Sun Jul 19 15:33:08 2020 UTC ()

Expand on importance of not using fpu for crypto if there's no fpu.


(riastradh)

diff -r1.17 -r1.18 src/crypto/external/bsd/openssl/dist/crypto/ppccap.c

--- src/crypto/external/bsd/openssl/dist/crypto/ppccap.c 2020/07/15 08:14:41	1.17
+++ src/crypto/external/bsd/openssl/dist/crypto/ppccap.c 2020/07/19 15:33:08	1.18

 @@ -364,28 +364,31 @@ void OPENSSL_cpuid_setup(void)
     memset(&ill_act, 0, sizeof(ill_act));
     ill_act.sa_handler = ill_handler;
     ill_act.sa_mask = all_masked;
     sigprocmask(SIG_SETMASK, &ill_act.sa_mask, &oset);
     sigaction(SIGILL, &ill_act, &ill_oact);
 #ifndef OSSL_IMPLEMENT_GETAUXVAL
 # ifdef __NetBSD__
     int error, val;
     size_t len = sizeof(val);
     /*
-     * If machdep.fpu_present == 0, FPU is absent and emulated by software.
+     * If machdep.fpu_present == 0, FPU is absent and emulated by
-     * Avoid using it for better performance.
+     * software.  In that case, using FPU instructions hurts rather
      * than helps performance, and the software is unlikely to run in
      * constant time so it would expose us to timing side channel
      * attacks.  So don't do it!
      */
     error = sysctlbyname("machdep.fpu_present", &val, &len, NULL, 0);
     if (error != 0 || (error == 0 && val != 0))
 # endif
     if (sigsetjmp(ill_jmp,1) == 0) {
         OPENSSL_fpu_probe();
         OPENSSL_ppccap_P |= PPC_FPU;
         if (sizeof(size_t) == 4) {
 # ifdef __linux
             struct utsname uts;
             if (uname(&uts) == 0 && strcmp(uts.machine, "ppc64") == 0)
 # endif