X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/1b07c4f340465551b7d12c3be3bcecd258a3c32d..00b52725bf15e844360d07248de1d8cbbc1e165e:/base/dispatch-x86ish.S

diff --git a/base/dispatch-x86ish.S b/base/dispatch-x86ish.S
index b3b6d1cb..9510f969 100644
--- a/base/dispatch-x86ish.S
+++ b/base/dispatch-x86ish.S
@@ -155,13 +155,47 @@ FUNC(dispatch_x86ish_xmmregisters_p)
 ENDFUNC
 
 ///--------------------------------------------------------------------------
+/// Checking extended control registers.
+
+FUNC(dispatch_x86ish_xgetbv)
+	// Call with two arguments: a pointer Z_OUT to 8 bytes of output space, and
+	// a 32-bit integer C.  Read the 64-bit value of XCR(C), and store it
+	// at Z_OUT.
+
+#if CPUFAM_X86
+#  define Z_OUT edi
+	mov	edi, [esp + 4]
+	mov	ecx, [esp + 8]
+#endif
+#if CPUFAM_AMD64 && ABI_SYSV
+#  define Z_OUT rdi
+	mov	ecx, esi
+#endif
+#if CPUFAM_AMD64 && ABI_WIN
+#  define Z_OUT r8
+	mov	r8, rcx
+	mov	ecx, edx
+#endif
+  endprologue
+
+	xgetbv
+	mov	[Z_OUT + 0], eax
+	mov	[Z_OUT + 4], edx
+
+	ret
+
+#undef Z_OUT
+ENDFUNC
+
+///--------------------------------------------------------------------------
 /// Checking `rdrand'.
 
 FUNC(dispatch_x86ish_rdrand)
-	// Enter with two arguments: a code OP requesting `rdrand' (0), and a
-	// pointer X_OUT to a 32-bit word.  Try to generate a random word
-	// using the requested instruction.  If successful, set *X_OUT to the
-	// generated word, and return zero; otherwise, return -1.
+	// Enter with two arguments: a code OP requesting either `rdrand' (0)
+	// or `rdseed' (1), and a pointer X_OUT to a 32-bit word.  Try to
+	// generate a random word using the requested instruction'.  If
+	// successful, set *X_OUT to the generated word, and return zero;
+	// otherwise, return -1.
 
 #if CPUFAM_X86
 #  define OP eax
@@ -182,13 +216,22 @@ FUNC(dispatch_x86ish_rdrand)
 #endif
   endprologue
 
+	cmp	OP, 0
 	mov	COUNT, 16		// fairly persistent
+	jne	1f
+
 0:	rdrand	eax
 	jc	9f
 	dec	COUNT
 	jnz	0b
 	jmp	8f
 
+1:	rdseed	eax
+	jc	9f
+	dec	COUNT
+	jnz	1b
+	jmp	8f
+
 	// Failed to come up with a random value.
 8:	mov	eax, -1
 	ret