[PATCH v4 08/15] powerpc: Implement ARCH_HAS_KERNEL_FPU_SUPPORT

[Samuel Holland]

PowerPC provides an equivalent to the common kernel-mode FPU API, but in
a different header and using different function names. The PowerPC API
also requires a non-preemptible context. Add a wrapper header, and
export the CFLAGS adjustments.

Acked-by: Michael Ellerman <m...@ellerman.id.au> (powerpc)
Reviewed-by: Christoph Hellwig <h...@lst.de>
Signed-off-by: Samuel Holland <samuel.holl...@sifive.com>
---

(no changes since v1)

 arch/powerpc/Kconfig           |  1 +
 arch/powerpc/Makefile          |  5 ++++-
 arch/powerpc/include/asm/fpu.h | 28 ++++++++++++++++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 arch/powerpc/include/asm/fpu.h

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1c4be3373686..c42a57b6839d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -137,6 +137,7 @@ config PPC
        select ARCH_HAS_GCOV_PROFILE_ALL
        select ARCH_HAS_HUGEPD                  if HUGETLB_PAGE
        select ARCH_HAS_KCOV
+       select ARCH_HAS_KERNEL_FPU_SUPPORT      if PPC_FPU
        select ARCH_HAS_MEMBARRIER_CALLBACKS
        select ARCH_HAS_MEMBARRIER_SYNC_CORE
        select ARCH_HAS_MEMREMAP_COMPAT_ALIGN   if PPC_64S_HASH_MMU
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 65261cbe5bfd..93d89f055b70 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -153,6 +153,9 @@ CFLAGS-$(CONFIG_PPC32)      += $(call cc-option, 
$(MULTIPLEWORD))
 
 CFLAGS-$(CONFIG_PPC32) += $(call cc-option,-mno-readonly-in-sdata)
 
+CC_FLAGS_FPU           := $(call cc-option,-mhard-float)
+CC_FLAGS_NO_FPU                := $(call cc-option,-msoft-float)
+
 ifdef CONFIG_FUNCTION_TRACER
 ifdef CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY
 KBUILD_CPPFLAGS        += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
@@ -174,7 +177,7 @@ asinstr := $(call as-instr,lis 
9$(comma)foo@high,-DHAVE_AS_ATHIGH=1)
 
 KBUILD_CPPFLAGS        += -I $(srctree)/arch/powerpc $(asinstr)
 KBUILD_AFLAGS  += $(AFLAGS-y)
-KBUILD_CFLAGS  += $(call cc-option,-msoft-float)
+KBUILD_CFLAGS  += $(CC_FLAGS_NO_FPU)
 KBUILD_CFLAGS  += $(CFLAGS-y)
 CPP            = $(CC) -E $(KBUILD_CFLAGS)
 
diff --git a/arch/powerpc/include/asm/fpu.h b/arch/powerpc/include/asm/fpu.h
new file mode 100644
index 000000000000..ca584e4bc40f
--- /dev/null
+++ b/arch/powerpc/include/asm/fpu.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2023 SiFive
+ */
+
+#ifndef _ASM_POWERPC_FPU_H
+#define _ASM_POWERPC_FPU_H
+
+#include <linux/preempt.h>
+
+#include <asm/cpu_has_feature.h>
+#include <asm/switch_to.h>
+
+#define kernel_fpu_available() (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE))
+
+static inline void kernel_fpu_begin(void)
+{
+       preempt_disable();
+       enable_kernel_fp();
+}
+
+static inline void kernel_fpu_end(void)
+{
+       disable_kernel_fp();
+       preempt_enable();
+}
+
+#endif /* ! _ASM_POWERPC_FPU_H */
-- 
2.44.0