kernel: add avx support (#75)

Author: icexin

kernel/asm_amd64.s

@@ -35,6 +35,21 @@ TEXT ·sseInit(SB), NOSPLIT, $0
 	MOVL AX, CR4
 	RET
 
+TEXT ·avxInit(SB), NOSPLIT, $0
+	// enable XGETBV and XSETBV
+	MOVL CR4, AX
+	ORL  $1<<18, AX
+	MOVL AX, CR4
+
+	// enable avx
+	XORQ CX, CX
+	XGETBV
+
+	ORQ  $7, AX
+	XORQ CX, CX
+	XSETBV
+	RET
+
 TEXT ·rdmsr(SB), NOSPLIT, $0-16
 	MOVL reg+0(FP), CX
 	RDMSR
@@ -55,3 +70,12 @@ TEXT ·getg(SB), NOSPLIT, $0-8
 	MOVQ BX, ret+0(FP)
 	RET
 
+TEXT ·cpuid(SB), NOSPLIT, $0-24
+	MOVL fn+0(FP), AX
+	MOVL cx+4(FP), CX
+	CPUID
+	MOVL AX, eax+8(FP)
+	MOVL BX, ebx+12(FP)
+	MOVL CX, ecx+16(FP)
+	MOVL DX, edx+20(FP)
+	RET

kernel/rt0.go

@@ -13,9 +13,6 @@ func rt0()
 //go:nosplit
 func go_entry()
 
-//go:nosplit
-func sseInit()
-
 //go:nosplit
 func wrmsr(reg uint32, value uintptr)
 
@@ -24,7 +21,7 @@ func rdmsr(reg uint32) (value uintptr)
 
 //go:nosplit
 func preinit(magic, mbiptr uintptr) {
-	sseInit()
+	simdInit()
 	gdtInit()
 	idtInit()
 	multiboot.Init(magic, mbiptr)

kernel/simd.go

@@ -0,0 +1,40 @@
+package kernel
+
+const (
+	_CPUID_ECX_XSAVE = 1 << 26
+	_CPUID_ECX_AVX   = 1 << 28
+	_CPUID_EBX_AVX2  = 1 << 5
+
+	_CPUID_FN_STD = 0x00000001
+	_CPUID_FN_EXT = 0x80000001
+)
+
+//go:nosplit
+func sseInit()
+
+//go:nosplit
+func avxInit()
+
+//go:nosplit
+func cpuid(fn, cx uint32) (eax, ebx, ecx, edx uint32)
+
+//go:nosplit
+func simdInit() {
+	sseInit()
+
+	// init for avx
+	// first check avx function
+	_, _, ecx, _ := cpuid(_CPUID_FN_STD, 0)
+	if ecx&_CPUID_ECX_XSAVE == 0 {
+		return
+	}
+	if ecx&_CPUID_ECX_AVX == 0 {
+		return
+	}
+	_, ebx, _, _ := cpuid(0x0007, 0)
+	if ebx&_CPUID_EBX_AVX2 == 0 {
+		return
+	}
+	// all check passed, init avx
+	avxInit()
+}

magefile.go

@@ -135,7 +135,7 @@ func Graphic() error {
 	detectQemu()
 
 	mg.Deps(Iso)
-	return eggrun(QEMU_OPT, "-k", "eggos.iso")
+	return eggrun(QEMU_OPT, "eggos.iso")
 }
 
 // GraphicDebug run eggos.iso on qemu in debug mode.
@@ -144,7 +144,7 @@ func GraphicDebug() error {
 
 	GOGCFLAGS += " -N -l"
 	mg.Deps(Iso)
-	return eggrun(QEMU_DEBUG_OPT, "-k", "eggos.iso")
+	return eggrun(QEMU_DEBUG_OPT, "eggos.iso")
 }
 
 func Egg() error {