LoongArch: implement ARCH_HAS_KERNEL_FPU_SUPPORT

LoongArch already provides kernel_fpu_begin() and kernel_fpu_end() in
asm/fpu.h, so it only needs to add kernel_fpu_available() and export the
CFLAGS adjustments.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Samuel Holland <[email protected]>
Acked-by: WANG Xuerui <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Acked-by: Christian König <[email protected]> 
Cc: Alex Deucher <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nicolas Schier <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Russell King <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: SiFiveHolland

arch/loongarch/Kconfig

@@ -18,6 +18,7 @@ config LOONGARCH
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_KCOV
+	select ARCH_HAS_KERNEL_FPU_SUPPORT if CPU_HAS_FPU
 	select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PTE_SPECIAL

arch/loongarch/Makefile

@@ -26,6 +26,9 @@ endif
 32bit-emul		= elf32loongarch
 64bit-emul		= elf64loongarch
 
+CC_FLAGS_FPU		:= -mfpu=64
+CC_FLAGS_NO_FPU		:= -msoft-float
+
 ifdef CONFIG_UNWINDER_ORC
 orc_hash_h := arch/$(SRCARCH)/include/generated/asm/orc_hash.h
 orc_hash_sh := $(srctree)/scripts/orc_hash.sh
@@ -59,7 +62,7 @@ ld-emul			= $(64bit-emul)
 cflags-y		+= -mabi=lp64s
 endif
 
-cflags-y			+= -pipe -msoft-float
+cflags-y			+= -pipe $(CC_FLAGS_NO_FPU)
 LDFLAGS_vmlinux			+= -static -n -nostdlib
 
 # When the assembler supports explicit relocation hint, we must use it.

arch/loongarch/include/asm/fpu.h

@@ -21,6 +21,7 @@
 
 struct sigcontext;
 
+#define kernel_fpu_available() cpu_has_fpu
 extern void kernel_fpu_begin(void);
 extern void kernel_fpu_end(void);