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      1 /* Copyright (c) 2014, Google Inc.
      2  *
      3  * Permission to use, copy, modify, and/or distribute this software for any
      4  * purpose with or without fee is hereby granted, provided that the above
      5  * copyright notice and this permission notice appear in all copies.
      6  *
      7  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      8  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
      9  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
     10  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     11  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
     12  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
     13  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
     14 
     15 #include <openssl/cpu.h>
     16 
     17 #if (defined(OPENSSL_ARM) || defined(OPENSSL_AARCH64)) && \
     18     !defined(OPENSSL_STATIC_ARMCAP)
     19 
     20 #include <inttypes.h>
     21 #include <string.h>
     22 
     23 #include <setjmp.h>
     24 #include <signal.h>
     25 
     26 #include <openssl/arm_arch.h>
     27 
     28 
     29 /* We can't include <sys/auxv.h> because the Android SDK version against which
     30  * Chromium builds is too old to have it. Instead we define all the constants
     31  * that we need and have a weak pointer to getauxval. */
     32 
     33 unsigned long getauxval(unsigned long type) __attribute__((weak));
     34 
     35 extern uint32_t OPENSSL_armcap_P;
     36 
     37 char CRYPTO_is_NEON_capable_at_runtime(void) {
     38   return (OPENSSL_armcap_P & ARMV7_NEON) != 0;
     39 }
     40 
     41 static char g_set_neon_called = 0;
     42 
     43 void CRYPTO_set_NEON_capable(char neon_capable) {
     44   g_set_neon_called = 1;
     45 
     46   if (neon_capable) {
     47     OPENSSL_armcap_P |= ARMV7_NEON;
     48   } else {
     49     OPENSSL_armcap_P &= ~ARMV7_NEON;
     50   }
     51 }
     52 
     53 char CRYPTO_is_NEON_functional(void) {
     54   static const uint32_t kWantFlags = ARMV7_NEON | ARMV7_NEON_FUNCTIONAL;
     55   return (OPENSSL_armcap_P & kWantFlags) == kWantFlags;
     56 }
     57 
     58 void CRYPTO_set_NEON_functional(char neon_functional) {
     59   if (neon_functional) {
     60     OPENSSL_armcap_P |= ARMV7_NEON_FUNCTIONAL;
     61   } else {
     62     OPENSSL_armcap_P &= ~ARMV7_NEON_FUNCTIONAL;
     63   }
     64 }
     65 
     66 int CRYPTO_is_ARMv8_AES_capable(void) {
     67   return (OPENSSL_armcap_P & ARMV8_AES) != 0;
     68 }
     69 
     70 int CRYPTO_is_ARMv8_PMULL_capable(void) {
     71   return (OPENSSL_armcap_P & ARMV8_PMULL) != 0;
     72 }
     73 
     74 #if !defined(OPENSSL_NO_ASM) && defined(OPENSSL_ARM)
     75 
     76 static sigjmp_buf sigill_jmp;
     77 
     78 static void sigill_handler(int signal) {
     79   siglongjmp(sigill_jmp, signal);
     80 }
     81 
     82 void CRYPTO_arm_neon_probe(void);
     83 
     84 // probe_for_NEON returns 1 if a NEON instruction runs successfully. Because
     85 // getauxval doesn't exist on Android until Jelly Bean, supporting NEON on
     86 // older devices requires this.
     87 static int probe_for_NEON(void) {
     88   int supported = 0;
     89 
     90   sigset_t sigmask;
     91   sigfillset(&sigmask);
     92   sigdelset(&sigmask, SIGILL);
     93   sigdelset(&sigmask, SIGTRAP);
     94   sigdelset(&sigmask, SIGFPE);
     95   sigdelset(&sigmask, SIGBUS);
     96   sigdelset(&sigmask, SIGSEGV);
     97 
     98   struct sigaction sigill_original_action, sigill_action;
     99   memset(&sigill_action, 0, sizeof(sigill_action));
    100   sigill_action.sa_handler = sigill_handler;
    101   sigill_action.sa_mask = sigmask;
    102 
    103   sigset_t original_sigmask;
    104   sigprocmask(SIG_SETMASK, &sigmask, &original_sigmask);
    105 
    106   if (sigsetjmp(sigill_jmp, 1 /* save signals */) == 0) {
    107     sigaction(SIGILL, &sigill_action, &sigill_original_action);
    108 
    109     // This function cannot be inline asm because GCC will refuse to compile
    110     // inline NEON instructions unless building with -mfpu=neon, which would
    111     // defeat the point of probing for support at runtime.
    112     CRYPTO_arm_neon_probe();
    113     supported = 1;
    114   }
    115   // Note that Android up to and including Lollipop doesn't restore the signal
    116   // mask correctly after returning from a sigsetjmp. So that would need to be
    117   // set again here if more probes were added.
    118   // See https://android-review.googlesource.com/#/c/127624/
    119 
    120   sigaction(SIGILL, &sigill_original_action, NULL);
    121   sigprocmask(SIG_SETMASK, &original_sigmask, NULL);
    122 
    123   return supported;
    124 }
    125 
    126 #else
    127 
    128 static int probe_for_NEON(void) {
    129   return 0;
    130 }
    131 
    132 #endif  /* !OPENSSL_NO_ASM && OPENSSL_ARM */
    133 
    134 void OPENSSL_cpuid_setup(void) {
    135   if (getauxval == NULL) {
    136     // On ARM, but not AArch64, try a NEON instruction and see whether it works
    137     // in order to probe for NEON support.
    138     //
    139     // Note that |CRYPTO_is_NEON_capable| can be true even if
    140     // |CRYPTO_set_NEON_capable| has never been called if the code was compiled
    141     // with NEON support enabled (e.g. -mfpu=neon).
    142     if (!g_set_neon_called && !CRYPTO_is_NEON_capable() && probe_for_NEON()) {
    143       OPENSSL_armcap_P |= ARMV7_NEON;
    144     }
    145     return;
    146   }
    147 
    148   static const unsigned long AT_HWCAP = 16;
    149   unsigned long hwcap = getauxval(AT_HWCAP);
    150 
    151 #if defined(OPENSSL_ARM)
    152   static const unsigned long kNEON = 1 << 12;
    153   if ((hwcap & kNEON) == 0) {
    154     return;
    155   }
    156 
    157   /* In 32-bit mode, the ARMv8 feature bits are in a different aux vector
    158    * value. */
    159   static const unsigned long AT_HWCAP2 = 26;
    160   hwcap = getauxval(AT_HWCAP2);
    161 
    162   /* See /usr/include/asm/hwcap.h on an ARM installation for the source of
    163    * these values. */
    164   static const unsigned long kAES = 1 << 0;
    165   static const unsigned long kPMULL = 1 << 1;
    166   static const unsigned long kSHA1 = 1 << 2;
    167   static const unsigned long kSHA256 = 1 << 3;
    168 #elif defined(OPENSSL_AARCH64)
    169   /* See /usr/include/asm/hwcap.h on an aarch64 installation for the source of
    170    * these values. */
    171   static const unsigned long kNEON = 1 << 1;
    172   static const unsigned long kAES = 1 << 3;
    173   static const unsigned long kPMULL = 1 << 4;
    174   static const unsigned long kSHA1 = 1 << 5;
    175   static const unsigned long kSHA256 = 1 << 6;
    176 
    177   if ((hwcap & kNEON) == 0) {
    178     return;
    179   }
    180 #endif
    181 
    182   OPENSSL_armcap_P |= ARMV7_NEON;
    183 
    184   if (hwcap & kAES) {
    185     OPENSSL_armcap_P |= ARMV8_AES;
    186   }
    187   if (hwcap & kPMULL) {
    188     OPENSSL_armcap_P |= ARMV8_PMULL;
    189   }
    190   if (hwcap & kSHA1) {
    191     OPENSSL_armcap_P |= ARMV8_SHA1;
    192   }
    193   if (hwcap & kSHA256) {
    194     OPENSSL_armcap_P |= ARMV8_SHA256;
    195   }
    196 }
    197 
    198 #endif  /* (defined(OPENSSL_ARM) || defined(OPENSSL_AARCH64)) &&
    199            !defined(OPENSSL_STATIC_ARMCAP) */
    200