Add basic RISC-V cpuid and OPENSSL_riscvcap

RISC-V cpuid implementation allows bitmanip extensions Zb[abcs] to
be enabled at runtime using OPENSSL_riscvcap environment variable.

For example, to specify 64-bit RISC-V with the G,C,Zba,Zbb,Zbc
extensions, one could write: OPENSSL_riscvcap="rv64gc_zba_zbb_zbc"

Architecture string parsing is still very primitive, but can be
expanded in the future. Currently, only bitmanip extensions Zba, Zbb,
Zbc and Zbs are supported.

Includes implementation of constant-time CRYPTO_memcmp in riscv64 asm,
as well as OPENSSL_cleanse. Assembly implementations are written using
perlasm.

Reviewed-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Signed-off-by: Henry Brausen <henry.brausen@vrull.eu>

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17640)

1 files changed, 86 insertions, 0 deletions

diff --git a/crypto/riscvcap.c b/crypto/riscvcap.c
new file mode 100644
index 0000000000..1cbfb4a574
--- /dev/null
+++ b/crypto/riscvcap.c
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdint.h>
+#include <openssl/crypto.h>
+#include "internal/cryptlib.h"
+
+#define OPENSSL_RISCVCAP_IMPL
+#include "crypto/riscv_arch.h"
+
+static void parse_env(const char *envstr);
+static void strtoupper(char *str);
+
+uint32_t OPENSSL_rdtsc(void)
+{
+    return 0;
+}
+
+size_t OPENSSL_instrument_bus(unsigned int *out, size_t cnt)
+{
+    return 0;
+}
+
+size_t OPENSSL_instrument_bus2(unsigned int *out, size_t cnt, size_t max)
+{
+    return 0;
+}
+
+static void strtoupper(char *str)
+{
+    for (char *x = str; *x; ++x)
+        *x = toupper(*x);
+}
+
+/* parse_env() parses a RISC-V architecture string. An example of such a string
+ * is "rv64gc_zba_zbb_zbc_zbs". Currently, the rv64gc part is ignored
+ * and we simply search for "_[extension]" in the arch string to see if we
+ * should enable a given extension.
+ */
+#define BUFLEN 256
+static void parse_env(const char *envstr)
+{
+    char envstrupper[BUFLEN];
+    char buf[BUFLEN];
+
+    /* Convert env str to all uppercase */
+    OPENSSL_strlcpy(envstrupper, envstr, sizeof(envstrupper));
+    strtoupper(envstrupper);
+
+    for (size_t i = 0; i < kRISCVNumCaps; ++i) {
+        /* Prefix capability with underscore in preparation for search */
+        BIO_snprintf(buf, BUFLEN, "_%s", RISCV_capabilities[i].name);
+        if (strstr(envstrupper, buf) != NULL) {
+            /* Match, set relevant bit in OPENSSL_riscvcap_P[] */
+            OPENSSL_riscvcap_P[RISCV_capabilities[i].index] |=
+                (1 << RISCV_capabilities[i].bit_offset);
+        }
+    }
+}
+
+# if defined(__GNUC__) && __GNUC__>=2
+__attribute__ ((constructor))
+# endif
+void OPENSSL_cpuid_setup(void)
+{
+    char *e;
+    static int trigger = 0;
+
+    if (trigger != 0)
+        return;
+    trigger = 1;
+
+    if ((e = getenv("OPENSSL_riscvcap"))) {
+        parse_env(e);
+        return;
+    }
+}