diff options
Diffstat (limited to 'arch/arc')
| -rw-r--r-- | arch/arc/Kconfig | 15 | ||||
| -rw-r--r-- | arch/arc/include/asm/arcregs.h | 2 | ||||
| -rw-r--r-- | arch/arc/include/asm/fpu.h | 28 | ||||
| -rw-r--r-- | arch/arc/kernel/Makefile | 2 | ||||
| -rw-r--r-- | arch/arc/kernel/fpu.c | 27 | ||||
| -rw-r--r-- | arch/arc/kernel/process.c | 6 |
6 files changed, 68 insertions, 12 deletions
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index c4409eab07a9..fd351001d8b9 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -351,9 +351,8 @@ config NODES_SHIFT Accessing memory beyond 1GB (with or w/o PAE) requires 2 memory zones. -if ISA_ARCOMPACT - config ARC_COMPACT_IRQ_LEVELS + depends on ISA_ARCOMPACT bool "Setup Timer IRQ as high Priority" # if SMP, LV2 enabled ONLY if ARC implementation has LV2 re-entrancy depends on !SMP @@ -361,14 +360,10 @@ config ARC_COMPACT_IRQ_LEVELS config ARC_FPU_SAVE_RESTORE bool "Enable FPU state persistence across context switch" help - Double Precision Floating Point unit had dedicated regs which - need to be saved/restored across context-switch. - Note that ARC FPU is overly simplistic, unlike say x86, which has - hardware pieces to allow software to conditionally save/restore, - based on actual usage of FPU by a task. Thus our implemn does - this for all tasks in system. - -endif #ISA_ARCOMPACT + ARCompact FPU has internal registers to assist with Double precision + Floating Point operations. There are control and stauts registers + for floating point exceptions and rounding modes. These are + preserved across task context switch when enabled. config ARC_CANT_LLSC def_bool n diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h index 5134f0baf33c..f7e432448e4b 100644 --- a/arch/arc/include/asm/arcregs.h +++ b/arch/arc/include/asm/arcregs.h @@ -39,6 +39,8 @@ #define ARC_REG_CLUSTER_BCR 0xcf #define ARC_REG_AUX_ICCM 0x208 /* ICCM Base Addr (ARCv2) */ #define ARC_REG_LPB_CTRL 0x488 /* ARCv2 Loop Buffer control */ +#define ARC_REG_FPU_CTRL 0x300 +#define ARC_REG_FPU_STATUS 0x301 /* Common for ARCompact and ARCv2 status register */ #define ARC_REG_STATUS32 0x0A diff --git a/arch/arc/include/asm/fpu.h b/arch/arc/include/asm/fpu.h index de467423d99b..64347250fdf5 100644 --- a/arch/arc/include/asm/fpu.h +++ b/arch/arc/include/asm/fpu.h @@ -11,6 +11,8 @@ #include <asm/ptrace.h> +#ifdef CONFIG_ISA_ARCOMPACT + /* These DPFP regs need to be saved/restored across ctx-sw */ struct arc_fpu { struct { @@ -18,11 +20,35 @@ struct arc_fpu { } aux_dpfp[2]; }; -extern void fpu_save_restore(struct task_struct *p, struct task_struct *n); +#define fpu_init_task(regs) #else +/* + * ARCv2 FPU Control aux register + * - bits to enable Traps on Exceptions + * - Rounding mode + * + * ARCv2 FPU Status aux register + * - FPU exceptions flags (Inv, Div-by-Zero, overflow, underflow, inexact) + * - Flag Write Enable to clear flags explicitly (vs. by fpu instructions + * only + */ + +struct arc_fpu { + unsigned int ctrl, status; +}; + +extern void fpu_init_task(struct pt_regs *regs); + +#endif /* !CONFIG_ISA_ARCOMPACT */ + +extern void fpu_save_restore(struct task_struct *p, struct task_struct *n); + +#else /* !CONFIG_ARC_FPU_SAVE_RESTORE */ + #define fpu_save_restore(p, n) +#define fpu_init_task(regs) #endif /* CONFIG_ARC_FPU_SAVE_RESTORE */ diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile index e784f5396dda..75539670431a 100644 --- a/arch/arc/kernel/Makefile +++ b/arch/arc/kernel/Makefile @@ -23,7 +23,9 @@ obj-$(CONFIG_PERF_EVENTS) += perf_event.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o obj-$(CONFIG_ARC_FPU_SAVE_RESTORE) += fpu.o +ifdef CONFIG_ISA_ARCOMPACT CFLAGS_fpu.o += -mdpfp +endif ifdef CONFIG_ARC_DW2_UNWIND CFLAGS_ctx_sw.o += -fno-omit-frame-pointer diff --git a/arch/arc/kernel/fpu.c b/arch/arc/kernel/fpu.c index 7a3b56ce56bb..c67c0f0f5f77 100644 --- a/arch/arc/kernel/fpu.c +++ b/arch/arc/kernel/fpu.c @@ -8,6 +8,8 @@ #include <linux/sched.h> #include <asm/fpu.h> +#ifdef CONFIG_ISA_ARCOMPACT + /* * To save/restore FPU regs, simplest scheme would use LR/SR insns. * However since SR serializes the pipeline, an alternate "hack" can be used @@ -50,3 +52,28 @@ void fpu_save_restore(struct task_struct *prev, struct task_struct *next) : "r" (zero), "r" (*(readfrom + 3)), "r" (*(readfrom + 2)) ); } + +#else + +void fpu_init_task(struct pt_regs *regs) +{ + /* default rounding mode */ + write_aux_reg(ARC_REG_FPU_CTRL, 0x100); + + /* set "Write enable" to allow explicit write to exception flags */ + write_aux_reg(ARC_REG_FPU_STATUS, 0x80000000); +} + +void fpu_save_restore(struct task_struct *prev, struct task_struct *next) +{ + struct arc_fpu *save = &prev->thread.fpu; + struct arc_fpu *restore = &next->thread.fpu; + + save->ctrl = read_aux_reg(ARC_REG_FPU_CTRL); + save->status = read_aux_reg(ARC_REG_FPU_STATUS); + + write_aux_reg(ARC_REG_FPU_CTRL, restore->ctrl); + write_aux_reg(ARC_REG_FPU_STATUS, restore->status); +} + +#endif diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c index bfd4cbe74aa3..315528f04bc1 100644 --- a/arch/arc/kernel/process.c +++ b/arch/arc/kernel/process.c @@ -20,6 +20,8 @@ #include <linux/elf.h> #include <linux/tick.h> +#include <asm/fpu.h> + SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr) { task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr; @@ -263,7 +265,7 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long usp, /* * Do necessary setup to start up a new user task */ -void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp) +void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp) { regs->sp = usp; regs->ret = pc; @@ -279,6 +281,8 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp) regs->eflags = 0; #endif + fpu_init_task(regs); + /* bogus seed values for debugging */ regs->lp_start = 0x10; regs->lp_end = 0x80; |