libsel4bench: Add support for RISC-V

Added initial support for RISC-V architecture.

libsel4bench/arch_include/riscv/sel4bench/arch/sel4bench.h

diff --git a/libsel4bench/arch_include/riscv/sel4bench/arch/sel4bench.h b/libsel4bench/arch_include/riscv/sel4bench/arch/sel4bench.h
new file mode 100644
index 0000000..51cb7da
--- /dev/null
+++ b/libsel4bench/arch_include/riscv/sel4bench/arch/sel4bench.h
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2020, Data61
+ * Commonwealth Scientific and Industrial Research Organisation (CSIRO)
+ * ABN 41 687 119 230.
+ *
+ * This software may be distributed and modified according to the terms of
+ * the BSD 2-Clause license. Note that NO WARRANTY is provided.
+ * See "LICENSE_BSD2.txt" for details.
+ *
+ * @TAG(DATA61_BSD)
+ */
+#pragma once
+
+#include <autoconf.h>
+#include <sel4bench/types.h>
+#include <sel4/sel4.h>
+#include <utils/util.h>
+
+#define FASTFN inline __attribute__((always_inline))
+
+#define SEL4BENCH_READ_CCNT(var) asm volatile("rdcycle %0" :"=r"(var));  
+
+#define SEL4BENCH_RESET_CCNT do {\
+    ; \
+} while(0)
+
+#define SEL4BENCH_EVENT_EXECUTE_INSTRUCTION 0x00
+#define SEL4BENCH_EVENT_CACHE_L1I_MISS 0xf0
+#define SEL4BENCH_EVENT_CACHE_L1D_MISS 0xf1
+#define SEL4BENCH_EVENT_TLB_L1I_MISS   0xf2
+#define SEL4BENCH_EVENT_TLB_L1D_MISS   0xf3
+#define SEL4BENCH_EVENT_BRANCH_MISPREDICT   0xf4
+#define SEL4BENCH_EVENT_MEMORY_ACCESS       0xf5
+
+#define CCNT_FORMAT "%"PRIu64
+typedef uint64_t ccnt_t;
+
+static FASTFN void sel4bench_init()
+{
+}
+
+static FASTFN void sel4bench_destroy()
+{
+}
+
+static FASTFN seL4_Word sel4bench_get_num_counters()
+{
+    return 0;
+}
+
+static FASTFN ccnt_t sel4bench_get_cycle_count()
+{
+    ccnt_t val;
+    return val;
+}
+
+/* Being declared FASTFN allows this function (once inlined) to cache miss; I
+ * think it's worthwhile in the general case, for performance reasons.
+ * moreover, it's small enough that it'll be suitably aligned most of the time
+ */
+static FASTFN ccnt_t sel4bench_get_counter(counter_t counter)
+{
+    uint32_t val = 0;
+    return val;
+}
+
+/* This reader function is too complex to be inlined, so we force it to be
+ * cacheline-aligned in order to avoid icache misses with the counters off.
+ * (relevant note: GCC compiles this function to be exactly one ARMV7 cache
+ * line in size) however, the pointer dereference is overwhelmingly likely to
+ * produce a dcache miss, which will occur with the counters off
+ */
+static inline ccnt_t sel4bench_get_counters(counter_bitfield_t mask, ccnt_t *values)
+{
+    return 0;
+}
+
+static FASTFN void sel4bench_set_count_event(counter_t counter, event_id_t event)
+{
+    return;
+}
+
+static FASTFN void sel4bench_start_counters(counter_bitfield_t mask)
+{
+    return;
+}
+
+static FASTFN void sel4bench_stop_counters(counter_bitfield_t mask)
+{
+    return;
+}
+
+static FASTFN void sel4bench_reset_counters(void)
+{
+    return;
+}