Patch set updated for coreboot: libpayload: Enable SSE and FPU when present

[Patrick Rudolph]

Patrick Rudolph ([e-mail]) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/18345

-gerrit

commit af7b7fcd70ebea8df74384ef0e012b28c203cb2e
Author: Patrick Rudolph 
Date:   Sun Jan 15 10:49:48 2017 +0100

libpayload: Enable SSE and FPU when present

Allows to use SSE and floating point in payloads without digging to
    much into x86 assembly code.

Tested on Lenovo T500 (Intel Core2Duo).
    Both floating point operation and SSE is properly working.

Change-Id: I4a5fc633f158de421b70435a8bfdc0dcaa504c72
    Signed-off-by: Patrick Rudolph 
---
 payloads/libpayload/arch/x86/head.S | 43 +++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/payloads/libpayload/arch/x86/head.S b/payloads/libpayload/arch/x86/head.S
index 94a4d41..7f2ea15 100644
--- a/payloads/libpayload/arch/x86/head.S
+++ b/payloads/libpayload/arch/x86/head.S
@@ -2,6 +2,7 @@
  * This file is part of the libpayload project.
  *
  * Copyright (C) 2008 Advanced Micro Devices, Inc.
+ * Copyright (C) 2017 Patrick Rudolph 
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -89,6 +90,48 @@ _init:
    movl $_stack, %esp
    pushl %eax

+	/* Enable special x86 functions if present. */
+	pushl %eax
+	pushl %ebx
+	pushl %ecx
+	pushl %edx
+
+	movl $0, %eax
+	cpuid
+	/* Test if CPUID(eax=1) is available. */
+	test %eax, %eax
+	je cpuid_done
+
+	/* Get CPU features. */
+	movl $1, %eax
+	cpuid
+
+cpuid_fpu:
+	/* Test if x87 FPU is present */
+	test $1, %edx
+	je cpuid_see
+
+	fninit
+	movl %cr0, %eax
+	andl $0xFFFFFFFB, %eax	/* clear EM */
+	orl $0x00000022, %eax	/* set MP, NE */
+	movl %eax, %cr0
+
+cpuid_see:
+	/* Test if SSE is available */
+	test $0x02000000, %edx
+	je cpuid_done
+
+	movl %cr4, %eax
+	orl $0x00000600, %eax	/* set OSFXSR, OSXMMEXCPT */
+	movl %eax, %cr4
+
+cpuid_done:
+	popl %edx
+	popl %ecx
+	popl %ebx
+	popl %eax
+
    /* Let's rock. */
    call start_main