diff options
| author | Jisheng Zhang | 2021-05-12 22:55:45 +0800 |
|---|---|---|
| committer | Palmer Dabbelt | 2021-05-25 22:56:57 -0700 |
| commit | 37a7a2a10ec525a79d733008bc7fe4ebbca34382 (patch) | |
| tree | c4d7257ecfe7a54eec0286b274de15ae56eb68a7 /arch/riscv/include | |
| parent | 8237c5243a614d33fe339bc844f90aa2b393c2a8 (diff) | |
riscv: Turn has_fpu into a static key if FPU=y
The has_fpu check sits at hot code path: switch_to(). Currently, has_fpu
is a bool variable if FPU=y, switch_to() checks it each time, we can
optimize out this check by turning the has_fpu into a static key.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv/include')
| -rw-r--r-- | arch/riscv/include/asm/switch_to.h | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index 407bcc96a710..0a3f4f95c555 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -6,6 +6,7 @@ #ifndef _ASM_RISCV_SWITCH_TO_H #define _ASM_RISCV_SWITCH_TO_H +#include <linux/jump_label.h> #include <linux/sched/task_stack.h> #include <asm/processor.h> #include <asm/ptrace.h> @@ -55,9 +56,13 @@ static inline void __switch_to_aux(struct task_struct *prev, fstate_restore(next, task_pt_regs(next)); } -extern bool has_fpu; +extern struct static_key_false cpu_hwcap_fpu; +static __always_inline bool has_fpu(void) +{ + return static_branch_likely(&cpu_hwcap_fpu); +} #else -#define has_fpu false +static __always_inline bool has_fpu(void) { return false; } #define fstate_save(task, regs) do { } while (0) #define fstate_restore(task, regs) do { } while (0) #define __switch_to_aux(__prev, __next) do { } while (0) @@ -70,7 +75,7 @@ extern struct task_struct *__switch_to(struct task_struct *, do { \ struct task_struct *__prev = (prev); \ struct task_struct *__next = (next); \ - if (has_fpu) \ + if (has_fpu()) \ __switch_to_aux(__prev, __next); \ ((last) = __switch_to(__prev, __next)); \ } while (0) |