From: Mark Wooding <mdw@distorted.org.uk>
Date: Mon, 16 Dec 2019 17:21:25 +0000 (+0000)
Subject: Merge branch '2.5.x'
X-Git-Tag: 2.6.0~54
X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/commitdiff_plain/119bdfc4c80e313417047de10700e6b8c3955d0d

Merge branch '2.5.x'

* 2.5.x:
  debian/catacomb2.symbols: Bump versions for fixed functions.
  rand/rand.c: Mix the pool key in `rand_gate' and `rand_stretch'.
  rand/lcrand.c: Swap flags and max so generator not advertised as strong.
  pub/dh-kcdsa.c: Free the correct factor.
  math/limlee.c: Don't leak the factor vector on overall failure.
  math/limlee.c: Handle an abort from `pgen' correctly.
  math/pgen.c: Don't free the tester if it's not set up.
  math/ec-exp.h: Fix segfault when base point is at infinity.
  key/key-data.c (key_copydata): Fix catastrophic bug.
  key/key-data.c (key_split): Fix long-standing reference leak.
  key/key-misc.c (key_bytag): Don't give up because a by-id search fails.
  base/dispatch.c, etc.: Check that `rdrand' works.
---

119bdfc4c80e313417047de10700e6b8c3955d0d
diff --cc base/dispatch.c
index c8bbc0b9,abd019f6..459302f0
--- a/base/dispatch.c
+++ b/base/dispatch.c
@@@ -95,12 -162,98 +95,65 @@@ static int cpuid_features_p(unsigned db
  
  static int xmm_registers_available_p(void)
  {
 -#ifdef __GNUC__
 -  unsigned f;
 -  /* This hack is by Agner Fog.  Use FXSAVE/FXRSTOR to figure out whether the
 -   * XMM registers are actually alive.
 -   */
 -  if (!cpuid_features_p(CPUID1D_FXSR, 0)) return (0);
 -#  if CPUFAM_X86
 -  __asm__ ("movl %%esp, %%edx; subl $512, %%esp; andl $~15, %%esp\n"
 -	   "fxsave (%%esp)\n"
 -	   "movl 160(%%esp), %%eax; xorl $0xaaaa5555, 160(%%esp)\n"
 -	   "fxrstor (%%esp); fxsave (%%esp)\n"
 -	   "movl 160(%%esp), %%ecx; movl %%eax, 160(%%esp)\n"
 -	   "fxrstor (%%esp); movl %%edx, %%esp\n"
 -	   "xorl %%ecx, %%eax"
 -	   : "=a" (f)
 -	   : /* no inputs */
 -	   : "%ecx", "%edx");
 -#  elif CPUFAM_AMD64
 -  __asm__ ("movq %%rsp, %%rdx; subq $512, %%rsp; andq $~15, %%rsp\n"
 -	   "fxsave (%%rsp)\n"
 -	   "movl 160(%%rsp), %%eax; xorl $0xaaaa5555, 160(%%rsp)\n"
 -	   "fxrstor (%%rsp); fxsave (%%rsp)\n"
 -	   "movl 160(%%rsp), %%ecx; movl %%eax, 160(%%rsp)\n"
 -	   "fxrstor (%%rsp); movq %%rdx, %%rsp\n"
 -	   "xorl %%ecx, %%eax"
 -	   : "=a" (f)
 -	   : /* no inputs */
 -	   : "%ecx", "%rdx");
 -#  else
 -#    error "I'm confused."
 -#  endif
 +  int f = dispatch_x86ish_xmmregisters_p();
 +
    dispatch_debug("XMM registers %savailable", f ? "" : "not ");
    return (f);
 -#else
 -  dispatch_debug("GNU inline assembler not available; can't check for XMM");
 -  return (0);
 -#endif
  }
  
+ /* --- @rdrand_works_p@ --- *
+  *
+  *
+  * Arguments:	---
+  *
+  * Returns:	Nonzero if the `rdrand' instruction actually works.  Assumes
+  *		that it's already been verified to be safe to issue.
+  */
+ 
+ #ifdef __GNUC__
+ static int rdrand(unsigned *x)
+ {
+   int i, rc;
+   unsigned _t;
+ 
+   i = 16;
+   __asm__ ("" : "=g" (_t));
+   __asm__ ("0: rdrand %2; jc 1f; decl %1; jnz 0b\n"
+ 	   "mov $-1, %0; jmp 9f\n"
+ 	   "1: movl %2, (%3); xorl %0, %0\n"
+ 	   "9:"
+ 	   : "=r" (rc), "+r" (i), "+r" (_t)
+ 	   : "r" (x)
+ 	   : "cc");
+   return (rc);
+ }
+ #endif
+ 
+ static int rdrand_works_p(void)
+ {
+   unsigned ref, x, i;
+ 
+   /* Check that it doesn't always give the same answer.  Try four times: this
+    * will fail with probability %$2^{-128}$% with a truly random generator,
+    * which seems fair enough.
+    */
+   if (rdrand(&ref)) goto fail;
+   for (i = 0; i < 4; i++) {
+     if (rdrand(&x)) goto fail;
+     if (x != ref) goto not_stuck;
+   }
+   dispatch_debug("RDRAND always returns 0x%08x!", ref);
+   return (0);
+ 
+ not_stuck:
+   dispatch_debug("RDRAND instruction looks plausible");
+   return (1);
+ 
+ fail:
+   dispatch_debug("RDRAND instruction fails too often");
+   return (0);
+ }
+ 
  #endif
  
  /*----- General feature probing using auxiliary vectors -------------------*/