linux-kernel - [PATCH 2/2] riscv: switch has_fpu() to the unified static key mechanism

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Date:   Wed, 18 May 2022 02:44:53 +0800
From:   Jisheng Zhang <jszhang@...nel.org>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Atish Patra <atishp@...shpatra.org>,
        Anup Patel <anup@...infault.org>
Cc:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] riscv: switch has_fpu() to the unified static key mechanism

This is to use the unified static key mechanism instead of putting
static key related here and there.

Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
---
 arch/riscv/include/asm/switch_to.h | 5 +++--
 arch/riscv/kernel/cpufeature.c     | 7 -------
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
index 0a3f4f95c555..3f407182080d 100644
--- a/arch/riscv/include/asm/switch_to.h
+++ b/arch/riscv/include/asm/switch_to.h
@@ -8,6 +8,7 @@
 
 #include <linux/jump_label.h>
 #include <linux/sched/task_stack.h>
+#include <asm/hwcap.h>
 #include <asm/processor.h>
 #include <asm/ptrace.h>
 #include <asm/csr.h>
@@ -56,10 +57,10 @@ static inline void __switch_to_aux(struct task_struct *prev,
 	fstate_restore(next, task_pt_regs(next));
 }
 
-extern struct static_key_false cpu_hwcap_fpu;
 static __always_inline bool has_fpu(void)
 {
-	return static_branch_likely(&cpu_hwcap_fpu);
+	return riscv_isa_have_key_extension(RISCV_ISA_EXT_d) ||
+		riscv_isa_have_key_extension(RISCV_ISA_EXT_f);
 }
 #else
 static __always_inline bool has_fpu(void) { return false; }
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 89f886b35357..0235391be84b 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -21,9 +21,6 @@ unsigned long elf_hwcap __read_mostly;
 /* Host ISA bitmap */
 static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
 
-#ifdef CONFIG_FPU
-__ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_fpu);
-#endif
 __ro_after_init DEFINE_STATIC_KEY_ARRAY_FALSE(riscv_isa_ext_keys, RISCV_ISA_EXT_KEY_MAX);
 EXPORT_SYMBOL(riscv_isa_ext_keys);
 
@@ -239,8 +236,4 @@ void __init riscv_fill_hwcap(void)
 		if (j >= 0)
 			static_branch_enable(&riscv_isa_ext_keys[j]);
 	}
-#ifdef CONFIG_FPU
-	if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
-		static_branch_enable(&cpu_hwcap_fpu);
-#endif
 }
-- 
2.34.1