From fce8249cafa7e841c89838378167702ad5f12d46 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <slankes@eonerc.rwth-aachen.de>
Date: Fri, 24 Jul 2015 06:27:46 +0200
Subject: [PATCH] code cleanups, increasing the readability, add some comments

---
 hermit/arch/x86/kernel/processor.c | 33 ++++++++++++++++++------------
 hermit/kernel/tasks.c              |  4 ++--
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/hermit/arch/x86/kernel/processor.c b/hermit/arch/x86/kernel/processor.c
index 0988765ac..e2ec26f5b 100644
--- a/hermit/arch/x86/kernel/processor.c
+++ b/hermit/arch/x86/kernel/processor.c
@@ -104,12 +104,12 @@ static void fpu_init_fxsr(union fpu_state* fpu)
 
 static void save_fpu_state_xsave(union fpu_state* state)
 {
-	asm volatile ("xsaveq %0" : "=m"(state->xsave) : "a"(1), "d"(1) : "memory");
+	asm volatile ("xsaveq %0" : "=m"(state->xsave) : "a"(-1), "d"(-1) : "memory");
 }
 
 static void restore_fpu_state_xsave(union fpu_state* state)
 {
-	asm volatile ("xrstorq %0" :: "m"(state->xsave), "a"(1), "d"(1));
+	asm volatile ("xrstorq %0" :: "m"(state->xsave), "a"(-1), "d"(-1));
 }
 
 static void fpu_init_xsave(union fpu_state* fpu)
@@ -117,7 +117,7 @@ static void fpu_init_xsave(union fpu_state* fpu)
 	xsave_t* xs = &fpu->xsave;
 
 	memset(xs, 0x00, sizeof(xsave_t));
-	//xs->fxsave.twd = 0xffffu;
+	xs->fxsave.cwd = 0x37f;
 	xs->fxsave.mxcsr = 0x1f80;
 }
 
@@ -218,8 +218,9 @@ int cpu_detection(void) {
 			xcr0 |= 0x2;
 		if (has_avx())
 			xcr0 |= 0x4;
-		kprintf("Set XCR0 to 0x%llx\n", xcr0);
 		xsetbv(0, xcr0);
+
+		kprintf("Set XCR0 to 0x%llx\n", xgetbv(0));
 	}
 
 	if (cpu_info.feature3 & CPU_FEATURE_SYSCALL) {
@@ -257,7 +258,11 @@ int cpu_detection(void) {
 	}
 
 	if (first_time) {
-		kprintf("CPU features: %s%s%s%s%s%s%s%s%s%s%s%s%s\n",
+		// reload feature list because we enabled OSXSAVE
+		a = b = c = d = 0;
+                cpuid(1, &a, &b, &cpu_info.feature2, &cpu_info.feature1);
+
+		kprintf("CPU features: %s%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
 			has_sse() ? "SSE " : "",
 			has_sse2() ? "SSE2 " : "",
 			has_sse3() ? "SSE3 " : "",
@@ -270,26 +275,26 @@ int cpu_detection(void) {
 			has_x2apic() ? "X2APIC " : "",
 			has_fpu() ? "FPU " : "",
 			has_fxsr() ? "FXSR " : "",
-			has_xsave() ? "XSAVE " : "");
+			has_xsave() ? "XSAVE " : "",
+			has_osxsave() ? "OSXSAVE " : "");
 	}
 
-	if (first_time && has_xsave()) {
-#if 0
+	if (first_time && has_osxsave()) {
 		a = b = d = 0;
 		c = 2;
-		cpuid(0, &a, &b, &c, &d);
+		cpuid(0xd, &a, &b, &c, &d);
 		kprintf("Ext_Save_Area_2: offset %d, size %d\n", b, a);
 
 		a = b = d = 0;
 		c = 3;
-		cpuid(0, &a, &b, &c, &d);
+		cpuid(0xd, &a, &b, &c, &d);
 		kprintf("Ext_Save_Area_3: offset %d, size %d\n", b, a);
 
 		a = b = d = 0;
 		c = 4;
-		cpuid(0, &a, &b, &c, &d);
+		cpuid(0xd, &a, &b, &c, &d);
 		kprintf("Ext_Save_Area_4: offset %d, size %d\n", b, a);
-#endif
+
 		save_fpu_state = save_fpu_state_xsave;
 		restore_fpu_state = restore_fpu_state_xsave;
 		fpu_init = fpu_init_xsave;
@@ -315,8 +320,10 @@ int cpu_detection(void) {
 		kprintf("Maximum input value for hypervisor: 0x%x\n", a);
 	}
 
-	if (first_time)
+	if (first_time) {
 		kprintf("CR0 0x%llx, CR4 0x%llx\n", read_cr0(), read_cr4());
+		kprintf("size ofxsave_t: %d\n", sizeof(xsave_t));
+	}
 
 	return 0;
 }
diff --git a/hermit/kernel/tasks.c b/hermit/kernel/tasks.c
index 347458c32..2582713ca 100644
--- a/hermit/kernel/tasks.c
+++ b/hermit/kernel/tasks.c
@@ -111,12 +111,12 @@ void fpu_handler(struct state *s)
 	spinlock_irqsave_lock(&readyqueues[core_id].lock);
 	// did another already use the the FPU? => save FPU state
 	if (readyqueues[core_id].fpu_owner) {
-		save_fpu_state(&task_table[readyqueues[core_id].fpu_owner].fpu);
+		save_fpu_state(&(task_table[readyqueues[core_id].fpu_owner].fpu));
 		readyqueues[core_id].fpu_owner = 0;
 	}
 	spinlock_irqsave_unlock(&readyqueues[core_id].lock);
 
-	if (!(task->flags & TASK_FPU_INIT))  {
+	if (BUILTIN_EXPECT(!(task->flags & TASK_FPU_INIT), 0))  {
 		// use the FPU at the first time => Initialize FPU
  		fpu_init(&task->fpu);
 		task->flags |= TASK_FPU_INIT;