LoongArch: Add vector extensions support

Add LoongArch's vector extensions support, which including 128bit LSX
(i.e., Loongson SIMD eXtension) and 256bit LASX (i.e., Loongson Advanced
SIMD eXtension).

Linux kernel doesn't use vector itself, it only handle exceptions and
context save/restore. So it only needs a subset of these instructions:

* Vector load/store:   vld vst vldx vstx xvld xvst xvldx xvstx
* 8bit-elements move:  vpickve2gr.b xvpickve2gr.b vinsgr2vr.b xvinsgr2vr.b
* 16bit-elements move: vpickve2gr.h xvpickve2gr.h vinsgr2vr.h xvinsgr2vr.h
* 32bit-elements move: vpickve2gr.w xvpickve2gr.w vinsgr2vr.w xvinsgr2vr.w
* 64bit-elements move: vpickve2gr.d xvpickve2gr.d vinsgr2vr.d xvinsgr2vr.d
* Elements permute:    vpermi.w vpermi.d xvpermi.w xvpermi.d xvpermi.q

Introduce AS_HAS_LSX_EXTENSION and AS_HAS_LASX_EXTENSION to avoid non-
vector toolchains complains unsupported instructions.

Signed-off-by: Huacai Chen <[email protected]>

Author: chenhuacai

arch/loongarch/Kconfig

@@ -164,14 +164,6 @@ config 32BIT
 config 64BIT
 	def_bool y
 
-config CPU_HAS_FPU
-	bool
-	default y
-
-config CPU_HAS_PREFETCH
-	bool
-	default y
-
 config GENERIC_BUG
 	def_bool y
 	depends on BUG
@@ -247,6 +239,12 @@ config AS_HAS_EXPLICIT_RELOCS
 config AS_HAS_FCSR_CLASS
 	def_bool $(as-instr,movfcsr2gr \$t0$(comma)\$fcsr0)
 
+config AS_HAS_LSX_EXTENSION
+	def_bool $(as-instr,vld \$vr0$(comma)\$a0$(comma)0)
+
+config AS_HAS_LASX_EXTENSION
+	def_bool $(as-instr,xvld \$xr0$(comma)\$a0$(comma)0)
+
 menu "Kernel type and options"
 
 source "kernel/Kconfig.hz"
@@ -487,6 +485,43 @@ config ARCH_STRICT_ALIGN
 	  to run kernel only on systems with h/w unaligned access support in
 	  order to optimise for performance.
 
+config CPU_HAS_FPU
+	bool
+	default y
+
+config CPU_HAS_LSX
+	bool "Support for the Loongson SIMD Extension"
+	depends on AS_HAS_LSX_EXTENSION
+	help
+	  Loongson SIMD Extension (LSX) introduces 128 bit wide vector registers
+	  and a set of SIMD instructions to operate on them. When this option
+	  is enabled the kernel will support allocating & switching LSX
+	  vector register contexts. If you know that your kernel will only be
+	  running on CPUs which do not support LSX or that your userland will
+	  not be making use of it then you may wish to say N here to reduce
+	  the size & complexity of your kernel.
+
+	  If unsure, say Y.
+
+config CPU_HAS_LASX
+	bool "Support for the Loongson Advanced SIMD Extension"
+	depends on CPU_HAS_LSX
+	depends on AS_HAS_LASX_EXTENSION
+	help
+	  Loongson Advanced SIMD Extension (LASX) introduces 256 bit wide vector
+	  registers and a set of SIMD instructions to operate on them. When this
+	  option is enabled the kernel will support allocating & switching LASX
+	  vector register contexts. If you know that your kernel will only be
+	  running on CPUs which do not support LASX or that your userland will
+	  not be making use of it then you may wish to say N here to reduce
+	  the size & complexity of your kernel.
+
+	  If unsure, say Y.
+
+config CPU_HAS_PREFETCH
+	bool
+	default y
+
 config KEXEC
 	bool "Kexec system call"
 	select KEXEC_CORE