X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/a90d420cbe87490c844ae422c966e746d3134b07..1b07c4f340465551b7d12c3be3bcecd258a3c32d:/base/dispatch-x86ish.S

diff --git a/base/dispatch-x86ish.S b/base/dispatch-x86ish.S
index c3725fc6..b3b6d1cb 100644
--- a/base/dispatch-x86ish.S
+++ b/base/dispatch-x86ish.S
@@ -132,16 +132,17 @@ FUNC(dispatch_x86ish_xmmregisters_p)
 
 	// Save the floating point and SIMD registers, and try to clobber
 	// xmm0.
+	lea	DX, [SP + 160]
 	fxsave	[SP]
-	mov	eax, [SP + 160]
-	xor	dword ptr [SP + 160], 0xaaaa5555
+	mov	eax, [DX]
+	xor	dword ptr [DX], 0xaaaa5555
 	fxrstor	[SP]
 
 	// Save them again, and read back the low word of xmm0.  Undo the
 	// clobbering and restore.
 	fxsave	[SP]
-	mov	ecx, [SP + 160]
-	mov	[SP + 160], eax
+	mov	ecx, [DX]
+	mov	[DX], eax
 	fxrstor	[SP]
 
 	// The register are live if we read different things.
@@ -157,22 +158,27 @@ ENDFUNC
 /// Checking `rdrand'.
 
 FUNC(dispatch_x86ish_rdrand)
-	// Enter with one argument: a pointer X_OUT to a 32-bit word.  Try to
-	// generate a random word using `rdrand'.  If successful, set *X_OUT
-	// to the generated word, and return zero; otherwise, return -1.
+	// 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.
 
 #if CPUFAM_X86
+#  define OP eax
 #  define X_OUT edx
 #  define COUNT ecx
-	mov	X_OUT, [SP + 4]
+	mov	OP, [SP + 4]
+	mov	X_OUT, [SP + 8]
 #endif
 #if CPUFAM_AMD64 && ABI_SYSV
-#  define X_OUT rdi
+#  define OP edi
+#  define X_OUT rsi
 #  define COUNT ecx
 #endif
 #if CPUFAM_AMD64 && ABI_WIN
-#  define X_OUT rcx
-#  define COUNT edx
+#  define OP rcx
+#  define X_OUT rdx
+#  define COUNT r8d
 #endif
   endprologue
 
@@ -181,9 +187,10 @@ FUNC(dispatch_x86ish_rdrand)
 	jc	9f
 	dec	COUNT
 	jnz	0b
+	jmp	8f
 
 	// Failed to come up with a random value.
-	mov	eax, -1
+8:	mov	eax, -1
 	ret
 
 	// Success.