Define HW-feature flags per architecture

* random/rand-internal.h (_gcry_rndhw_poll_slow): Add requested length
parameter.
* random/rndhw.c (_gcry_rndhw_poll_slow): Limit accounted bytes to 50%
(or 25% for RDRAND) - this code is moved from caller side.
* random/rndlinux.c (_gcry_rndlinux_gather_random): Move
HWF_INTEL_RDRAND check to _gcry_rndhw_poll_slow.
* src/g10lib.h (HWF_PADLOCK_*, HWF_INTEL_*): Define only if
HAVE_CPU_ARCH_X86.
(HWF_ARM_*): Define only if HAVE_CPU_ARCH_ARM.
(HWF_PPC_*): Define only if HAVE_CPU_ARCH_PPC.
(HWF_S390X_*): Define only if HAVE_CPU_ARCH_S390X.
--

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>

1 files changed, 12 insertions, 3 deletions

diff --git a/random/rndhw.c b/random/rndhw.c
index 2829382c..3cf9acc3 100644
--- a/random/rndhw.c
+++ b/random/rndhw.c
@@ -198,24 +198,33 @@ _gcry_rndhw_poll_fast (void (*add)(const void*, size_t, enum random_origins),
 
 
 /* Read 64 bytes from a hardware RNG and return the number of bytes
-   actually read.  */
+   actually read.  However hardware source is let account only
+   for up to 50% (or 25% for RDRAND) of the requested bytes.  */
 size_t
 _gcry_rndhw_poll_slow (void (*add)(const void*, size_t, enum random_origins),
-                       enum random_origins origin)
+                       enum random_origins origin, size_t req_length)
 {
   size_t nbytes = 0;
 
   (void)add;
   (void)origin;
 
+  req_length /= 2; /* Up to 50%. */
+
 #ifdef USE_DRNG
   if ((_gcry_get_hw_features () & HWF_INTEL_RDRAND))
-    nbytes += poll_drng (add, origin, 0);
+    {
+      req_length /= 2; /* Up to 25%. */
+      nbytes += poll_drng (add, origin, 0);
+    }
 #endif
 #ifdef USE_PADLOCK
   if ((_gcry_get_hw_features () & HWF_PADLOCK_RNG))
     nbytes += poll_padlock (add, origin, 0);
 #endif
 
+  if (nbytes > req_length)
+    nbytes = req_length;
+
   return nbytes;
 }