From 040341007cf4492fdc8aa2d3f198dd22c2288ced Mon Sep 17 00:00:00 2001
From: Paul Selkirk <paul@psgd.org>
Date: Tue, 10 Mar 2020 19:18:33 -0400
Subject: auto-detect cores

---
 aes_keywrap.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++-------------
 hal.h         |  2 +-
 modexp.c      | 32 +++++++++++++++++++++-------
 3 files changed, 78 insertions(+), 23 deletions(-)

diff --git a/aes_keywrap.c b/aes_keywrap.c
index b849304..d43a96f 100644
--- a/aes_keywrap.c
+++ b/aes_keywrap.c
@@ -51,15 +51,40 @@
 #include "hal_internal.h"
 
 /*
- * Enable use of the experimental keywrap core, if present.
+ * Enable use of the keywrap core, if present.
  */
 
-static int use_keywrap_core = 0;
+static enum {
+  unknown = -1,
+  aes_core = 0,
+  keywrap_core = 1
+} which_core = unknown;
 
-int hal_aes_use_keywrap_core(int onoff)
+static char *core_name[] = {
+  AES_CORE_NAME,
+  KEYWRAP_NAME
+};
+
+static inline hal_error_t init_aes_keywrap(void)
+{
+  if (which_core != unknown)
+    return HAL_OK;
+  else if (hal_core_find(KEYWRAP_NAME, NULL) != NULL)
+    return (which_core = keywrap_core), HAL_OK;
+  else if (hal_core_find(AES_CORE_NAME, NULL) != NULL)
+    return (which_core = aes_core), HAL_OK;
+  else
+    return HAL_ERROR_CORE_NOT_FOUND;
+}
+
+hal_error_t hal_aes_use_keywrap_core(int onoff)
 {
-  use_keywrap_core = (onoff && hal_core_find(KEYWRAP_NAME, NULL) != NULL);
-  return use_keywrap_core;
+  if (onoff && hal_core_find(KEYWRAP_NAME, NULL) != NULL)
+    return (which_core = keywrap_core), HAL_OK;
+  else if (!onoff && hal_core_find(AES_CORE_NAME, NULL) != NULL)
+    return (which_core = aes_core), HAL_OK;
+  else
+    return HAL_ERROR_CORE_NOT_FOUND;
 }
 
 
@@ -246,14 +271,16 @@ hal_error_t hal_aes_keywrap(hal_core_t *core,
   if (core) {
     const hal_core_info_t *info = hal_core_info(core);
     if (memcmp(info->name, KEYWRAP_NAME, 8) == 0)
-      use_keywrap_core = 1;
-    else if (memcmp(info->name, AES_CORE_NAME, 8) != 0)
+      which_core = keywrap_core;
+    else if (memcmp(info->name, AES_CORE_NAME, 8) == 0)
+      which_core = aes_core;
+    else
       /* I have no idea what this is */
       return HAL_ERROR_BAD_ARGUMENTS;
   }
   else {
-    const char *core_name = (use_keywrap_core ? KEYWRAP_NAME : AES_CORE_NAME);
-    if ((err = hal_core_alloc(core_name, &core, NULL)) != HAL_OK)
+    if ((err = init_aes_keywrap()) != HAL_OK ||
+        (err = hal_core_alloc(core_name[which_core], &core, NULL)) != HAL_OK)
       return err;
   }
 
@@ -277,7 +304,11 @@ hal_error_t hal_aes_keywrap(hal_core_t *core,
 
   n = calculated_C_len/8 - 1;
 
-  if (use_keywrap_core) {
+  /* Make sure the key expansion has completed. */
+  if ((err = hal_io_wait_ready(core)) != HAL_OK)
+    goto out;
+
+  if (which_core == keywrap_core) {
     err = do_keywrap_core(core, C, n);
   }
   else {
@@ -335,14 +366,16 @@ hal_error_t hal_aes_keyunwrap(hal_core_t *core,
   if (core) {
     const hal_core_info_t *info = hal_core_info(core);
     if (memcmp(info->name, KEYWRAP_NAME, 8) == 0)
-      use_keywrap_core = 1;
-    else if (memcmp(info->name, AES_CORE_NAME, 8) != 0)
+      which_core = keywrap_core;
+    else if (memcmp(info->name, AES_CORE_NAME, 8) == 0)
+      which_core = aes_core;
+    else
       /* I have no idea what this is */
       return HAL_ERROR_BAD_ARGUMENTS;
   }
   else {
-    const char *core_name = (use_keywrap_core ? KEYWRAP_NAME : AES_CORE_NAME);
-    if ((err = hal_core_alloc(core_name, &core, NULL)) != HAL_OK)
+    if ((err = init_aes_keywrap()) != HAL_OK ||
+        (err = hal_core_alloc(core_name[which_core], &core, NULL)) != HAL_OK)
       return err;
   }
 
@@ -354,7 +387,11 @@ hal_error_t hal_aes_keyunwrap(hal_core_t *core,
   if (Q != C)
     memmove(Q, C, C_len);
 
-  if (use_keywrap_core) {
+  /* Make sure the key expansion has completed. */
+  if ((err = hal_io_wait_ready(core)) != HAL_OK)
+    goto out;
+
+  if (which_core == keywrap_core) {
     err = do_keywrap_core(core, Q, n);
   }
   else {
diff --git a/hal.h b/hal.h
index be49f67..a03c891 100644
--- a/hal.h
+++ b/hal.h
@@ -380,7 +380,7 @@ extern const hal_hash_descriptor_t *hal_hmac_get_descriptor(const hal_hmac_state
  * AES key wrap functions.
  */
 
-extern int hal_aes_use_keywrap_core(int onoff);
+extern hal_error_t hal_aes_use_keywrap_core(int onoff);
 
 extern hal_error_t hal_aes_keywrap(hal_core_t *core,
                                    const uint8_t *kek, const size_t kek_length,
diff --git a/modexp.c b/modexp.c
index 8fea2ea..82c79b8 100644
--- a/modexp.c
+++ b/modexp.c
@@ -49,23 +49,41 @@
 #include "hal_internal.h"
 
 /*
- * Whether we want to use the new ModExpNG core.
+ * Enable use of the ModExpNG core, if present.
  */
 
-static int use_modexpng = 0;
+static enum {
+  unknown = -1,
+  modexpa7_core = 0,
+  modexpng_core = 1
+} which_core = unknown;
 
-hal_error_t hal_modexp_use_modexpng(const int onoff)
+static inline hal_error_t init_modexp_core(void)
 {
-  if (onoff && (hal_core_find(MODEXPNG_NAME, NULL) == NULL))
+  if (which_core != unknown)
+    return HAL_OK;
+  else if (hal_core_find(MODEXPNG_NAME, NULL) != NULL)
+    return (which_core = modexpng_core), HAL_OK;
+  else if (hal_core_find(MODEXPA7_NAME, NULL) != NULL)
+    return (which_core = modexpa7_core), HAL_OK;
+  else
     return HAL_ERROR_CORE_NOT_FOUND;
+}
 
-  use_modexpng = onoff;
-  return HAL_OK;
+hal_error_t hal_modexp_use_modexpng(const int onoff)
+{
+  if (onoff && hal_core_find(MODEXPNG_NAME, NULL) != NULL)
+    return (which_core = modexpng_core), HAL_OK;
+  else if (!onoff && hal_core_find(MODEXPA7_NAME, NULL) != NULL)
+    return (which_core = modexpa7_core), HAL_OK;
+  else
+    return HAL_ERROR_CORE_NOT_FOUND;
 }
 
 int hal_modexp_using_modexpng(void)
 {
-  return use_modexpng;
+  return (init_modexp_core() == HAL_OK &&
+          which_core == modexpng_core);
 }
 
 /*
-- 
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