Messages in this thread Patch in this message |  | | From | Alan Kao <> | Subject | [PATCH v4 4/5] Allow to disable FPU support | Date | Wed, 8 Aug 2018 11:24:44 +0800 |
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FPU codes have been separated from common part in previous patches. This patch add the CONFIG_FPU option and some stubs, so that a no-FPU configuration is allowed.
Signed-off-by: Alan Kao <alankao@andestech.com> Cc: Greentime Hu <greentime@andestech.com> Cc: Vincent Chen <vincentc@andestech.com> Cc: Zong Li <zong@andestech.com> Cc: Nick Hu <nickhu@andestech.com> --- arch/riscv/Kconfig | 9 +++++++++ arch/riscv/include/asm/switch_to.h | 10 ++++++++++ arch/riscv/kernel/Makefile | 2 +- arch/riscv/kernel/process.c | 4 +++- arch/riscv/kernel/signal.c | 5 +++++ 5 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 6debcc4afc72..6069597ba73f 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -232,6 +232,15 @@ config RISCV_BASE_PMU endmenu +config FPU + bool "FPU support" + default y + help + Say N here if you want to disable all floating-point related procedure + in the kernel. + + If you don't know what to do here, say Y. + endmenu menu "Kernel type" diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h index dd6b05bff75b..093050b03543 100644 --- a/arch/riscv/include/asm/switch_to.h +++ b/arch/riscv/include/asm/switch_to.h @@ -18,6 +18,7 @@ #include <asm/ptrace.h> #include <asm/csr.h> +#ifdef CONFIG_FPU extern void __fstate_save(struct task_struct *save_to); extern void __fstate_restore(struct task_struct *restore_from); @@ -55,6 +56,15 @@ static inline void __switch_to_aux(struct task_struct *prev, fstate_restore(next, task_pt_regs(next)); } +#define DEFAULT_SSTATUS (SR_SPIE | SR_FS_INITIAL) + +#else +#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) +#define DEFAULT_SSTATUS (SR_SPIE | SR_FS_OFF) +#endif + extern struct task_struct *__switch_to(struct task_struct *, struct task_struct *); diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index bd433efd915e..f13f7f276639 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -13,7 +13,6 @@ extra-y += vmlinux.lds obj-y += cpu.o obj-y += cpufeature.o obj-y += entry.o -obj-y += fpu.o obj-y += irq.o obj-y += process.o obj-y += ptrace.o @@ -32,6 +31,7 @@ obj-y += vdso/ CFLAGS_setup.o := -mcmodel=medany +obj-$(CONFIG_FPU) += fpu.o obj-$(CONFIG_SMP) += smpboot.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_MODULES) += module.o diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index cb209139ba53..3820d89e2db9 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -83,7 +83,7 @@ void show_regs(struct pt_regs *regs) void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) { - regs->sstatus = SR_SPIE /* User mode, irqs on */ | SR_FS_INITIAL; + regs->sstatus = DEFAULT_SSTATUS; regs->sepc = pc; regs->sp = sp; set_fs(USER_DS); @@ -91,12 +91,14 @@ void start_thread(struct pt_regs *regs, unsigned long pc, void flush_thread(void) { +#ifdef CONFIG_FPU /* * Reset FPU context * frm: round to nearest, ties to even (IEEE default) * fflags: accrued exceptions cleared */ memset(¤t->thread.fstate, 0, sizeof(current->thread.fstate)); +#endif } int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index 6a18b9819ead..2450b824d799 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -37,6 +37,7 @@ struct rt_sigframe { struct ucontext uc; }; +#ifdef CONFIG_FPU static long restore_fp_state(struct pt_regs *regs, union __riscv_fp_state *sc_fpregs) { @@ -85,6 +86,10 @@ static long save_fp_state(struct pt_regs *regs, return err; } +#else +#define save_fp_state(task, regs) (0) +#define restore_fp_state(task, regs) (0) +#endif static long restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) -- 2.18.0
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