Merge "plat/arm: juno: Refactor juno_getentropy()" into integration
diff --git a/plat/arm/board/juno/juno_decl.h b/plat/arm/board/juno/juno_decl.h
index cd87c3b..21e56c0 100644
--- a/plat/arm/board/juno/juno_decl.h
+++ b/plat/arm/board/juno/juno_decl.h
@@ -7,6 +7,6 @@
#ifndef JUNO_DECL_H
#define JUNO_DECL_H
-int juno_getentropy(void *buf, size_t len);
+bool juno_getentropy(uint64_t *buf);
#endif /* JUNO_DECL_H */
diff --git a/plat/arm/board/juno/juno_stack_protector.c b/plat/arm/board/juno/juno_stack_protector.c
index 236eb5b..8c51f57 100644
--- a/plat/arm/board/juno/juno_stack_protector.c
+++ b/plat/arm/board/juno/juno_stack_protector.c
@@ -13,20 +13,16 @@
u_register_t plat_get_stack_protector_canary(void)
{
- u_register_t c[TRNG_NBYTES / sizeof(u_register_t)];
- u_register_t ret = 0;
- size_t i;
+ uint64_t entropy;
- if (juno_getentropy(c, sizeof(c)) != 0) {
+ if (!juno_getentropy(&entropy)) {
ERROR("Not enough entropy to initialize canary value\n");
panic();
}
- /*
- * On Juno we get 128-bits of entropy in one round.
- * Fuse the values together to form the canary.
- */
- for (i = 0; i < ARRAY_SIZE(c); i++)
- ret ^= c[i];
- return ret;
+ if (sizeof(entropy) == sizeof(u_register_t)) {
+ return entropy;
+ }
+
+ return (entropy & 0xffffffffULL) ^ (entropy >> 32);
}
diff --git a/plat/arm/board/juno/juno_trng.c b/plat/arm/board/juno/juno_trng.c
index 7869d3e..b38e49f 100644
--- a/plat/arm/board/juno/juno_trng.c
+++ b/plat/arm/board/juno/juno_trng.c
@@ -5,6 +5,8 @@
*/
#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
#include <string.h>
#include <lib/mmio.h>
@@ -16,7 +18,10 @@
#define NSAMPLE_CLOCKS 1 /* min 1 cycle, max 231 cycles */
#define NRETRIES 5
-static inline int output_valid(void)
+/* initialised to false */
+static bool juno_trng_initialized;
+
+static bool output_valid(void)
{
int i;
@@ -25,59 +30,58 @@
val = mmio_read_32(TRNG_BASE + TRNG_STATUS);
if (val & 1U)
- break;
+ return true;
}
- if (i >= NRETRIES)
- return 0; /* No output data available. */
- return 1;
+ return false; /* No output data available. */
}
/*
- * This function fills `buf` with `len` bytes of entropy.
+ * This function fills `buf` with 8 bytes of entropy.
* It uses the Trusted Entropy Source peripheral on Juno.
- * Returns 0 when the buffer has been filled with entropy
- * successfully and -1 otherwise.
+ * Returns 'true' when the buffer has been filled with entropy
+ * successfully, or 'false' otherwise.
*/
-int juno_getentropy(void *buf, size_t len)
+bool juno_getentropy(uint64_t *buf)
{
- uint8_t *bp = buf;
+ uint64_t ret;
assert(buf);
- assert(len);
- assert(!check_uptr_overflow((uintptr_t)bp, len));
+ assert(!check_uptr_overflow((uintptr_t)buf, sizeof(*buf)));
- /* Disable interrupt mode. */
- mmio_write_32(TRNG_BASE + TRNG_INTMASK, 0);
- /* Program TRNG to sample for `NSAMPLE_CLOCKS`. */
- mmio_write_32(TRNG_BASE + TRNG_CONFIG, NSAMPLE_CLOCKS);
+ if (!juno_trng_initialized) {
+ /* Disable interrupt mode. */
+ mmio_write_32(TRNG_BASE + TRNG_INTMASK, 0);
+ /* Program TRNG to sample for `NSAMPLE_CLOCKS`. */
+ mmio_write_32(TRNG_BASE + TRNG_CONFIG, NSAMPLE_CLOCKS);
+ /* Abort any potentially pending sampling. */
+ mmio_write_32(TRNG_BASE + TRNG_CONTROL, 2);
+ /* Reset TRNG outputs. */
+ mmio_write_32(TRNG_BASE + TRNG_STATUS, 1);
- while (len > 0) {
- int i;
+ juno_trng_initialized = true;
+ }
+ if (!output_valid()) {
/* Start TRNG. */
mmio_write_32(TRNG_BASE + TRNG_CONTROL, 1);
- /* Check if output is valid. */
if (!output_valid())
- return -1;
+ return false;
+ }
- /* Fill entropy buffer. */
- for (i = 0; i < TRNG_NOUTPUTS; i++) {
- size_t n;
- uint32_t val;
+ /* XOR each two 32-bit registers together, combine the pairs */
+ ret = mmio_read_32(TRNG_BASE + 0);
+ ret ^= mmio_read_32(TRNG_BASE + 4);
+ ret <<= 32;
- val = mmio_read_32(TRNG_BASE + i * sizeof(uint32_t));
- n = MIN(len, sizeof(uint32_t));
- memcpy(bp, &val, n);
- bp += n;
- len -= n;
- if (len == 0)
- break;
- }
+ ret |= mmio_read_32(TRNG_BASE + 8);
+ ret ^= mmio_read_32(TRNG_BASE + 12);
+ *buf = ret;
- /* Reset TRNG outputs. */
- mmio_write_32(TRNG_BASE + TRNG_STATUS, 1);
- }
+ /* Acknowledge current cycle, clear output registers. */
+ mmio_write_32(TRNG_BASE + TRNG_STATUS, 1);
+ /* Trigger next TRNG cycle. */
+ mmio_write_32(TRNG_BASE + TRNG_CONTROL, 1);
- return 0;
+ return true;
}