Support changing OPENSSL_armcap with environment variable on Apple 64…

…-bit ARM systems (aws#1045)

* use handle_cpu_env from cpu_aarch64_linux.c to cpu_aarch64_apple.c

* always use OPENSSL_armcap() when detecting hardware capabilities on arm

* refactor duplicated into cpu_aarch64.h/c

* add ifdefs to cpu_aarch64.h/c

* Update comments

Co-authored-by: Nevine Ebeid <66388554+nebeid@users.noreply.github.com>

* adjust line length of comment

* set arm capabilities functions to fillow format of x86 ones

* make rest of the arm capability functions in line with x86 ones

---------

Co-authored-by: Nevine Ebeid <66388554+nebeid@users.noreply.github.com>
Co-authored-by: Bill Yang <wbyang@amazon.com>

crypto/fipsmodule/cpucap/cpu_aarch64.c

@@ -0,0 +1,52 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0 OR ISC
+
+#if defined(OPENSSL_AARCH64) && !defined(OPENSSL_STATIC_ARMCAP)
+
+#include "cpu_aarch64.h"
+
+void handle_cpu_env(uint32_t *out, const char *in) {
+  const int invert = in[0] == '~';
+  const int or = in[0] == '|';
+  const int skip_first_byte = invert || or;
+  const int hex = in[skip_first_byte] == '0' && in[skip_first_byte+1] == 'x';
+  uint32_t armcap = out[0];
+
+  int sscanf_result;
+  uint32_t v;
+  if (hex) {
+    sscanf_result = sscanf(in + skip_first_byte + 2, "%" PRIx32, &v);
+  } else {
+    sscanf_result = sscanf(in + skip_first_byte, "%" PRIu32, &v);
+  }
+
+  if (!sscanf_result) {
+    return;
+  }
+
+  // Detect if the user is trying to use the environment variable to set
+  // a capability that is _not_ available on the CPU:
+  // If the runtime capability check (e.g via getauxval() on Linux)
+  // returned a non-zero hwcap in `armcap` (out)
+  // and a bit set in the requested `v` is not set in `armcap`,
+  // abort instead of crashing later.
+  // The case of invert cannot enable an unexisting capability;
+  // it can only disable an existing one.
+  if (!invert && armcap && (~armcap & v))
+  {
+    fprintf(stderr,
+            "Fatal Error: HW capability found: 0x%02X, but HW capability requested: 0x%02X.\n",
+            armcap, v);
+    exit(1);
+  }
+
+  if (invert) {
+    out[0] &= ~v;
+  } else if (or) {
+    out[0] |= v;
+  } else {
+    out[0] = v;
+  }
+}
+
+#endif // OPENSSL_AARCH64 && !OPENSSL_STATIC_ARMCAP

crypto/fipsmodule/cpucap/cpu_aarch64.h

@@ -0,0 +1,31 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0 OR ISC
+
+#ifndef OPENSSL_HEADER_CPUCAP_CPU_AARCH64_H
+#define OPENSSL_HEADER_CPUCAP_CPU_AARCH64_H
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#include <inttypes.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if defined(OPENSSL_AARCH64) && !defined(OPENSSL_STATIC_ARMCAP)
+
+// cpu_aarch64 contains common functions used across multiple cpu_aarch64_* files
+
+// handle_cpu_env applies the value from |in| to the CPUID values in |out[0]|.
+// See the comment in |OPENSSL_cpuid_setup| about this.
+void handle_cpu_env(uint32_t *out, const char *in);
+
+#endif // OPENSSL_AARCH64 && !OPENSSL_STATIC_ARMCAP
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif // OPENSSL_HEADER_CPUCAP_CPU_AARCH64_H

crypto/fipsmodule/cpucap/cpu_aarch64_apple.c

@@ -22,6 +22,7 @@
 
 #include <openssl/arm_arch.h>
 
+#include "cpu_aarch64.h"
 
 extern uint32_t OPENSSL_armcap_P;
 
@@ -67,6 +68,21 @@ void OPENSSL_cpuid_setup(void) {
   if (has_hw_feature("hw.optional.armv8_2_sha512")) {
     OPENSSL_armcap_P |= ARMV8_SHA512;
   }
+
+  // OPENSSL_armcap is a 32-bit, unsigned value which may start with "0x" to
+  // indicate a hex value. Prior to the 32-bit value, a '~' or '|' may be given.
+  //
+  // If the '~' prefix is present:
+  //   the value is inverted and ANDed with the probed CPUID result
+  // If the '|' prefix is present:
+  //   the value is ORed with the probed CPUID result
+  // Otherwise:
+  //   the value is taken as the result of the CPUID
+  const char *env;
+  env = getenv("OPENSSL_armcap");
+  if (env != NULL) {
+    handle_cpu_env(&OPENSSL_armcap_P, env);
+  }
 }
 
 #endif  // OPENSSL_AARCH64 && OPENSSL_APPLE && !OPENSSL_STATIC_ARMCAP

crypto/fipsmodule/cpucap/cpu_aarch64_linux.c

@@ -22,46 +22,13 @@
 #ifndef __STDC_FORMAT_MACROS
 #define __STDC_FORMAT_MACROS
 #endif
-#include <inttypes.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 
 #include <openssl/arm_arch.h>
 
+#include "cpu_aarch64.h"
 
 extern uint32_t OPENSSL_armcap_P;
 
-// handle_cpu_env applies the value from |in| to the CPUID values in |out[0]|
-// and |out[1]|. See the comment in |OPENSSL_cpuid_setup| about this.
-static void handle_cpu_env(uint32_t *out, const char *in) {
-  const int invert = in[0] == '~';
-  const int or = in[0] == '|';
-  const int skip_first_byte = invert || or;
-  const int hex = in[skip_first_byte] == '0' && in[skip_first_byte+1] == 'x';
-
-  int sscanf_result;
-  uint32_t v;
-  if (hex) {
-    sscanf_result = sscanf(in + invert + 2, "%" PRIx32, &v);
-  } else {
-    sscanf_result = sscanf(in + invert, "%" PRIu32, &v);
-  }
-
-  if (!sscanf_result) {
-    return;
-  }
-
-  if (invert) {
-    out[0] &= ~v;
-  } else if (or) {
-    out[0] |= v;
-  } else {
-    out[0] = v;
-  }
-}
-
 void OPENSSL_cpuid_setup(void) {
   unsigned long hwcap = getauxval(AT_HWCAP);