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)

(cherry picked from commit 360f6dcc5aa1a86ec3ff9a94612b88e3d960ee2e)

3 files changed, 178 insertions, 0 deletions

diff --git a/crypto/build.info b/crypto/build.info
index a45bf8deef..f568234081 100644
--- a/crypto/build.info
+++ b/crypto/build.info
@@ -51,6 +51,8 @@ IF[{- !$disabled{asm} && $config{processor} ne '386' -}]
 
   $CPUIDASM_c64xplus=c64xpluscpuid.s
 
+  $CPUIDASM_riscv64=riscvcap.c riscv64cpuid.s
+
   # Now that we have defined all the arch specific variables, use the
   # appropriate one, and define the appropriate macros
   IF[$CPUIDASM_{- $target{asm_arch} -}]
@@ -130,6 +132,7 @@ GENERATE[armv4cpuid.S]=armv4cpuid.pl
 INCLUDE[armv4cpuid.o]=.
 GENERATE[s390xcpuid.S]=s390xcpuid.pl
 INCLUDE[s390xcpuid.o]=.
+GENERATE[riscv64cpuid.s]=riscv64cpuid.pl
 
 IF[{- $config{target} =~ /^(?:Cygwin|mingw|VC-|BC-)/ -}]
   SHARED_SOURCE[../libcrypto]=dllmain.c
diff --git a/crypto/riscv64cpuid.pl b/crypto/riscv64cpuid.pl
new file mode 100644
index 0000000000..675e9b6111
--- /dev/null
+++ b/crypto/riscv64cpuid.pl
@@ -0,0 +1,89 @@
+#! /usr/bin/env perl
+# 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
+
+
+# $output is the last argument if it looks like a file (it has an extension)
+# $flavour is the first argument if it doesn't look like a file
+$output = $#ARGV >= 0 && $ARGV[$#ARGV] =~ m|\.\w+$| ? pop : undef;
+$flavour = $#ARGV >= 0 && $ARGV[0] !~ m|\.| ? shift : undef;
+
+$output and open STDOUT,">$output";
+
+{
+my ($in_a,$in_b,$len,$x,$temp1,$temp2) = ('a0','a1','a2','t0','t1','t2');
+$code.=<<___;
+################################################################################
+# int CRYPTO_memcmp(const void * in_a, const void * in_b, size_t len)
+################################################################################
+.text
+.balign 16
+.globl CRYPTO_memcmp
+.type   CRYPTO_memcmp,\@function
+CRYPTO_memcmp:
+    li      $x,0
+    beqz    $len,2f   # len == 0
+1:
+    lbu     $temp1,0($in_a)
+    lbu     $temp2,0($in_b)
+    addi    $in_a,$in_a,1
+    addi    $in_b,$in_b,1
+    addi    $len,$len,-1
+    xor     $temp1,$temp1,$temp2
+    or      $x,$x,$temp1
+    bgtz    $len,1b
+2:
+    mv      a0,$x
+    ret
+___
+}
+{
+my ($ptr,$len,$temp1,$temp2) = ('a0','a1','t0','t1');
+$code.=<<___;
+################################################################################
+# void OPENSSL_cleanse(void *ptr, size_t len)
+################################################################################
+.text
+.balign 16
+.globl OPENSSL_cleanse
+.type   OPENSSL_cleanse,\@function
+OPENSSL_cleanse:
+    beqz    $len,2f         # len == 0, return
+    srli    $temp1,$len,4
+    bnez    $temp1,3f       # len > 15
+
+1:  # Store <= 15 individual bytes
+    sb      x0,0($ptr)
+    addi    $ptr,$ptr,1
+    addi    $len,$len,-1
+    bnez    $len,1b
+2:
+    ret
+
+3:  # Store individual bytes until we are aligned
+    andi    $temp1,$ptr,0x7
+    beqz    $temp1,4f
+    sb      x0,0($ptr)
+    addi    $ptr,$ptr,1
+    addi    $len,$len,-1
+    j       3b
+
+4:  # Store aligned dwords
+    li      $temp2,8
+4:
+    sd      x0,0($ptr)
+    addi    $ptr,$ptr,8
+    addi    $len,$len,-8
+    bge     $len,$temp2,4b  # if len>=8 loop
+    bnez    $len,1b         # if len<8 and len != 0, store remaining bytes
+    ret
+___
+}
+
+
+print $code;
+close STDOUT or die "error closing STDOUT: $!";
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;
+    }
+}