[PATCH v8 4/5] Allow to disable FPU support
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
Cc: Greentime Hu
Cc: Vincent Chen
Cc: Zong Li
Cc: Nick Hu
Reviewed-by: Christoph Hellwig
---
arch/riscv/Kconfig | 9 +
arch/riscv/Makefile| 2 +-
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 +
6 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a344980..a63f9db 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -208,6 +208,15 @@ 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/Makefile b/arch/riscv/Makefile
index 01393e1..901770f 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -44,7 +44,7 @@ KBUILD_CFLAGS += -Wall
riscv-march-$(CONFIG_ARCH_RV32I) := rv32im
riscv-march-$(CONFIG_ARCH_RV64I) := rv64im
riscv-march-$(CONFIG_RISCV_ISA_A) := $(riscv-march-y)a
-riscv-march-y := $(riscv-march-y)fd
+riscv-march-$(CONFIG_FPU) := $(riscv-march-y)fd
riscv-march-$(CONFIG_RISCV_ISA_C) := $(riscv-march-y)c
KBUILD_CFLAGS += -march=$(subst fd,,$(riscv-march-y))
KBUILD_AFLAGS += -march=$(riscv-march-y)
diff --git a/arch/riscv/include/asm/switch_to.h
b/arch/riscv/include/asm/switch_to.h
index dd6b05b..093050b 100644
--- a/arch/riscv/include/asm/switch_to.h
+++ b/arch/riscv/include/asm/switch_to.h
@@ -18,6 +18,7 @@
#include
#include
+#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 bd433efd..f13f7f2 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 d7c6ca7..07d5156 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -76,7 +76,7 @@ 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);
@@ -84,12 +84,14 @@ 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(>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 6a18b98..2450b82 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)
--
2.7.4
[PATCH v8 4/5] Allow to disable FPU support
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
Cc: Greentime Hu
Cc: Vincent Chen
Cc: Zong Li
Cc: Nick Hu
Reviewed-by: Christoph Hellwig
---
arch/riscv/Kconfig | 9 +
arch/riscv/Makefile| 2 +-
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 +
6 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a344980..a63f9db 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -208,6 +208,15 @@ 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/Makefile b/arch/riscv/Makefile
index 01393e1..901770f 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -44,7 +44,7 @@ KBUILD_CFLAGS += -Wall
riscv-march-$(CONFIG_ARCH_RV32I) := rv32im
riscv-march-$(CONFIG_ARCH_RV64I) := rv64im
riscv-march-$(CONFIG_RISCV_ISA_A) := $(riscv-march-y)a
-riscv-march-y := $(riscv-march-y)fd
+riscv-march-$(CONFIG_FPU) := $(riscv-march-y)fd
riscv-march-$(CONFIG_RISCV_ISA_C) := $(riscv-march-y)c
KBUILD_CFLAGS += -march=$(subst fd,,$(riscv-march-y))
KBUILD_AFLAGS += -march=$(riscv-march-y)
diff --git a/arch/riscv/include/asm/switch_to.h
b/arch/riscv/include/asm/switch_to.h
index dd6b05b..093050b 100644
--- a/arch/riscv/include/asm/switch_to.h
+++ b/arch/riscv/include/asm/switch_to.h
@@ -18,6 +18,7 @@
#include
#include
+#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 bd433efd..f13f7f2 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 d7c6ca7..07d5156 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -76,7 +76,7 @@ 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);
@@ -84,12 +84,14 @@ 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(>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 6a18b98..2450b82 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)
--
2.7.4
