE_ADDR)};
   const dif_edn_t edn0 = {
       .base_addr = mmio_region_from_addr(TOP_EARLGREY_EDN0_BASE_ADDR)};
   const dif_edn_t edn1 = {
       .base_addr = mmio_region_from_addr(TOP_EARLGREY_EDN1_BASE_ADDR)};
 
-  // Disable CSRNG.  This is required to abort the generate command of boot
-  // mode, which is likely still running.
-  CHECK_DIF_OK(dif_csrng_stop(&csrng));
-
-  // Stop both EDNs.
+  // Disable entropy complex
   CHECK_DIF_OK(dif_edn_stop(&edn0));
   CHECK_DIF_OK(dif_edn_stop(&edn1));
+  CHECK_DIF_OK(dif_csrng_stop(&csrng));
+  CHECK_DIF_OK(dif_entropy_src_stop(&entropy_src));
 
-  // Re-enable the CSRNG.
+  // re-eanble entropy src and csrng
+  setup_entropy_src(&entropy_src);
   CHECK_DIF_OK(dif_csrng_configure(&csrng));
 
   // Re-enable EDN0 in auto mode.
@@ -61,75 +72,30 @@ void entropy_testutils_auto_mode_init(void) {
           {
               .len = 1, .data = {0x00001003},  // One generate returns 1 block.
           },
-      .reseed_interval = 1,  // Reseed after every generate.
+      .reseed_interval = 4,  // Reseed after every 4 generates.
   };
   CHECK_DIF_OK(dif_edn_set_auto_mode(&edn1, edn1_params));
 }
 
-static void setup_entropy_src(void) {
-  dif_entropy_src_t entropy_src;
-  CHECK_DIF_OK(dif_entropy_src_init(
-      mmio_region_from_addr(TOP_EARLGREY_ENTROPY_SRC_BASE_ADDR), &entropy_src));
-
-  // Disable entropy for test purpose, as it has been turned on by ROM
-  CHECK_DIF_OK(dif_entropy_src_set_enabled(&entropy_src, kDifToggleDisabled));
-
-  const dif_entropy_src_config_t config = {
-      .fips_enable = true,
-      .route_to_firmware = false,
-      .single_bit_mode = kDifEntropySrcSingleBitModeDisabled,
-      .health_test_window_size = 0x0200, /*default*/
-      .alert_threshold = 2,              /*default*/
-  };
-  CHECK_DIF_OK(
-      dif_entropy_src_configure(&entropy_src, config, kDifToggleEnabled));
-}
+void entropy_testutils_boot_mode_init(void) {
+  const dif_entropy_src_t entropy_src = {
+      .base_addr = mmio_region_from_addr(TOP_EARLGREY_ENTROPY_SRC_BASE_ADDR)};
+  const dif_csrng_t csrng = {
+      .base_addr = mmio_region_from_addr(TOP_EARLGREY_CSRNG_BASE_ADDR)};
+  const dif_edn_t edn0 = {
+      .base_addr = mmio_region_from_addr(TOP_EARLGREY_EDN0_BASE_ADDR)};
+  const dif_edn_t edn1 = {
+      .base_addr = mmio_region_from_addr(TOP_EARLGREY_EDN1_BASE_ADDR)};
 
-static void setup_csrng(void) {
-  dif_csrng_t csrng;
-  CHECK_DIF_OK(dif_csrng_init(
-      mmio_region_from_addr(TOP_EARLGREY_CSRNG_BASE_ADDR), &csrng));
+  CHECK_DIF_OK(dif_entropy_src_stop(&entropy_src));
+  CHECK_DIF_OK(dif_csrng_stop(&csrng));
+  CHECK_DIF_OK(dif_edn_stop(&edn0));
+  CHECK_DIF_OK(dif_edn_stop(&edn1));
 
+  setup_entropy_src(&entropy_src);
   CHECK_DIF_OK(dif_csrng_configure(&csrng));
-}
-
-static void setup_edn() {
-  // Temporary solution to configure/enable the EDN and CSRNG to allow OTBN to
-  // run before a DIF is available,
-  // https://github.com/lowRISC/opentitan/issues/6082
-  // disable edn.
-  uint32_t reg = 0;
-  reg =
-      bitfield_field32_write(0, EDN_CTRL_EDN_ENABLE_FIELD, kMultiBitBool4False);
-  reg = bitfield_field32_write(reg, EDN_CTRL_BOOT_REQ_MODE_FIELD,
-                               kMultiBitBool4False);
-  reg = bitfield_field32_write(reg, EDN_CTRL_AUTO_REQ_MODE_FIELD,
-                               kMultiBitBool4False);
-  reg = bitfield_field32_write(reg, EDN_CTRL_CMD_FIFO_RST_FIELD,
-                               kMultiBitBool4False);
-  mmio_region_write32(mmio_region_from_addr(TOP_EARLGREY_EDN0_BASE_ADDR),
-                      EDN_CTRL_REG_OFFSET, reg);
-  mmio_region_write32(mmio_region_from_addr(TOP_EARLGREY_EDN1_BASE_ADDR),
-                      EDN_CTRL_REG_OFFSET, reg);
-
-  reg =
-      bitfield_field32_write(0, EDN_CTRL_EDN_ENABLE_FIELD, kMultiBitBool4True);
-  reg = bitfield_field32_write(reg, EDN_CTRL_BOOT_REQ_MODE_FIELD,
-                               kMultiBitBool4True);
-  reg = bitfield_field32_write(reg, EDN_CTRL_AUTO_REQ_MODE_FIELD,
-                               kMultiBitBool4False);
-  reg = bitfield_field32_write(reg, EDN_CTRL_CMD_FIFO_RST_FIELD,
-                               kMultiBitBool4False);
-  mmio_region_write32(mmio_region_from_addr(TOP_EARLGREY_EDN0_BASE_ADDR),
-                      EDN_CTRL_REG_OFFSET, reg);
-  mmio_region_write32(mmio_region_from_addr(TOP_EARLGREY_EDN1_BASE_ADDR),
-                      EDN_CTRL_REG_OFFSET, reg);
-}
-
-void entropy_testutils_boot_mode_init(void) {
-  setup_entropy_src();
-  setup_csrng();
-  setup_edn();
+  CHECK_DIF_OK(dif_edn_set_boot_mode(&edn0));
+  CHECK_DIF_OK(dif_edn_set_boot_mode(&edn1));
 }
 
 void entropy_testutils_wait_for_state(const dif_entropy_src_t *entropy_src,

diff --git a/sw/device/tests/entropy_src_edn_reqs_test.c b/sw/device/tests/entropy_src_edn_reqs_test.c
@@ -209,8 +209,6 @@ static void alert_handler_test(entropy_src_test_context_t *ctx) {
 void test_initialize(entropy_src_test_context_t *ctx) {
   LOG_INFO("%s", __func__);
 
-  entropy_testutils_boot_mode_init();
-
   mmio_region_t addr =
       mmio_region_from_addr(TOP_EARLGREY_ENTROPY_SRC_BASE_ADDR);
   CHECK_DIF_OK(dif_entropy_src_init(addr, &ctx->entropy_src));